TaiLG Electric Bicycle Scooter 48 Volt 12 Ah 250 Watt

[ProDigit]

I would never use a fan on a bike like this. It's only adding weight and cooling very little, and consuming more battery.

If it was me, I'd look to see if the controller is mounted in a way that you can scoop air from underneath the scooter into the chamber where the controller is (probably under the seat or under the feet compartment).
That way as you drive you'll bring fresh air in without the need for fans. I'd make a small slit into the plastic and bend it in such a way that it scoops air from the front of the bike.
Then I'd create another slit on the back, bending it in such a way that whatever air gets pushed into the chamber by the first slit, will exit by the rear slit.

With a natural flow of air the controller will cool lots better than with a fan. Besides a fan is only good in spreading the heat of the controller into the chamber. If the chamber does not have a flow of cool air, or a lot of metal in it connected to the frame, it will heat up, and the fan will become useless in such a case as a fan's performance decreases the hotter the air in a chamber is.
(metal is a good heat conductor, plastic is not).

[ProDigit]

Well, first lets get one thing straight. You say you have a 48v controller of 20 amps. Watts is amps x volts. So you have about a 1000w scooter, with a handy sticker to make it cheap at the licence place.

Second, you do need to improve the ventilation to your controller somehow. A small fan run on a 3s lipo pack would help, as well as some kind of way to scoop wind and direct it to your controller. Your controller is likely getting no ventilation at all now, and will run cool enough if it gets some breeze. So it's not so much a fan it needs, but just to have some wind reach it when you ride. You'd think engineers who design these things would have some commonsense, but they don't sometimes.

One thing you should know about controllers is that they make less heat when you ride wide open throttle. Half throttle makes the controller work harder, to shorten the pulse of the power, which makes some heat in the fets. So when possible, do more riding full throttle, then coast. It will help some with the hot controller.

As for the bike on hills. Well, just because they put a cool looking seat for a passenger on the thing to make it sell does not mean it was designed with climing a hill with two passengers on it. No real solution to that, 1000w is enough to get 180 pounds up a hill fine, But if you both combined weigh 300, better stick to the less steep hills as much as possible. A second scooter is the real solution. It's ok though on flat ground and mild hills to carry your girl. Just avoid really steep hills. It's very important not to overload the bike up steep hills. If it can't climb the hill at 20-25 kph, you are going to be heating up the motor real bad as well as the controller. A very short steep hill can be ok, just avoid long steep ones.

On to the batttery. Install a set of new connectors between the battery and the controller that you can get to easily. When you have discharged your lead battery as much as you want to, you can then disconnect the lead and connect some RC lipo. No need to use the inverter and charger.

Two 6s 5ah packs will do for a small range extender. 4 packs makes a nice battery with a bit more range. Connect the packs in series to have a 12s pack. If you have 4 packs, paralell connect two packs to make 6s 10 ah, then do the series connection.

12s RC lipo will charge to 50v, and finish at 44v. You will need a voltmeter added to the bike to be sure you don't go below 44v. Your scoot will run fine with 12s lipo. For a bit more pep, your controller can handle up to a maximum of 14s lipo. That's about 59v fully charged.

Another option would be a lifepo4 battery. A 48v lifepo4 battery of 48v 20 ah would be a perfect replacement for your lead. It would extend your range a lot further than you get from the lead now. One thing about short range though, you have to stop before things fry. With lots of range, you can ride till things melt.

How do you know when to stop? Lots of us use inexpensive thermometers to know. With a remote sensor, you put the sensor on the motor axle, or the controller, and the display on the thermometer will tell you when you are getting hotter and hotter, or if you are just warm, but stabilzed at that temperature.

This made me think,
Dogman, do you know, I have an Xtreme XB-700Li bike coming soon;
It has a LiPo4 48V 10A battery pack in it (you know, the Chinese love to exaggerate, naming it 48V 40Ah, which it is not, it's 48V12 or 20A at best),

If instead of installing a second 48V battery pack, I could install 2x6V batteries in parallel, in series with the pack to increase voltage from 48V to 54V?
I believe the controller can handle upto 60ah, right? If Instead of using 12V batteries, I could use 6V batteries in series, I'd upgrade the voltage somewhat.

Would that help in improving speed? Or would the controller still limit the speed to 20MPH?

[Alastor]

I would never use a fan on a bike like this. It's only adding weight and cooling very little, and consuming more battery.

If it was me, I'd look to see if the controller is mounted in a way that you can scoop air from underneath the scooter into the chamber where the controller is (probably under the seat or under the feet compartment).
That way as you drive you'll bring fresh air in without the need for fans. I'd make a small slit into the plastic and bend it in such a way that it scoops air from the front of the bike.
Then I'd create another slit on the back, bending it in such a way that whatever air gets pushed into the chamber by the first slit, will exit by the rear slit.

With a natural flow of air the controller will cool lots better than with a fan. Besides a fan is only good in spreading the heat of the controller into the chamber. If the chamber does not have a flow of cool air, or a lot of metal in it connected to the frame, it will heat up, and the fan will become useless in such a case as a fan's performance decreases the hotter the air in a chamber is.
(metal is a good heat conductor, plastic is not).

I know exactly what you are trying to say but i took all the parameters you wrote in consideration while i was installing the second heat-sink and fan .The fan sucks fresh air from a large hole under the feet-chamber and directing it on the 2 heat-sinks and there is good space for air circulation as well.Also the fun is redirecting the hot air at the back of the scooter as natural air should flow and circle.It will be more clear when i manage to take some pictures.Even when the fun is off the scooter is not overheating i made a nice climbing with a second person and it didn't even got hot as before so i think its working ok.More testing will prove it or not

[Alastor]

Well, first lets get one thing straight. You say you have a 48v controller of 20 amps. Watts is amps x volts. So you have about a 1000w scooter, with a handy sticker to make it cheap at the licence place.

Second, you do need to improve the ventilation to your controller somehow. A small fan run on a 3s lipo pack would help, as well as some kind of way to scoop wind and direct it to your controller. Your controller is likely getting no ventilation at all now, and will run cool enough if it gets some breeze. So it's not so much a fan it needs, but just to have some wind reach it when you ride. You'd think engineers who design these things would have some commonsense, but they don't sometimes.

One thing you should know about controllers is that they make less heat when you ride wide open throttle. Half throttle makes the controller work harder, to shorten the pulse of the power, which makes some heat in the fets. So when possible, do more riding full throttle, then coast. It will help some with the hot controller.

As for the bike on hills. Well, just because they put a cool looking seat for a passenger on the thing to make it sell does not mean it was designed with climing a hill with two passengers on it. No real solution to that, 1000w is enough to get 180 pounds up a hill fine, But if you both combined weigh 300, better stick to the less steep hills as much as possible. A second scooter is the real solution. It's ok though on flat ground and mild hills to carry your girl. Just avoid really steep hills. It's very important not to overload the bike up steep hills. If it can't climb the hill at 20-25 kph, you are going to be heating up the motor real bad as well as the controller. A very short steep hill can be ok, just avoid long steep ones.

On to the batttery. Install a set of new connectors between the battery and the controller that you can get to easily. When you have discharged your lead battery as much as you want to, you can then disconnect the lead and connect some RC lipo. No need to use the inverter and charger.

Two 6s 5ah packs will do for a small range extender. 4 packs makes a nice battery with a bit more range. Connect the packs in series to have a 12s pack. If you have 4 packs, paralell connect two packs to make 6s 10 ah, then do the series connection.

12s RC lipo will charge to 50v, and finish at 44v. You will need a voltmeter added to the bike to be sure you don't go below 44v. Your scoot will run fine with 12s lipo. For a bit more pep, your controller can handle up to a maximum of 14s lipo. That's about 59v fully charged.

Another option would be a lifepo4 battery. A 48v lifepo4 battery of 48v 20 ah would be a perfect replacement for your lead. It would extend your range a lot further than you get from the lead now. One thing about short range though, you have to stop before things fry. With lots of range, you can ride till things melt.

How do you know when to stop? Lots of us use inexpensive thermometers to know. With a remote sensor, you put the sensor on the motor axle, or the controller, and the display on the thermometer will tell you when you are getting hotter and hotter, or if you are just warm, but stabilzed at that temperature.

This made me think,
Dogman, do you know, I have an Xtreme XB-700Li bike coming soon;
It has a LiPo4 48V 10A battery pack in it (you know, the Chinese love to exaggerate, naming it 48V 40Ah, which it is not, it's 48V12 or 20A at best),

If instead of installing a second 48V battery pack, I could install 2x6V batteries in parallel, in series with the pack to increase voltage from 48V to 54V?
I believe the controller can handle upto 60ah, right? If Instead of using 12V batteries, I could use 6V batteries in series, I'd upgrade the voltage somewhat.

Would that help in improving speed? Or would the controller still limit the speed to 20MPH?

In my experience its not safe to connect different types of batteries and if you do it after all make sure you check the main battery total AH and parallel a battery with the same total amps.If the batteries are not the same ah and if you don't install heavy duty blocking diodes the larger ah batteries might want to discharge on the smaller ones and this might be a hazard.Also i think that having different ah batteries will cause the blocking diodes to engage all the times consuming some power by heating up.Usually heavy duty blocking diodes consume 1v each as well.

Also controllers don't have a max Ah cap at my knowledge the only issue you might have and please correct me if i am wrong about this is that probably your bikes battery meters might not work properly because they are made for a specific amount of ah reading.

[ProDigit]

6V battery in series with the battery pack, to up the voltage from 48 to 54V
Instead of one 6V battery (with 7A), I wanted to use 2 in parallel with each other, to be able to handle the 10-20A from the battery pack.
it's a series-parallel connection, like this:


The batteries won't discharge when the bike is off.
When the bike is on, and driving, all you need to make sure you do, is make sure the 2 x 6V batteries are the same, and the sum of the current handling of the two batteries somewhat is the same as the battery pack.
IoW, if your bike has a 20A battery pack, and you'll use above schematic, and the 6V batteries are only 7A, you'll be limiting your motor to 14A sustained current.
If you only put 1 x 6V battery in series, no harm will be done to the battery, but you will be limiting your engine to 7A (or in other words to 364W, in my case about half my motor's power handling

[Alastor]

6V battery in series with the battery pack, to up the voltage from 48 to 54V
Instead of one 6V battery (with 7A), I wanted to use 2 in parallel with each other, to be able to handle the 10-20A from the battery pack.
it's a series-parallel connection, like this:


The batteries won't discharge when the bike is off.
When the bike is on, and driving, all you need to make sure you do, is make sure the 2 x 6V batteries are the same, and the sum of the current handling of the two batteries somewhat is the same as the battery pack.
IoW, if your bike has a 20A battery pack, and you'll use above schematic, and the 6V batteries are only 7A, you'll be limiting your motor to 14A sustained current.
If you only put 1 x 6V battery in series, no harm will be done to the battery, but you will be limiting your engine to 7A (or in other words to 364W, in my case about half my motor's power handling

Nice to know thanks.Really useful information.With the proper wiring this setup can also work as a speed booster (safer imo) because if you want to use it all the way as i suspect you will have to make sure that your controller can handle 59 + 14 ~ 74 volts in full charge.

[dnmun]

no, it is a bad idea because you will destroy all the batteries by over discharging them if placed in series like that. the LVC of a 48V controller is 40V.

you have to remember that when you ask for free advice, you get what you pay for.

why would someone buy two 6V SLA just to put them in parallel instead of just getting a large battery? why would someone use SLA anyway?

if you want to know what the controller can handle then open it up and look. no need to guess.

[ProDigit]

ok, The idea was more for me, since I've read the controller on my bike handles upto 60V. I would not know who would power a 40V controller (presumably meant for 24/36V operation I guess), with 48V

[Alastor]

I knew it was not safe to do this.Thanks for clearing this up.Something else is it safe to to connect SLA's and lipos together if they are the same voltage and Ah's ?
I am asking because in my knowledge it is not safe to connect different types of battery's but with all this conversation i am not sure .

p.s.
Jesus 2300 mah nims require 10 hours of charge the first time my inverter will melt .....

[dnmun]

it is not that it is unsafe, but that when you drain an SLA below about 10V it is damaged and doesn't fully charge up again.

i you have 4 1/2 of them in series and a 40V LVC on the controller then the voltage across each of the SLA is below 9V and that is hard on them.

combining batteries in parallel is fairly simple to understand.

if you have 2 lifepo4 packs which have the same voltage then you can combine them directly without diodes.

this includes a situation in which you combine different capacity packs as well, such as combining a 10Ah pack with a 20Ah pack in parallel.

after charging them up to the same voltage with the charger, you combine them by connecting the P- leads together first, then you put a resistor across the two positive (red) leads to equalize the voltage on each pack , then connect the two red leads together. from this point on you always keep the two batteries connected and charge them up together.

do not put switches between them, do not put diodes between them. when they are connected together this way, they share the load when discharging and they will split the charging current between themselves as well so that they both will climb in voltage together and reach full charge at the same time.

if you disconnect them and one pack is discharged separately, then you have to go through the same procedure, charging up and using the resistor to finally equalize them every time you recombine them in parallel.

you should never use a lifepo4 pack wihout a BMS, combining the two packs in parallel does not affect the BMS which functions normally and when one pack has reached LVC and the output mosfets shut off on that side then the current will continue to be delivered by the other pack until it cuts out at LVC.

this will be at two different pack voltages usually so you should recharge immediately when the first pack reaches LVC. at this point the battery remaining is having to produce more than twice the current it did at the start and so you want to restrict it's discharge rate at that time.

resetting the BMS that shut off and then continuing at dramatically reduced power may allow you enuff travel distance to get the packs back to the charger.

when charging two different capacity packs in parallel, the charging current will be split between the two packs proportionally to their capacity and they will both charge up to their full capacity at the final charger voltage. and then they balance at that voltage until the charger shuts off.

you should not combine two packs in parallel with different voltages, such as a 36V and a 48V pack even with a diode to protect the lower pack from the upper pack.

but if you have different chemistries, such as nicad or nimh or SLA combined with the lifepo4 in parallel you need to use a diode on the output of two packs to combine them, to prevent current from flowing from one pack to the other.

for this situation where you combine the two different types of packs, you would select a schottky diode capable of withstanding the maximum voltage difference between the two packs.

so a 48V nicad pack fully charged is about 54V and a 48V lifepo4 pack is about 58V so you would need a schottky diode of at least 4-5V but something around 20V is the smallest they sell for these power diodes and the higher the breakdown voltage the more expensive it costs. but more important is that the forward voltage across the diode when it is conducting is directly related to the the reverse breakdown voltage. you want this forward voltage to be small because that determines how much heat the diode produces. power =VxI.

the schottky diode has three legs in the To-220AB package. the current comes out of the center leg called the cathode, and you connect each battery's positive terminal to the outside leg of the schottky. that is called the anode.

all the current from the two packs flows out of the center leg and that is what you connect to the motor controller positive lead.

you can also use two axial schottky diodes, one for each pack, with the cathodes soldered together to the controller lead and the anodes to each of the packs.

after you know what voltage diode you need, then select the diode current carrying capacity that is able to handle all the current you expect your battery pack to produce at maximum discharge. this is why they are expensive because a large schottky capable of handling a lot of current gets expensive fast.

the problem with combining different battery chemistries in parallel is the restricted voltage range of the older SLA and nicad chemistries compared to lifepo4. a fully discharged 48V nicad pack is around 40V but the 48V lifepo4 pack will continue producing current down to about 32V.

to protect the nicad pack, the controller LVC of 40V will shut off the controller so the nicad pack is not over discharged. this leaves a lot of charge on the lifepo4 pack so you only are able to produce about 65% of the lifepo4 pack power.

so if you wish to combine the lifepo4 and the nicad, use a 36V controller and a 36V nicad pack. the 30V LVC of the controller will protect the nicad pack. then you would combine a 48V lifepo4 pack with the 36V nicad in parallel using a 20-30V diode since the nicad would be charged to about 40V and the fully charged lifepo4 would be around 57V.

in this case, the nicad would be restricted from releasing current through the diode because the output voltage is so much higher than the nicad fully charged voltage, and the lifepo4 would not be pushing current inot the nicad because the 20V diode blocks it.

when the lifepo4 pack has been discharged down to the 40V of the nicad then the nicad would add current through the diode to the current from the lifepo4 until the LVC of the controller shut off. this protects the nicad. the BMS on the lifepo4 protects that pack.

in this case with the 36V nicad and the 48V lifepo4, you would only need one axial schottky diode on the output of the nicad pack, and no diode would be needed on the lifepo4 at all.

looking in mouser catalog, ON semiconductor 1N5817G, 20V 25A axial diode is $.20. it has Vforward of .45V so when the max 25A current is flowing the diode is only producing about 10 watts of heat.

but that heat is only produced at the end of the discharge of the packs. if you also had a big diode in the lifepo4 pack output, it would be producing a lot more heat because it produces more current over a longer period, so it would need a heatsink.

but that axial diode on the nicad pack will get hot so mount it so it is not touching anything that will melt and is out in the open air for cooling.

that is the only situation in which i can see the need for diodes to combine two packs in parallel. a 36V nicad and a 48V lifepo4, in which you would be able to get the maximum capacity out of the two packs. and only a 20 cent diode needed.

this requires common sense to manage. charge the nicad up first and the lifpo4 next to insure that the voltage between the 2 packs does not exceed the 20V breakdown, or choose a 30V diode to be safer, 1N5818G 20V 25A .55V forward bias, 13 watts of heat at max current.

you can also find the same features in TO-220AC packages, so you could dissipate the heat with a heat sink too.

[ProDigit]

I never said of charging them together!
my post was also aimed at 2 packs in series, not in parallel.
2 different packs in series won't harm each other; in parallel they might,especially with high power li battery packs.

after you know what voltage diode you need, then select the diode current carrying capacity that is able to handle all the current you expect your battery pack to produce at maximum discharge. this is why they are expensive because a large schottky capable of handling a lot of current gets expensive fast.

My suggestion, buy 2 or 4 lower powered diodes, and solder them in parallel with each other to increase max current flow.

in this case with the 36V nicad and the 48V lifepo4, you would only need one axial schottky diode on the output of the nicad pack, and no diode would be needed on the lifepo4 at all.

I don't know anyone who would do such a thing,
It's much better to have 2 battery packs of the same voltage, so both of them are working together all the time.
By the time the voltage of the 48V dropped far enough for the 36V to kick in, the 48V battery will have a too low voltage per cell already.

If you know the discharge cycle of both batteries of SAME voltage you're going to buy, or know that one battery has a higher capacity than the other (eg: one has 10A, the other same voltage, but 15 or 20A, you can also make use of one single diode on the weaker battery. That way you also only have one diode.

You will have to charge them separately though.

after charging you can always measure the battery voltage to be sure.

and now I see what you mean by having 2 different battery packs connecting together; however with the use of one diode the issue is nearly non existent (unless you charge the extension battery, and forget to charge the internal battery, yes, that would be bad...

That, and if the 'unprotected' battery pack would have a bad cell. For that reason it's better to have both batteries protected by diodes.

I was thinking of buying 4x amazon item B005OFLMQW; D92-02 Integrated Circuit 20A 200V Fast Recovery Diode. That it's voltage is overrated can do no harm. These babies only cost $3,50 per item.
2 in parallel with each other to get a 40A power handling per battery.
I'm just unsure why this diode has a third leg, probably a ground or so,
They're very easy to mount on an aluminum bar, drill a hole in it, and the bar will act as a heat sink (just in case).

[dnmun]

mr pro, my comments about the SLA were to explain why the addition of another SLA in series was detrimental. i realize you do not understand my rational is based on the fixed LVC of this controller. you can make a pack built up anyway you wish. this guy has no electrical experience so i was trying to educate him and protect him from making a mistake and taking advice that would damage his battery pack.

i then proceeded to explain why some batteries can be combined, in parallel, not series since i consider combining different batteries in series backwards, not progressive.

i did explain the only situation in which i thought it made sense to combine two different chemistries in parallel which would allow one to recover all the power stored in each battery within the confines of the limits established by the LVC of the controller and using that LVC to protect the nicad pack. the BMS of the lifepo4 pack would protect it.

in that case, as i explained, you would only need a small axial diode of 20-30V breakdown, and about 25A max on the output of the nicad pack. no diode should be placed on the lifepo4 pack.

i explained the reason for selecting a diode with a small breakdown voltage (the heat produced when current flows through it), and why the reverse voltage a diode can withstand is related to the voltage across the diode when current flows through it in the forward direction. in this case the forward bias of that axial diode is specified to be .45V, not the one volt plus of the 200V diode. this is related to the doping of the semiconductor silicon during the diode manufacture.

you can also learn this stuff by taking courses in electrical engineering like i did. you don't have to learn anything from reading this but there may be someone out there who does learn something, that is who i explained it for, the person who reached this using a google search.

i hate for the endless sphere to be a source of misinformation that would denigrate its reputation with electrical hobbiest who get to the point where they are considering their options in combining different battery packs.

i had recommended that the original poster actually not combine his 48V SLA with anything else, but that he should actually buy another battery and sell the SLA. then if he did that we can open his controller and adjust the LVC of the controller down so he could use the 48V lifepo4 pack and get the maximum available capacity for use.

that is the simplest and most cost effective solution, and since all these little electric scooters are made in china, which is all of them, and all use the SLA for a battery, then this discussion should be relevant for these millions of people, not just the OP. so if the thread has no accurate information or explanation then many people who use google to find answers would be misinformed and the sphere would be responsible.

for the new or electronically naive person considering how to purchase an ebike kit to use, this is also important since the LVC of the ebike controller will determine their options when combining chemistries also which is why i explained that one should purchase a 36V ebike kit to use with a 48V lifepo4 battery since most people want to ditch their SLA and go to using the new lifepo4 packs. in that case, the only sensible combination of different battery chemistries is in parallel and it would be using a 36V nicad and a 48V lifepo4 with the small axial diode on the nicad. really very simple, and very cheap, and the heat produced by the diode would be the minimum available to this configuration of packs.

[Alastor]

Dnmun i really appreciate taking all this time to explain all this details in depth.I had no idea about LVC on controllers but now i can understand why it need modification if i use a lifepo4 battery on an SLA setup.Also i totally agree with you that the best way to go is buying a new lifepo4 battery as a replacement for the SLA's and modifying the controller should also be a nice project if not replacing ti.From my point of view the ebike is a way to move around and it has to be build to use easy.Sometimes we all might do a mistake and regret doing any modifications in the first place but knowing how it works it really helps to understand all the parameters and decide how to proceed.

I also use shock diodes in my solar setup and the only reason i was asking to clarify the connection which you did excellent for almost all theoretically battery connectivity is that in both theoretically DC circuits solar,e-scooters there is a controller in between with different limitations and functions.Knowing how the ebike controller works is the key to understand all the things you wrote.

You really helped me clarify a lot of things and save a lot of money.

[dnmun]

the little schottky diode i found was in the newark catalog, in the mouser catalog they have the ON diodes
for the axial diodes>
use mouser prefix 863-1N5817G 20V, 25A, .41Vforward vias, 28 cents each
-1N5818G 30V, 25A, .55Vforward bias, 26 cents


and for SMA package> 863-MBRA120ET3G 20V, 40A, .53V 27 cents
-MBRA130LT3G 30V,25A, .41V 24 cents

i cannot imagine a nicad pack pushing more than 25A but there are 40A series also. remember i am saying that the only diode needed for the 36V nicad, 48V combination is the diode on top of the 36V nicad pack. no diode would be needed in the lifepo4 current path since it is always superior in voltage.

i was thinking again of another combination, with the 48V SLA that you have on this scooter. or with a 48V nicad pack, and how to combine it with a lifepo4 pack so you could get all the storage of the lifepo4 and the SLA or nicad. this is using the 40V LVC of this scooter.

if you add a 60V lifepo4 pack in parallel, then that 20S pack would be discharged at around 42V, so it would be able to be drawn down totally along with the SLA or nicad to 40V.

the SLA will charge to about 56V and a nicad would charge to about 54V, and the 20S lifepo4 would charge to 73-74V. again in this case you could add a 20V or 30V axial diode, such as those listed above, and the 20S lifepo4 would provide all the power until the pack voltage dropped to the 54V of the nicad or SLA, and then both packs would be providing the current. sag would push them to 40V and shut down the controller while both packs were in safe regions, and the lifepo4 BMS would protect it if the voltage on any individual cell dropped below the 2.1V LVC. that would leave the SLA or nicad to push power to keep the bike running, and you could nurse it to a charger.

so consider the option of not selling the SLA, but add a 60V lifepo4 pack in parallel. that will give you good top speed when the pack is fresh and the old SLA will have the lifepo4 to share the load at the end so the peukert effect is minimized because the current draw is so much lower.

the problem with going to the 60V lifepo4 is the 74V charging voltage. that will be too much for the 63V caps on the input and the S/D busses. so they would need to be replaced with 100V input caps, along with changing the input power resistor to get the controller voltage regulation to work over the entire 40-74V range. that is pretty simple.

the other thing will be to look at the mosfets and see if they can handle the 74V and i bet they can. with any luck, you have the ubiquitous P75FN75 mosfets with the 75V 75A rating and they would work fine at that voltage.

i hope this makes more sense, now you can look at the capital investment in terms of one item, a new 60V lifepo4 pack.

say a 60V 15Ah pack from mr li ping since BMS battery does not carry that size, but that would give you the most bang for the buck. you could use that one lifepo4 pack until the SLA wore out and then add another 60V lifepo4 pack in parallel with it because you would still be using the 40V LVC controller. or you could use the existing BMS and add a second set of cells in parallel. especially easy if it is the headway since you would just buy another 20 cells and connect them in series with a sense wire jumper over to the other cells in the same row.

the problem with the lights and the need for an input power resistor swap could be managed by using a DC/DC converter from the 48V pack to produce the 12V rail for the controller and 12V lighting. less heating of the controller by the input power drop, and then add led lights to replace the incandescents to conserve juice.

the DC converter would have to be based on the 2596hv version of the 5 pin converter chip made to work up to 60V so it would run just off the lower pack at the 54V, of the SLA or nicad.

looking at worst case where the DC converter is left on to sink current through the controller, and then it reaches the 40V minimum for the SLA or nicad. if this happened while the 60V lifepo4 is fully charged then as the SLA or nicad drops below the breakdown voltage difference between the charged lifepo4 (67V resting) and the nicad/SLA. using the 20V diode, it would begin conducting reverse current around 47V and the nicad would take charge from the lifepo4 as the reverse current avalanched backwards through the schottky. but that current would be charging the nicad up as the lifepo4 dropped at the 20V breakdown level between the two packs, and stay there. so it would not break anything, but it would not stop the discharge of the pack if the controller stayed on because the DC converter was left on. that is another problem.

so i think this might be a reasonable option to pursue for your scooter. i never thought 60V lifepo4 pack would be relevant, but it seems the best fit, 72V lifepo4 is too high unless it has the irfb4110 mosfets, and the 60V lifepo4 will work with the p75fn75 mosfets. maybe $10-15 for the caps, 20 cents for input power resistor swap or $20 for the DC converter.

maybe you can special order the 60V pack with headway cells from BMS battery too. hope this makes more sense, kinda the least things to have to change, just add the 60V in parallel with the diode on top of the SLA, and swap the caps and the input power resistor.

there is no LVC change, no need to sell the SLA and the SLA would be preserved by reducing the current demand in operation if it is shared with the last portion of the lifepo4 pack.

call BMS battery and i see that EVassemble also can build you a 60V pack: http://www.evassemble.com/index.php?mai ... n7prv0k696

you should be able to get them to build you a headway pack for about $550. either one of them. that
would give you about 4 times the range you have now.

[Alastor]

Really nice to know .Thanks again man for explaining all this details

I found some times and took some more pictures from the computer fan installation and the heat sink also i installed a mono radio so i can hear some music while i travel The bicycle is slow as hell top speed 32kmph so i need to entertain myself till i get to my destination .

Everything is rechargeable and cost me nothing to recharge

My next move is to get a nice waterproof thermometer install it and make some uphill test rides to check how the system is performing.

[ProDigit]

Really nice to know .Thanks again man for explaining all this details

I found some times and took some more pictures from the computer fan installation and the heat sink also i installed a mono radio so i can hear some music while i travel The bicycle is slow as hell top speed 32kmph so i need to entertain myself till i get to my destination .

Everything is rechargeable and cost me nothing to recharge

My next move is to get a nice waterproof thermometer install it and make some uphill test rides to check how the system is performing.

Heat sink:
You could drill a hole in it, and use a bolt to bolt it to the chassis (where you now use those plastic bands)
Bolt it preferably with the flat surface on the black pipe, sand off the pipe a bit so there might be a direct contact between the sink and the pipe.
In your case I'd get a multi convertor, to convert the 36VDC to 12V and 5V. That way you can put the whole motorbike on 12V (lights), except for the motor of course, and plug the mp3 and speaker into the 5V (or just use a 12 to 5V adapter plug).

To get a better sound, you can drill a hole in the glove box (where you have your speaker stowed away, and use a gluegun to glue the speakers in the lid of the glovebox. It'll sound quit good!

[dnmun]

i used a 12V computer fan motor to replace the burned out heater fan in my car. i had to wire tie it to the return air grill on the heater fan box, and then surrounded it with duct tape to seal it. where the old fan motor once fit in the bottom of the fan box, i siliconed and bolted a coffee can lid across the circular opening. exact fit!

[Alastor]

Its always a pleasure fixing something from scrap i guess you also having the microbe
Well today i was searching for a nice cheap waterproof thermometer that will not cost a lot of money and believe it or not i found out that fish tank thermometers are the best in the price range i was looking for it has all easy attach stickers a large display and two sensors one for outside and inside temperature.

I will install it today and start testing the scooter in uphill to check how the hole system works.I will post some pictures when i installed it

P.S.
Wasps nesting in my front porch WTF !!!!

[Alastor]

Next update will take some time.Damn weather is not letting me test it in real situations but in 20 seconds i had the fan on the temp dropped 2 degrees.

Thanks for all the help again mates

[ProDigit]

I suppose once you've done some testing, the thermometer won't be necessary anymore, as you can almost guess which temperatures there will be under what kind of weather. Perhaps when there's a hot day, you will want to measure it, but if it works fine on a normal day, it'll work really fine on a cold or rainy day!

[Alastor]

I suppose once you've done some testing, the thermometer won't be necessary anymore, as you can almost guess which temperatures there will be under what kind of weather. Perhaps when there's a hot day, you will want to measure it, but if it works fine on a normal day, it'll work really fine on a cold or rainy day!

Yea i know .I just got the setup because summer is kicking in.The asphalts temperatures is very very hot and i really don't want the poor thing to melt hahahaahah

Lets hope it will survives the summer.With the new battery i will install latter on during summer its range will be greater so cooling issues might rise up again and if they do more fun for me .

[Alastor]

Hello again , after a lot of test rides with two people i found out that the extra sink is more thank enough for cooling the hot controller now i get a maximum internal temperature of 30 degrees.
I will make more testing during summer i can't believe that an additional heat sink is doing so well

I found out that its total range with two persons is close to 30 km with aprox half way uphill .So with the battery upgrade i plan to do will get me 60km with two people with 30 km of hill climbing in between .

I feel like something is not right it should give up more kilometers per charge so the next plan is probably taking a nice whats up meter connect it with the battery and take some reliable data about the consumption while with one and two peoples riding it.The motor is geared motor it has a switch with 3 positions this might mean that the motor is consuming more when i use gear 2 and 3.Anyone has any experience in that ?

Thanks in advance

[ProDigit]

The motor you have is considered extremely underpowered for the type of bike you have for one person.
For reference, most one person bikes are equipped with a 500W motor.
So I can imagine you getting not much miles out of your battery, because your motor is running nearly constantly at 100% (or 120% if it's overvolted from 36 to 48V).
The best, and most optimal would be to have an open throttle, and have the motor ballast at around 75-80%.

As far as gears, going into lowest gear is best to get extra traction when accelerating.
Every motor graph is different, but most motors have a torque graph that's like a mountain; It increases as you accelerate until a certain speed, and then it reduces in torque as the rpms go higher.
It'll take a while finding the sweet spot.
Best way to test it, is to go into lowest gear, and accelerate full throttle.
You'll see your speed decreases in acceleration once you reach a certain speed (for example: fast acceleration from 0-15kmh, medium acceleration ~20kmh, really slow acceleration until 25Kmh).
at a certain point, usually around 75% of the maximum speed in first gear, when the motor is running at that speed, it's best for acceleration; but the exact value really depends from motor to motor. Some motors have most torque at near standstill, some have a torque spike up at a fixed speed!

Once you're at a certain speed,which is not it's top speed (imagine your motorcycle can go upto 35kmh, but you're in a street where you can only drive 25kmh), and are driving on flat land, there are 2 trains of thought:
1- Get into high gear, as you don't need acceleration or torque, but just maintain speed. High gear has the benefit of low rotations, so lower resistance, and higher efficiency. This is especially true if you're running the motor close to it's highest efficiency.
Cons to this: Low torque, controller runs less efficient, every time you will want to accelerate, the motor will draw more peak amps.

2- Get into medium gear, as you'll be able to fully open the throttle, and therefor have less controller losses (the controller will not heat up as much). Also, when accelerating the motor will draw less peak amps.
Cons: The motor will be ballasted higher, and possibly run less efficient;

There are other situations where the following might benefit you:
When you find yourself running at max speed most of the time, it's best to stay into highest gear.

When you're going up a hill, or have to go against the wind, and you see your max speed dropping from eg: 35kmph to 25kmph, and you know in middle gear you can go faster (eg: 27 or 30kmph) on that hill (all depending on highest efficiency of the motor), it is best to shift to that lower gear. It seems simple, but in reality it is best to do what works best.

High gear is not meant for acceleration, because as you accelerate you put a lot of power into the motor though you accelerate only slowly.
In a lower gear, you can accelerate much faster, or accelerate at a same acceleration, but not taxing the motor as hard.

I would also suggest you to swap out the fan for a simple aluminum bar.
I'm planning on putting diodes in my bike, and bought an aluminum bar like this one for cooling:
http://www.amazon.com/gp/product/B003JOOR3K


You can always find them in different sizes, or perhaps even get it from scrap material!
Make 4 holes in 2 aluminum bars, and screw them to the controller with a thread rod and some nuts.


Make sure the aluminum bars are longer than the controller, as it has excellent heat transfer properties, and the extension acts like a heat sink.
aluminum also is a more affordable metal, and very flexible, so you can bend it with your bare hands, or use a hammer to bend it into a shape fitting the housing.

[Alastor]

Ok i will try to explain how the gears work on this bicycle

Gear 1: Has full torque as all other three speeds but it limits the top speed to 25km
Gear 2 :Top speed close to 30km In strait line terrain
Gear 3 :Top speed close to 40km In strait line terrain

There is no over voltage anywhere its just a geared motor ?? that has a geared controller or just a geared controller and a motor that can handle a little bit more wattage.The trick they are probably doing is feeding 5-7 amp in gear 1 , 7-12 amp in gear 2 and 12-17 in gear 3.And i am guessing that because i looked again at the controller and its rated for a max 17A and not the 5-7 that they told me so they feeding the motor with more A's And the motor is probably rated 250 watt but can handle a little more power.Smart trick if you ask me.

And i am telling you this because its the only way i can explain its behavior with my electronic skills and the things i saw.Thats kinda explains the dudes response when i asked him how many km will it run in gear 3 and he told me close to 40 in gear one it gets 60km in gear two gets 50 km.

For the heat sink now i believe that the extra heat-sink is more that ok for the job.The thermometer is there to let me know when things will heat up so i will keep the fun installed for now till the summer passes and will see how i will proceed.

I just hope to sell my other electric bicycle any time soon to invest in new battery pack or packs to get some real range out of my little toy.
Also i am doing all this with the gear shifting already but thanks for explaining it

So if the lead acid heavy batteries can get me and my girl up to 40 km at a capacity of 576 watt - 20% losses from motor efficiency 461 watts of true consumption i will need one 48lipo30A lipo to get close to 120 km.My battery pack is 25 kilos so the bicycle will not be over weighted if i installed a big lipo pack.Or two smaller ones 48*20A and one 48*10 or 12A.

Tell me i am thinking this the right way i am trying to make my calculations for maximum load 65 kilos the bicycle 120 kilos me and my girl.Two batteries ? or one is the way to go in your opinion ?

Thanks again

[Alastor]

Hello again , today it was hot in here 36 degrees in the road and 38 degrees on the controller using the fun dropped the internal temperature 5 degrees so i guess it will survive the summer