Karl's Other Question Thread

K

Karl

100 W
Joined
Oct 25, 2010
Messages
183
Hello,
I have been making some reserch in the past months to build a good E-bike for my needs. But I have a feeling that if I leave the bike locked somewhere I might be getting my lithium battery stolen or controler stolen...

I thought of making a E-Backpack.

The concept:
A backpack filled with batteries, controler and a charger.

How will I use it?
at home - plug it into a wall outlet to charge
before the trip - plug backpack with e-bike
at work - plug it into a wall outlet to charge
etc...

Before building,
I need to choose my setup

Batteries - Headway 40160S (3.65c 16AH ) plugged into 14s1p for 51.1v
Controller - (Unknown) need recomendations buying a E-Bike conversion kit
Charger - (Unknown) need recomendations buying a E-Bike conversion kit
Throttle control - (Unknown) need recomendations buying a E-Bike conversion kit
Motor Hub - (Unknown) need recomendations buying a E-Bike conversion kit

Should I purchase a E-Bike conversion kit or should I buy everything separate?

If the kit is the anwser. I will need recommendations. Their is just way to many kits down there and I hate regretting a purchase.

thanks,
karl
 
Hello, welcome to the sphere..

If you are in the US, www.e-bikekit.com

if in canada www.ebikes.ca

get the whole kit so that the parts fit without you having to mix and match connectors and wire colors that won't match up...

16ah of headways in a backpack will be heavy, ok for short trips, not so much for long trips..

I would suggest mounting the motor/controller/throttle to the bike, and the battery in the backpack.. if you have the controller in the back pack it may overheat and the connections to th e motor and throttle are not meant for frequent disconect..
 
Karl said:
I need to choose my setup

Batteries - Headway 40160S (3.65c 16AH ) plugged into 14s1p for 51.1v
Controller - (Unknown) need recomendations buying a E-Bike conversion kit
Charger - (Unknown) need recomendations buying a E-Bike conversion kit
Throttle control - (Unknown) need recomendations buying a E-Bike conversion kit
Motor Hub - (Unknown) need recomendations buying a E-Bike conversion kit
Click to expand...

Ok I found most of the electronics at e-bikekit.com

Batteries - currentevtech.com - Headway 40160S (3.65c 16AH ) plugged into 14s1p for 51.1v
Controller -E-bikekit.com - Electric bike intelligent motor controller 48v(hope it is going to do the job) a lot of missing informations
Charger - E-bikekit.com - Intelligent Lipo Charger...my battery pack is 51.1v and charger output is 44VDC 3.5AMP... will this work?
Throttle control - E-bikekit.com full twist
Motor Hub - E-bikekit.com Front wheel motor 500-750watts 26'' wheel with e-bakes

will it do the job right?

thanks,
karl
 
That charger won't do. you'll need one ment for your LiFePo4 14s pack. LiPo is a diffrent chemestry with diffrent voltages per cell. you will also need a BMS to manage that battery


As for the throttle, you'll want one of the split twist throttles. It may seem like an odd idea, but after riding one, you'll see how much better it is. Full twist grips work like a motorcycle, but you can't lean into them when standing up to peddle, or pulling up the front wheel to get up a curb or over a storm grate
 
Ahahah! you are right! I forgot about pedaling
thanks!

About the BMS I want to go with
http://currentevtech.com/Battery-Management/Mini-BMS/MiniBMS-Cell-Module-p157.html

but I still have issues understanding how they work... I race RC cars and the BMS is handled by the charger

set the nominal voltage 3.2, 7.4, 11.1 etc... and then set amount of AH

Press start and it automatically stops at max voltage 4.2, 8.4, 12.6, etc..

how does the minibms of the URL above work?
 
Hello,

I will fabricate a 14s1p headway 16AH battery pack

51.1v max voltage but I cannot seem to find the right charger

Anybody able to help?

thanks
 
I would pick up a Meanwell S-350-48 and modify it for output max voltage of 51.1v, then you have CC/CV and without current modification it should push around 420w of power really for a charge rate of approx: 8.21 A or 1/2C which is 2 hours + to a full recharge for about 40.00 + s&h, there are other options.. none quite as cheap.

-Mike
 
Since you have lipo experience, any particular reason you are set on the headways? For a back pack battery, I'd really want lipo myself.

Most of us running lipo just use some kind of voltage monitoring to discharge. Then do the balancing and stuff with either a lipo charger or a bms they more or less fabricated.
 
mwkeefer said:
I would pick up a Meanwell S-350-48 and modify it for output max voltage of 51.1v, then you have CC/CV and without current modification it should push around 420w of power really for a charge rate of approx: 8.21 A or 1/2C which is 2 hours + to a full recharge for about 40.00 + s&h, there are other options.. none quite as cheap.

-Mike
Click to expand...

Mwkeefer,
thank you for the help. Since the charger will need to fit in a back pack with the battey and controller I was more thinking of a basic charger

do you think this one will do?
http://cgi.ebay.com/ebaymotors/60V-...6800162QQptZMotorcyclesQ5fPartsQ5fAccessories
 
That charger will trash your pack in very short order. Suggest you spend some research time out here and try to understand the many nuances related to charging and maintaining multi cell lithium packs. You'll need to fully understand concepts of cell balancing and HVC (high voltage cut off) before getting too deep into this. I think you'll soon discover that there is no "simple" solution for your ambitions, as it is not at all like charging up some Lead acid batteries, and 14s is a very uncommon and potentially awkward cell count for Headway or any other LiFePO4 pack.
 
Hi Karl,

eCity/bmsbattery does custom chargers. I have a 14s (51.1v) 2 amp charger that I ordered from them.



I can sell this to you for $30 plus $13 for shipping.

PM me if you are interested.
 
The 14s is a bit of a problem as most balancing chargers are max 10s. I personally would go with two 8s chargers and use isolated power supplies to drive them. One would fully charge and balance 8 cells, the other charge and balance 6 cells. This would be the easiest way. If you are more self sufficient in the electronics department, you can buy a kit to build your own battery management and just use a current limited power supply with a set voltage to charge/balance the pack. You have nothing but options. Go to www.hobbyking.com and look at their charger and power selection as a start.
 
For lifepo4, 14s is a weird choice. Usually it's 12s for 36v or 16s for 48v. Any particular reason? Like you happen to have 14? Tons of good choices in chargers in 16s lifepo4.

In lipo, 14s is just about exactly the same voltage as 48v lifepo4. Is that where you get the idea of 14s?

The suggestion of using chargers from hobby king is a good one. Not too hard to make a split pack, and then charge with two lipo chargers. Those HK chargers can do lots of stuff, lipo , lifepo4, nicad, etc. And you get balancing charge so you don't need a bms, just a voltage monitor.
 
Dogman, from what I can understand the Headways are Lipo's... I wanted to use them because of their cylindrical shape

imagin the interior of the backpack, the surface touching your back inside the bag will have elastic sowed from top to bottom vertically, then sowed every inch horizontally resulting of 16 slots for cylindrical batteries. Resulting in a very nice weight distribution.

Here's what I have made

2v93s4g.jpg


Please feel free to comment

I need this setup to be as light as possible
 
Karl said:
Dogman, from what I can understand the Headways are Lipo's...
Click to expand...

Headways are LiFePo4, Lithium Ferrus Phosphate. Lipos are Lithium Polymer. Two very different animals. Headways will last longer if treated correctly, but are heavier and a little more difficult to build a pack.

Karl said:
I need this setup to be as light as possible
Click to expand...

You want Lipo.

Also, you are missing the phase and hall connections in your diagram. That will add 8 more connections, which are condensed to two connectors. But as Ypedal suggested above, you do not want to repeatedly use these connectors, as thay will fall apart eventually. They are not made for that type of abuse.

Check out http://www.hobbyking.com for some really great battery products and prices. Most people use the 5s or 6s lipo packs in the 5000mAH capacity. Good Luck!
 
number1cruncher said:
Karl said:
Dogman, from what I can understand the Headways are Lipo's...
Click to expand...

Headways are LiFePo4, Lithium Ferrus Phosphate. Lipos are Lithium Polymer. Two very different animals. Headways will last longer if treated correctly, but are heavier and a little more difficult to build a pack.

Karl said:
I need this setup to be as light as possible
Click to expand...

You want Lipo.

Also, you are missing the phase and hall connections in your diagram. That will add 8 more connections, which are condensed to two connectors. But as Ypedal suggested above, you do not want to repeatedly use these connectors, as thay will fall apart eventually. They are not made for that type of abuse.

Check out http://www.hobbyking.com for some really great battery products and prices. Most people use the 5s or 6s lipo packs in the 5000mAH capacity. Good Luck!
Click to expand...

very good Idea! thank you for explanation it really helps my learning curve :D
I am actually good with these kind of battery. Purchasing 14 2s t form 7s2p will only weight 8.68LBS!!! wow huge differance

Now my issue is how to setup the charger for 14 x 7.4 battery packs
I know how to charge them individually but not in series
May I have an hand on that?
Thanks!
 
Karl said:
Now my issue is how to setup the charger for 14 x 7.4 battery packs
I know how to charge them individually but not in series
May I have an hand on that?
Thanks!
Click to expand...


You could charge Lipo in series, but its a Pain in the A$$ to figure out a BMS that will work. if you charge them by individual pack, you can use the charger's balance feature and won't need a BMS.

14S is fine, but 15s makes the packs break down into 3 5S packs, which makes the charging easier. 15S charge to 63 volts peak, which is the rated peak for the parts used in the Ebikekit.com controllers. It will handle it.

Controllers and chargers get hot. you wouldn't want them in the backpack. And 15SX10Amp worth of Lipo are small enough to be pointless in a backpack. a small triangle bag hold all of mine. Besides, wires hanging out of a bag just might make someone think you had a bomb.
 
Thanks but I need all that in a backpack for my lawn care equipment also :p

electric trimmer, edge trimmer, lawnmower...ETC you get the point :p

here's my new setup

fjopdi.jpg


Please help me out making the connections I get told Y switch wont cut it

Please help me find better diagram this is where my knowledge stops

thanks
 
3A:
http://www.batteryspace.com/Smart-Charger-3.0A-for-51.2V-LiFePO4-Battery-Pack-110-240V-----CE-listed.aspx

6A:
http://www.batteryspace.com/smartcharger6afor512v16cellslifepo4batterypack110vonlystandardfemaletamiyaplug.aspx

Don't get a charger that is over 2C. Thats about the max safe charge current for the Headway cells. Try to keep it at 1C or below if possible and you'll stress the cells less and get more life out of them.
 
Yes. lipo makes more sense for a backpack setup for sure. Smaller lighter, easier to connect with bullets or your favorite connector. etc.
But,,,

1. The controller belongs on the bike. Belive me, nobody is going to take just the controller. If it goes, the whole bike will go. It can be mounted steath in many ways, but it needs some breeze unless you live way north.

2. charging paralelled packs is not so hard. So if you need more ah, paralell similar packs till you have what you want for size. Then make one series connection. So if 14s is what you want, then some 6s packs and some 8s packs would do it. So would three packs, 2 5s and one 4s. In my opinion 15s lipo on typical 48v controllers is a risk since they have 63v caps in them. But 15s would be fine with other controllers with bigger caps.

To charge, undo the single series connection and charge as two packs. (or three) Use two chargers if in a hurry. You can carry the chargers in the pack, but they don't stay connected at all times.

12s is a handy voltage. two paralell sets of 6s packs. It falls halfway between 36v nominal and 48v nominal voltage. 6s can run a 24v trimmer nicely too.

Now you have a backpack with just two wires coming out of it, that go to the bike to connect.
 
I really like my 36v 10ah LifePo4 but, I'm definitely going Lipo on the full suspension build I'm working on.

It difficult to argue with the lower weight, smaller size, and (most importantly imo) the much higher C ratings that Lipo units offer. This, and the fact that I've been running them in my RC stuff for several years now, makes them just about impossible for me to ignore.
 
Karl said:
Thanks but I need all that in a backpack for my lawn care equipment also :p

electric trimmer, edge trimmer, lawnmower...ETC you get the point :p

Please help me out making the connections I get told Y switch wont cut it

Please help me find better diagram this is where my knowledge stops

thanks
Click to expand...

You just can't carry the controller in a backpack. it gets hot. Potentially hot enough to melt through a nylon backpack. And it needs airflow or it will burn out. I've blistered my hand on a Ebikekit.com controller that was out in open air.

Chargers that balance Lipo can't be left hooked up while the battery is being used, and the batteries shouldn't be left connected in series while it's being charged. you can carry them anywhere you want, but they need to be disconnected. No simple switch will do it. A simple 5S1P battery has 8 wires to connect to the charger.
 
Drunkskunk said:
Karl said:
Thanks but I need all that in a backpack for my lawn care equipment also :p

electric trimmer, edge trimmer, lawnmower...ETC you get the point :p

Please help me out making the connections I get told Y switch wont cut it

Please help me find better diagram this is where my knowledge stops

thanks
Click to expand...

You just can't carry the controller in a backpack. it gets hot. Potentially hot enough to melt through a nylon backpack. And it needs airflow or it will burn out. I've blistered my hand on a Ebikekit.com controller that was out in open air.

Chargers that balance Lipo can't be left hooked up while the battery is being used, and the batteries shouldn't be left connected in series while it's being charged. you can carry them anywhere you want, but they need to be disconnected. No simple switch will do it. A simple 5S1P battery has 8 wires to connect to the charger.
Click to expand...

Yea, well I will have to find a solution for the controller it needs to be attached to me because as I said I will use that portable power pack for my lawn care equipments (on lower voltages)
If I have to, I will mount the ESC outside the backpack on an aluminum plate with a fan...
 
Here's an onboard video of me racing with my R/C 4x4 Shortcourse truck

(the straight is 200ft)

[youtube]UcSAu0qJaAA[/youtube]

enjoy
 
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