First E-bike Conversion advice

General Discussion about electric bicycles.
SkinZ   100 µW

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First E-bike Conversion advice

Post by SkinZ » Jan 07 2018 12:55pm

Hi,

I have been researching and reading the forums for a couple of weeks, and am about to take the first plunge into the exciting world of Electric Bikes!

I have got an old steel framed mountain bike sitting in the shed, that is asking for an electric conversion!

My use case is for riding in the UK on gravel tracks at weekends, probably using pedal assist more than throttle, so may not be hammering the battery too hard (not too concerned by the legality of throttle/wattage- as long as I don't ride like an idiot then no-one will know or care plus some use may be on private land).

For my first attempt, I have decided to go for a 1000w 48v ebay special with LCD display from here.

I am considering going for 52v 20ah battery made up from a 6s, and 2x4s from HK listed as "Multistar High Capacity 5200mAh 4S 10C Multi-Rotor Lipo Pack" here and "Multistar High Capacity 10000mAh 6S 10C Multi-Rotor Lipo Pack XT90" here. Is this a suitable setup or have I made any glaring errors?

I understand that I need to carefully select a decent LiPo balancing charger and power supply.
Can anyone point me in the right direction as to a decent balancing charger, that doesn't cost the earth or would it be cheaper and less hassle to bulk charge with a cheaper charger and then check with a standalone balancer periodically (every 10 cycles maybe) without a nice warm LiPo fire?

Also I have been reading about BMS. Is BMS necessary with this setup? How is it used? Does it strap to the battery group, for both charge and discharge whilst riding? is it one per block or cells (4s or 6s) or 1 for the entire block in series (14s)?

Thanks in advance for any help that you can give me! And I hope I have got the terminology correct as it is quite a steep learning curve!

Kind regards

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Re: First E-bike Conversion advice

Post by ScooterMan101 » Jan 07 2018 1:17pm

First : Those " not so special " e-bay kits , sell hubs that are Very Heavy DD hubs.

Most people here do not need such a heavy hub.

You have someone in your country ( D8veh , he lives in Telford ) that has been using the little Q100 c or freewheel Q100, or the Q128 , either the cassette version or the freewheel version which has a little more torque and can use / run on a little more wattage for the same hub. He has gone through and done all that you want to do .
A Q128 or a Mac hub motor is all you would probably need.

Now in regards to H.K. lipo's , If you get them you do ... Not need to use a BMS, the controller you get will have a low voltage shut off, what I do is tape a voltage that I will not go below when riding it is around 3.65 v per cell with lipo's.
Also
You can just buy a few Lipo low voltage alarms and plug them into the balance wire connectors and they will sound an alarm when there is a cell in the pack that reaches the voltage you set. Example you can set it to 3.5 v per cell or 3.6 v or 3.7. etc .

https://hobbyking.com/en_us/hobbykingtm ... 2s-6s.html

When using any Lipo's from any source like H.K. or elsewhere , make yourself a home made Lipo Bunker. I use a combination of Concrete Bricks and large Concrete Paver Blocks.
Best to charge them outside, if you must charge inside make a separate lipo Bunker , smaller in size to hold the pack/s you are charging at the time, Concrete Paver Blocks under and on top with sides of bricks , so that if there is a fire nothing else catches on fire, just allot of smoke.

Read what D8veh has done on his conversions.
My first conversion ...

https://endless-sphere.com/forums/viewt ... 1#p1077497

It's 2018 already, lets get some real , improved e-bike / e-velomobile / e-motorcycle designs .

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Re: First E-bike Conversion advice

Post by markz » Jan 07 2018 4:46pm

Be extra careful with them LiPo's.
iCharger would be ideal, but has a higher cost.
HobbyKing sells Balance Chargers - Just dont buy a low wattage unit, find something that can charge up your LiPo's in a half decent time. So you are looking for 6S Charger

https://hobbyking.com/en_us/0620-20a-30 ... ion-2.html

Then buy a Dell PSU to power it.
These units are dirt cheap on fleabay
https://www.ebay.com/itm/Dell-PSU-Power ... SwbF1Z8PtG

easy to mod

Also you forgot TORQUE ARMS
www.ebikes.ca sells them

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Re: First E-bike Conversion advice

Post by wturber » Jan 07 2018 5:52pm

Many people build something similar, and I think that approach is pretty darned good for a commuter bike in the U.S. They are simple, durable, and give you pretty good speed. It is what I chose to do over here in the Phoenix metro area of Arizona.

But in the UK, they have much stricter power limits and you'll need to decide if you care about that or not. As described, your design won't be legal on the roads in the UK. I have no idea how that will translate to the gravel tracks that you mention. So, if you haven't considered the possibility of riding it on the roads, then now's the time. Of course, if the laws aren't enforced rigorously, then maybe you don't care. It would be worth considering a smaller geared hub motor - even if you are going to run it at more than the 250 watt legal limit. The smaller hubs are less conspicuous. So if you pack the battery with some stealth, the bike will look more "normal" and attract less attention.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

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Re: First E-bike Conversion advice

Post by Raisedeyebrows » Jan 07 2018 10:43pm

I used one of those same ebay hubmotor s on a steel MTB frame for my first hubmotor experience, I have a couple mid-drives but just wanted to assemble one and see what they were about. I will confirm that they are indeed very heavy. Running it at 52V, it gets up to somewhere around 30 mph pretty quickly with flyweight me on it, it's heavy and not fun to pedal without the power of the motor on. I have no other experience with other hubmotors, I'd like to try lighter ones. That said it has plenty of power and is lots of fun to ride.
Yuba Mundo w/BBSHD
Specialized Hard Rock w/9c clone, statoraid, hubsink
Trek Fuel 90 w/BBSHD
Above all run on 14s4p 52v li-ion
Ecobike folder 36v
Currie Flyer scooter 24v on 24ah of SLA

Every trip made with electric bike is one less car trip, saves money, no toxic fumes, less noise, less impact on roads.

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Re: First E-bike Conversion advice

Post by ScooterMan101 » Jan 08 2018 2:14am

Here is what is probably the best charger for the price , to charge lipo's
Not only is it AC or DC input , but output is for 2 batteries at once , this saves allot of time for charging.

The only drawback to this charger is that it will only charge up to 6s packs, Many of us are using 7s packs these days , and more of us will be using 8s packs in the near future. For you and the packs you will be buying this charger is the best for the price.

These were not available a couple of years ago when I bought my batteries, too bad, I have to charge one pack at a time since HK no longer sells the charger I bought back a couple of years ago.
The one I will link to is a AC and DC charger , most lipo chargers are DC only and you need to buy a Power Supply , when both are bought it comes to the price of this charger.
The link is to the ISDT with U.S. plug, it is the same unit only a different plug than what you have in the EU, when I click on the $ 144 dollar EU version the page goes to an ISDT DC only charger.

https://hobbyking.com/en_us/d2-smart-ba ... -plug.html

https://hobbyking.com/en_us/batteries/b ... ac-dc.html

Write to Hobby King and ask for them to get the company iSDT to make the same charger that will charge up to 8s packs.

* For anyone living in the U.S. or Canada here is the link to one sold by Buddy RC
( Call Buddy RC and ask them to get iSDT to make the same charger with 8s battery pack charging )

http://www.buddyrc.com/isdt-d2-smart-ba ... utput.html
My first conversion ...

https://endless-sphere.com/forums/viewt ... 1#p1077497

It's 2018 already, lets get some real , improved e-bike / e-velomobile / e-motorcycle designs .

SkinZ   100 µW

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Re: First E-bike Conversion advice

Post by SkinZ » Jan 08 2018 3:59am

Firstly, thanks for all the replies!

I may now forget the 1000w kit, as I didn't realise quite how heavy it was despite ticking most of my boxes.

I like the idea of a smaller geared hub motor staying smaller in size and therefore less likely to be noticed, but similar power output once over-volted. I have since seen smaller motors in a wheel kit form from bmsbattery (Q128h) @ 94USD, but the shipping to the uk is 169USD, so unless I can find a reasonable UK/EU supplier it might kill the cheap ebike dream.

Thanks for all the charger advice, I'll definitely look at those once I've got the motor part sorted.

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Re: First E-bike Conversion advice

Post by Patchogue » Jan 08 2018 2:34pm

Hey SkinZ

Great to see another enthusiast taking off with another build. I used to build electric bikes in a shop in Mid Wales but I had to close it last year.
If you're close to London, it's very worthy to talk with David from this website: https://ampedebikes.myshopify.com/
He has some stuff in stock that might suit you and the prices are quite good. Small bafang hub motors (geared or not) with small custom made batteries. Cool stuff, he runs a tiny bafang with 800w and no issues.

I had a magic pie vector 4 with Lipos on my first ebike, had so much fun. Learned a lot and never had any issues with Lipos. If you take care of them, they can last a good amount of years / cycles without a problem. The bike was sold to a friend and it still goes great.
But in reality, you can buy very cheap batteries from aliexpress with all the juice you need and a charger. I really like Lipos in many ways but the comfort of not having to worry about them is priceless. The other day I've just ordered a 52V 15Ah 30A constant w/ charger included in a bottle cage with BMS for £250 with shipping included. Lipos will cost you the same once you buy the balancer, power supply and connectors plus labour of putting this together.

If I can be of any help let me know. G luck and don't forget to keep us posted with pics or vids.

Cheers

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Re: First E-bike Conversion advice

Post by SkinZ » Jan 08 2018 6:57pm

Thanks again everyone for all the help.

I like the sound of a physically smaller decent discreet motor running a bit over volted.

What is my cheapest route to buy in UK?

I've had a look at the links provided but think I'm confusing myself but lots of good projects undertaken by so many talented people.

I'm not too concerned by warranty if I go for a decent brand such as Bafang- I just want to start and get some bits together.

There is a swhx 48v 350w on AliExpress for £105 delivered without anything else here which could be a potential start?

Obviously got a steep learning curve coming with attaching it to spokes. What do you think? Too complicated? Should I just buy a kit and be happy? I feel like that would be cheating!


Thanks again

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Re: First E-bike Conversion advice

Post by wturber » Jan 08 2018 8:23pm

SkinZ wrote:
Jan 08 2018 6:57pm

Obviously got a steep learning curve coming with attaching it to spokes. What do you think? Too complicated? Should I just buy a kit and be happy? I feel like that would be cheating!
Starting with a kit isn't "cheating" at all IMO. I think kits provide a greater likelihood for success while also giving you some hands-on that lets you learn a bit about things. Having good success early is generally a good thing.

OTOH, if you've had a hankering to learn how to build a bike wheel, and/or you want to make sure your wheel is built to a high standard then buy the motor either build the wheel yourself or have someone else build it. Most kit wheels aren't built with the best components. So having the wheel built locally might be a good thing. OTOH, my cheap kit wheel is doing just peachy after 1500 or so miles.

This is your project. Read lots on this forum, and do what you think you'll enjoy most.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

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Drunkskunk   100 GW

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Re: First E-bike Conversion advice

Post by Drunkskunk » Jan 08 2018 8:54pm

Skip those 350w motors. They aren't robust enough to survive off road. a 500w Bafang or MAC is what you need.

And if cost is an issue, the direct drive hubs are still a good option. Heavy, but bullet proof with only 1 moving part. They make a great motor to get started out with. They have some advantages, too.

Don't go for Aliexpress for a battery. Forum member Dogman had his house burned down recently by one of those. And he's someone who preaches battery safety to newcomers. Battery fires are rare-ish, but he isn't tho only member of this forum to have lost a house. Buy the best battery system you can afford, skimp on other parts if necessary. The battery, not the motor, is the heart of a good ebike.

Lipo from HK works. it is risky and not always the cheapest option. you need a good balance charger to make it safe, and usually several chargers to make it practical. those chargers are expensive. Since you need to monitor Lipo while it charges, it's better to have a bunch of chargers so you can get it Finnish faster. i use Lipo. my bank of 4 chargers plus power supplies cost more than many people spend on conventional batteries and the charger.

Here's a video of a single HK 5000mah cell i caused to burst. your 52v 20ah battery would have 56 cells this size.
Buy the ticket, take the ride.
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Re: First E-bike Conversion advice

Post by MadRhino » Jan 09 2018 10:54am

I use RC lipo too, yet I don’t recommend using them if you don’t need the Amps.

Your requirements are well served with a much safer battery, and one that you can let charging without supervision.

When you need RC lipo, you need to be strict with the rules. Lots of rules, that one could describe generally: When you can’t be with them, they have to be where it is safe to start a bonfire.
Make it fool-proof, and I will make a better fool.
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SkinZ   100 µW

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Re: First E-bike Conversion advice

Post by SkinZ » Jan 09 2018 11:57am

Hi guys, thanks for all the advice.

I'm fairly confident that I won't burn my house down with a LiPo pack, as I've read so many guides about BMS, balancing rules, charging rules, maximum minimum voltages so I'm quite happy.

Also I think I'll just charge them outside in my back garden under a metal cover if I need to leave them unattended.

My first purchase problem is still with picking the best rear hub motor I can afford, without it being too heavy or having to pay £150 to ship from China..

Ideally I'd like either a 250 or 500w rated motor that isn't too large to run about 750-1000w using a 52v battery pack at 20ah. I'd like to pay about £150 for the motor alone delivered to UK. I can worry about the controller and wheel mounting and battery requirements afterwards as some of the kits tend to cut corners on these bits and I don't mind paying for decent separate components but don't want to spend all my budget on shipping.

Am I asking too much? Be honest!

Thanks again

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wturber   100 kW

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Re: First E-bike Conversion advice

Post by wturber » Jan 09 2018 1:15pm

SkinZ wrote:
Jan 09 2018 11:57am

Ideally I'd like either a 250 or 500w rated motor that isn't too large to run about 750-1000w using a 52v battery pack at 20ah. I'd like to pay about £150 for the motor alone delivered to UK. I can worry about the controller and wheel mounting and battery requirements afterwards as some of the kits tend to cut corners on these bits and I don't mind paying for decent separate components but don't want to spend all my budget on shipping.

Am I asking too much? Be honest!

Thanks again
I don't know if you are asking too much or not. But I will say that one of the main advantages I found with purchasing my ebay kit was that all the parts were selected to work together properly. This was especially true of the controller, motor, throttle, connectors and LCD display. The LCD display in particular was a fairly important unit since it provides an interface to change option is the motor controller. I had no clue about that when I purchased the kit.

If the kit at the link below had a 48v controller, I'd think it might be a reasonable choice if you are budget minded (interestingly the large photo of the kit shows a 48v controller while the group photo of the kit shows an obviously differently shaped controller). The parts are generally on the cheap side of things (though there are common reports of such kits working fine for many thousands of miles. So with a kit like this you may find yourself wanting to upgrade things later. And if that's you, then perhaps an inexpensive kit like this doesn't make sense. OTOH, if you enjoy fiddling/modifying/learning then perhaps it does. :^)

https://www.ebay.co.uk/itm/LCD-Display- ... emftijY4wg

You could spend more time and research in-depth the parts. You'll probably pay more, but the overall quality of what you get will probably be higher (if you choose and shop wisely with advise from the veterans here). But you may still find yourself wanting to fiddle and upgrade later. It seems that few of the long term ebikers here just build one bike and then ride it without changing things.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

SkinZ   100 µW

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Re: First E-bike Conversion advice

Post by SkinZ » Jan 11 2018 8:59am

Hi,
Just a quick update.

I've ordered a 250w eBay kit for £105 delivered.

I'm sure that I will melt or burn something whilst playing around with it (hopefully not a LiPo pack!), but it's a dirt cheap disposable kit to test how far I can push 250w and the controller as a bit of an experiment.

I can't imagine it lasting the year, but that's ok, I'll know more for the next one!

Thanks to everyone for their help, it's been a real learning curve! Pictures to follow soon!

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Re: First E-bike Conversion advice

Post by Patchogue » Jan 11 2018 7:17pm

what's the make and model?

SkinZ   100 µW

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Re: First E-bike Conversion advice

Post by SkinZ » Jan 12 2018 3:22am

Hi,
Not sure it has a make and model. Generic Chinese kit: here

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Re: First E-bike Conversion advice

Post by meaargee » Jan 17 2018 1:59am

I have just built my first electric bike using the Voilamart 1000W rear-drive-with-LCD that you linked to.
I don't feel it's too heavy, I'm just testing the range and performance battery pack I built for it (I have a small, constant supply of used 2200mAH 18650 batteries in packs from work that would normally be dumped.)
Be careful with batteries, but don't be too scared by the seemingly every second battery pack could burst into flames and burn your house down. I only charge while I'm around during the day and at low (<2Amp charge currents).

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geoff57   10 kW

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Re: First E-bike Conversion advice

Post by geoff57 » Jan 17 2018 12:23pm

Hi
First a bit about UK law, it states the motor must not be more than 250w , the speed the motor can drive the cycle to must be no more than 15mph, you need pedals to make it a ebike no pedals and it is an electric motorbike and subject to its rules.

The motor wattage is a joke I have a 250w motor on my ebike scooter running at 72v, at full throttle I can pull2.5kw out of the battery and get a speed of 30 mph(mesurments taken with a calibrated cycle analyst).
As long as you stay around 15mph max speed the law will not bother you, some of us have stuck a 250w label on a much larger motor. The law is bothered about speed not watts.when it comes to pulling you over.

From the looks of things you have bought a geared motor probably a Bafang when you are peddling the bike you will find a geared bike a lot easier I would not run the motor above 14s LiPo or you will turn the gears into peanut butter, for a first bike you will find this quite powerful enough.

For the battery pack you have to be very careful, for the cells I would use 5000mah 20c turnigy battery packs, you will need a minimum of 10ah so for a simple 10ah 14s battery pack buy 4 5s 5ah battery’s and 2 5ah 4s battery pack you will need extra 12gauge wire and connectors. if you want more info I will explained how to link the battery’s together.

After a lot of bad experiences I would definitely recomend a BMS, you can get one from AliExpress with no problem search for a BMS 14s you will find countless hits they will say lithium ion but they can be used with LiPo just do not go for a lipo4 type as this is for a different chemistry. The BMS will save you from over charge and overdischarge of the battery it checks each cell individually some cell balancing may be done as well but I would still have balance connectors avalible to check the battery pack.

For a charger look on AliExpress again for a 14s lithium ion charger 58.8v, with a 10ah battery pack you will need no more than 2Amp charger.

Between the battery and the controller on the red wire I would advise that you put in a 40a MCB (mini circuit breaker) this will storm the battery drain overnight and put a stop to connector spark as well.

Geoff

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Re: First E-bike Conversion advice

Post by SkinZ » Jan 19 2018 10:09am

Hi all,

Finally got my 250w kit installed (pics to follow!)

It's not looking very pretty as I only got it put together at 10pm last night, so all cables held to the bike with cable ties.

I measured top speed of approx 22mph on the flat running 14s 10ah @ 3.8v storage charge (just testing it out before I put on charge).

Surprisingly the 36v rated controller didn't blow @ 52v/15A. Theoretically, this should mean 780w. Is that fair power/top speed ratio? It didn't seem very torquey on hill climb however.

I assume that if I got a better controller, it would pull more amperage and give me a greater torque and higher wattage- ignoring the fact that it would probably break the gears in the motor?

The batteries are 10C rated, so how do you stop the controller pulling too many amps - apart from not twisting the throttle too far?

Sorry - batteries and controllers power use blows my mind!

Thanks again

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Re: First E-bike Conversion advice

Post by wturber » Jan 19 2018 12:10pm

That is a geared hub motor and it has plastic/nylon planetary gears. If you apply lots-o-power and the motor gets hot, you risk damaging the gears. The motor is at even more risk if you do this on uphills at slow speeds. So make sure you monitor the hub temperature and keep your speeds up above about 10mph or so going up hills. In IR "gun" type thermometer works well for doing spot checks.

I'm not sure how to limit the amps on your particular controller. I use a KT controller and the LCD display provides a means to set controller parameters. There may be a similar LCD display available for your controller. The generic answer is to get a Grin Technologies Cycle Analyst. The CA works with just about any controller and provides all kinds of nifty options. If you think you are going to be doing more builds with different motors and batteries, it might make sense to just get one now. OTOH, if you post an image of the label on your controller, someone here may have specific info on that brand and model.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
53T/42T Sakae Road cranks - 30mph+ on flats
viewtopic.php?f=2&t=90369

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geoff57   10 kW

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Re: First E-bike Conversion advice

Post by geoff57 » Jan 24 2018 3:24am

You’d be suppressed how many amps you can pull from a 10c battery.
You have a 36v 10ah battery pack to work out the maximum amps you can draw you take the 10ah and drop the letters do the same with the c rating so you have 10 x 10 = 100 that is the maximum amps you can draw before you start to loose voltage due to current draw.
With a 36v pack that’s 3.6kw much higher than the 780w you are drawing.
You are drawing at 780w with 36v just over 21a.
Kendrick

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Chalo   100 GW

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Re: First E-bike Conversion advice

Post by Chalo » Jan 24 2018 10:06am

geoff57 wrote:
Jan 24 2018 3:24am
You’d be suppressed how many amps you can pull from a 10c battery.
Your analysis disregards that the batteries in question are grossly overrated for current. Those numbers mean short circuit current or something, not an operating current you can expect to use. It's customary here where voltage sag is a factor to de-rate hobby batteries by a factor of 4. So Multistar batteries are workable for 2.5C or so.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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geoff57   10 kW

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Re: First E-bike Conversion advice

Post by geoff57 » Jan 24 2018 6:22pm

I use 20c batteries from turnigy in mostly in 72v 10 ah setups I have never had a voltage sage when at full power which is 2.5kw or higher, I would call them hobby batteries in my mind if the batteries are good enough for the isles of man zero TT race they are good enough for me, if you want to spend extra money on high c rated batteries you can.
I will say this the rating of 10c is dependent on where it came from but the main thin is the proof is in the pudding or to put it another way test it and see what the results are.
Kendrick

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Re: First E-bike Conversion advice

Post by amberwolf » Jan 30 2018 2:54am

geoff57 wrote:
Jan 24 2018 6:22pm
I use 20c batteries from turnigy in mostly in 72v 10 ah setups I have never had a voltage sage when at full power which is 2.5kw or higher,
That's only about 30-35A, whcih for a 10Ah pack is only 3C. ;)


If you've never had voltage sag, then that means you never see the voltage drop at all when you accelerate from a stop, or climb a hill (except over a long period of time as the battery drains along it's normal discharge curve). Meaning, if your voltage starts out at 84.00v fully charged, and you hit full throttle from a stop, the voltage stays at 84.00V and never flickers.

If the voltage drops under load *at all*, then you *do* get voltage sag (that's what it is), even if it's just a little.

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