Re-Celling a Phylion battery with Lipos

[Pedant]

I’ve been reading Old Dave’s new build thread with interest, particularly with regard to his use of RC hobby Lipos.

My Alien kit came with an aluminium cased Phylion 10s LiMn 10 ah rear rack battery which is performing well after a glitch which was cured by Alien doing some conditioning cycles earlier in the year.

It will obviously eventually need to be replaced / refurbished and I would be very interested in effectively re-celling it with Lipos. I’m pretty sure that I could fit sufficient Lipo packs in the case to provide more capacity at lower weight and less cost than replacing like for like. The trouble is that I enjoy the usability of the current set up. That is: I can simply plug in the charger to recharge and rely on the BMS to balance the charge and control the discharge to keep everything safe.

So my question to the experts here is: Can I find a BMS that will control 2 or more Lipo packs for an ebike application? Or can I use the BMS in my Phylion battery to do this? Or are there any ebike batteries based on RC hobby Lipos that I could use directly or canabalise to fit my Phylion case?

 

[NRG]

I've had the same idea as you with the failing battery on my Alien GSII. I've shelved the idea though, firstly there's not enough space in my casing to get a 10Ah battery using Lipos, the case is different to the Aurora one....I've tried a number of configurations and packs but none seem to work. I could go 6Ah and retain space for a BMS. I considered experimenting with the existing BMS, it should work but the LVC is a bit low at 3v...3.2 or even 3.4 would be better IMHO. Given all the faffing and BMS issues I'll probably go with a Kudos rack and battery, they have good life and will be easier to fit!

For other BMS, BMS Battery do a range and you can ask them to set the appropriate LVC so might be better than using the original.

 

[Deleted member 4366]

The problem with lipos is that you need to get access to the packs for charging. It could be done if you have the patience to make a nice charging pane. Look at the connectors hanging out of my one on each side for each 6S pack.

This Cyclamatic has a 5.6aH 12S pack in the case, which can be qickly removed for charging because the top's not screwed on, but is held in place by the lock. There's also a higher rated controller bolted at the bottom of the case - hence the extra four screws. It did 32mph like that!

 

[Old_Dave]

Look at the connectors hanging out of my one

Could put a condom on for protection

 

[Old_Dave]

I’ve been reading Old Dave’s new build thread with interest, particularly with regard to his use of RC hobby Lipos.

So my question to the experts here is: Can I find a BMS that will control 2 or more Lipo packs for an ebike application? Or can I use the BMS in my Phylion battery to do this? Or are there any ebike batteries based on RC hobby Lipos that I could use directly or canabalise to fit my Phylion case?

AFAIK ... a bms isn't needed. (or what I really mean is, I aint going to use one)

Reasoning is that the balancing is done by the charger, so no point in duplicating the circuitry, over current / short circuit protection for the battery can be easily achieved by a suitable wire or poly fuse, the only thing that needs to be thought about (I'm still thinking) is an easy peasy way to set the LVC.. d8veh's idea for a very simple fix is to have a voltmeter and keep an eye on it, but I'd prefer to add an electronic safe guard as well as the meter... I'll get around to thinking when all my bits have arrived or I stumble upon a ready made solution

 

[Pedant]

AFAIK ... a bms isn't needed. (or what I really mean is, I aint going to use one)

Reasoning is that the balancing is done by the charger, so no point in duplicating the circuitry, over current / short circuit protection for the battery can be easily achieved by a suitable wire or poly fuse, the only thing that needs to be thought about (I'm still thinking) is an easy peasy way to set the LVC.. d8veh's idea for a very simple fix is to have a voltmeter and keep an eye on it, but I'd prefer to add an electronic safe guard as well as the meter... I'll get around to thinking when all my bits have arrived or I stumble upon a ready made solution

Thanks for the replies. I guess I may not have made it clear what I want to achieve.

I realise that I don't NEED a BMS if I use a Lipo charger with a per cell connector, but I wanted to use one so that I can just attach a charger using the (reasonably water resistant) two wire connector on the current case. Similarly I realise that I could get a controller that could be programmed to enforce the appropriate LVC, but I'd prefer that to be done by electronics in the battery casing.

I'd be surprised if the bits to do what I want aren't available, because I would have thought many would want to take advantage of the economical power storage hobby Lipos can provide.

I'll have a look at the BMSes on BMS Battery.

 

[Deleted member 4366]

AFAIK the only failsafe way is to make some electronics. First you need an electronic switch like the oe Jeremy designed. It works by applying battery voltage to the switch, which then switches on 4 FETs to connect the battery.

You'd could use a transistor to do the battery voltage switching and then need a LVC detection circuit to switch the transistor. The lvc detection circuits that I''ve seen are complicated. It should also be possible to use a Cellog external alarm to swiitch the switch, but that'll take a bit of figuring out.

You can adjust the controller lvc to whatever you want as we figured out in a recent post where the guy wanted to use a 36v battery with a 48v controller. You just have to change one resistor. The controller then will cease to give ower. This is probably the best solution.

Also, the Cycle Analyst and Speedict will cut your throttle when you reach your pre-set LV point, but then it's up to you to switch off the battery, because the controller will still draw a bit of power, though not enough to damage your battery before you get home, but it's easy to forget - as I did - and switch off the controller, but I left my Speedict running for two weeks which completely killed two 8aH lipos that cost £150. It's best to use the LEDs on your throttle to show that the battery's switched on. I didn't have any.

 

[Old_Dave]

I was toying with a MOSFET idea, source to the battery, drain to the controller, and a Zener with a bleed resistor between source and the gate, component count = 3 lol, there's of course the short circuit current issue that needs to avoid melting the MOSFET but that's not a major problem




Sent from my iPhone using Tapatalk

 

[NRG]

Using an RC charger is a faff at best though as it cant balance cells on an individual basis on a large paralleled pack, this is what the BMS does. Also, IME you need to provide LVC at the cell level not the pack using Lipo's...I would not trust the LVC cutoff of my controller to protect individual cells in my packs.

 

[Deleted member 4366]

Using an RC charger is a faff at best though as it cant balance cells on an individual basis on a large paralleled pack, this is what the BMS does. Also, IME you need to provide LVC at the cell level not the pack using Lipo's...I would not trust the LVC cutoff of my controller to protect individual cells in my packs.

You're absolutely right; however, I've always managed by monitoring pack voltage. As long as you check cell voltages when you charge, you get an idea of how the cells are behaving. If there were a duff one it would show itself, but when you see that they're all more or less the same every time, it gives the confidence in what your doing. The real danger is in charging, but most of the chargers tell you if you have a cell that's too low and won't charge in that case. So between intelligent observations and intelligent chargers, i believe that it's a fairly safe strategy, and I never go below 3.7v per cell average, which leaves a pretty good margin of safety. There's not much power left after that anyway.

One time I forgot to chage half the pack. When I switched on I could see staight away that instead of 50v, I only had about 48v and significant sag when I opened up the throttle, which wasn't normal, so alarm bells rang in my head. I checked and found the problem. This is where intelligence and knowledge are necessary. Just going by what was on the meter would have sent one pack into the danger zone.

 

[NRG]

3.7v is very concervative Dave, theres probably a good 20% or more battery capacity left but I understand the need to not let the voltage drop too low. I used to run mine down to 3.2v monitoring on a cell by cell basis, more recently I've been using 3.4v and feel its a good compromise.

 

[Deleted member 4366]

I find that once my battery's down to nominal (3.7v), it accelerates down rapidly after that. There's a nicw video on Youtube of a guy on a bike with a meter on his handlebars. I'm guessing 12S, so 3.7v per cell would be 44.4v. At 1.27, he has 42.22v (3.8aH). At 2.34, he has 36.0v (4.56aH) and at 3.09, you can see volts in the 20s when he grinds to a halt and 4.?aH on the meter. I know he's running quite high current with what I guess is a 5aH battery, but it shows how quickly they can go down.
The video's under the graphs:
Endless-sphere.com • View topic - Did i kill my new lipo pack?

 

[NRG]

If he's pulling a high C rate from 5ah then I can understand the LVC set at 3.7v

I pull no more than 2c from my 10ah zippy pack and 3.7v would leave quite a bit of unused capacity in the pack.

 

[Gens Ace battery]

I’ve been reading Old Dave’s new build thread with interest, particularly with regard to his use of RC hobby Lipos.

My Alien kit came with an aluminium cased Phylion 10s LiMn 10 ah rear rack battery which is performing well after a glitch which was cured by Alien doing some conditioning cycles earlier in the year.

It will obviously eventually need to be replaced / refurbished and I would be very interested in effectively re-celling it with Lipos. I’m pretty sure that I could fit sufficient Lipo packs in the case to provide more capacity at lower weight and less cost than replacing like for like. The trouble is that I enjoy the usability of the current set up. That is: I can simply plug in the charger to recharge and rely on the BMS to balance the charge and control the discharge to keep everything safe.

So my question to the experts here is: Can I find a BMS that will control 2 or more Lipo packs for an ebike application? Or can I use the BMS in my Phylion battery to do this? Or are there any ebike batteries based on RC hobby Lipos that I could use directly or canabalise to fit my Phylion case?

Hi Pedant.
I got your point. You just want to recell your Phylion 10S 36V 10Ah battery and maybe try to extend the capacity with the your original case... Right ? please check the answer as below:

Can I find a BMS that will control 2 or more Lipo packs for an ebike application? Or can I use the BMS in my Phylion battery to do this?

Yes, you can use your old battery 10S BMS to do it, just find the suitable cells for connection to be 10S1P pack or 10S2P if you want to extend the capacity and you think there are enough space in your case. If you want to change to a new BMS, just find a suitable 10S BMS with the current which can fit your controller and can power your motor.

Or are there any ebike batteries based on RC hobby Lipos that I could use directly or canabalise to fit my Phylion case?

No, do not use the RC hobby lipos to build your E-bike battery. There are different. I checked Alien kit for the battery part. I think the cells they are using is 1-3C cells. but the most of RC hobby batteries are 10-40C cells. they are not suitable for you. you do not need that kind of powerful cells. 1-3C is enough for the normal E-bikes. Of course, it depends on the power of the motor. and the high rate RC hobby battery's cycle life is lower than common 1-3C E-bike batteries.

Thanks
Benson

 

[Old_Dave]

Of course, it depends on the power of the motor. and the high rate RC hobby battery's cycle life is lower than common 1-3C E-bike batteries.

Hmmmmmmm..

As already explained by our very own battery guru.. the high rate lipos lower cycle life is based upon them being discharged at that high C rate, using them in an application of a much kinder low C requirement gives an extended life.

As testified to on this and the other forum.

 

[NRG]

Indeed and if you charge and discharge limit them you get extremely good life from them.