Li-poly noob questions.

Gypsy · Feb 11, 2014

Hello, I have some questions regarding building and charging a Li-poly pack. I know this info is on here somewhere but I am having trouble with a few things.

I found a really good deal on some packs with these specs:
Minimum Capacity: 5000mAh
Configuration: 4S1P / 14.8v / 4Cell
Constant Discharge: 20C
Peak Discharge (20sec): 30C
Max Charge Rate: 5c
Pack Weight: 528g
Pack Size: 139 x 45 x 44mm
Charge Plug: JST-XH
Discharge plug: 4mm Bullet-connector

My questions are:
Can I run a 36V controller/motor system with these in a 3S2P setup? It would be a 44.4V 10aH pack.
Is there a charger that will charge the whole system at once. If so what if I made it 15aH?
I would like to use a BMS from http://www.bestekpower.com/148v4spcmbmspcbforli-ionli-polymerbatterypack/. Which one is best for this application and how many do I need?
Would this be a decent battery for light commuting on a cruiser bike?
I will be replacing the controller as well, any suggestions on that?

Any advice would be appreciated!

Thanks,
Gypsy

dogman dan · Feb 11, 2014

In general, many 36v controllers can tolerate 48v. Your plan is only 50v fully charged, so even if you have a 50v capacitor in your controller, you still could use 12s lico. Many 36v controllers have 63v caps in them, and they can take up to 14s.

I don't know much about using the bms, so somebody else will have to take up that question.

It shouldn't matter if you run 5 ah 10 ah or 15 ah, as long as you stick to 12s, or 14s if you have 63v as the top limit. More in parallel only needs more wire to parallel them.

Even with a bms, don't charge or store lico where you wouldn't build a fire.

dnmun · Feb 11, 2014

if you use three of the 4S in series then it is a 12S pack. you would use a 12S BMS or you can buy four of those 4S packs and it would be 16S. use 4.2V for fully charged and you end up with a 50.4V DC pack of 12S or 67.2V for the 16S pack. most of the 36V-48V controllers cannot handle the 67V since they have 63V caps on the input.

Gypsy · Feb 11, 2014

Do you know a good charger that would charge the whole pack if it were 12S2P or I might go 12S3P for 15aH.

Thanks for your help fellas

Rutiger · Feb 11, 2014

Gypsy said:
Do you know a good charger that would charge the whole pack if it were 12S2P or I might go 12S3P for 15aH.

Hyperion EOS 1420i NET3 will do up to 14s at 550w
Thunder 1220 will do up to 12s at 300w

I have read some people say that the Hyperion isn't fantastically accurate at balancing, but it's almost twice as powerful at 550w compared to 300w.

dogman dan · Feb 12, 2014

People worry way too much about .01v balancing. Are you going to discharge your pack till it's life or death for a cell by .01v? Not if you are smart you won't.

Stop discharging before your dive cells off of the discharge cliff, and you can have a pack .1v off and no worries. Even 3.5v stopping point works fine for this. 3.6v even better. Don't hammer your pack out of balance every cycle with very deep discharges.

If you have a cell that's needing balancing every cycle, get rid of it before it burns your house down. Better balancing is not the solution, sorting out the crappy cells is.

friendly1uk · Feb 12, 2014

Rutiger said:
Gypsy said:

Do you know a good charger that would charge the whole pack if it were 12S2P or I might go 12S3P for 15aH.

Click to expand...

Hyperion EOS 1420i NET3 will do up to 14s at 550w
Thunder 1220 will do up to 12s at 300w

I have read some people say that the Hyperion isn't fantastically accurate at balancing, but it's almost twice as powerful at 550w compared to 300w.

That is RC stuff not EV like the OP wants.

There are heaps of chargers to choose from. I imagine a 240w unit would do 10ah in about 2.5 hours.

Bestek don't supply chargers do they? That is quite a shame as it means buying from two source's to get a bms and charger.

I run 3 of them bricks to make a 12s 5ah pack, using bmsbattery stuff. About $100 delivered for a smart bms and 240w charger.

edit:

http://www.bmsbattery.com/smart/330-lifepo4lithium-ion-smart-bms-for-513-cells-in-series.html
http://www.bmsbattery.com/alloy-shell/25-alloy-shell-240w-lifepo4li-ionlead-acid-battery-ebike-charger.html

Edit2, For clarity: You can get a 2nd string of 12s and parallel it with the 1st, wire for wire. And a 3rd...4th...

dogman dan · Feb 12, 2014

You are quite correct, that if he uses the bms, then he will have no need to use an RC type balancing charger.

All he will need if he uses a bms is a lithium type charger. A metal shell 5 amps model should work well with the bms, since they generally have pots that allow adjusting both output amps and volts, so the charger can be set to match the bms.

EM3ev is one source, and he will adjust the charger for you if you tell him what you want. You can buy both a bms and the charger from him.

Gypsy · Feb 17, 2014

Thanks fellas, ElectricRider is supplying what I need.

drew12345 · Mar 13, 2014

Gypsy said:
Thanks fellas, ElectricRider is supplying what I need.

Curious how this charger worked out for you? I might buy one soon. Or anyone else who has used one from them.

DAND214 · Mar 13, 2014

So Gypsy,
what is Electric Avenue that is in you signature?
Supplier, you, a local source or what?

Dan

Gypsy · Mar 13, 2014

It is me, I am building eBikes for local customers in Oklahoma City. As far as I can tell the only eBikes available around here are Curries and online sources. We are just getting started but awareness is growing rapidly. We are hoping to convert bunch of brand new eBikers in OKC this summer!

Gypsy · Mar 13, 2014

drew12345 said:
Gypsy said:

Thanks fellas, ElectricRider is supplying what I need.

Click to expand...

Curious how this charger worked out for you? I might buy one soon. Or anyone else who has used one from them.

I went with one from http://em3ev.com/store/index.php?route=product/product&path=37&product_id=120. It is the same as the one from electric rider but it charges at 5A and was cheaper. I use the electric rider charger for my LifePO4 though. These are bulk chargers and you do need a BMS to use them.

drew12345 · Mar 13, 2014

Oh, did you add add 2s to your pack?

Gypsy · Mar 13, 2014

I ended up building a 14S3P pack because I got a good deal on some 18650 cells. I still want to build the 12S pack from those Hobbyking hardcases though for a cruiser or fixie build. Electric rider can supply the charger and EM3ev can probably tune one for it.

dnmun · Mar 13, 2014

avoid the hardcase hobby king packs. they are for the guys with RC cars, and they develop dents inside where the foam tape sticks to the pouches.

drew12345 · Mar 13, 2014

Gypsy said:
I ended up building a 14S3P pack because I got a good deal on some 18650 cells. I still want to build the 12S pack from those Hobbyking hardcases though for a cruiser or fixie build. Electric rider can supply the charger and EM3ev can probably tune one for it.

Great. Unfortunately, EM3ev won't tune down to 12s. I asked him already. He only builds whatever supports batteries he's selling and he is not selling 12s.

dogman dan · Mar 14, 2014

There is a voltage pot inside the EM3ev charger I have. I run 14s though, so I don't know if the 48v charger will be able to turn the voltage down a full 8.4v to 12s. If Paul wouldn't do it, I suspect that it's not able to turn down far enough for 12s.

rborger73 · Mar 14, 2014

dnmun said:
avoid the hardcase hobby king packs. they are for the guys with RC cars, and they develop dents inside where the foam tape sticks to the pouches.

Still don't understand why you think the hardpack 4s turnigy 5000mah packs are for some reason bad. There are people on this forum with thousands of miles on them with no issues. Mine are all packed tight together and can't move a mm.

dnmun · Mar 14, 2014

it is not because they 'can't move a mm' it is because there are strips of double stick foam inside the case that create dents in the pouch when the pouch expands with age inside the hardcase. i have learned that uneven compression and distortion of the pouches as they expand with age is directly associated with the pouch failure.

most people don't think outside the box they are in so all i can do is try to inform them of things they never see because they have never opened a battery to look inside. even fewer people would have enuff experience with pouches to be able to put the information to use anyway. nobody here builds batteries when they can buy them from HK just the way they have to use them with the balancing chargers.

rborger73 · Mar 14, 2014

Well I have 20 of them sitting here so I guess I'll find out.

dnmun · Mar 14, 2014

i doubt it. i have never read of anybody else here ever opening up a lipo pack. very few people ever even opened up their ping packs either.

the damage from the shrink wrap and swelling of the ping packs is obvious if you open them up but nobody ever talked about the damages except me. but i have taken about 15 ping packs apart too.

dogman dan · Mar 15, 2014

You see the same kind of problems with RC packs. Distortion of the outside packs from the shrink wrap crushing in the corners.

This is not much of a problem initially, but as the cell ages it puffs slightly, and that's when the damage happens.

Inside the hard packs, it's just a different kind of the same problem, due to how they tape them up. Since they do change pack contruction from time to time, each time you buy hard packs, you have no way whatsoever of knowing what has been done inside. I would not go quite so far as to say hard packs suck. I have some myself. But I sure don't think they are perfect. I'm not sure what is perfect. Certainly nothing real cheap is going to be ideal.

Back to the soft pack, pings or any other kind, I have been preaching for years to box the tightly in some kind of semi hard container. This helps prevent damage to the outer packs from chafing, or dings in the corner or bottom. But once any kind of soft pack starts growing, it sure puts some pressure on that outer cell in the corner.

rborger73 · Mar 15, 2014

dnmun said:
i doubt it. i have never read of anybody else here ever opening up a lipo pack. very few people ever even opened up their ping packs either.
I would see by how they last not opening them up. The only reason to open a hardpack is if one cell dies and you want to salvage the other cells. No I'm not just going to tear one open for fun. lol

The soft packs as Dogman said will do that on the corners. However the hardpacks to me provide a whole lot more protection from accidental damage. Which I think is the idea for them obviously. They also make it much easier to make solid packs with. Next 2 to 5 years this is all going to change anyways. Battery size density is about to go through some big changes.

Arbol · Apr 26, 2014

Having three 4s of these hardpacks connected in series (no parallel), one has three 5-pin (4s plus ground) JST-XH, so 15 pin.

A 12s BMS has AFAIK 13 pin (12s plus ground).

How is everything connected? Through a balance board?

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