Running parallel battery pack. I need help please.

[fechter]

You can run the packs in parallel. Just get the voltages really close before connecting.

I have a similar setup on my Sur-ron. Two packs, each with their own BMS, in parallel. One BMS is a "single port" so it can protect during both charge and discharge. The other pack as a "two port" BMS and I charge through that one.

It's good if the two packs are very close in terms of sag. If one pack is a lot stiffer, it will do more of the work during high loads and the other pack will have to shuttle some charge during light load. You want to avoid a lot of current passing between the packs as this is lossy and generates heat. If the packs are identical, they will share the load evenly and there should be virtually no charge passing between packs.

The setup has worked out very well and I have quite a few rides on it. Not only does it double my range, but I can pull 2x more current without overheating anything.

 

[john61ct]

but will the controller demand 40 from each battery or will the controller recognize that one can drain faster and do so?

Soon as you connect in parallel nothing electrical will see anything but a single battery / pack.

The lower resistance sub-pack will always deliver more of the energy

but as I keep saying it gets automatically balanced out in practice does not matter much.

Nothing to do with any control circuitry, just the chemistry & physics of how batteries work.

 

[webosplash]

but will the controller demand 40 from each battery or will the controller recognize that one can drain faster and do so?

it depends on what each battery can give. there are too many variables for that. the controller does not care in the slightest wich battery gives him the power nor does it have control over that.

Do you have any suggestions based on the info i gave?

 

[flippy]

Do you have any suggestions based on the info i gave?

not really , it will work and each battery will simply give depending on their internal resistance, but even the connectors and wires you are using to tie the batteries together are a factor.

unless a bms trips i would not worry so much.

 

[Loydbrawn101@gmail.com]

Hello, can I ask a question about lipo wire guage? I've seen alot of mixed answers on this. Im buying 5 of the turnigy 10c,20 ah, 4series lipo. I'm replacing the xt90s it comes with,with as150 connectors. Il be connecting them in series to get 72volt nominal. I'm putting the as150 directly where the main leads come out of the battery, as short as possible. Since pos and neg as150 connector can be separated, I can plug the pos wire of one battery directly to the neg wire of the next battery( no need for adapters).il separate them to balance charge one at a time. Il be pulling around 80 amps cont and 120 peak battery amps for my kelly controller escooter setup with 8000w qs 260 hubmotor.

So here's my question, will the 12 awg main lead wire the lipo battery comes with be sufficient for 80 amps cont and 120 peak?

The wire will only be 1.5 inches from the battery tab to the as150 connector. Since it's so short,do u think it can handle those amps? I don't really want to connect new wire to the battery tabs, I hear the heat can do damage unless I have the correct spot welder(which I dont),and have the correct knowledge to do it without ruining it(also which I dont). I have a solder pot and was thinking about soldering a thicker wire on the old wire but Since I'm putting the as150 directly where the wire comes out of the packaging, it wouldn't make sense to add extra wire to make it longer. I will only be riding for 15-30 mins. Not many hills but alot of start and stops,and about 350lbs total weight of rider and scooter. The wire that will go from the controller to the battery main pos and neg will be 4 awg wire. I will have an as150 to 4 awg adapter for the final connection that goes to the battery.
Any info would be greatly appreciated

 

[fechter]

Heating is the limiting factor. Having very short leads will help as the heat can get dissipated by the battery on one side and the XT150 connector on the other side. For sure it will handle that much current for a short burst, but for longer durations it might get pretty warm. The amount of air cooling the pack has will also be a big factor. If the cells are all packaged up in a box/bag with no air, things could overheat pretty fast.

In practice, if you have a good gear ratio and you aren't over driving the motor too hard, your average current will be a lot lower than the peak, so wire heating isn't as much of an issue.

 

[flippy]

Hello, can I ask a question about lipo wire guage? I've seen alot of mixed answers on this. Im buying 5 of the turnigy 10c,20 ah, 4series lipo. I'm replacing the xt90s it comes with,with as150 connectors. Il be connecting them in series to get 72volt nominal. I'm putting the as150 directly where the main leads come out of the battery, as short as possible. Since pos and neg as150 connector can be separated, I can plug the pos wire of one battery directly to the neg wire of the next battery( no need for adapters).il separate them to balance charge one at a time. Il be pulling around 80 amps cont and 120 peak battery amps for my kelly controller escooter setup with 8000w qs 260 hubmotor.

So here's my question, will the 12 awg main lead wire the lipo battery comes with be sufficient for 80 amps cont and 120 peak?

The wire will only be 1.5 inches from the battery tab to the as150 connector. Since it's so short,do u think it can handle those amps? I don't really want to connect new wire to the battery tabs, I hear the heat can do damage unless I have the correct spot welder(which I dont),and have the correct knowledge to do it without ruining it(also which I dont). I have a solder pot and was thinking about soldering a thicker wire on the old wire but Since I'm putting the as150 directly where the wire comes out of the packaging, it wouldn't make sense to add extra wire to make it longer. I will only be riding for 15-30 mins. Not many hills but alot of start and stops,and about 350lbs total weight of rider and scooter. The wire that will go from the controller to the battery main pos and neg will be 4 awg wire. I will have an as150 to 4 awg adapter for the final connection that goes to the battery.
Any info would be greatly appreciated

if you plan to make this your commuter scooter i would recommend getting different batteries. no way those will survive riding 40~50mph constantly.

 

[Loydbrawn101@gmail.com]

No,maybe 2-3 times a week

 

[Loydbrawn101@gmail.com]

I was thinking of 1/8 or .25 inch spacers between each battery because they will be stacked with only the sides exposed

 

[Loydbrawn101@gmail.com]

Ideally I would get something bigger but I would need to spend about double for 21700 or lifepo4. Plus I don't know if I could wire and program bms. And buying a pack pre-built is like 3 times as much as these lipos

 

[Loydbrawn101@gmail.com]

Actually there 12c not 10c,if that makes a difference. So I would be running Them at 6c peaks and 4c constant. Maybe I can do 5c and 3c to start out with and see if they heat up at all

 

[flippy]

i doubt you will get beyond 150 cycles with your planned setup. especially if you dont compress the batteries in a frame.

the C rating on those batteries is fictional. please ignore.

Its best to start a new thread for your situation.