connecting three 48v15ah

[Onvolts]

Hello, i could use some help!

I want to buy headway batteries but i have one big and one small box to fit a new battery.
So i thought, maybe i could connect 3 packs, 48v15ahparallel .

Is this possible? If so, how? Can i use one charger and one bms ?

Hope somebody can help!

 

[dnmun]

so it will be three 15Ah packs in parallel? this is like 60lbs of battery. 200A output? for a scooter or elmoto?

yes, one charger, one BMS. the BMS is in the ground, so all three packs would have their B- black wire tied to the B- on the BMS. the three red wires go to the controller with a splice for the charger. the charger negative, for all three, would be a single wire from the charger to C- on the BMS from the negative charging lead.

you do not have to put each cell adjacent each other, the three packs can be in different locations, but all of the cells have to be attached to each other in parallel by wires that allow each cell to balance with the others, and the BMS sense wire lead would be attached to that wire. the sense wire is tiny, the combining wires could be larger, but don't have to be massive like the serial connections of the cells in each pack. so 24-28G even, but 20-22 would be better for allowing the pack to share slight imbalances during discharge.

 

[dogman dan]

Agree, yes, but the wiring gets more complicated. Since it's headways, it would also be possible to rebuild the packs into two pieces. So it would be 48v 45 ah, but one piece would be say 10s in one location, and then the other 6s in another location. Slightly less wire that way, but still a fairly big job for you to do.

 

[JimmieD]

Hey Onvolts,

dogman and dnmun are correct, you can build a battery in a few separate areas/boxes and still be connected to one BMS and use one charger. Many full sized EV's are built this way. If you have any questions or need any suggestions please do not hesitate to ask, here is a 16S battery that I am building now that needed to fit into the gas tank of the bike.

Dogman is correct though, it can be a spaghetti factory, so be patient and be sure to label your wires!

Cheers!

 

[dnmun]

that thing is artistic.

you can see the new headway BMS on top of those cells on the left side with the big PP75 connector above it.

this new headway BMS is super thin and has like 10 or 12 of the RUI chip 190A 3.8mohm mosfets in the output so that is like .3-.4mohm output impedance. as in no power loss to heat by the BMS. like 40mW heat at 100A. way cool, as in cool cool.

the old headway BMS would not even fit in there. plus this one is now digital. i have always thought the headway BMS was superior, this one is a notch up.

you guys who think a BMS eats current and makes heat should talk to jimmyD and see about getting one from him. especially for the high amp A123 hacks.

he can't be making money at the price he charges either.

 

[Onvolts]

Thanks guys, and nice picture!

I will think about what is the best solution for me. If I go through with it, don't mind me bothering you guys

 

[JimmieD]

Thanks dnmun,

Yes, these BMS's are fantastic, have onl1 had 1 return that I can think of since we have been using them.

Onvolts, that is what most of us are here for, so pick our brains!

Cheers!