Build-A-Battery

ESK8 Electronics
1

I’m thinking about building a 12S battery from a bunch of the Turnigy 1S 5Ah flat packs for the slim profile. http://www.hobbyking.com/hobbyking/store/_18560__Turnigy_5000mAh_1S_20C_Lipoly_Single_Cell.html

I’m pretty good at soldering (work as an EE), but I’ve never tried soldering battery packs. Any tips or tricks for these packs?

For this build I’m hoping to use a BMS for this from here http://www.batterysupports.com/44v-48v-504v-12s-100a-12x36v-lithium-ion-lipolymer-battery-bms-p-393.html

Based on what I’ve read here on the forums, at 12S 5000mAh 20C, I should be able to pull 100A so is that BMS correct? Any suggestions on a charger? What kind of range should I be expecting from this battery? I plan on using Hummina’s hub motors and VESC.

2

not worth it, just do two 6s packs in series

3

obviously that’s the easy way to go but this does seem like a pretty cool project. Could make a super flat pack like this. But I guess you could just pull the 6s packs apart and get the same result lol might need a little resoldering though

As for the 100A, pretty sure that’s just the max the BMS can handle I don’t think these boards really pull that much current. Your battery could technically handle that (20x5Ah) but it would drain in a few minutes and probably toast the motors/esc in the process

4

There is some info on the forum about disassembling 6s packs and laying the cells out in a flatter configuration. I don’t know what your budget is, But if you really want a low profile battery. The S.P.A.C.E Cell is only 1" thick. It has a built in BMS, on/off switch and a capacity meter. Is 36 volts nominal at 270 watt hour which is good for about 10-12 mile range. And there are very nice enclosures that are specifically made to house that battery. Also it is made of lithium ion cells which are less hazardous, last longer and as I understand, they don’t drop voltage as there depleted like lipos do. It stays at 36 volts. Another option would be the Zippy Flight Max 8000 3s 30c. there only about 1" thick and you could put 4 in series 12s 8000mah good for maybe as much as 16 miles and 240 amps

5

@Namasaki I could disassemble some 6s packs but then I’d be at almost the same pricepoint and require more work/risk in taking them apart. For 12 of these at $84 +BMS I’m still way under the price of a S.P.A.C.E Cell.

@SpartanScrub What BMS limit should I go for if 100A is overkill? 60A?

6

The space cell is rated at 30A discharge and thats generally all you need for normal usage. But if you want a little more headroom 40A should do, 60A should be plenty even if you plan to ride aggressively. In perspective, the dual motor Raptor uses a space cell with good effect.

At least that’s what i’ve gathered from reading around on the forum here for while.

7

The SPACE Cell is 60 amp continuous I’m pretty sure. It’s 10s3p.

8

Looking at this old space cell thread, it was (or was going to be?) a 50A BMS.

Edit: My bad. Says right on the website it’s 60A

9

Interesting, not sure if it’s been an update then, since mine got a 30A fuse. Maybe it’s just a lower rated fuse for safety reasons.

1 Like
10

I’ve tested for peak amps going 5 degs uphill hard with dual hub motors running on 12s and still pulled less than 60amps total.

11

30amp fuses can burst 60amps for a couple seconds, which is usually just the very beginning of your acceleration.

Unless you pull the trigger down all the way from a dead stop, you aren’t likely to blow the fuse: especially if you have the space cell optimized VESC settings.

12

I, personally, would go for the overkill. I usually wire the BMS to not be limited. Only use it for balancing the cells. The tabs on the singe 5000mah Turnigy cells have solder friendly tabs. The only downside is you spend a little more money on the single cells as opposed to the 3s or 6s packs.

1 Like
13

Was just going to say that but you can lay them down like three 2S packs in series for a super low profile.

14

That’s what I do with two 4s packs to make 8s. Lower profile than 18650 li-ions!

15

Lipos are the economy route! I love the regular 3S pack profile though

16

which 4s packs are you using?

17

Maybe these? : http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9177

18

I used the multistars. They do not have adhesive or glue between the cells.

19

Is their “C” rating adequate or is more than 10C needed?

20

Very interested in this the dual hub amp draw. Planning out a dual hub build on 12s now. What was the peak amps you’ve observed? Did you notice heat in the motors?