Author Topic: Batteries on Evolv Charge Board (Read 6696 times)

redwolfe · « **on:** July 01, 2013, 03:12:15 PM »

OK so 1 and 2 batteries in parallel on the DNA charge board seems to be common, has anyone gone to 3 or 4 in parallel on the charger? I got a prototype case on Saturday to test out but I want to put it together before I show it off.

Thanks

Poppy26 · « **Reply #1 on:** July 01, 2013, 03:46:30 PM »

It all boils down to how many milliamps the batteries total. Whether you are using One big (ma rating) battery or several smaller ones.
The DNA charger, charges at 500ma so the bigger the ma rating the longer it will take to charge. I believe 1000ma would take 2 hrs.

CraigHB · « **Reply #2 on:** July 01, 2013, 10:07:26 PM »

If you run batteries in parallel, hard mount them. If you try to do it with removable cells, you'll inevitably forget to check the charge is the same or worse, put one in backwards. Either one could cause a battery fire.

If you're using flat cells, you can run as many as you want in parallel assuming the tabs are soldered together. There's really no limit there. It lowers the impedance seen by the battery charger, but generally, they can go quite low. I've had no issue with batteries as low as 6 mOhms, which would be equal to 4 of the 1000mAh 20C cells in parallel.

If you want a battery comprised of flat cells with greater thickness, you have to run them in parallel anyway. 6mm is a common thickness for flat cells and I have yet to see one thicker than 9mm. The shop that did some custom cells for me said their jig only goes up to 10mm when I asked. I was thinking of using a flat cell 18mm thick at the time, but found I would have to parallel two 9mm cells. I ended up just using a couple hard mounted round cells in parallel instead.

redwolfe · « **Reply #3 on:** July 01, 2013, 11:14:19 PM »

Thanks that clarifies it then. I can use the 1000mah cells I have on hand.

Just curious, where would the place be to go to get custom lipo cells made? I want them to be at least 1400-1600mah 10C like yours.

I could get some 1500mah 3S 20C packs I found at aliexpress and take them apart but that takes up more time than I want it to. I might have to go that route though. With this new case I have exactly 21mm of space to work with between the DNA20 board and box wall. Lot of room for options. Though the length of the cells I can use is limited to 68mm. Most cells I have seen aren't much wider than 34mm so that's no problem. I also need to get the case drilled out for the charge board since the guy who did it put it right on the bottom in the middle, and there is no room to put what I want with it like that so I need to make a new spot on the side walll.

CraigHB · « **Reply #4 on:** July 02, 2013, 04:15:57 PM »

It's probably going to be cost prohibitive for you to get customs cells. You can get sample orders in small quantities, but all the shops that make flat cells are in China and shipping makes it expensive, though they don't charge much for the samples.

Probably your best bet will be to parallel two of the 1000mAh 20C cells or cannabalize a 2s or 3s pack. You can also find individual cells of various dimensions from these guys; http://www.batteryspace.com/polymerli-ioncells.aspx The prices are a bit high though.

redwolfe · « **Reply #5 on:** July 03, 2013, 12:41:55 AM »

I tried looking at the 1400mah cells on that site, the PLH-703562-10C but for some reason when I click on it, it loops me to the site home page. I wonder if that means they don't carry them anymore or special order or something like that. Odd. I might end up going with 3 1000mah lipos in parallel instead for this one.

CraigHB · « **Reply #6 on:** July 03, 2013, 01:44:17 PM »

You really can't beat the price on those 1000mAh cells. That would be the cheapest way to go.

You can probably use 2C cells if you want since putting them parallel increases the current output. For example if you parallel three 1.5Ah 2C cells you would get a maximum current output of 9 Amps which is plenty.

http://www.batteryspace.com/polymerli-ioncell37v1500mah703562-2c555wh3arate-ullisted.aspx

thadass · « **Reply #7 on:** July 07, 2013, 03:27:20 AM »

The mod I'm currently working on is going to use 3 lipo cells in parallel, good to know it should work. They're on their slow way from China so I hope they fit when they get here! Going to use the Evolv charger as well.

CraigHB · « **Reply #8 on:** July 07, 2013, 04:40:43 PM »

Just check they're all at the same voltage (within a few hundredths of a volt) before connecting them up. They should be. New cells normally ship at 3.8V withing a few hundredths. That's the optimal storage charge (40%).