13BRV3

Greetings,

I've just finished making up 3 new 3S1P A123 packs, and have been unable to charge them with the Sonic charger today. I tried all 3 packs, and didn't notice any difference between them. I had asked about the proper balance connection, and hope what I was told (not by A123) is correct. I know that the charger will give you an error light if you unplug the balance connector, so I presume it would also give an error if the wires were reversed. Since I don't have an error light, I'll assume it's wired correctly.

These were new cells from a popular yellow and black pack, and each cell was 3.3v initially, and the pack total was 9.9v. I ran one pack down until the power fell off, then measured the voltage at 8.45v when I put it on the charger. The charging light blinked constantly for a long time, then slowly started to settle down, until it's on solid, with occasional blinks. I have a clamp DC ammeter on the leads, and am seeing virtually no current flow into the pack. 3 hours later, the pack is up to only 9.52v.

I also tried a single cell, which just sits at 3.31v whether the charger is plugged into it or not. The charging light is on, but there's no current flowing.

Does the first charge of these cells just take forever, or is my charger not working correctly? I fear the latter []

Cheers,
Rusty

Marv829

Rusty, here is the print I used for the balance wires. Your wiring should be correct (A123s have the case as + and the tab as -). What are you using for the charger power supply?

-Marv

13BRV3

Thanks for the great pics Marv. That's exactly how I have it set up, and I have to believe the charger would give me an error light if I had the balance wires backwards. Also, I have very nice 13.8v 23A supplies, to no problems there.

FWIW, it looks like the balancing part of the supply is working, but not the charging part. The cells were about .2v out of balance when I finished running it, but now (after hours of balancing) they're almost exactly the same. Unfortunately, there's only about 20 ma of current flowing, so it would take a long time to finish the charge. I finally gave up, and guess I'll have to call A123 tomorrow.

I have one of the 50v 20a variable supplies that others are using on order, and it might be here tomorrow or Saturday. Hopefully, I can still test these packs this weekend.

Cheers,
Rusty

13BRV3

I got a message from the folks at A123, and already have my charger on the way back to them. Looks like the variable supply I ordered from Tanic won't be here until Monday, so I guess I won't be flying A123s this weekend []

Marv, where did you get the documentation that you posted? Was it part of a developers kit? Is it posted on the A123 site anywhere?

Thanks,
Rusty

Marv829

I requested a wiring diagram when I ordered my balance cables. I do think it is part of the developers hit also.

13BRV3

Thanks Marv. I didn't think to ask when I placed my order, because I assumed they'd send a wiring diagram with either the charger or cables.

I did charge them via my old Dymond Super Turbo Charger. I started at 5A, then stopped it when it hit 11.1v for the 3s pack. I then stepped down in current until the last run was 100ma. I didn't do too much testing, but I think there aren't going to be any surprises.

My biggest wish is that I hadn't gone to LiPos before I tried these. They would be awesome if you had only used NiCd or NiMh batteries. They have enough advantages to still make them a contender compared to LiPos, but performance to weight isn't going to be one of them. It will also be nice if the A123 cells become available in other sizes, because there are applications where these simply won't work. Can't have everything I guess.

Cheers,
Rusty

13BRV3

I got my charger back from A123 today. Thanks for the fast turnaround Brian! Works like a charm now.

Rusty