A123 charging problem

[JThiessen]

It seems that my battery saga will never end. I HAD thought that I had found the solution with the new A123 packs and new Hyperion DUO. I ran them twice, and they have more punch than I can drive right now. My packs are A123 brand, 6.6V 4600 (2s2p). I run two of them in my Revo with a HV-4.5.

I was initially concerned that I couldnt use the A123 balancer since the plug didnt match up to my chargers balance ports, but an actual customer service email from A123 they said I didnt need to worry about it (maybe it helps that I sent it from work - they'd love to have our airplanes running A123's!).

So yesterday, we ran the trucks hard enough that we both came home with broken parts! Tonight I put the A123's on the charger, but with each set of batteries, the charger only detects 1 cell (3.3V) on one battery. Did I most likely damage a cell on each one?

[Arct1k]

Sounds a bit fishy - what does the multimeter say?

[tc3_racer_001]

i added hyperion taps on mine, just spliced the wires onto the +ve and -ve bullets and soldered a conector directly onto the shortened orange wire. then it ends up nice and neat! cost around $2 each battery to do... ive got a pic in my hyper 8.5 build page.

[JThiessen]

I measured 3.18V on one pack, and 3.8 on the other.

TC, I saw you post on the adaptor. I'll have to do that. Hyperion taps are the same as Flightpower, right?

[jhautz]

Did you run them totally dead. Even though a123 are resistant to abuse you still cant just run them totally dead until the truck just stops. They have a minimum voltage of 2v/cell and running them down below that is not healthy for them.

Fortunately you can probably save them because they are such resilient cells. Set your charger to NiMH and a very low current setting like 0.5 amps and hook the pack to the charger for just a few minutes so you can raise them above 4v. then stop the charge and set the charger to a proper a123 charge cycle, but if you can set the current very low (like 0.5v again) and charge them like that. You should be able to get them back up to full voltage but it will take a few hours to get them there.

Be careful when doing this initial bump charge with the NiMH setting and don't forget and leave them on there. It shouldn't take much at all to bump them back over the 4v minimum so your charger will recognize them properly.

Once you start feeling the power drop off noticeably stop running them. Discharging them to that low repeatedly will certainly effect the life of the cells.

[jhautz]

Oh yea... and if you can balance them while you charge them it would be a good idea, at least during this recovery charge.

[tc3_racer_001]

flight power im not sure... im pretty sure they are different. there are many tables on which taps fit which (i thin kthere is one on www.b-p-p.com somewhere...)

[JThiessen]

Thank's jhautz. I did in fact run them down pretty low - it seems that they have a relatively short drop off. I'm learning here.....but it seems that I may in fact be an old dog.

Originally Posted by JThiessen

I measured 3.18V on one pack, and 3.8 on the other.

TC, I saw you post on the adaptor. I'll have to do that. Hyperion taps are the same as Flightpower, right?

No, not quite- Hyperion same as Polyquest, E-Tec, Poly RC, True RC, Maxamps, Xcite and Impulse.

FlightPower same as ThunderPower Apex, MPX and someothers I've not heard of. If you'll ck ALL eRC site for bamance adapter, they list the common ones.

http://www.allerc.com/product_info.p...oducts_id=3160

[tino_ale]

What is the open-circuit voltage you should not pass with A123?
Typically, when I check the voltage of my packs after running the truck, what's the minimum I should see If I don't want to abuse my A123?

[BrianG]

3.6v/cell peak at full charge, 3.3v/cell nominal, 2.2v/cell discharge (but should rebound back up somewhat).

[tino_ale]

Originally Posted by BrianG

3.6v/cell peak at full charge, 3.3v/cell nominal, 2.2v/cell discharge (but should rebound back up somewhat).

After I've run my pack empty, what is the safe voltage is should bouce back to? Sorry if I ask is because I have no way to know at what voltage they go down to under load...
After my run of tonight, I waited 15 mins and measured 2.7V per cell with no load. Is this too low?

[JThiessen]

Not a single one of our LHS carry balance taps of any brand. So I put in an order last night for six of these http://www.maxamps.com/HYP-2S-Tap.htm and since I couldn't make up my mind, I also bought a couple of these http://www.maxamps.com/HYP-MULTI-GOLD.htm.
The first one will require that I modify every one of my packs, not something that I really look forward to, but I can do it. With the second part, I think I can just make a pair of charging adaptors. I couldnt find 2mm bullet adaptors at Maxamps, but for the balance wire, I could probably use any type of female/male connection system, correct?
Any thoughts?

[Arct1k]

Sorry maybe I've lost the plot - what are you trying to do?

Add a hyperion balance taps to a A123 pack? Are these the "orginal" A123 performance packs with just one tap point?

[JThiessen]

Originally Posted by Arct1k

Sorry maybe I've lost the plot - what are you trying to do?

Add a hyperion balance taps to a A123 pack? Are these the "orginal" A123 performance packs with just one tap point?

Yes, I am trying to make up a balancing set up to replace the "original" single tap, so that I can "rescue" my packs.