Hey guys,

Got a battery issue that has me stumped. I'm trying to charge a 5000mAH 2S Gen Ace LiPo on a Venom Pro Duo charger. Not doing anything different that I have been for months now, but tonight I'm getting an "Over Voltage" error when trying to charge with the balance cable connected (even if I'm not balance charging).

I've confirmed the LiPo program mode is set properly at 3.7v. When accessing the LiPo Battery Meter, the cells show balanced at 3.8v. Charge rate is set at 5.0 amps and cell count is set to 2S(7.4v). Charging fails after it checks the battery, telling me it's "Over Voltage".

Tried measuring the charge with a voltmeter. Here's what I'm looking at:


With the red voltmeter lead on the red contact and the black voltmeter lead on the middle black contact, voltage reads 3.81v (consistent with what the battery meter read). However, with the red lead on the red contact and the black lead on the far left black contact, voltage reads 7.62v. This startled me at first, but this seems to be the voltage of the whole pack. I assumed the two black wires would correspond to the two cells in the pack individually. Is this not the case?

Can anyone set me straight on what's going on here?

Why is program mode set to 3.7 volts? You're charging a 2 cell battery, right? Should be 7.4 volts for a 2 cell.

It's 3.7v per cell.

Correct, but shouldn't there be a setting for 2S pack? Don't know anything about these Venoms.

Maybe "program mode" isn't the correct term. What I mean is that in the general settings the LiXX mode is set to LiPo at 3.7V (as opposed to LiFE at 3.3V for example). The actual charge mode is set to 2S at 7.4V.

Some questions to find out:

- Is it on both ports?
- is it also with another battery?
- Is the message not from the input voltage?

That's what I was referring to.

- Yes, it does happen on both ports.
- Yes, happens with both a 2S and 3S Gens Ace battery I have. Doesn't seem to happen with the two 4S SMC batteries I have. I doubt it matters, but Gens Ace batteries have Traxxas connectors, SMC have EC5.
- Not sure what you mean by input voltage. I have it plugged into the wall via an AC power cable just as I normally do.

I can charge the batteries without the balance cable plugged in, but I'm a bit leary about doing that. The voltmeter seems to indicate the packs aren't actually over voltage. Would it be safe to go ahead and let them charge without the balance cable attached?

Are you using a balancer board or do you stick the balancer cable directly into the balancer port?

1 case 1 try to skip the balancer board and in case 2 be sure you stick the connector right.

I am using a balance board, but I'm seeing the same results on two different balance boards using two different channels on the charger. Charger is packed up for some practice today, but I'll try plugging it in directly when I can.

It dawned on me last night that I also had a Hobbywing LCD Program Box that has a battery voltmeter on it. Voltages on all my batteries are all within acceptable ranges (lower than 4.2v, higher than 3.5v). It's really looking to me like its something up with the charger, but that still doesn't explain why my 4S SMC batteries balance and charge just fine.

My buddy has a single Venom charger and I think I'll try them on his today and see if I get a similar error.

I have seen this happen before and was never able to pinpoint exactly what caused it, but it does seem that if you just charge them without the balance plug in standard charge mode it will work OK.