aftermarket

My Feedback: (2)

Hey all, I just acquired some 7 cell Corally matched gp3300 packs from my lhs. They seem a bit outdated, but they are perfect for my usages. I was wondering, how should I charge these? Like, what mv should I use for each cell?

From my understanding, it should be 5mv/cell, so for a 7 cell pack, 35 mv, correct? I'm assuming different brand cells require different mv ratings...I just read ener-g's need 3 mv/cell..

Thanks.

Dale Gribble

My Feedback: (4)

Do you mean the peak cutoff voltage drop in mV? Or do you mean mA for charging? I would usually charge a pack like that between 3-4A with a 5mV drop peak detection.

aftermarket

My Feedback: (2)

Yes, I meant the peak cutoff voltage drop in mV..

So 3 amps at 35mv is fair enough, correct?

Dale Gribble

My Feedback: (4)

I don't think that is right. I am used to seeing a 3-15mV peak sensitivity range for NiMH batteries which is for the entire pack. I think a 35mV peak sensitivity would lead to overcharging. I usually run an 8mV peak sensitivity, and that's for the whole pack.

aftermarket

My Feedback: (2)

Oh man..

I've always charged my 6 cell packs at 30 mv and they didn't seem terribly hot, depending on the amps they were charged at.. can someone confirm on what they should be charged at?

I charged the 7 cell packs at 1 amp/35mV and they were barely warm. What's that mean? (Just curious, not trying to prove anyone wrong.)

Dale Gribble

My Feedback: (4)

When a pack peaks, it dissipates additional incoming current as heat. So, if you are charging at 1 AMP, the cells are able to dissipate the extra current and just become warm. If you are charging at 3A, the battery can't dissipate the higher incoming current and will get very hot and likely be ruined.

That is how RTR companies can offer plug in overnight chargers for their batteries. It is an overnight charger and charges at such a low rate then even when the battery peaks it can still effectively dissipate the extra current without overheating.

35mV peak detect will overcharge the batteries @ 3A.

86waterpumper

I've got battery packs that like a lower mv, and some packs that I can charge at 3.5 or 4 amps at 40 or 45 mv without them becoming too hot. If I set it lower they simply don't peak and remain cold. I think it depends on the pack and the cells being used. Plus every charger peaks differently even if you set the same mv. I would just go by what the temp gun says and pull the pack off when it hits 120 degrees or so myself.

Chris_RC

I charge my batteries at 3-6mV just because they are high quality batteries. For my eneerg 4600 platinums I charge them at 5 amps, 3mV. Lower quality cells sometimes go down in voltage a bit, which causes a "false peak." So if you have some nicads and charging them at 3mV, they are going to false peak. But with higher quality batteries, they dont go down in voltage when charging but they dont like to be overcharged. I have some practice gp3300s matched that I charge at 6mV.

Dale Gribble

My Feedback: (4)

A lot has to do with how clean the power supply is. If you run a really clean 12v power supply for your charger, you can run a lower peak sensitivity. If you are running an AC/DC charger and plugging into the wall, the power won't be as clean as it would be from a power supply and that can lead to false peaks. 60Hz 110AC power can actually get very noisy. This noise if not properly filtered by the AC/DC conversion in the charger can cause false peaks.

I run a big Bullydog 12V supply that is super clean so I can get away with zero peak-3mV depending on the cells.

86waterpumper

yeah guilty as charged, using a superbrain 960, and my accucel is using some sort of a laptop supply. But it probably just has alot to do with the quality of the cells too. I find that the dtx 4200 cells take more mv to charge than the IB'S and gp3300s Iv'e got do...

hands without shadows

As a rule of thumb, 5mv for Ni-mhs and 8 mv for Ni-cads are good starting points. Every pack and charger is a little different and you can make adjustments as needed, but thats what I would start at.

aftermarket

My Feedback: (2)

Thanks. When you guys refer to "I charge my pack at 3-6 mV", you do mean 3-6 mV per cell, right?

guver

My Feedback: (325)

Yes.