PDA

View Full Version : Problem charging batteries...



offroader
06-17-2004, 06:18 AM
I am having trouble charging my batteries and I can't figure out what is going on. I have discharged them on my Trinity discharge tray, but when I try and charge them they charge for less than 2 minutes before the charger says they are done (they only reach about 8.5 volts).

The batteries are GP 3300's (4 of packs of them) and Sanyo 3000's (2 packs of them). 2 of the GP packs are brand new (been charged and discharged a couple of times) the other 2 GP's I bought used but are in good condition. The Sanyo packs are less than a year old (ran in last years points races). I have tried them on both my Novak mellenium charger as well as my MRC Super Brain 959 and the same thing happens.

I ran them all last weekend and they were charging with no problems at all. I'm a little confussed and frustrated with what is going on. I find it hard to believe that there would be something wrong with all 6 packs of batteries, but the fact that the same thing is happening on 2 different chargers is kinda weird..anybody have any idea's?

SteveK
06-17-2004, 07:07 AM
It sounds like they flase-peaking for whatever reason. New or freshly built packs can do this for a short time. What you do is simply keep hitting the charge button until they have peaked. Usually packs will only false peak in the first few minutes of a charge, and if they go for about 10 minutes, they will probably make it all the way.

Eventually, at least with NiCads, after a few complete cycles the false peaking will stop.

offroader
06-17-2004, 07:27 AM
Thanks for the reply. Out of curiousity...around what voltage should they be when they are done charging?

SteveK
06-17-2004, 08:20 AM
I don't really know, my old peak charger doesn't have a volt meter. I go by temperature, but I still use NiCads and I don't think NiMH cells are supposed to get warm/hot like NiCads do.

highroller
06-17-2004, 10:40 AM
I have not encountered any false peaking problems with the GP3300 cells or packs that I've purchased. Sanyo and Panasonics were the ones I had that did have false peaking problems even those that were matched so what I do is just restart the charge, if voltage and MA rate isn't what is normal.

The other problems that could be the cause for GP3300. Cells need time to cool properly before you attempt to recharge them 1.5 to 3 hour depending on ambient temperature. Let them come to room temperture on their own, do not use a fan. If cells are stick packs it could be the tab or weld or connector that's not making proper contact that's causing a break in current. If pack was built using loose cells it possible there is a bad solder joint. After soldering on all the battery bars, and giving time for solder to cool, I check each joint by appling gentle lifting pressure to each bar. If you notice a slight gap or able to lift battery bar the joint isn't solid, just apply a little heat and solder to close the joint.

Best way of soldering cells is to sand or rough up the Positive and Negative end of each cell (Dremel med sanding drum or sand paper), align cells using a pack builder, place a bar on the side you are working on, I use a soldering tool or the Dean's battery jig that holds bars in place. Apply iron to bar, then solder allowing solder to flow over bar and cell surface (try not limit heat 3-5 sec or so) allow solder to solidify then move to next. When holding bar with a soldering tool or screwdriver (small tip) I do all positive tabs allowing me to position bars correctly and giving soldering joint to be solid, then I go back and solder the negative bar tabs. I try to lightly pry up the bars to ensure the joints are solid then move to other side of pack.

After packs are assembled, I then charge them both to further ensure joint and connectors are solid and to get an idea of pack voltage and MA levels.
Peak voltage vary's but on average I'd say it's around 9.38 to 9.45 with ma being 3800-4000 it can vary depending on charger, plus the amp rate and voltage cutoff used.