Battery Probelm

[Dr. Monstaa]

Okay so I drove my truck yesterday. Some hard bashing and jumps. After I was done running one battery was really hot. Maybe 130-140 degrees. Enough to shrink the shrink wrap even more. So I put it on the charger after it cooled and my Onyx 220 showed 5.99 volts. So I let it charge and the alarm went off within 20 min. So I started it again and I went for another 20 min and it went off again. The total volts was near 11.00, so I put it and the other fully charged battery in my summit and it would barely move. Then I put it on the charger for 3 min and then put it in my summit, and it lasted for about 5 min. So if anyone can tell me what is wrong, PLEASE TELL!!!

[swift06]

I'm not sure, but it sounds like a cell or two went south (bad). Be interesting to see what others think.

[smokeGR]

x2 on the dead cells.

[quadiak]

Okay so I drove my truck yesterday. Some hard bashing and jumps. After I was done running one battery was really hot. Maybe 130-140 degrees. Enough to shrink the shrink wrap even more. So I put it on the charger after it cooled and my Onyx 220 showed 5.99 volts. So I let it charge and the alarm went off within 20 min. So I started it again and I went for another 20 min and it went off again. The total volts was near 11.00, so I put it and the other fully charged battery in my summit and it would barely move. Then I put it on the charger for 3 min and then put it in my summit, and it lasted for about 5 min. So if anyone can tell me what is wrong, PLEASE TELL!!!

total volts near 11? on a 8.4 volt pack, or both packs together? when fully charged you should have 1.2 volts per cell. So if you dropped 2 cells after charging you should have 5 x 1.2 = 6 volts.

If you are reading 11 volts the charger must still be on and you are reading the charging voltage at 11 volts. make sure charger is off for a few minutes, to get rid of any surface charge and check your voltage again.

[NOFX]

Hi guys, 1 of mine did that after I put a 2 motor conversion in.Some thing about electric getting pushed back into the battery .! of the cells at the end burst open .So I cut it off ,resoldered the pack,it works fine now.

[Dr. Monstaa]

total volts near 11? on a 8.4 volt pack, or both packs together? when fully charged you should have 1.2 volts per cell. So if you dropped 2 cells after charging you should have 5 x 1.2 = 6 volts.

If you are reading 11 volts the charger must still be on and you are reading the charging voltage at 11 volts. make sure charger is off for a few minutes, to get rid of any surface charge and check your voltage again.

I let it set for 10 min and it showed 9.57 volts. So I guess I was reading the charging volts. So did it just get to hot and the volts dropped or did I fry a cell? They look fine. Just a little rusty from water.

[Dr. Monstaa]

Ok so I just plugged the battery that got really hot onto my Onyx 210 charger at 3 amp. It started to charge normally, but within a minute it showed the charging volts at 15.35!! Which I belive is NOT GOOD! So I'm pretty sure I fried at least 2 cells. Ebay here I come! Do I have to get two new batteries or can I just get one series 3 just like the other one? Or would this cause bad things to happen?

[scotthw]

Ok so I just plugged the battery that got really hot onto my Onyx 210 charger at 3 amp. It started to charge normally, but within a minute it showed the charging volts at 15.35!! Which I belive is NOT GOOD! So I'm pretty sure I fried at least 2 cells. Ebay here I come! Do I have to get two new batteries or can I just get one series 3 just like the other one? Or would this cause bad things to happen?

it should be fine but its just the newer pack will have better performence then your other pack
how many times have you used your packs

[phel]

total volts near 11? on a 8.4 volt pack, or both packs together? when fully charged you should have 1.2 volts per cell. So if you dropped 2 cells after charging you should have 5 x 1.2 = 6 volts.

The numbers vary slightly, but in general NIMH charging voltage is usually between 1.4 and 1.6 V/cell. A fully charged cell measures as much as 1.4-1.45V with no load, so slightly above 10V for a fully charged 7-cell battery (nominal 8.4V) is ok.

Low-end chargers do from time to time have problems detecting the right cut-off voltage for NIMH-cells, especially on high-capacity cells. The typical symptom is that the charger stops charging, or changes to trickle-mode after only a few minutes. Charging continues if the battery is disconnected and reconnected to the charger (repeat multiple times if necessary), but keep a close eye on the voltage and the temperature of the battery. The battery voltage is supposed to increase steadily until the cells reach full capacity when there's a slight drop in voltage. A charger is supposed to detect this and turn itself off or go into trickle-mode (low current). There is also a sudden increase in temperature that indicates that the battery has reached full capacity, but for that you'll have to use your fingers as sensors unless you've got an expensive charger with a temperature sensor.

The condition of the batteries may be improved if they're run through a controlled discharge-recharge-cycle on an appropriate charger.

[hugh jorgan]

After using any of my batteries, I always let them cool off and then put them on a discharge cycle of 0.5A to a cutoff of 7.2V before starting their charge cycle to 75% (or 2300mAh for a 3000 pack). Before I go out I put them on the Traxxas peak chargers to take them up to full capacity (takes 15 minutes).

Has worked really well so far and I get good long run times out of all of my packs.

Really want a dual charger/discharger though so I can get rid of the three chargers I have (yes 3). The Traxxas charger is just so cheap and foolproof though...

[Dr. Monstaa]

it should be fine but its just the newer pack will have better performence then your other pack
how many times have you used your packs

I have had my summit since December and have ran it almost every day. Almost.

[Bradbozarth]

Do These 8.4v 3000Mah 7cell NiMh batteries need to be cycled occasionally?

[zedorda]

If not used for awhile yes cycling can restore some of the mah but there is often some loss.