Battery got to hot...what caused this?

[MNRCnewb]

I just finished putting together my Matt Francis 2 which is what my Novak 5800 now resides in. On its maiden voyage, I noticed not only was the performance a little down but the battery dropped off rather quickly and gradually. The battery I am talking about is a Orion V-Maxx 2400mah and it's probably been charged 20 or so times.

After the first run I let the battery cool and recharged it. The second time the battery fell off after only a couple minutes driving. I ran the battery down until the wheels of the XXX-T would barely spin freely suspended in mid-air. I then charged it again and it seemed like it had life again but when I took it out it wasn't warm but litereally hot to the touch. Not only this but the blue wrap had actually cracked open in a couple spots exposing the cardboard covering the cells.

I'll admit I don't know much about the batteries in question here but I am wondering what happened here. Also, I use an auto-peak-detect charger set on 2amp charge on 6 cells. I was also using a 21T pinion which is a little taller than Novak recommends for the truck but the ESC was not hot and did not go into thermal protect mode at any time.

Thanks!
Tony

[monyet fangkeh]

2amp charge rate is too low. if your charger allow you to set it higher, set it at 3-4 amp. but still....charging 2 amps doesnt makes your batt go hot ( i think ). maybe you overgear and drain the batts quickly.

or maybe the batt just crap. because i used to have that orion v-maxx 2400 nicad. it just died after 2 months of proper care.

[cr250]

I believe you are slowly killing your battery packs by over discharging them. Running the vehicle until the wheels are barely turning pulls the pack down too low and most likely damages 1 or more cells in that pack. SPC batteries (http://www.specpointbatteries.com) has a good article on Battery Care (http://www.spcracing.com/html/battery_care.html) . The first half of the article deals with assembly, the 2nd half with battery care.

[rocknbil]

Welcome aboard MNRC! :D

Running a battery until the wheels stop turning will not discharge it too far, in fact if it's a nicad pack - that's not even discharged enough. What is important though for either nicads OR nimh's is to COMPLETELY let the battery cool before recharging. Generally the recommendation is 4 hours, safer once a day, but this is not a hard set rule - I've even thrown them in the fridge for half an hour between charges. :D (Not recommended - condensation . . . . )

Also you won't damage a pack by using a lower charge rate, but you'll definately get a charge with less punch.

I don't know that your charging method is the issue here. Note how it wasn't hot when you CHARGED it but when you were done running. This seems to indicate an overgeared or other issue that's causing excessive load on the pack. What motor are you using, is it a hot mod?

It's pretty normal for packs to get very hot after a run, you're moving a LOT of amps quickly and that causes friction amongst electrons. :D What's not normal are these abberations in performance.

As for the short drop-off time - although it may seem like it cooled, it could have just false peaked on recharge because it was recharged too soon, don't know. Try it the next day and see what happens.

[AlexV2024]

It sounds like your packs are just weak. they cant deliver the amps the BL needs to run good so the packs heat up and dont run very long. also charging at low amps some how affects how much punch the packs have and the higher the better. at 4/5 is the point of where theres incresed pucnch w/o life loss. 6-8a does give more punch but really cuts down on life.

You really need new batts and a charger. the novak ionic is a great sport charger and any GP 3300 cell would be an awsome upgrade. spc and promatchracing.com have awsome packs. you only need 1.15's from PMR or w/e spc's lowest matched packs are. and if unmatched GP packs are available those are fine too if your on a budget. GP's will give you much more acceleration, runtime and speed.

~Alex

[racer234]

I had one of those batteries, and it always worked pretty good in my 17 turn Stampede, but as soon as I started using it in my 12 turn T4 (which has pretty similar amp draw to your MF2) it went poof. The heat shrink broke open, just like yours.

[InspGadgt]

I was also using a 21T pinion which is a little taller than Novak recommends for the truck but the ESC was not hot and did not go into thermal protect mode at any time.

Even though your ESC wasn't hot I think your problem lies here. 21T may be a little taller in number of teeth but in 48 pitch it can be quite a bit taller in gear ratio. Though now that your batteries have been heated up enough to split the shrink wrap they very well could be damaged now. I've had some packs keep performing ok after overheating and others that were fried.

[gizmoguy303]

Use a 17 tooth pinion. 21 teeth is EXTREMELY high.


Make sure you let the pack completely cool after discharging it. I would wait 2-3 hours. Also, if your pack doesn't take AT LEAST an hour to charge, then your charger is false-peaking. If this is the case, either reset the charge process until the pack is finally charged, or better yet, buy a better charger.

Next time you buy batteries, get GP3300's. They are simply the best out there right now.

[highroller]

Any battery will get 2 times hotter after use than when it was charged. Several things seem to be contributing to your problem, not discharging correctly running in car is okay but doesn't get each cell to the same voltage level so each time pack is charged cells are never close to the same voltage levels and leads to one cell charging before the rest. Use a string of lightbulbs based on loads you see during use (5-10 bulbs each rated at 2amp) then use a single bulb to try and get all cells to the same voltage (leave bulb on until it dims or use a discharge resister 1w10 ohm value and leave on until it cools or pack voltage is below .10 volts). This methods works with both Nicad and NImH (even with NiMh cells the lower and closer you get each cell the same in voltage levels the better packs charge with less chance of false peaks). Improper car may have lead to premature failure in general: cells not at right voltage levels, not allowing sufficient time for cells to cool between charging (1-3 hours cooling at room temperature) with 2 times use in one day for Nicad, 3 rd use shows a higher decline in runtime (NiMh are about 3 times with the 4th showing the biggest decline in runtime), improper gearing leads to quicker battery failure but shouldn't have been this quick unless other things contributed - so a combination of things may have lead to failure. You may be able to rebuild a good pack or two use cells that are still good. You'll have to charge the batteries and take a voltage reading of each cell (should be above 1.35 volts) then discharge pack again taking a voltage reading of each cell. If pack is in stick form eliminate the ones that are getting warm to hot after 5-20 minutes during charging.

The GP3300 is a good choice for replacement while it is durable, consistant it too can be ruined if not used properly. Forget what you ever read about NiMh they do need to be discharged, the lower and closer you get all cells to each other the better it charges. Yes store them discharged down to 5.40 volts just before charging for use attach a single bulb or discharge resistor or place in an equalizing tray (side by side or saddle packs) packs will charge between (both in voltage, mah rating will less chance of encountering false peaks). Use the manufacturers gearing suggestions, increase by one tooth at a time noting the operating temperature and overal speed of vehicle if things get too hot or you notice a drop in speed go down one tooth until temperature, speed is consistant and normal.