NIMH Questions
 

1. What happens if I'm soldering a lead onto a NiMH battery and it gets pretty hot. Will it damage it permanantly? How will I know if it is damaged?

2. What is it safe voltage to discharge a NIMH down to?

3. What is C rating is it safe to charge a NIMH at?

4. I had to change the config of my battery setup and one of the batteries got pretty hot from soldering. I let the pack cool down and tried to hook it up to my charger. My charger didn't recognize that there was a pack the first few times and then it accepted it. For some reason when it started charging the voltage went up and peaked very fast, after adding like 70mah, when I tried to discharge it, it would bottom out after about 50-80mah. I did this several times and it kept doing the same thing. The last time I did it it has actually added close to 4000 mah to the pack, it's a 6 cell 4200. Do you think the pack is damaged? Whats the deal?

RE: NIMH Questions
 

You usually want to charge at or less than 1C for good Nimh cells, such as those IB4200s, unless you're racing and are willing to shorten the overall lifespan of the cells in favor of faster charge times, and better initial punch from a higher C rating charge.

I charge my 6-cell IB 4200 stick pack at 2.5-2.6 amps, or 2.9 amps in a "hurry." Takes about ~1.5 hours, because they are about 7.3-7.5 volts when the truck starts to just crawl or slow down big time.

RE: NIMH Questions
 

I charge at 1 or 2 amps after battery break in. I have a Trinity Thunder 3200 6 cell pack that runs good. And I have a GP 3300 6 cell from Radio Shack that goes noticeably better. I mean faster. I can charge it at a safe 1 amp and it will still go faster and longer than the Trinity. Guess where I'll be getting another battery pack or two.

RE: NIMH Questions
 

How hot is pretty hot? I was using a charger that was defective and the batteries got to 131F. I let is cool and used it normally things seem to be alright.

RE: NIMH Questions
 

You want to discharge nimh to .9 volts per cell. So 5.4 volts for a 6 cell pack and so on.

RE: NIMH Questions
 

If your using I.B. 4200 charge them at at 5 amps and it's normal for the pack to reach a 125-130 *F.

RE: NIMH Questions
 

If soldering you may have ruined that cell if you touched it for very long. I understand there are plastic dividers inside that can melt. Remember soldering irons are in the 400+ range of temps.

when I solder batteries I use a very hot iron, then touch the battery for a brief second to let the solder melt. If you hold a soldering iron on for very long the heat has time to build on the cell and conduct to the inside.

Make sure you scuff your battery posts clean with steel wool or fine sand paper before tinning them with solder so it will stick quickly. Otherwise you have to hold the soldering iron on and 'cook' the solder on with lots of heat.

If your charger can charge one cell, try charging just that cell.

If not, when charging, does that cell get warmer quicker than the rest? That could be an indicator that cell could be bad.

RE: NIMH Questions
 

no its not

RE: NIMH Questions
 

Sorry, I am wrong about the temp. I raced today and ckecked the temp of my batteries and the hottest temp was 112*f