dudeabides

Hey, just got my Thunder AC6 charger and am a bit confused about Nimh charging. Ihave both 6 cell 3300mah and 7 cell 3300mah batteries. Iwent into the user program setting and set it to stop charging at 3300mah. But was surprised to see that it took about an hour to charge the battery at 4 amps and that when it reached 3300mah the battery was pretty darn hot, especially on the end where the wires aren't. So, should I not be charging these at 4 amps? Local hobby shop said 4 amps is fine. If I charge at 3 amps, Iassume that will take longer to charge the battery. An hour seems like a long time to charge (my cheapo Radio Shack fast charger seemed to charge them in about 40 minutes, but then again, the battery barely even got warm before the charger shuts off). Or should I set it to shut off before 3300mah so that the battery doesn't get so hot? Want to be able to fast charge, but also don't want to damage the life of my batteries, so whatever advice you have is helpful.

Thanks!

guver

My Feedback: (325)

Welcome to RCU. Your hobbyshop is right, 4 amps is fine and if it never stops then that is 4000 in 1 hr.

A pack that is uneven temp is indicative of an unbalanced pack and could also explain why it took an hr and nearly 4000 mah (did it take almost 4000 mah?)

The pack should be balanced by doing a c/10 charge for 15 hrs. Then can be used and charged normally.

cooldriver385

c/10? I'm guessing it's 1/10C of the mAh rating? So a 3300 mAh pack c/10 would be 330mA?

dudeabides

Thanks for the welcome, Guver. Learning a lot by lurking in these forums. Unfortunately I don't understand what you mean by doing a c/10 charge. Could you explain a little more?And Iwas under the impression that you only have to worry about balancing lipo batteries, not nimh. Is that not the case? It took an hour to reach 3300mah. How long should it typically take to reach that? And should the battery be hot (uncomfortable to hold for more than 5 seconds) when it's finished charging? Thanks again.

guver

My Feedback: (325)

cooldriver has it. c/10 is 330 ma for a 3300 mah pack. Balancing NI packs is usually not an issue because it is done inadvertently many times anyways. The tip-off that yours is out of balance is "especially on the end where the wires aren't"

If you would do a 330 mah charge for 15 hrs then the pack would be as good as it ever will be.

As far as the time goes : 3.3 amps for 1 hr = 3300 mah
4 amps for 1 hr = 4000 mah This is why I asked you how much was delivered by the charger. 4 amps works out to 66.7 per minute.

The pack should be around 100-110 deg F when done.

cooldriver385

Ya, normally NiMH and NiCad packs don't need to be balanced. Every once in awhile you may wanna balance them.

dudeabides

Great. Thanks, guys!