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09-03-2010 08:32 AM | |
CanajunFlyBoy |
Re: NiMH Charging problem Thanks for the comments. Both chargers are pulse chargers... I discharged at 0.5A last night and charged up at 0.2A on my Super Nova. I was able to get 2245mA into her!! That's amazing eh? Whatever the Triton did the battery loved it and my Super Nova is working perfectly after all. I guess it just didn't like the fast charge at 1.0A for some reason, though, as I said, I've done it before lots of times. I'll charge at 0.2A from now on and see how that works. Thanks Guys for all your help. Cheers, CFB |
09-02-2010 07:56 PM | |
moo |
Re: NiMH Charging problem Another possibility is that the super nova is linear and the triton is pulse charging. Eventually batteries designed for 200mA charging are going to show signs of wear when charged at 1000mA. |
09-02-2010 07:42 AM | |
CanajunFlyBoy |
Re: NiMH Charging problem Thanks Guys for all the comments. My Super Nova has the ability to select for NiMH batteries....no question there. The part that I don't get is that it worked perfectly for two years and now I have these issues...could be the self discharge thing. I'm picking up the pack today and, assuming the Triton has "re-set" the pack, I'll try it again on my charger. If it works, then from what I'm hearing, I need to keep it fully charged to prevent the high self discharge issue. On the other hand, maybe I'll just switch to LiPO's !! Cheers, CFB |
09-02-2010 12:46 AM | |
wymbly1971 |
Re: NiMH Charging problem Cougar's touched on it.... And I can lend a limited understanding too. On proper NiMh chargers, the signal to stop charging comes from the delta peak detection threshold and I think it's 5mV for a NiMh. Better chargers also use a very sensitive temperature probe. This is kind of an educated guess but it's like the pressure cutoff switch on an air compressor. The compressor charges quickly and at high flow (current) until the pressure in the tank starts pushing back. At some point (before the tank ruptures), the pressure switch commands the motor to stop turning (compressing) and it is based on a preset system pressure (voltage). My understanding is that the delta V value is the difference between the voltage being exerted (must be higher than the cell to actually charge) and the voltage being pushed back. A NiMh cell will allow you to charge it to a certain voltage that is just before cell damage occurs. A NiMh cell that is overcharging will immediately start overheating, causing oxygen to start venting from a safety valve (if you will). The oxygen that is lost to the environment cannot rejoin the active chemicals in the cell, and so the cell's capacity starts to degrade. That's why Wally World (and NiCd) chargers roast NiMh cells relatively quickly. They simply get overcharged all the time. A hot cell is an overcharged cell. Maybe the Delta V peak detection setting is too low (causing it to be too sensitive)? Charging at a slower rate was a good tactic, BTW. The Triton manual is very good as a guide for other chargers. |
09-01-2010 04:59 PM | |
Cougar429 |
Re: NiMH Charging problem In general, NiMH batts do not require "Cycling" as NiCads do. They suffer from higher self-discharge, though, so storage for long periods will see a larger drop in voltage. There are also differences in how they show peak charge, so one set for NiCads will not work correctly with NiMH. There was a lot of info with my Triton regarding why. Can't remember the finer points, though I can look it up if you need. Don't know your charger, but does it have a selection for the different types? |
09-01-2010 03:01 PM | |
CanajunFlyBoy |
NiMH Charging problem I bought a 2500 mAh JR NiMH battery pack two seasons ago and it has charged flawlessly many times (say 10) on my Super Nova 250S charger. I last cycled it about 3 months ago. I went to charge it recently and I could only get about 250mA into it before the charger said it was full. I discharged and got 250mA out. Re-charged and got only 74mA in, etc., etc., with discharge/charge values between 75mA and 250mA. I did the discharge/charge at 1.0A but also tried it at 0.2A with no improvement. To check if the charger was acting up I charged up a 2000mAh NiCD pack and it worked just fine. I took the battery pack to A & J today and Arden was able to get 1900mA into her using a Triton. Any idea what the problem could be? My Super Nova was used when I bought it. Could it be dying? I was thinking that I should try to cycle it again on my Super Nova now that I know the Triton had no issues. Comments? Thanks, CFB |