So what am I doing wrong ? NiMH - RC Groups
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Dec 28, 2003, 10:16 PM
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So what am I doing wrong ? NiMH


Hi, Everyone,

So I ask, what am I doing wrong with these darn NiMH batteries? It seems that my sucess rate is at about 50% when it comes to getting these type battery packs to work. For example, I recently recieved two new packs of 8 cell, 650mah kan and slow charged them @50mah 13 hours, tried them out, one pack worked well and the other didn't. Did the same process again, with the same results, pack A held the charge, and pack B didn't. Tried it once more, same results. Mind you, this isn't the first time I've had this problem with NiMH. I had the same problem with a couple of packs of 8 cell 950 kan.

Please advise.

All the best and may everyone have a Happy and Safe New Year.


Angelo
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Dec 28, 2003, 11:51 PM
but it's a nice obsession
jgmtens's Avatar
Sounds like you better send pack B back for a replacement - that's bad luck. We have eight CBP650 packs (same as KAN) and they all worked fine right off the first charge. Jon
Dec 29, 2003, 12:11 AM
Registered User
check pack voltage on pack B if below 8 volts you possibly have a dead cell.
hope this helps
~johnboy~
Dec 29, 2003, 12:33 AM
Registered User
jerbear's Avatar
hello

the last packs i got ..... i had to charge fully - then completely discharge three times before they got up to a long lasting flight.
i have heard before .... when they are new, they need a few cycles to get really good.
Dec 29, 2003, 03:24 AM
Registered User
You're not really charging them for anywhere near long enough. Slow charging is inefficient, if you want 650mAh out you have to put around 50% more in e.g. 1000mAh. If you charge at 50mA you need something like 18-20 hours for a full charge.

Charge them fully a couple of times and see how they go.

Steve
Dec 29, 2003, 09:18 AM
Registered User
Thanks everyone for the quick feedback. I'll look into each one and hope for the best.

Take care everyone and Happy New Year!!!!
Dec 29, 2003, 10:38 AM
flyin' fool
goldguy's Avatar
I just bought a 7 cell pack of 300 mAh NiMH's from E-flight and have cycled them at least 20 times and can't get them over 225. The LOH is not interested in making good on my problem, tells me to e-mail Horizon. What a bunch of crap that is. Make one want to start his own hobby shop.
Dec 29, 2003, 12:51 PM
Registered User
goldguy,

That's Horizon's policy. End user has problems, the LHS is suppsed to tell them to contact Horizon directly. It's one of the few things large distributors do to help out struggling local shops. Most shops can't afford to order two of everything just in case, so they'd have to send it back to Horizon on your behalf anyway. It would take longer to go through the local shop for a replacement, plus the hobby shop ends up spending what little profit they made on your sale to send the item back. On top of that, Horizon gives them a hard time when they do send back defective products.

Don't blame the shop owner.
Dec 29, 2003, 11:44 PM
flyin' fool
goldguy's Avatar
Yes, I guess your right about the hobby shop getting stuck in the middle. Anyhow, how would the LOH owner know what someone did to something electrial and in the case of batteries, did the customer charge them properly. Auto parts suppliers allow no returns on anything electrical once installed.
Dec 29, 2003, 11:50 PM
flyin' fool
goldguy's Avatar
Forgot to mention..........I have a Super Nova, that's not so super, it doesn't like NiMH batteries. I took that 300 mAh pack to a friend and cycled it on his charger, got 310 mAh into it on the first charge.

I've switched over to using my Peak 400, which works flawless and will return my Super Nova to FMA.

I contacted FMA some time ago and was told to return it, they would replace all the switches and give it a dust and clean. I'm glad I waited, as now the new version will charge Lipo's as well. I'll see if my old one can be up-dated, with a new board or whatever. Now that would be great.

So, after all was said and done, it wasn't the batteries that were at fault. I'll make sure I inform the LHS as he has more invertory of those batteries, heck I may buy another pack.
Last edited by goldguy; Dec 29, 2003 at 11:59 PM.
Jan 11, 2004, 03:13 PM
Boffin
rpage53's Avatar
My SuperNova charges just fine, but the cutoff of 0.9V/cell sometimes means that small NiMH don't show a very high capacity on discharge. On a 1C discharge, they usually show full capacity.
So I worry less about what the discharge capacity is and just check that it doesn't deteriorate over time.

Rick.


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