[RAFster]

Has anyone noticed a loss of capacity on their NiMH packs?
My understanding was that NiMH packs do not suffer from memory effect but, I'm seeing lower voltages out of the packs that are a year old with maybe 100-150 cycles on them than I am seeing out of packs that same battery but newer. I never charge the batteries over 2A (1100mAH batteries) and leave them with about 1/2 charge when storing.
Is this an increase in Internal Resistance causing the voltage loss?

Some reading I've done on it tells me that for storage full charge is detrimental to the cells, where as 1/2 charge and lower storage temps are ideal.

I guess in the scheme of things the NiMH battery prices we see for 18th scale are low by comparison to 10th scale.

I understand that aging on the Lithium Ion and Lithium Polymer batteries is an issue. As these batteries get older their Internal Resistance and thus their voltage and capacity drop.
Doesn't make pricey batteries like the Lithium look so great then. Proves you can't have your cake and eat it too...

Anyone else seeing these problems?

 

[OvalmanPA]

I've over a period of a year seen the decline in capacity of NiMH cells I run also. As a matter of fact some reach the point of going from a 45 minute charge to 15 or less which indicates to me the pack is just plain going bad. I've also left a partial charge in my packs from week to week. Discharge the morning before using, charge that afternoon at 1.5A, and repeak the following day before racing. Speed seems to have always been there but the capacity drops.

 

[kanesurfguru]

Don't let the NiMH no memory effect fool you, they have been making NiMH batts for laptops for years and they do last longer then NiCads but what they mean by no memory effects on NiMH is that you can charge them half full and then let them sit for a week and then discharge and get a full charge out of them. Where as to the NiCads, if you did that they would only charge to the half way mark and they would "think" they are charged all the way, thus being a memory effect. As far as long term use, I have seen NiMH AA's take a major drop in Avg. discharge voltage in one years time, but not as much as I have seen NiCads take in one years time. Just my two cents. Thanks for all your posts Rafster it is nice to read them and find out what is going on in the world of BRP.....you too Ovalman....

 

[OvalmanPA]

Geez.......who's that smuck? :lol: Long time no hear from KSG.

 

[RAFster]

Thanks for the replies OvalmanPA and KSG. I appreciate the input.

Looks like NiMH cells require fresh replacements every season if you need them to be putting out the juice.

Other than the Lithium cell's light weight they sound like they have a way to go before they overcome some of the detractors. Not real suitable for car use because of the expense and difficulty handling/charging/etc.
Just need a high output 2/3A Nicad to compete with the AA power delivery.

RAFster
David