Maha C808M

[xcel730]

I've been using my Energizer 15-min quick charger (didn't know how bad it was for my batteries), and the Energizer compact travel charger for the past two years. I didn't really think much about it, until I joined CPF and started reading many insight posts ... some of the best posts were by SilverFox (thanks!). After deliberating for a long time, I finally decided to spend $90 of the Maha C808M charger (http://www.thomas-distributing.com/maha-mh-c808m-battery-charger.htm). I never imagined that I would spend so much money on a charger ... most people, including myself, would go with the easier option of buying the combo charger/NiMh package and use it.

I must say, even though the charger was expensive, it's very impressive! It's a pretty big charger, considering it will charge C and D cells, it has 8 independent channels, choice of rapid or soft recharge, and a condition function, which enables you to charge, discharge, and recharge your batteries.

:thinking: I'm a little confused about the condition function. On the manual, it recommends that for every 10 recharges for NiMh, you should condition the batteries. I thought this only applies to NiCad and no NiMh. Is it recommended?

 

[Raymond]

nicads have a memory effect, which means that if you don't discharge them, they'll loose their capacity really quickly.

nimh doesn't have this memory effect, but can still benefit from proper care. Not just more capacity, but also a lower internal resistance (which means higher possible discharge rates and a higher voltage under load).
People more knowleadgeable than me can explain this in detail, but that's the gist of it.

From personal experience, I can tell you it works. I had some nimh batteries that were severely neglected (5000mAh C-cells). They're about 4 years old and were hardly used. So When I tested them a week ago, they had hardly any capacity left (less than 500mAh), but after a few recondition cycles on my charger, they're almost back to their nominal capacity. I just tested the last one of the batch tonight and they all have more than 4700mAh! Simply charging and discharging (using them ) doesn't have the exact same effect. It has to be done slowly and controlled. And that's where your charger comes in, it has those features built-in. Simply select the right program and parameters, and 2 days later you have a cell with a new life ahead.
Or not . . in which case you recycle it

 

[xcel730]

I knew about the NiCad with memory effect, but didn't know how the NiMh could benefit from it. I probably won't recondition it every 10 recharges, but might do it once in awhile. I think I'm going to go ahead and recondition all my batteries now since I've been using them for about a year to two years on the sh*tty chargers that I've been using. :thumbsup:

 

[Turak]

nimh doesn't have this memory effect

Hi Raymond...

You may want to give the following document a once over.....section 2-5.

http://us.sanyo.com/batteries/pdfs/twicellT_E.pdf

Unfortunately, it is becoming a common misconception that NiMh batteries do not suffer from 'memory effect' or the newer term for it 'voltage depression'.

Believe me, they DO. It is nowhere near as bad as a NiCd and it usually goes away with just a couple complete charge discharge cycles. But, all in all, if they are constantly only shallow discharged, they will start to develop capacity problems as well as possibly discharge rate problems.

 

[Raymond]

Thanks for the info
I know that you can ruin a nimh by not taking proper care of it. I usually use the term memoryeffect like in my post above. From personal experience, I know that you can kill off a nicad with just a few wrong discharge/charge cycles. Nimh's can deal with that a lot better, and can be brought back to a healthy state with just a few proper maintenance cycles.

I think that's why the term memory effect sticks so easily to nicads.

At least for me

 

[NA8]

Whatever became of the "pulse" charging method that Maha used on their old MH-C401FS model ? That model didn't have a discharge mode as they claimed the Pulse charging circuit broke up or otherwise negated the crystal growth associated with memory effect in the cells. Do they still use this in their current chargers ? I've read the discharge recharge method works better.

 

[Black Rose]

My Maha C9000 and C800S use pulse charging.

 

[45/70]

Whatever became of the "pulse" charging method that Maha used on their old MH-C401FS model ? That model didn't have a discharge mode as they claimed the Pulse charging circuit broke up or otherwise negated the crystal growth associated with memory effect in the cells. Do they still use this in their current chargers ? I've read the discharge recharge method works better.

I found this to be an interesting read. I've heard this before and believe it's probably true. But hey, at least it doesn't hurt any.

Dave