Maha C808M - condition batteries every time or just soft charge?

[ualdriver]

Hi-

After reading all the threads on the various chargers, I bought a Powerex C808M. As you all know, one of the features of the charger is the ability to condition your rechargeable batteries.

I have numerous NiMh batteries of various ages. I've ran them all through the charger once, on the condition/soft charge cycle. When I use and recharge these batteries in the future, does it help or prolong the life of the batteries if I condition and soft recharge them each time they are charged, since charging time really isn't an issue with me? Or should I just soft charge them and not bother with the conditioning feature once I've already done it once?

Thanks.

 

[Black Rose]

The C808M is only for NiCd and NiMh batteries, not Lithium-ion.

 

[ualdriver]

The C808M is only for NiCd and NiMh batteries, not Lithium-ion.

Yeah, that's what I meant. I was reading about an electric car just before I posted and had Lithium-ion on my mind Original posted edited.

 

[SilverFox]

Hello Ualdriver,

Welcome to CPF.

First of all, the 808M is designed for NiMh chemistry and will not work with Lithium Ion chemistry. I assume that was a simple typo...

The frequency of conditioning cells is related to how they are used. If cells are in storage and you are doing the monthly charge/discharge cycle, you should plan on conditioning them once a year. In normal use where you are using most of the capacity of the cell, you can plan on conditioning them after 20 - 30 charge/discharge cycles. If you are only using less than half of the capacity before recharging, you can stretch the number of cycles out to 50 - 100 before conditioning.

In the last case you will most likely suffer some voltage depression, but since you only need half the capacity of the cell for your use, it will not have a lot of impact on your everyday use.

In my personal use of that charger, I very seldom use the soft charge feature. As a matter of fact, the most frequent use of the soft charge feature, in my case, is when doing a conditioning cycle.

Tom

 

[ualdriver]

Hello Ualdriver,

Welcome to CPF.

First of all, the 808M is designed for NiMh chemistry and will not work with Lithium Ion chemistry. I assume that was a simple typo...

The frequency of conditioning cells is related to how they are used. If cells are in storage and you are doing the monthly charge/discharge cycle, you should plan on conditioning them once a year. In normal use where you are using most of the capacity of the cell, you can plan on conditioning them after 20 - 30 charge/discharge cycles. If you are only using less than half of the capacity before recharging, you can stretch the number of cycles out to 50 - 100 before conditioning.

In the last case you will most likely suffer some voltage depression, but since you only need half the capacity of the cell for your use, it will not have a lot of impact on your everyday use.

In my personal use of that charger, I very seldom use the soft charge feature. As a matter of fact, the most frequent use of the soft charge feature, in my case, is when doing a conditioning cycle.

Tom

Tom-

Thanks for the info and the welcome. Glad to hear that I don't need to condition that often- that will save some time. I am surprised to read that you don't use the soft charge feature. After reading some various posts on this forum, I assumed that soft charging would always be the best way to go as it would minimize heat and prolong cell life? Then again, I don't know much about this stuff, either.

And yes, it was a typo. I fixed it.

 

[SilverFox]

Hello Ualdriver,

I most recently used the soft charge feature while charging some 600 mAh NiCd cells...

Tom

 

[VidPro]

the "soft" charge is not nessiarily a "slow" charge, it pulses, so if i have time i like it , it is still "forming" at the same rate, just doing so much slower, with very little heat.

I dont like its version of "condition" so much :-( because i would prefer that it just discharge then charge, not charge first , then discharge and charge.
but just like Silver said, it totally depends on if they need that VS wasting a cycle over nothing.

put condition and soft together and a D cell, and it just takes WAY to freaking long.
this week i noticed the Last slot on the right gets hotter :-( grrr, why do they do that, they make the thing the size of a boxcar, then have an Area where there is more heat from the curcuitry.
so because i was doing 20, i just avoided the last slot.
mabey i get the drill out and modifry it up a bit

 

[gswitter]

this week i noticed the Last slot on the right gets hotter :-( grrr, why do they do that, they make the thing the size of a boxcar, then have an Area where there is more heat from the curcuitry.
so because i was doing 20, i just avoided the last slot.
mabey i get the drill out and modifry it up a bit

IIRC, they mention that in the manual. I'd rather it didn't get hot(ter) too, but at least they're up front about it.

 

[CyberCT]

But wouldn't just charging (2 amps) without the soft charge mode (1 amp) slowly cause damage to the batteries over time? Shouldn't all NIMH batteries be charged at 1 amp or less? My Tenergy D cells' instruciton says to charge at 1 amp.

 

[hjjaleon]

But wouldn't just charging (2 amps) without the soft charge mode (1 amp) slowly cause damage to the batteries over time? Shouldn't all NIMH batteries be charged at 1 amp or less? My Tenergy D cells' instruciton says to charge at 1 amp.

I'd like to know as well. The reviews which I found on Amazon website said it caused or was likely to cause a fire. I worry if it due to 2A current.

 

[SilverFox]

Hello Hjjaleon,

Welcome to CPF.

If you charge crap cells at 2 amps they will heat up. On the other hand good quality cells won't. When crap cells heat up, most people are unfamiliar with the amount of heat that can come from a cell, so they jump to the conclusion that the charger can catch fire.

With that said, fire is always a possibility when using something that runs on electricity. Also, no charger is perfect.

It is always advisable to monitor your charging, and to set the charger up so that it is not directly in contact with materials that will catch fire in the event of an upset condition.

A cell can heat up to the point where it melts the charger, but the plastic that the charger is made from is flame retardant. Now if things melt to the point of shorting out the circuit board, then you may have some smoke and a possible ignition source.

Before that happens, the high temperature sensor on the charger should kick in, the cell should vent, and you end up with a crap cell that is even more crappy and a charger that has melted plastic damage.

C and D sized cells should be able to handle a 2 amp charge without problems, but if you are concerned just use the soft charge setting. I think you get a more reliable end of charge signal using the higher charge rate, so you run the risk of damaging the cells using a lower charge rate IF the charger doesn't recognize the end of charge signal and continues to charge the cells after they are full.

Bottom line is to use quality and most likely they won't heat up during a 2 amp charge.

Tom

 

[mauiblue]

Thanks Tom for your input. I did a search a couple minutes ago and got to this thread. Ordered this charger last night from Amazon and looking forward in getting it. I always monitor my chargers as I hate to have something happen. I always get good quality batteries from reliable sources so that that will be one less issue to think about.

 

[Anzycpethian]

Hi,

I own a TK70 and Tenergy 10000mah premium cells. When I charge them with my Maha 808M, should I stick to the soft-charge option all the time or is the normal charging better for the cells?

People say that the softcharging can overcharge the D cells but is that really a risk using a high-end device like the Maha and prime cells?
I have enough time, I just want to know the best way to maintain my TK70 setup...

Please help!

 

[CKOD]

Hi,

I own a TK70 and Tenergy 10000mah premium cells. When I charge them with my Maha 808M, should I stick to the soft-charge option all the time or is the normal charging better for the cells?

People say that the softcharging can overcharge the D cells but is that really a risk using a high-end device like the Maha and prime cells?
I have enough time, I just want to know the best way to maintain my TK70 setup...

Please help!

I dont know what the 808M has for D cell current, but you should shoot for 1/2-1C charge rate for a Ni-Mh cell to get a strong -dV singnal for smart/rapid chargers, so 5-10A. If the full power charging doesnt even do 5A definitely go with that all the time.

 

[SilverFox]

Hello Anzycpethian,

Welcome to CPF.

The 808 charges D cells at 2 amps. That is a good recommended charge rate and I would suggest you use that. As the cells age you will have fewer issues with charge termination at the normal charge rate than if you use the soft charge rate.

Tom

 

[SilverFox]

Hello CKOD,

The rule of thumb to charge NiMh cells at 0.5 - 1.0C is targeted to AAA, AA, and Sub C sized cells. Most consumer C and D cells have a suggested upper limit of 2 amps for charging.

Higher charging rates cause more heat build up in these larger cells, and higher heat tends to degrade the cells and these cells tend to have a little higher internal resistance.

With that said, I have charged high quality C and D cells at 0.5C and had no problems. The best thing to do is to review the manufactures data sheet on the cell and follow their instructions. If no data sheet is available, limit the charge rate to 2 amps for these cells.

Tom

 

[CKOD]

Hello CKOD,

The rule of thumb to charge NiMh cells at 0.5 - 1.0C is targeted to AAA, AA, and Sub C sized cells. Most consumer C and D cells have a suggested upper limit of 2 amps for charging.

Higher charging rates cause more heat build up in these larger cells, and higher heat tends to degrade the cells and these cells tend to have a little higher internal resistance.

With that said, I have charged high quality C and D cells at 0.5C and had no problems. The best thing to do is to review the manufactures data sheet on the cell and follow their instructions. If no data sheet is available, limit the charge rate to 2 amps for these cells.

Tom

Good point, wasnt thinking about cube-square issues. and since the 808 goes at 2A for Ds also, looks like it should work out nicely.

 

[dusty99]

Wasn't pulse charging supposed to solve the low charge rate/termination problem?

 

[hank]

Tenergy says (for their current 10,000mAh D cells):
http://www.tenergy.com/10105?sc=59&category=38145

Charge Current:
Standard: 950mA x 16 Hours
Rapid: 1900mA x 7 Hours
Standard Discharge: 0.2C - 1.0C

(Note advice found elsewhere to use a UPS because if the AC power flickers, the Maha defaults to the high rate of charge even if you were doing a low rate)

 

[CyberCT]

Tenergy says (for their current 10,000mAh D cells):
http://www.tenergy.com/10105?sc=59&category=38145

Charge Current:
Standard: 950mA x 16 Hours
Rapid: 1900mA x 7 Hours
Standard Discharge: 0.2C - 1.0C

(Note advice found elsewhere to use a UPS because if the AC power flickers, the Maha defaults to the high rate of charge even if you were doing a low rate)

I use the soft charging for my Tenergy D cells.