Maha MH-C9000 SUPPORT / FAQ Thread

[Mr Happy]

Hi, Mr. Happy, I used the cycle mode to charge the cells, so there was a two-hour rest period for topping up charge.

I don't believe there is a top up charge in cycle mode. You would have to use the regular charging mode.

To get a true idea of your cells' maximum capacity you should run them through a break-in cycle.

 

[Codeman]

Even using a mode that uses top off, I don't think the reported charge numbers include top off, do they? At least, I've never seen numbers go up after "Done" appears.

 

[alfablue]

Even using a mode that uses top off, I don't think the reported charge numbers include top off, do they? At least, I've never seen numbers go up after "Done" appears.

Yes, that's right. Also, in Break-in mode the reported capacity is from the discharge phase.

 

[Mr Happy]

Even using a mode that uses top off, I don't think the reported charge numbers include top off, do they? At least, I've never seen numbers go up after "Done" appears.

It's true, the charge numbers freeze when Done appears. However the voltage readings do remain live and if you watch them you may see them increase for an hour or two after Done, especially with LSD cells. The difference in charge may be seen in the discharge readings if you do a manual discharge test after waiting for the top off to complete.

 

[jusko]

My Powerex 2700 cells have been used for a few times, so now break-in is necessary. I bought the 1st version of C9000 when it came out. The reading from the 1st version was around 28xxmah charging capacity and around 26xxmah discharged capacity. But the 1st version sometimes failed to cut off, the dealer was very kind and replaced it with the latest version. The charging and discharging readings are lower with this newer version no matter which mode I use.

Best Regards
jusko

 

[BabyDoc]

According to the specifications for the C9000, the charger should stop discharging once the voltage has gotten down to 1.00 volts. My charger, one of the newer versions, consistently ends discharge cycle when the cell reaches 0.90 volts. Is this normal? Maha service says not to worry about it, but I thought that over discharging a cell could shorten a cell's life.

 

[Mr Happy]

It's normal. That is 0.9 V under load though -- you will see the voltage jump back up to about 1.2 V after the discharge cycle finishes. Also when you watch the numbers, it only seems to take a matter of seconds for the voltage to go down from 1.0 to 0.9. At that point there is really no energy left in the cell.

Don't worry about it. It's reverse charging in battery sets that does the damage. Draining a single cell to 0.9 V is harmless.

 

[Power Me Up]

According to the specifications for the C9000, the charger should stop discharging once the voltage has gotten down to 1.00 volts. My charger, one of the newer versions, consistently ends discharge cycle when the cell reaches 0.90 volts. Is this normal? Maha service says not to worry about it, but I thought that over discharging a cell could shorten a cell's life.

Yes, that's quite normal - I got an older unit which stops the discharge at 1.0 volts (with the load removed) and a couple of newer units which stop the discharge at 0.9 volts whilst the cell is loaded.

I don't think that the difference is significant enough to cause a problem...

 

[hydrazoon]

I've just bought a c9000 version 0G0KA. It's been running 24 hours a day for the last week and I am happy with it, but I have noticed on Refresh and Analyse, that as it completes it's final charge, the time display increases by a couple of hours. For example: slot 3 completes charging, time 129 mins. "DONE" appears and time jumps to 244 mins.
What's this all about?

 

[Mr Happy]

I believe that when Done appears after charging, the display switches to the information measured and stored from the discharge cycle. So you see the discharge capacity and the time it took. The instructions don't specifically say this about the displayed time, but I'm guessing that's what it is.

 

[Codeman]

That's correct. 129 minutes is how long the final charge took, while 244 minutes is how long the discharge took. Since the purpose of R&A mode is to determine available capacity, it shows the discharge amount and discharge time once the mode is complete (DONE).

 

[hydrazoon]

I assume that the refresh and analyse mode is the same as the cycle mode but only cycling once.

If this is the case, wouldn't it be a good idea for later versions to have a mode where you could choose to terminate on time. You choose the charging current and the length of charge.

I'd feel a lot happier leaving the charger unattended in this mode than relying on -deltaV

 

[SilverFox]

Hello Hydrazoon,

Welcome to CPF.

Terminating on time isn't a good way to go either. Often, you want to just charge up your cells when they are partially used. There isn't a good way to tell what state of charge they are at, so you run the risk of overcharging them if you set your timer wrong. The way around this is to first do a complete discharge every time you charge, but that will cause your cells to wear out faster.

Also, as your cells age, the time to charge them changes.

If you want to play around with timed charges, get yourself a kitchen timer and pull the cells when your time period has ended. This will give you a back up of -dV in case you guess wrong on your time estimate.

Tom

 

[sstmax]

Re: Maha MH-C9000 - reviving old cells

Recently picked up one of these and trying to revive some Jessops (UK camera shop) brand Nimh 2300 AA's.

The instructions recommend:

1: Refresh and Analyze for 1-3 times

2: If capacity is still low, use Break-in Mode

3: If >10% improvement, repeat break-in mode for 1-3 times.

I'm onto stage 3 now in the above process, should I be using the discharge function in between the break-in cycles to avoid overcharge or just apply each charge on top of the last?

I have been discharging between break-ins as it feels like the Right Thing To Do rather than give each cell 3.2xcapacity between discharges which is essentially what running a break-in after a break-in does?

[edit: to tidy formatting]

 

[Mr Happy]

Re: Maha MH-C9000 - reviving old cells

The instructions recommend:

1: Refresh and Analyze for 1-3 times

2: If capacity is still low, use Break-in Mode

3: If >10% improvement, repeat break-in mode for 1-3 times.

I'm onto stage 3 now in the above process, should I be using the discharge function in between the break-in cycles to avoid overcharge or just apply each charge on top of the last?

I have been discharging between break-ins as it feels like the Right Thing To Do rather than give each cell 3.2xcapacity between discharges which is essentially what running a break-in after a break-in does?

Hello sstmax,

Welcome to CPF! :welcome:

There was some discussion on the topic towards the end of this thread. I don't think you will find anything more illuminating on the subject than what was previously said there.

 

[sstmax]

Re: Maha MH-C9000 - reviving old cells

Hello sstmax,

Welcome to CPF! :welcome:

There was some discussion on the topic towards the end of this thread. I don't think you will find anything more illuminating on the subject than what was previously said there.

Thanks Mr Happy,

Great information in that thread. I think I'll carry on discharging between cycles.

Incidentally, I also contacted Maha and was told the same thing, just apply the previous charge on top of the last.

Impressed with this charger. The cells were well down on their 2300 rating, perhaps due to the abuse the 30 min charger dished out to them.

They're still in a sorry state though, having only climbed from 959mAh to 1335 so far.

 

[webfors]

Hello All,

following up on this thread after almost a year. I was one of the original firmware owners that had termination issues. I got both my c9000 replaced with the 0G0B01 model and they have worked quite well, other then a few quirks with fugly old batteries. I would love to spend an hour reading all the pages to see if there were subsequent issues with this firmware, but no can do with two kids in diapers climbing and yelling at me

I see there have been a few firmware updates since the B01. Anyone know off hand a list of changes? Thanks!

 

[Mr Happy]

We are told there has only been one revision to the firmware since the original release. The changing numbers on the back of the C9000 are just batch numbers and don't signify any change to the operating software.

I have never seen a list of exactly what was changed in that one revision that was made.

 

[Unforgiven]

Continued