Test/Review of Analyzing Charger Powerex MH-C9000

The t.s.backup, was it tested? :) To me, it looks like the top-off charge is timed, exact 120min long, as described in the operator's manual. If this is true, then the charging algorithm is very primitive and goes like this:

However the FAQ's state

"How does the MH-C9000 detect end-of-charge signals from the batteries?

The MH-C9000 uses a combination of Negative Delta V, Zero Delta V, Peak Voltage, time and temperature to determine the end-of-charge. In addition, proprietary algorithms are used."

The CADEX site states

"Modern chargers achieve this by combining NDV, voltage plateau, delta temperature (dT/dt), temperature threshold and time-out timers into the full-charge detection algorithm", unfortunately without going into the technical details and proposing an algorithm in form of a schematic graph.

Do you know of any information site which proposes a sophisticated termination algorithm in form of words or schematic graph, or do you believe that such info is industry secret? :D

It is possible it does have these algorithms, but because the voltage termination is rather low, that will stop the eneloop charge. That was the case with the SKY charger, before I reprogrammed it.

No, the actual implementations are probably kept secret, because a stable termination is a competitive advantage.

Very good review, thanks!

Thanks for the review HKJ.

The power supply on my C9000 failed after 3 years and 4 months of use. I had put 4 Eneloop AA’s in the machine and walked away when the screen lit up. I walked by later and the screen was completely dark. I checked the power supply and it was completely dead. Zero volts. I thought maybe the call for all four slots to put out 1A each (at the same time) was a bit much for the power supply. In any regard, my original power supply looks different from the one in the OP photo. Mine is more square shaped.

And now for the Hollywood happy ending. I found a replacement at a thrift store. Yes, rated at 12V, 2000mA output. I note that these are also available from Powerex, and some clones on eBay. The machine seems to work fine after switching out the power supply.

I am not understanding how this top off charge works, how does the charger know when to go into top off mode, and how does it terminate and go into trickle mode?

I lost my Maha power adapter but dug out a Sony, 12v 3A one that looks more expensive, and has the extra plugin cord going to a box, like the power adapter for laptops.

The positive and negative seem to be the same, so my question is, I think that I have learned here that the higher amps is good, as long as the voltage is the same.

So this adapter is actually better, correct? Does this apply in all cases for all of our adapters?

This is it.

Termination is on voltage, i.e. when the battery reach a specified voltage the charger terminates, then it does two hours of top-off charge.

Higher amp is neither good or bad. The power adapter must deliver enough amps for the device, anything more is not used.

I understand that it can’t use what it can’t use, but for instance, doesn’t the BC3100 benefit from the higher amps?

Is it correct to feel free to interchange adapters as long as I stay with the simple match up of 1. volts, 2. neg/positive, and 3. at least the same amps?

How about a 5% difference in listed volts? Is that close enough? For instance an 18.5 volt adapter for a laptop that calls for 19v?

Some version of the BT-C3100 needed more current than the supplied adapter could deliver, that was the reason a adapter with higher current was better. The has been fixed in the latest version of the charger.

Generally yes. Especially if the equipment is marked with voltage and current.

That will depend on the equipment, generally I would not be worried about trying an adapter that is slightly below the specified voltage. The problems are more likely to occur if the adapter has too high a voltage.

Thanks, that was very helpful.

Since I use so much used and discarded second hand stuff, I am building up a collection of adapters, and worry about stressing things or ruining them straight out.

exactly two hours or does that have a proper termination?

The termination is on time, there is no sensing about the actual charge condition.

Ouch, i see what you mean about no delta v termination, i have noticed different brands of batteries terminate at different voltages, i hope they tuned this to eneloop batteries, since thats what mode people who invest in such a charger will use. On the plus side this can’t miss terminations, i would like to see a charger that has both so if delta v one fails the voltage/time is a backup.

Some chargers do have it, but the voltage termination is often too low, i.e. eneloop will always termination on voltage before they are full.

In my latest charger tests I have added the powerex cell and hope it will show if the charger also has a -dv/dt termination. But it looks like the chargers either uses top-off charge or not and it does not depend on termination method.

I have a Lacrosse BC700 (i am sure you reviewed a similar charger but i can’t find the review) and it terminates on delta v but if thats not a full charge then should i leave it on for a few hours afterwards and let the trickle charge finish charging it?

I have reviewed on La Crosse: http://lygte-info.dk/review/Review%20Charger%20La%20Crosse%20RS1020%20UK.html

It did hit the correct termination each time.

With -dv/dt termination there is never a reason for top-off charge with LSD cells.

sorry, you said voltage termination was not fully charged, i need to get some sleep
thanks for the link, i searched your posts on BLF and couldn’t find it but i remember reading it and even posting on that thread!


thanks, i was going to re-read it in case you already answered a question i have about it, when its charging why does it oscillate around the selected charge current (if i pick 500 it will go from roughly 493-507 updating every second)

Current adjustment is never step-less, the actual number of steps will depend on the hardware. The actual current will depend on selected step and battery voltage.

This means the charger will select a current step, say 507mA. Then the battery voltage will slowly increase while the current drops, when the current is down to 493mA, current will again be increased a step.

It might not be as smooth as described above, because there will also be some noise, that can make it take a step up or down at random times.