MH-C9000 with Eneloop or Powerex Precharged batteries

11 years ago I purchased an MH-C9000, but soon stopped using it because of the poor performance of the NiMH rechargeable batteries of that era. I've now become aware of LSD NiMH batteries, and intend to buy a number of Eneloop Pro or Powerex Precharged batteries, but I have a few basic questions first.

I'm aware that when charging Eneloop batteries with the MH-C9000, the charger reports the batteries to be fully charged when their voltage reaches 1.48V, even though at this level the batteries are not fully charged. Is there a similar problem with Powerex Precharged batteries?

I've read that if Eneloop batteries are left in the MH-C9000 for 3 hours beyond the point at which the MH-C9000 falsely reports them to be fully charged, they do become fully charged. Is this the case?

Do chargers such as the MH-C9000 and the BQ-CC65 automatically stop charging when the batteries are full? If not, does this harm the batteries (eg. reduce their life)?

I'm not sure that I need all the capabilities of MH-C9000. If I simply need to recharge Eneloop Pro or Powerex Precharged batteries to their full capacity and keep them healthy, would a simpler charger (such as the Panasonic BQ-CC65) do just as well for both Eneloop and Powerex Precharged batteries?

Hello Ubtree,

Welcome to CPF.

The MH-C9000 actually has three methods of termination. One is maximum capacity, one is -dV, and the third is maximum voltage of 1.47 volts. After termination there is a 2 hour top off charge and then it settles down to a trickle charge. Actually there also is a termination if the cell gets too hot as well.

Many people charge at low charge rates and observe that their termination is frequently maximum voltage. Faster charge rates trigger the -dV termination, but there are times when the charge is terminated at maximum voltage too.

Heat and a long term trickle charge seems to damage low self discharge cells. The MAHA charger seems to be gentle on that type of cell by limiting the bulk charge and also by using a very low trickle charge after the charge is completed.

If your needs are immediate, use the cells as soon as the charger says DONE. If you have some extra time, let the top off charge go to completion. To get the most life from your cells remove them from the charger when the charge is complete and don't subject them to extended trickle charge.

One way to keep track of this is to set a timer when you start the charge. Set the timer for something like 4 hours and then pull the cells. Note that this assumes charging at 1000 mA and that the cells are not completely empty prior to the charge.

Tom

SilverFox said:

One way to keep track of this is to set a timer when you start the charge. Set the timer for something like 4 hours and then pull the cells. Note that this assumes charging at 1000 mA and that the cells are not completely empty prior to the charge.

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Another way is to set a timer for 2 hours as soon as the charger says "DONE". When the timer runs out, take the cell(s) off the charger. The top-off charge is 2 hours, then it drops to a 10 mA trickle charge.

Or if you want the maximum cycle lifetime for your cells (but not have them charged to 100%) take them off as soon as they say "DONE".

Thank you for the replies - they are very helpful.

One thought occurs: are there any intelligent chargers that switch off completely as soon as the batteries are fully charged, so that the batteries are no longer charging at all (and are not discharging)? I would find it helpful not to have to be around in order to take them out as soon as they are fully charged.

I guess I don't really think of "fully charged" cells in the same way that, say, a glass of water is either "full" / partly full / or "empty" ....

There are safe and unsafe voltages, which reflect a state-of-charge and an amount of stored potential energy, but even within the safety limits there are still certain tradeoffs.

The endpoints selected to represent "full" and "empty" are not entirely arbitrary, but not necessarily fixed either.

Ubtree said:

Thank you for the replies - they are very helpful.

One thought occurs: are there any intelligent chargers that switch off completely as soon as the batteries are fully charged, so that the batteries are no longer charging at all (and are not discharging)? I would find it helpful not to have to be around in order to take them out as soon as they are fully charged.

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Sky rc m 3000

If you want a simple smart charger that terminates charging with no trickle charging afterwards, I like the Panasonic bq-cc17. It charges AAA and AA batteries independently, (1,2,3 or 4)but it's pretty slow at about ~300 ma (150 for AAA) average current (1200 ma pulsed at 25% duty cycle). It seems to be doing a great job for my eneloops and amazon basics, but I would like to pick up a smart charger with discharging capability that is capable of charging multiple chemistries, including up to D cell nimh batteries with no top off or trickle charging.

I prefer to use the C9000 to recharge my good cells. That charger is good for charging as it it'll extend battery life with the premature termination with a soft top off charge. I'll use the Panasonic charger if the C9000 is busy charging or refreshing cells and I need to charge some cells right away.

Nev said:

Sky rc m 3000

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I have been unable to find anyone in the UK who still stocks the SkyRC M3000, and wonder whether it has been discontinued. The only other chargers I've been able to find that cut off the current when the charger considers the battery to be fully charged are the Ansmann "Zero Watt" models, but I'm unsure about the quality of Ansmann chargers.