Battery charger

It's time to replace some of my tired NiMh 2700s with some low discharge batteries.
Can I use my existing MAHA MH-C800S charger with the new ones? Any recommendations on batteries and good place to buy?

Thanks and hoping Doug Paul sees this.

MH-C800S will be fine for any NiMH battery. I use my C9000 on Maha's Immedion batteries. Conventional wisdom seems to be that the Eneloops are your best bet for low self-discharge these days, and as my Immedions die I'm going that route. I've pored over the tech specs and I can't see any reason to go with the Eneloop Pro unless you have very specific need for the slightly higher capacity; half the charge cycles and higher price don't seem worth it, and I'm not seeing any indication that they hold up better under high drain conditions (other than the higher capacity.)

It should have no trouble with low discharge NiMH batteries.

David Metsky said:

It should have no trouble with low discharge NiMH batteries.

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Don't the low discharge batteries generally require a slower charge rate? At least the MAHA is adjustable, unlike a lot of cheap-o chargers.

But I attempted to charge a set of low-discharge AAAs the other day (claimed capacity about 850mAh), and the MAHA C9000 reported at the end that it had managed to jam 3000mAh into each cell before pronouncing them "charged". I've never seen this behavior on the numerous AAs I've charged, either regular or low-discharge.

Eneloop AA and AAA are what I've been using for I would say 2 years now. GR8 for XBox controllers, headlamps, and such but my GPS seems to eat em up pretty quickly.

JCarter said:

Don't the low discharge batteries generally require a slower charge rate? At least the MAHA is adjustable, unlike a lot of cheap-o chargers.

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The MAHA smart chargers should be fine with low discharge batteries. Mine works fine.

I can get 2 x 10 hour days out a pair of AA Eneloops (2700 mAh) in my Garmin 76CSx.

Tim

Peakbagr said:

It's time to replace some of my tired NiMh 2700s with some low discharge batteries.
Can I use my existing MAHA MH-C800S charger with the new ones? Any recommendations on batteries and good place to buy?

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Any smart charger for NiMH should work with low-discharge NiMH.

I haven't looked at the market for a while now, but Sanyo (now Panasonic) Eneloops have a good reputation. There is a nice summary of the models at http://en.wikipedia.org/wiki/Eneloop I have no opinion pro or con on other brands.

In general, cells which push to the highest capacities tend to be more delicate and have shorter lifetimes--pay attention to the number of cycles as well as the capacity. (ie "standard" cells will often last longer than "high capacity" cells.)

I bought most of my NiMH cells from http://www.thomasdistributing.com/. It may be worth firing up a search engine to search for suppliers.

Doug

JCarter said:

Don't the low discharge batteries generally require a slower charge rate? At least the MAHA is adjustable, unlike a lot of cheap-o chargers.

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No. C/2 (capacity / 2, ie 1000mA for 2000mAh cells) is a good charging rate for all kinds of NiMH cells. Use a "smart" charger--trickle or timed chargers will damage the cells.

But I attempted to charge a set of low-discharge AAAs the other day (claimed capacity about 850mAh), and the MAHA C9000 reported at the end that it had managed to jam 3000mAh into each cell before pronouncing them "charged". I've never seen this behavior on the numerous AAs I've charged, either regular or low-discharge.

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Are the cells old or damaged? Old or damaged cells can exhibit anomalous charging behavior. (In fact, such behavior is an indication that the cells are worn or damaged...)

Chargers will also occasionally fail to detect that a cell is full and will continue charging too long. Over-charging can damage NiMH cells.

I have some old cells which I use for light duty use around the house--they are worn and the charger will often reject (ie fail the pre-charge test) them if I attempt to charge them at C/2. However, the charger will accept and charge them at a lower rate.

Sometimes a fully-discharged worn cell will be rejected at any setting of a smart charger. I use a short period (eg 1 hr) of trickle charging (on a Maha MH-C124S trickle charger) to put a small charge in the cell and finish the job with the smart charger.

One advantage of chargers such as the Maha C9000 is that one can use their test modes to measure the health of one's cells. I do most of my charging with a simpler charger (Maha MH-C401FS), but have a similar charger for testing and rejuvenation.

Note: the above advice applies to NiMH cells only.

Doug

jniehof said:

Conventional wisdom seems to be that the Eneloops are your best bet for low self-discharge these days, and as my Immedions die I'm going that route. I've pored over the tech specs and I can't see any reason to go with the Eneloop Pro unless you have very specific need for the slightly higher capacity; half the charge cycles and higher price don't seem worth it, and I'm not seeing any indication that they hold up better under high drain conditions (other than the higher capacity.)

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I have a mix of normal and low-discharge cells and also plan to replace the normal cells with Eneloops as they die. I too have concluded that the normal-capacity Eneloops are preferable to the Eneloop Pros. High capacity cells are often more susceptible to damage in high drain applications. (Some headlamps might draw enough (eg >500mA) to be considered high drain for AA cells. GPSes are generally medium drain for AA cells, eg 100-200mA.)

I haven't studied the latest products, so I have no specific opinions on them. However, the general guidelines probably still apply.

Doug

DougPaul said:

Are the cells old or damaged? Old or damaged cells can exhibit anomalous charging behavior. (In fact, such behavior is an indication that the cells are worn or damaged...)

Chargers will also occasionally fail to detect that a cell is full and will continue charging too long. Over-charging can damage NiMH cells.

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I had 2 sets of 4 AAAs, all basically new. They claim to come pre-charged, but failed to operate when put in the device, so I popped them in the charger. Next morning the C9000 said it had successfully charged them to 4 times their rated capacity.... All "Energizer Recharge". I'll see what the analyze cycle says about them.

JCarter said:

I had 2 sets of 4 AAAs, all basically new. They claim to come pre-charged, but failed to operate when put in the device, so I popped them in the charger. Next morning the C9000 said it had successfully charged them to 4 times their rated capacity.... All "Energizer Recharge". I'll see what the analyze cycle says about them.

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The fact that pre-charged cells arrived discharged is suspicious... And all cells being discharged suggests that the problem is systematic rather than random. (Every now and then, one gets a bad cell or a cell that dies prematurely.)

AAA's typically have a capacity ~800mAh, so a charging current around 400mA would be good.

You might try several rejuvenate cycles to see what happens. (2 or 3 should be enough--you won't gain anything beyond that.)

Once charged, is the runtime in a device (eg headlamp or GPS) normal? (A short runtime could be due to weak or incompletely charged cells.)

Also the brand may be important. I once bought some cheap made-in-China cells... They were junk and didn't last very long.

There is also the possibility that the charger is defective--if it works properly with other cells it is probably ok.

Doug

bikehikeskifish said:

I can get 2 x 10 hour days out a pair of AA Eneloops (2700 mAh) in my Garmin 76CSx.

Tim

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I'm new to my Garmin 62sc. I had it out on Camel's Hump trying to learn it by using it and it tore through a pair of AA Eneloops. It sure could have been user error

DougPaul said:

Also the brand may be important. I once bought some cheap made-in-China cells... They were junk and didn't last very long.

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Energizer is basically synonymous with cheap made-in-China. I bought these locally because we needed a bunch of AAAs on short notice, and the bulk of my NIMH batteries are AAs. Probably a mistake.

JCarter said:

Energizer is basically synonymous with cheap made-in-China. I bought these locally because we needed a bunch of AAAs on short notice, and the bulk of my NIMH batteries are AAs. Probably a mistake.

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Energizer is at least a recognizable brand--the cheap made-in-China cells that I was referring to were not from a recognizable brand.

I would hope that Energizer would be better than no-name...

Doug

BISCUT said:

I'm new to my Garmin 62sc. I had it out on Camel's Hump trying to learn it by using it and it tore through a pair of AA Eneloops. It sure could have been user error

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Or some design problems/bugs...

The Garmin 62sc has a rated battery life of 15 hrs. See https://buy.garmin.com/en-US/US/on-the-trail/handhelds/gpsmap-62sc/prod89556.html. Using the backlight and the camera will shorten the lifetime.

Read http://www.vftt.org/forums/showthre...e-GPS-Plunge-w-GPSMAP-62s-Have-Many-Questions. It has several pertinent points:
* Nessmuk observed a 7hr battery lifetime for the 62s when running a (continuous) compass rose display.
* Paradox found that leaving the camera in the page sequence on a 62sc results in a <6hr battery lifetime.
* A bunch of other good info.

IMO, GPS batteries failing prematurely in the field can be dangerous**. Shortening the lifetime by excessive use of the backlight is obvious, but the hidden power draw of the compass rose display and an unused camera are not. All reasons for experimenting with a GPS before relying on it and for carrying spare batteries. If one needs really long lifetimes (eg weeks), one can leave the GPS off and only turn it on for short periods to get position fixs.

** One should also know and be able to use non-GPS methods of navigation to augment and back up the GPS.

Doug

What the real Doug said. I use lithium batteries exclusively, up to ten times the life and I can leave my Petzl and my Garmin in the car throught the winter. I do not use rechargeables because of their shorter shelf and use times.

Gremlin said:

I use lithium batteries exclusively, up to ten times the life and I can leave my Petzl and my Garmin in the car throught the winter. I do not use rechargeables because of their shorter shelf and use times.

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Lithium batteries perform better than NiMH (and even better than alkaline) in the cold. However, in the warm all three technologies perform similarly for GPSes.

I have used NiMHs very successfully down to temps of 5-10F in my (medium drain) headlamps and GPS. (I generally use NiMHs with NiMH and/or lithium backups.)

In the warm:
* All three battery technologies have similar capacities (~2500 mAh).
* GPSes consume ~100-200 mA (medium drain) which all three technologies handle well.
* Lithium and NiMH handle high drain devices (eg digital cameras) well, alkaline poorly.

So the significantly greater lifetime of lithiums only occurs for high drain devices and/or cold below ~5-10F. (Note: the effective capacities of all cells decay gradually with decreasing temp rather than a sharp cutoff.)

See http://data.energizer.com/PDFs/l91.pdf (AA) or http://data.energizer.com/PDFs/l92.pdf (AAA) for more info.

Rechargeable cells, in addition to being cheaper over the long run, have the advantage that one can always start with fully charged cells without accumulating a stock of half-used non-rechargeable cells...

BTW, some older electronics (including GPSes and headlamps) can be damaged by lithium cells. (Very fresh cells can put out up to 1.8V which is too much for some devices. The voltage tapers fairly rapidly so one can sometimes bleed off the peak voltage in a tolerant device before using lithiums in an intolerant device.)

Doug

I'm a Canuck and I judge everything by how it will work in the cold. Good point about compatibility, I use only Petzl 2 (won't use any other headlamp - but that's another conversation). Ten year shelf life, even in the cold and cold weather performance (I don't have to roll over them in my sleeping bag) do it for me.

Gremlin said:

I'm a Canuck and I judge everything by how it will work in the cold. Good point about compatibility, I use only Petzl 2 (won't use any other headlamp - but that's another conversation). Ten year shelf life, even in the cold and cold weather performance (I don't have to roll over them in my sleeping bag) do it for me.

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OK--lithiums will certainly do the job. For really cold temps, headlamps with separate battery packs (which can be kept warm under one's clothing) are best.

BTW: Batteries don't need to be kept warm in one's sleeping bag--they only need to be warm when you are using them. And batteries which become too weak when cold are generally useable after they have been warmed back up. (I store a number of my batteries in my refrigerator to extend their shelf lives...)

BTW2: Even lithiums have reduced capacity when cold--they simply go to lower temps than the other technologies.

Doug