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Rechargeable NiMH Batteries

 I and some friends have been using rechargeable NiMH batteries in Digitrax throttles for quite some time. All of our batteries and chargers (except the Radio Shack ones mentioned below) have been purchased from Thomas Distributing (http://www.thomasdistributing.com) -- they have been excellent to deal with, and always seem to have the latest technology on the market. (I have no financial interest in this company except as a satisfied customer.)

Batteries

We have used successfully these nominal "9V" batteries:

  • Plainview 9.6V 170mah
  • Maha 9V - 160mAH
  • Tysonic 9V - 200maH

All of these batteries will charge to 9V or greater, as compared NiCD batteries and some NiMH 9V  batteries (like the Radio Shack) which are really 8.4V batteries. For example the Maha & Tysonic will actually test at 9.5V, and Plainview at 10.1V (no load).

A few notes:

  1. Plainview -- initial rechargeable 9V NiMH on the market -- has its own charger. The charger is a small plug in cube that charges one battery at the time. Requires an overnight charge. The documentation with the charger says not to leave the battery on the charger greater than the specified time, or the battery will degrade (I have confirming experience with this!). Been using these a number of years and still have some in use. Appears that as long as they were not overcharged, they are good batteries. Negatives: no fast charging, only two chargers available -- the one battery at a time dumb charger mentioned above, and a smart 10 battery charger (have not tried this but as I recall it's around $225 (special order through Thomas Distributing))
  2. Maha 9V - one of the big names in rechargeable NiMH batteries. Battery works well.
  3. Tysonic 9V - new battery on the market in the last few months. I've received 6, but don't have much usage time on them yet. So far very pleased. It's my choice (of the current crop) for any additional 9V rechargeable NiMH battery purchases.

Chargers

9V NiMH charger technology has substantially lagged the AA/AAA NiMH chargers. Amongst us we have half a dozen Maha NiMH AA/AAA chargers in use and they are excellent. But until recently no one made really smart NiMH chargers for 9V batteries. I mentioned the Plainview chargers above. I was interested in trying the Plainview high end charger, since it keeps a small trickle charge on the battery, unlike the single battery charger. But could not justify the expense.

(NiMH are great for high drain apps, but one of their issues is that they lose a significant amount of their charge over a relatively short shelf life (1-2 months), so I like to have some in the charger ready to go when I need them. The AAA/AA chargers like the Maha C204 are excellent in maintaining batteries at their ready. Having a charger like the Plainview single charger is a pain, because if you have several batteries to charge, you need several chargers, and you need to plan their use right before you need them to get the optimal charge at time of use. I always wished Plainview would do a 4-6 battery version of their high end charger. Note Plainview batteries were designed for the cordless microphone market, and thus for commercial A-V use the 10 battery charger and its price aren't really an issue.)

Radio Shack makes (?made - perhaps recently discontinued) a NiMH charger (23-422) that is a Fast charger for up to 8 AA/AAA batteries (in pairs) or a slow charger for 1 or 2 9V batteries. We've tried these and they seem to work OK -- I've used it to charge the Maha 9V's I have. A buddy says they even charge his Plainview batteries OK. The nice thing about the Radio Shack 9V charger circuit is that even though it is slow, it has a timer, and shuts off after a given amount of time (9 or 10 hours as I recall), so the battery won't be over-charged.  An improvement over the Plainview charger, but it doesn't address the trickle charge issue.

A new product on the market recently is the AccuPower AccuManager 20 charger. From a German firm, the product has six independent charging circuits and will charge up to 4 AA/AAA/C/D batteries (any mix) simultaneously with 1 or 2 9V batteries. And smart technology for the fast charging/trickle charging that is normally found on the AA/AAA chargers also exists on the 9V battery charging circuits. I have two of them in use, but with limited time on them so far. We'll see how they perform over time. If they perform as advertised they will be a great solution. In fact the firm claims to sense the particular battery composition/technology in use and adjusts the charge appropriately. Because they support trickle charging 9V's, I keep them loaded with 4 NiMH batteries. I've been carefully measuring and recording batteries, so hopefully in a few months I can really tell how they are performing.

Another new charger to the market is the Maha MH-C1090F 9V Multi-Channel Smart Charger. This one has smart charging technology as well, and will charge up to ten 9V batteries simultaneously on independent charging circuits. And it will charge the 9.6V batteries as well. A friend just purchased one, and his experience to date is that it has identified some bad batteries, and reconditioned others -- both items that his other chargers had not done.

A few other notes:

  • Do not bother trying the AccuPower 9V battery -- these are also a new 200maH battery, but they are too big. They won't even fit in the DT300, and are an extremely tight fit in the DT400. Use the Tysonic instead.
  • I would not recommend the Radio Shack 9V NiMH battery these days, because the new 9V rechargeables on the market, have a 9V+ charge instead of 8.4, but I know some folks have been using them successfully. The RS batteries are also very expensive compared to sources like Thomas, unless they are on sale. But of course you can walk in and buy one off the shelf.

 

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