Author Topic: 9v rechargeable batteries  (Read 307 times)

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9v rechargeable batteries
« on: April 23, 2012, 09:51:41 PM »
Our choir director was criticized for roaming the stage during service to collect and turn off the wireless mics to save batteries, so I went shopping for rechargeable replacements from eBay.

I settled on these 8-cell NiMH batteries and they work well

These LiFePO4 rechargeables have a working voltage very similar to alkaline batteries as well but the capacity is pathetic. High capacity 9v alkaline one-use batteries hold about .6 Ah.

The problem with most rechargeable "9v" batteries is that they only have 7 cells and claim 9v based on charging to 1.35v/cell. That surface charge doesn't last long and the working voltage (about 8.4) looks half dead to most devices that use a standard alkaline 9v/PP3 battery.

I had 2 Harbor Freight nicad/nimh multi chargers but wanted another charger as a backup. I spent $40 at Radio Shack for an Enercell 23-790 nimh only multicharger. That turned out to be a gem for off-grid use. It works directly from 12v, either by a car adapter or a 120vac-12vdc switching power supply, charges AA, AAA, C, D, 9v batteries and has a USB charge port on the front.. It charges the 9v Digimaxes in about an hour.

Bruce S

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Re: 9v rechargeable batteries
« Reply #1 on: April 24, 2012, 01:01:52 PM »
For my telecom testing equipment , I use the Powerex "TRUE" 9.6V NiMh ones, great little buggers.230mAh.

I may have a look at the RS charger since it works directly off 12Vdc.
Bruce S
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Re: 9v rechargeable batteries
« Reply #2 on: May 15, 2012, 06:27:57 PM »
The BC1HU charger also runs on 12V, and can handle all those sizes.  Cheaper than the RS charger, but is slower in charging 9V (dumb charge for those?) and does not have USB output.  Otherwise it has worked well for me, although AA/C/D cells in it get fairly warm due to the fairly quick smart charge.  Since I got the BC700 charger I use that for AAs since it keeps them cool (200mA slower charge) plus it's super-smarter - but does not run on 12V.