Comments on: A More Powerful, Long Lasting Rechargeable 9V: Lithium-Polymer!

By: Aaron

Aaron — Sun, 11 Nov 2007 05:54:57 +0000

I have 7 of these batteries that I use in Shure ULX series mics as well as a Shure PSM400 inear monitor and a Sennheiser wireless mic system.

I originally had the 450mAh batteries and they only lastest a few months before they stopped holding a charge. After calling Ipower US, who replaced them all for free even though only a few had died. I have now had them in use for a couple of years.

I charge them once a week at the recomendation of the tech support guy and I have never had a problem with them losing a charge. We use them about 5-6 hours per week with a sustained runtime of 30minutes minimum to 3 hours max.

I am actually online buying more of them for new mics I bought and stumbled upon this posting, so I figured I would post my results. The only thing about them that I don’t like is they are slightly larger than a regular 9 volt, so they fit very tightly in the mics.
The biggest problem with Li-Ion batteries is that if you run them dead, you shorten the lifespan of the battery. The more often you charge them, the better they run. Considering that they should handle 1000 charge cycles, and I charge them once a week, it should be a long time before I need to replace them.

By: Clinton

Clinton — Mon, 15 Oct 2007 23:54:27 +0000

For anyone interested, here’s a more detailed spec sheets that lists that duty cycles at a much lower value.
http://ipowerus.com/specs/9v500mah_spec_060411.htm

By: Clinton

Clinton — Mon, 15 Oct 2007 23:49:46 +0000

Now if these guys can produces a AA sized cell that outputs a true 1.5v while maintaining a respectable mAh rating I’ll be impressed. As far as the duty cycle goes- yeah I wouldn’t expect them to live to see 500 cycles unless you’re charging them atleast every other day. I’m seriously considering picking up three of these and the charger for use in my paintball gear. Two would likely need to be charged every week from the loader but the third one would be most likely once a month or whenever I deem prudent. At that rate even the more heavily used pair would take 9 years to see 500 charge cycles. I doubt they’d last that long but I don’t need them to last more than a few months to make them cost-effective for me. Interestingly wikipedia says - “When compared to the lithium-ion battery, Li-poly has a greater life cycle degradation rate. However, in recent years, manufacturers have been declaring upwards of 500 charge-discharge cycles before the capacity drops to 80%” but the article says nothing about degradation with time. I’d like to see what the voltage/time plot looks like when discharged at a constant load.

By: Nate Bezanson

Nate Bezanson — Sun, 14 Oct 2007 09:29:29 +0000

Good point! I’ve dealt with that finite lifespan effect in laptop batteries. Presumably, rechargeables wouldn’t be deployed except in applications where they’d be cost-effective, which means they’d be getting used pretty hard. But you’re totally right, if somebody stuck one in a smoke detector, it’d die of old age after a few years, during which time it may or may not have ever needed charging.

On the other hand, I have some Radio Shack “high-capacity” NiCd AA’s from about fifteen years ago, when 1000mAh was something to crow about. They still work just fine, and I use them in my Icom scanner which has exceptionally dumb charging logic and would cook any newer chemistry. Poor things just don’t hold a charge more than a week.

By: Daniel Rutter

Daniel Rutter — Sun, 14 Oct 2007 08:41:03 +0000

Note that these batteries may or may not actually survive long enough to be cycled 500 times. Rechargeable lithium batteries of all kinds slowly degrade even if you never even charge them once.

Some LiI batteries only survive for a couple of years from the date of manufacture - so it’s perfectly possible for a “new old stock” laptop or mobile phone battery to be useless out of the package.

Fortunately, some other LiI batteries last much longer, and the lifespan trend has been upward over the last few years. But I still wouldn’t bet on these things making it to 500 cycles unless you’re using them hard enough that they need recharging a couple of times a week.