jump to example.com

How many 9V gadgets do you have around the shop — or the house? Let’s count: there’s the studfinder, the moisture meter, the fox-and-hound wire tracer, a handful of multimeters, a flashlight, a transistor radio. Wow. The list goes on and on! I’m a big advocate of rechargeable batteries, but the nickel-based chemistries aren’t ideal for most nine-volt applications. Now there’s an alternative: Lithium!

Nine-volt batteries aren’t known for their vast capacity or cost-effectiveness, so they typically fill standby applications where just a trickle of power is needed — and where the high voltage simplifies the device’s circuitry. But sometimes their compact size means they end up in applications like flashlights and intercoms, where they don’t last very long because of their low capacity. Using rechargeables in these devices can save money — and landfill space.

Unlike nickel-cadmium and nickel-metal hydride rechargeables, the new lithium-polymer 9V batteries actually offer more capacity than the alkalines they replace — 500 mAh in the lithium versus 150-200 mAh for NiMH and 300-490mAh for alkaline. They also perform better at low temperatures, and can sustain a higher discharge rate.

But the real kicker is that they exhibit very low self-discharge, the annoying property that made older chemistries inappropriate for most of the applications where nine-volt batteries and up installed.

If you work in a studio, these are the batteries you want in your intercoms, wireless mics, and other gadgetry! And at a street price of around $15, they’ll pay for themselves many times over before reaching the end of their 500-cycle lifespan. The charger sells for $35 or so, and will also charge older 8.4-volt NiCd and NiMH rechargeables, if you have ’em around.

9v Lithium Polymer Rechargeable Battery [Thomas Distributing]
Four-bay 9v Lithium Battery Charger [Thomas Distributing]
Street Pricing [Google Products]


5 Responses to A More Powerful, Long Lasting Rechargeable 9V: Lithium-Polymer!

  1. 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.

  2. 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.

  3. Clinton says:

    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.

  4. Clinton says:

    For anyone interested, here’s a more detailed spec sheets that lists that duty cycles at a much lower value.

  5. Aaron says:

    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.

Leave a Reply

Your email address will not be published.