9v rechargeables and charger

[johns]

I'm looking for help to find a good quality 9v charger and rechargeable batteries.
Want to use it in a tens machine.
Thanks for any suggestions!

 

[Light Sabre]

I always stayed away from 9v rechargeable because of their low capacity. I always thought that they were low like 150 mAh, but I see now that some manufacturers are up to 300 mAh. That compared to ~600 mAh for primary 9V's (Best ones are Energizers, best price Home Depot in the 6 pack). Lithium 9V primaries are ~1200 mAh (Ultralife brand, ~$6 or $7 at Lowes). The voltage for rechargeable 9V's are multiples of 1.2v (they have multiple single cells in them). So they have a voltage output of 7.2, 8.4, or 9.6V depending on manufacturer. If your tens machine is voltage sensitive the 7.2 ones might be too low. So the 8.4V ones or the 9.6V ones would be the way to go. The voltage cutoff point for a 9V battery is considered to be 5.4V by manufacturers. Your equipment may have it's own idea what voltage is too low.

No idea on chargers. There is one charger that only handles only 9V's and has slots for 4 batteries. From what I have gathered 9V rechargeables do not quick charge so it's more like a 12+ hour charge time.

Here are links about 9V batteries and chargers:

9V batteries: Thomas Distributing

9V only chargers: Thomas Distributing

AA - AAA - 9V Chargers: Thomas Distributing

AA - AAA - C - D - 9v Chargers: Thomas Distributing

Thomas Distributing just came up doing a search and seemed to have a good selection. I have no personal experience with them, but they have been around a long time.

Hope this helps.

 

[johns]

Great information - thanks much!

 

[SilverFox]

Hello Johns,

The major problem with 9V rechargeable batteries is that often the cells get out of balance. In addition, they are not fast movers, so the chance of getting batteries that have been sitting for an extended period of time on the shelf is high.

The best thing to do is to measure the batteries before you charge them. A 7 cell battery (8.4 volt) should have a voltage above 6.5 volts. If it is below 6 volts when you first get it, you may have your work cut out for you trying to bring it back to life.

Also, most of the chargers are designed for the 8.4 volt batteries. If you try to charge a 9.6 volt battery on them, you will not end up with a full charge and will experience short run times. Keep in mind that the 9.6 volt batteries are generally larger in size and may not fit in some devices.

The best bet may be to go with the 7 cell battery and hope you get a decent battery to start with.

Tom

 

[rmteo]

There is also Li-Ion's such as this 400mAH:

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2644

 

[johns]

Thank you - I appreciate your help!

 

[VidPro]

when you go to look be sure you know the diff between the li-ion type (& li-poly) and the ni-mh type, and the different voltages depending on the need.
like a 9V that uses 2xli-ion has a voltage range of about 8.4-6, which will not work for some things. these thing have a lot of capacity AS LONG AS, the device will still work good with the lower voltages it will get to.
i think there is now also a 3xli-fe too, higher voltage minimal capacity

then if i remember right there are 2 voltages of ni-mh too. using one more cell item, to punch up the voltage at a reduction of total capacity.

 

[GarageBoy]

So which is the preferred type in something like wireless mics?

 

[clintb]

So which is the preferred type in something like wireless mics?

I seem to remember reading a thread on a pro audio forum that the Maha 9.6V NiMh is favored.