NiMH vs Alkaline Voltage

[catch228]

Not sure if this is the right place to post this but, I have portable speakers that runs on 8 alkaline c cells but will not run on the 8 Accupower Evolution 4500mah batteries.

I haven't had any problems using NiMH batteries in anything else and was wondering if the 1.2V vs 1.5V is a problem.

Any insight would be very much appreciated!

 

[SilverFox]

Hello Catch,

Most times, the problem has to do with the cell not making contact. Some of the Alkaline cells have larger nipples than some of the NiMh cells do. This has nothing to do with the nominal voltages of either type.

By the way, Alkaline cells start out at around 1.5 volts, whereas NiMh cells start out at around 1.4 volts. The nominal 1.2 volt rating has to do with what you can expect the voltage to be half way through the discharge.

Tom

 

[mdocod]

I agree with Tom 100% here, it's probably a contact issue...

I've noticed on my NIMH cells, the "button" on the top is the only contact surface for the positive side, it is surrounded by an insulating material, on Alkaline cells, there is a large portion of metal surrounding the button that also serves as a contact point, I have 2 flashlights that use a strange "spring" on the positive side that wrapped "around" the button top rather than making direct contact with it, this results in faulty connection when using NIMH cells. (these are C cell flashlights in question)...

A quick look at the contacts, and possibly a minor modification should being it up to working.

 

[catch228]

I posted this same question on the Polk Audio website and no one seemed to have an answer...

You guys were exactly correct!! I put a little magnet (the ones from Lighthound) on the positive side of each cell at the end and it works perfectly :thanks:

Don't know what I was thinking posting on the manufacturer site when I already knew all the smart dudes are the guys with the flashlights