# How to test 6 volt sound system batteries?



## Jerry McColgan (Feb 8, 2008)

After years of minimal use and ever weakening performance have finally bought replacement batteries for several of my Sierra Soundtraxx and Phoenix 6 volt batteries.

As I replaced them I noticed that there does not appear to be a recharging circuit other than to direct wire (via a plug in jack) the batteries to a 6 volt 100mA AC adapter.

With that in mind I made a couple of off-loco rechargers where I can recharge batteries before installation or after removal from locomotives. Some locos have plug in jacks for recharging the batteries and some do not. I do not like removing the cover from a tender or from a loco just to get access to the batteries to recharge them so many of my sound systems never get recharged.

Now my question has become whether any of my old and just removed batteries are worth keeping but I do not know of an easy way to test them. I could wire a 6 volt light to them but first I would have to find the 6 volt lights, then wire them, and then keep watch on them to see how long they last.

There must be an easier and more accurate way.

Does anyone have any ideas on how to make a 6 volt 500 mA battery tester?

Thanks,

Jerry


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## Dan Love (Jan 3, 2008)

R=E/I discharge rate 

http://power-sonic.com/site/doc/prod/45.pdf 

Dan


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## Jerry McColgan (Feb 8, 2008)

Hi Dan,

Thanks for the link.

Can you be more specific (its been 40 years since I had electronics training).

Regards,

Jerry



Posted By Dan Love on 03/07/2008 1:49 AM
R=E/I discharge rate 

http://power-sonic.com/site/doc/prod/45.pdf 

Dan


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## astrayelmgod (Jan 2, 2008)

Well, the easy way is to charge it at the float voltage (6.75V for a 6V battery) for at least 10 hours, or until you remember to finish the test. Then, take the charger off it, and put a load of 0.1A to 1A, depending on what large (10W min for 1A load) resistors you have. Measure the voltage, and the time it takes to discharge enough to be visible on page 2 of Dans' reference. As the battery ages, it will get down the curve faster and faster. So, does your time match the curve in the diagram? 

You can also draw a much larger current for just a few seconds, but drawing the proper conclusion is trickier.


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## Jerry McColgan (Feb 8, 2008)

I finally came up with the idea of connecting a series of lights to the batteries and running them all at the same time to compare the 5 old batteries with each other.

I have an abundance of 3 volt (AA) flashlight bulbs along with sockets so I figured 2 lights in series (to get 6 volts) per battery should work fine.

After making up one set I tried each of the 5 of the old 6 volt batteries and not a single one would illuminate the light bulbs. This was after an overnight recharge for each of the batteries.

My conclusion was that none of the batteries have any ability to hold a charge anymore so it's time to throw them away.

If they cannot light two 3 volt AA flash light bulb they cannot be much good for anything.

Thanks,


Jerry


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