Question About Vanner Equalizer

[Jerry32]

What happens when two batteries that are are not in equal condition are hooked to the Vanner? The wind was blowing hard the other day and I hooked up my wind generator to the engine batteries one at a time. When looking at the foltage of each one they were vastly different. One was showing around 14.2 volts and the other was way up around `18 volts. this shows that the resistance of the two batteries are different. Jerry

[pvcces]

Jerry, you can't predict very well what will happen until you are sure both batteries are fully charged. It's possible for a cold battery that is fully charged to show 18 volts when a current is forced through it for a short time.

Since the fully charged battery is not charging but power is being consumed by it, that power is being used to do two different things. Some of that energy is causing water to split into it's elements, hydrogen and oxygen. Most of the rest of the energy is being turned into heat.

Warming the battery, no matter how you do it, will lower the voltage when you force a fixed current through it. This is how overcharging a battery changes it's behavior.

The other battery was showing a normal charging voltage, depending on it's temperature and condition.

If you use a 10 amp charger on the low one, it will stay pretty cool while it is absorbing the charge. As the battery finishes charging, any current still running through the battery will begin to warm it up. That's a sure sign that the battery is charged. Use a hydrometer to confirm.

If a battery quits charging but the hydrometer stays low, that means that the battery is sulfated. There are tools around to desulfate batteries, and it can be quite rewarding.

For what it's worth.

Tom Caffrey

[Stan]

It is not good policy to use a good battery and a bad battery together. A battery with high resistance will cause excessive charging currents in the good battery.

[Jerry Liebler]

Jerry,
    When first setting up the battery bank and the Vanner the battery showing the lowest terminal voltage should be the one with it's negative terminal grounded.  This is because the Vanner can take charge from the other and move it into the grounded battery.  !4.2 volts is about right for the absorption stage of charging, however 18 volts is very much too high.  !8 volts across a 12 volt battery probably indicates a very badly sulphated battery, the other possibility being a battery with no electrolyte (boiled dry).  In any event that is probably a useless battery.
Regards
Jerry 4107 1120