Battery Cooked

[markopolo]

Here's a question from a new member of this forum - revcon372 - he had trouble posting this question but was able to send it to me via email.

I own an 88 Xplorer that has a very basic power supply. When not on the highway I leave my cord connected to keep the air conditioner and fridge running and this cooks the battery. I know the wizard would probably be best but wonder if I could put a diode in line to prevent current to the battery and add a stand alone battery maintainer. Please ask the experts out there.
Thanks,
Barry

Anyone here have a suggestion for Barry?

I have a question for you Barry - have you been able to measure the output voltage of your converter at your house battery when plugged in?

Barry - if you still can't post on the forum feel free to email me.

[g1g]

A diode will allow current to flow one way but I don't really see how that is going to help you. A regulator would prevent overcharging. If you are hooked up to 110V for AC and the fridge both are 110V unless the fridge is 12V running off the power supply. Can't you disconnect it at least from the battery and have an automatic charger? I don't know what the "wizard" is that you mentioned.

[renrut]

If I leave my RV plugged in too long, it will kill the house battery. The regulator in the charging system doesn't work properly. It is over-charging the battery boiling the acid out of it. I have to keep a close eye on the acid level. It has to be plgged in a very long time to do this but it does.

If your battey is getting cooked when your unit is plugged in, the regulator in the charging system is probably not working properly. You can check the output voltage of the charging system to see how high it is. A standard battery is 13.8volts DC. The problem is, a lot of charging systems use the battery as part of the regulating circuit so the voltage may be harder to check.

If you try a diode, you would need a really big one. The battery charging system probably puts out quite a few amps. The diode wouldn't limit the current enough. A zenor diode and load resister in the circuit might help but that gets quite involved.

[markopolo]

Received from Barry:

I thank you for posting for me, in answer to the question of output the converter is putting out exactly 12 volts, however there is no current regulation so this voltage is present at the battery any time the 110v is connected,this is apparently destructive to the battery,my plan is to deny the battery this voltage with a 30 amp diode so that the battery will only charge from the alternator but I could still use the 12v when parked without shore power, the wizard I alluded to is part of the charging /desulfication circuitry that is present in the later converters. Thanks again for the link and the feedback. Barry

Barry - does your "cooked" battery boil out like renrut mentioned?

If it doesn't then the problem could be that your battery rarely gets much of a charge. That would kill it quickly. I would have expected you to see maybe 14 or more volts output. 12 volts won't charge a battery.

This chart is from The 12volt Side of Life:



Basically you never want to let your batteries get down to 12.24 volts. That's a 50% state of charge. That's the point when you need to fully charge them again to prevent permanent capacity loss. (tech note: true deep cycle batteries can go lower and recover)

Again, from The 12volt Side of Life:

Float voltage for Lead-Acid batteries should be about 2.15 to 2.23 volts per cell, or about 12.9 to 13.4 volts for a 12 volt battery.

The float voltage is a maintenance voltage. It keeps them happy. The charging voltage would be more like 14.4 volts to fully charge a battery.

I've seen upgrade kits for the old Magnetek converters for not much over $200. What brand is your converter?

The converter in my RV doesn't put out sufficient voltage to fully charge my batteries. I rely on my solar panels to top them off.

[markopolo]

update from Barry:

update, the boss said to quit messing with it, fix it right, and consider this an early Xmas gift, ordered Progressive Dynamics converter with the charge wizard from PPL less than $200, will let you know how that works out, thanks for the feed back, Barry