Charging My Battery For The First Time

HikinMike

I discharged my battery to 50% then connected my trailer to shore power (plugged it into my garage outlet). I turned my battery switch on and charged for 30 hours. The reading went from 12.06V to 13.69V at the end of the 30 hours. I turned the battery switch off and disconnected from shore power. The reading dropped from 13.69V to 13.09V in 5 minutes. Is that normal?

Thanks to All.

WilliamA

Try turning on a light and check it after 30 minutes.

WilliamA

HikinMike

Turned battery switch on, turned on one reading light for 30 minutes, turned battery switch off, took reading after 5 minutes: 12.98

WilliamA

It would be prudent to take it to a parts store and have it load tested. It will normally drop a bit after charging, but that sounds suspicious. Only way to tell is with a good amperage draw test.

WilliamA

HikinMike

I'm new to battery management, but it seemed odd to me as well.

HikinMike

I know 12.60+ is considered 100% charged, but dang!

WilliamA

@HikinMike said:
I know 12.60+ is considered 100% charged, but dang!

There are lots of factors that determine the surface charge of a battery. Temperature, amperage of the charger, etc. Most folks folks don't realize that while there are "normal" voltage ranges, it's different in each battery. It's also unpopular but true that voltage is a good first step in monitoring battery health but the "good" test is amperage over time. Often, a bad battery will charge to and hold a charged voltage, but drop off quickly when used because of amperage draw. Think of the analogy of a gas tank. The gauge may read "full" but if the tank is caved in and holds only a gallon or two, there's not much energy available. The gauge will still tell you the level, but not the volume of the tank.

My instincts tell me your battery is probably good, but without a high amperage draw test, there's really no way to know. Most reputable auto parts stores will test a battery for you with a strong draw-down tester.

Deep-cycle batteries are a different breed of cat as they don't respond the same to high amperage draw tests. They really aren't designed for high amperage use and it will cause internal swelling that could muddy the results even more. Regardless, it's still the best available test.

My trailer is coming up on its second birthday and has thousands of miles (and with that, charging cycles) on it. I pretty much do everything the experts say not to do with a battery. When I'm off the road, I leave it plugged into shore power for weeks to months. I have only turned the battery switch off once to move the wiring around. I pay little attention to its condition. I couldn't tell you how big it is, though I suspect it's a cheapo group 24. I have never had a power issue. I spend my battery maintenance time making sure my TV charging circuit is in top form. If my battery goes bad, I'll run to the store and get another one. Same size. Probably an Interstate brand. I figure that 2 years of battery life is good. Anything more is free voltage.....

WilliamA