How much voltage drop is normal with minimal usage

[Ready2gonow]

I have a 3 stage converter/charger, and 2, 1 year old 12 volt batteries. I have spent most of the last months hooked to shore power, but am planning more dry camping. Only the frig and any phantom amp eaters on. No lights, water pump, etc on. Checking voltage in AM, hooked to power, reads 13.4 volts. With electric off, the voltage drops immediately to 12.9 volts. 7 hrs later, the voltage is 12.4 volts. Is this normal drop? The frig is a double door, set on 2. It is hot in Oklahoma today....which means more BAD weather soon. The dual cooling fans seem to run excessively . I am wondering if the fans are using excessive amps? Do these numbers sound normal? I have a 2000w Yamaha gen. How long should it take to recharge batteries from low 12 v to upper 12 volts? Thanks

[69_Avion]

A voltage drop from a state of charging to the charger off is normal. Fans draw more power than you think. Folks can usually boondock for quite a while when they have all LED lights and no fans running. Usually you here this from folks running the furnace with a fan. Some refrigerators have the exhaust fans and they will create the same issue.

[Ready2gonow]

Thanks

[HiTech]

If you've been plugged in for months, after charging, be sure to check the electrolyte level and top off any low cells to just below the bottom of the filler tube.

Do you know what converter you have charging them? How high a voltage are you hitting for how long when recharging them?

Sounds like normal operation depending on what batteries you have and how much load is on them.

Jim

[mbopp]

To determine what's "normal" you'll need to measure the current draw of the fridge and fans, then calculate the amp-hr load.

[ScottG]

mena661 wrote:
X2 smk, also 12.4V is not 50%, 12.2 is closer to 50%.

X2

[mena661]

X2 smk, also 12.4V is not 50%, 12.2 is closer to 50%.

[time2roll]

Seems in the normal zone. Recharge as you get into the 12.0 to 12.2 range.

Once your battery hits 14.2+ volts then charge for one more hour. This will get you to about 90% charged. The last 10% would take another 4 to 8 hours.

Print this out and keep it with you for a season:

The 12 Volt Side of Life

[wolfe10]

The drop from 13.4 to 12.9 very quickly is just fine. 12.8-12.9 is a fully charged 12 VDC battery. Any voltage above that is just surface charge and will discharge very quickly.

And 12.4 (if measured with the batteries at rest) is a 50% discharged battery-- as low as you want to go before recharging. If the 12.4 reading was with a load on the battery, the battery is in better shape (less deeply discharged).

You don't say what size (in amp hrs) battery bank you have. But with that figure (actually 1/2 that figure, as you don't want to discharge below 50%) and the amp draw of the various appliances and their run time/day, you can calculate pretty closely what you will need to replenish.