Battery question

[tuna_fisher]

I have 1 group 27 battery in my Lance 185s TC, I only use it for LED lights and the water pump. My problem is as the sun sets and I'm reading say 13.5v on my meter, within 3 hrs.or less it's reading 12.5, by early morning it's still at 12.5. Why the fast drop in those first 3hours then not at all overnight. It leaves me with not enough power for me to use my heater in the am to take the chill of in the camper. I have a 100w solar panel that is enough for my min. need for juice, I don't remember having this problem in the past. Would this be that my battery is on it's way out or could it be something else? Any suggestions would be appreciated. I haven't done a load test on the battery yet but it's not that old of a battery for it to be on it's way out.

[ajriding]

It will run the heater fine but kills the battery quicklyIt will run the heater fine but kills the battery quickly.

I cannot help further.
The heater motor is a big amp draw, but should run off and on all night then be dead by morning. I have two batteries and even when they were new the heater would draw down the voltage quickly. On very cold nights when it would run half the time both batts would be pretty low by morning and the lights would be half as dim,though I had an ARB electric fridge running too, but it would not draw a lot of power on a cold night.

I would take the battery in to a auto parts store and have them load test it. Those test are not perfect, but will possibly identify issues. They will also want to fully charge it with a high quality batt charger, so you leave it, let them charge it, then they test it. At the least you get a free quality charge…

[tuna_fisher]

time2roll wrote:
Normal. 13.5 is charging, 12.7 full charge resting, 12.2 60% charge in use. You are good to go and the solar is working well for you.

The 12 Volt Side of Life

Good read, thanks for posting.

[tuna_fisher]

Grit dog wrote:
You’re saying it reads 12.5v in the morning but won’t run the heater.
Doesn’t make sense. Or are you saying you run the heater and kill the battery quickly?

It will run the heater fine but kills the battery quickly.

[ajriding]

I would not suspect a meter is the issue. I have never seen a bad one, but maybe there are bad ones.

Will your heater run at sunset? Will it run in the daytime?

Check that the wiring going to the heater is sufficient. Sometimes wires get broken (where there is just a few strands left), or corroded, and the wire can no longer carry the amps needed to power the propane fan motor (I think is what you have, not a electric one)

The fan motor on a propane heater should run even below 12 volts, though audibly slower.

[wa8yxm]

RE Cheep meters.. Now long ago and far away (Well not that far,,,Tekonsha MI and I'm not near (but not in) FLint) I had a very nice very "Consistant" Vacuum Tube Volt Meter (RCA WV77e)

It came with calibration instructions Today I use hand held not plug in meters. But the calibration test procedure should still work.. A brand new Carbon Zinc D-cell (Well you could use an aaa for that matter but the D will give a more accurate calibration on a cheap meter. Alas. What I forget is the voltage. I do recall it is not 1.5 but something else The manual for the WV77e Will tell you what it is

For a full lab calibration there are several things used

A variable voltage source hooked to a mercury cell via a Galvanometer (Amazing I got the spelling right) Hook meter under test to the variable source and adjust so the very very very very sensitive Galvanometer shows NO current flow.. Reading on meter should be voltage stamped on mercury cell.

Done that too.. 50 years ago.

[opnspaces]

12.5 volts should be enough to run the heater. Maybe check the voltage while a helper turns on the heater.

[philh]

turn the heater on from a minute or two to "shed" the surface charge, then take a voltmeter reading... or better yet get a good quality hydrometer.

[Grit_dog]

You’re saying it reads 12.5v in the morning but won’t run the heater.
Doesn’t make sense. Or are you saying you run the heater and kill the battery quickly?

[time2roll]

Normal. 13.5 is charging, 12.7 full charge resting, 12.2 60% charge in use. You are good to go and the solar is working well for you.

The 12 Volt Side of Life

[tuna_fisher]

Thanks for the quick answers to my problem. I'll do a load test on the battery to ck. it's condition, to start. Yes it's a cheap meter.

[pianotuna]

Hi,

Read up on the concept of "surface charge". The 13.5 down to 12.6 may well be the surface charge dissipating. I'd add a 2nd solar panel.

By heater you mean the furnace. I'd have no qualms running it at 12.5 volts.

[camperdave]

Sounds normal to me. As the solar goes away, the battery is going to settle to 12.6v. If your battery is reading 12.5 but can't run the heater, it may be on the way out.

Really you will be guessing until you install an amp counter type battery monitor. They are not that expensive, require a little wiring and putting a shunt on the ground side of the battery, but will answer all your power usage and battery questions.

[opnspaces]

Is your meter a handheld multimeter or one of the popular built in meters that people are installing as of late?
Link to meter

As wa8yxm suggested it is possible that your meter is slightly off especially if it's one of the $4.99 or sometimes free Harbor Freight meters. I have a Harbor Freight meter that was low by .2v when compared to my Fluke meter.

You might find another camper with a meter and compare a battery reading from both to see if they agree.

Have you tried shutting off all loads and then checking for a draw with your meter? It's entirely possible that something is still on and draining power.

[twodownzero]

What you're seeing is normal. 13.5 when there's sun on your panel, and battery voltage when there isn't. A fully charged battery is 12.8v, even with a little load, 12.5 isn't abnormal at all.