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.

The 13.5 you are reading is the "charging" voltage from the solar panel.And that really isn't enough to give it a good charge.What kind of "heater" are you trying to run ?If it is propane and the battery runs only the fan, 12.5 should be fine for a couple of hours.It is possible that your battery is sick from not being fully charged.....ever.

Heater???? you are running something other than pump and LEDs?bumpy

Bumpyroad wrote:Heater???? you are running something other than pump and LEDs?bumpyNice answer to my question

Sounds like the battery is failing, unless you have some parasitic loads that you don't know about.

Normal The resting voltage of a fully charged 12 volt Lead Acid battery is generally 12.6.. You are loosing 0.1 volt between battrer and meter or meter id off by o.1 volt.. The fact that it is still reading 12.5 several hours later suggests meter error.Oh and supporting that (Meter error) is the 13.5 volt Full Sun reading. 13.6 is float voltageSo your system is working very very very very very well save for the lack of lab grad calibration on the meter.> Be very happy.

Battery question | Good Sam Community

19 Replies

pianotuna
Nomad III
Sep 11, 2019
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
Explorer
Sep 11, 2019
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
Navigator III
Sep 11, 2019
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
Explorer
Sep 11, 2019
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.
wa8yxm
Explorer III
Sep 11, 2019
Normal The resting voltage of a fully charged 12 volt Lead Acid battery is generally 12.6.. You are loosing 0.1 volt between battrer and meter or meter id off by o.1 volt.. The fact that it is still reading 12.5 several hours later suggests meter error.

Oh and supporting that (Meter error) is the 13.5 volt Full Sun reading. 13.6 is float voltage

So your system is working very very very very very well save for the lack of lab grad calibration on the meter.> Be very happy.
drsteve
Explorer
Sep 11, 2019
Sounds like the battery is failing, unless you have some parasitic loads that you don't know about.
tuna_fisher
Explorer
Sep 11, 2019
Bumpyroad wrote:
Heater???? you are running something other than pump and LEDs?
bumpy
Nice answer to my question
Bumpyroad
Explorer
Sep 11, 2019
Heater???? you are running something other than pump and LEDs?
bumpy
Sam_Spade
Explorer
Sep 11, 2019
The 13.5 you are reading is the "charging" voltage from the solar panel.
And that really isn't enough to give it a good charge.

What kind of "heater" are you trying to run ?
If it is propane and the battery runs only the fan, 12.5 should be fine for a couple of hours.

It is possible that your battery is sick from not being fully charged.....ever.

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Battery question

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