Community Forums

PlaidPaisley · 05-16-2025, 12:26 PM

I am sure this is user error, but would appreciate you telling me exactly what I need to do to fix it.

I now have a single deep cycle marine battery (27dcm), two canisters of propane, and a 5000 W generator to power my camper. I want to be able to park for two weeks at a time with this set up. I can add a second battery in a month but not right now.

I use very little power, primarily to spark the fridge that runs off propane (I am not clear how that works as it is propane run, but needs electricity to do that job), the water pump, kitchen and bathroom vent fans as needed, minimal use of lights, and occasional use of the water heater. In other words, I should have an abundant excess of power.

What I am finding is that my electricity runs out after the first week and does not recover. When I run the generator, everything is powered great, but then it weans off by the next morning so that I wake to the fridge click-click-click-clicking that it needs to be checked as I have no power.

I am of the understanding that when I run my generator it recharges my battery. I have run my generator for long periods of time (3-5+ hours) for that sole purpose but the pattern repeated so that I woke without power again. I then thought that I might be using too much electricity while the generator is running because I periodically run the AC or furnace or an electric kettle, and frequently plug-in a small jackery and/or phone charger. I then tried to run the generator for several hours with as close to zero electricity use as possible, but the pattern repeated.

I have a trickle charger and battery recharger and battery power banks that I can use but do not know how to integrate those into the routine to meet my needs.

However, when I drive to a new location then the battery seems to be recharged and the weeklong cycle starts over again.

I am thinking that there is some sort of calculation on how long I need to run the generator to get the battery fully recharged.

What am I doing incorrectly here or what is it that I need to know?

Skip426 · 05-16-2025, 12:34 PM

Have you load tested the battery ?

JMHO: Should you load test the battery and it checks out OK.
You're letting the battery State of Charge , get too low before recharging .
A deep cycle battery of that size with a low SoC could take up to 24 hours of charge time to fully recover depending on your converter output .

wolfe10 · 05-16-2025, 12:35 PM

Please tell us exactly what converter and/or chargers you have that turn 120 VAC generator power into battery charging power.

A single Group 27 really doesn't give much capacity. Do you have room for another battery or larger battery?

PlaidPaisley · 05-16-2025, 12:42 PM

Quote:

Originally Posted by Skip426

Have you load tested the battery ?

JMHO: Should you load test the battery and it checks out OK.
You're letting the battery State of Charge , get too low before recharging .
A deep cycle battery of that size with a low SoC could take up to 24 hours of charge time to fully recover depending on your converter output .

How do I do this? I have a multimeter but it does not have a working battery which I can pick up today.

PlaidPaisley · 05-16-2025, 12:44 PM

Quote:

Originally Posted by wolfe10

Please tell us exactly what converter and/or chargers you have that turn 120 VAC generator power into battery charging power.

A single Group 27 really doesn't give much capacity. Do you have room for another battery or larger battery?

I do not understand the question. Do you mean the battery banks and trickle charger? I can take pictures of them this evening.

The trailer does not have a built-in space for another battery but I assume it would not be too difficult to figure that out. I would like to add a second battery and a third propane tank so that I can always have one at the generator, one tank connected to the camper, and one tank to take to be refilled.

Skip426 · 05-16-2025, 12:50 PM

For a battery load test , you either need to have the battery fully charged and carry it into a auto parts store ; where they will use their equipment to load test the battery ; or ; purchase your own 12 volt battery load tester ( $25/30 ) at a store like Harbor Freight .

wolfe10 · 05-16-2025, 12:52 PM

Quote:

Originally Posted by PlaidPaisley

I do not understand the question. Do you mean the battery banks and trickle charger? I can take pictures of them this evening.

What "device(s)" do you have for charging the battery? What is it's amp rating (or better-- make and model number and we can look it up)?

Wet cell batteries need to be in vented area. AGM batteries do not need to be in a vented compartment. So, AGM's are more flexible in terms of where you can safely install them.

Soppy · 05-16-2025, 01:42 PM

You need to know how many amps your converter is and the voltage. If you have a 20 amp converter, it could take 9 hrs or more to charge your battery. The voltage on your battery should be at least 14.4 volts when it is fully charged while still charging. If the wire size is to small from the converter to the battery, this will also extend your charging time. A fully charged 12v battery will measure 12.7v after sitting for an hr after being charged with no load connected. If you can go a week on one battery , you are managing your power requirements quite good. A quick solution would be to get an external 20 amp battery charger and connect it to your battery when it needs charging.

SafariBen · 05-16-2025, 04:13 PM

I agree, if you can go a week with your loads, then the battery is fine, or your extremely good at conserving power.

The question I have is how long do you drive that it recharges the battery better than 3-5hours of generator run time?

The battery voltage while resting will give a good indication of state of charge, 12.7v is full, 12.0 is half full, 11.5v is empty. That's with no load, especially toward the lower end of the range, if the battery bounces back to 12.5 right away when you shut off the load, you know it's fine. That's also with no charging, or after using a load after charging then resting.

To check the charging you need to read the voltage again, driving probably charges around 14.0V, the "shore power" charger that the generator should be powering should reach 14v or higher, but will also drop eventually to 13 something. If you have a single stage converter, you could have a battery half empty, or fully empty, 11v, and the charger would only charger at 13 v which would take forever, you'd want a 20-40A three stage charger ideally, but almost any battery charger bigger than a trickle charger sounds like it will be better than what you have.

So one possibility is you have a single stage converter, not a three stage battery charger, the other possibility is that your converter is not hooked to the battery somehow.

The fact that you have a TT and SUV, not a motorhome makes it even stranger, typically you'd get very little charge through all that wiring, but you say that's more effective than the generator.

Mark_K5LXP · 05-16-2025, 04:31 PM

By the symptoms described your converter is defective or not connected to the battery. Once you have a working voltmeter a simple check of voltage at the battery will confirm it. This could be a wiring fault, open fuse or breaker. The meter will lead you to it.

Mark B.
Albuquerque, NM

PlaidPaisley · 05-16-2025, 09:44 PM

Quote:

Originally Posted by Skip426

For a battery load test , you either need to have the battery fully charged and carry it into a auto parts store ; where they will use their equipment to load test the battery ; or ; purchase your own 12 volt battery load tester ( $25/30 ) at a store like Harbor Freight .

Ahhh! OK! I can do that this week.

PlaidPaisley · 05-16-2025, 09:46 PM

Quote:

Originally Posted by wolfe10

What "device(s)" do you have for charging the battery? What is it's amp rating (or better-- make and model number and we can look it up)?

Wet cell batteries need to be in vented area. AGM batteries do not need to be in a vented compartment. So, AGM's are more flexible in terms of where you can safely install them.

I am moving camp. I will take pictures of all of it when I am set up tomorrow afternoon. Thanks!

PlaidPaisley · 05-16-2025, 09:51 PM

Quote:

Originally Posted by Soppy

You need to know how many amps your converter is and the voltage. If you have a 20 amp converter, it could take 9 hrs or more to charge your battery. The voltage on your battery should be at least 14.4 volts when it is fully charged while still charging. If the wire size is to small from the converter to the battery, this will also extend your charging time. A fully charged 12v battery will measure 12.7v after sitting for an hr after being charged with no load connected. If you can go a week on one battery , you are managing your power requirements quite good. A quick solution would be to get an external 20 amp battery charger and connect it to your battery when it needs charging.

Silly question: what is the converter? I got the 9V battery I needed to run my multimeter so I can test things now.

I have a little black and red box (Gooloo?) that is meant to charge a vehicle battery. I will take a picture of the make and model tomorrow afternoon to see if that’s what you mean.

Eman85 · 05-16-2025, 10:03 PM

You are not going to recharge your battery with just short periods of time running your generator. Once the deep cycle battery gets discharged it will take many hours to charge it back. It sounds like you have a small capacity battery that is never getting back to fully charged. You sound like a candidate for solar power.