Generator won't charge batteries

[osuman15]

New to this and have a couple questions. Just purchased a 2009 Energy toyhauler. Went camping for a week and the brand new Interstate class 24 batteries would not stay charged. I would charge them during the day to a full charge. We would run the on-board generator for a couple of hours in the evening and use lights and stereo. By the time we would turn the generator off to go to bed the batteries would be dead. I'm thinking bad power transfer switch but I am not sure. One other question, should I disconnect the batteries when running the generator? Any advice would be greatly appreciated.

[twstdpear]

I'm not familiar with your trailer, so can't comment specifically about the way yours works. Two thoughts come to mind since you say you're new to this.

1) Most wet-cell and AGM batteries usually have a 5-7 year life span before they start showing their age and you should start thinking about replacing them. Depending on the original sale date of your trailer and whether the batteries have ever been replaced, your trailer could be approaching 5 years old and your batteries could be at the end of their effective life, especially if they've been treated poorly.

2) The lights shouldn't be *totally* dead immediately after turning off your generator unless the generator isn't actually charging them in the first place or there is no 12v power from the batteries going into your converter. If your other 120v AC appliances and outlets work when the generator is on and the 12v lights and radio are on when your generator is running, that suggests that your transfer switch is working at least to power your converter, which in-turn powers your 12v DC lights and radio. It could be something as simple as a dead fuse or tripped circuit breaker in the circuit between your converter and battery.

Here's a good read on everything you ever needed to know about RV batteries: http://www.marxrv.com/12volt/12volt.htm

EDIT: I originally included this, but I think you know this already after re-reading your post.

3) If you're expecting the batteries to power the 120v AC circuits in your trailer, things typically don't work that way. The batteries only power the 12v DC equipment (usually lights, furnace, radio, slide out motor, water pump, fridge controls, etc..) and the converter converts the 120v AC to 12v DC to power the above equipment and charge your batteries, but it doesn't work the other way around. If your unit has an inverter, that will allow you to power 120v AC equipment (e.g., TV, microwave, electrical outlets) from the 12v DC batteries when you're not plugged in or running the generator. Pretty much every trailer has a converter, but inverters are much less common.

[K4BEV]

Like twstdpear said - Your batteries are getting old - I know the feeling
Did they hold a charge before?
Do they both have water in them?
Had the previous owner disconnected them?

Get a VOM (Volt - Ohm - Meter) if you don't have one. You can get one pretty cheap from most auto supply places and big box hardware stores - They also make high dollar ones, but a cheap one will do fine for around the house use.

Also - Be sure all connections to the batteries are tight.
I'd remove the connections at the batteries NEGATIVE posts before I tried tightening anything and disconnect the RV from shore power before you start. That way if you should accidentally create a path from a positive wire to ground you won't burn anything up.

Good luck & have fun

P.S. IF either or both need water use ONLY distilled water!

[Jager]

I must be missing something. If your batteries are full and you start to run your generator . . . well the generator should be adding charge to them. If your batteries lose charge while the generator is running . . . you have a problem and it isn't your batteries. When your generator is running the voltage across the batteries should be like 14v.

You may still have weak batteries, who knows. But they shouldn't go dead while your generator is running.