12-Volt Battery Question

[rubyslippers6232]

Took the Airstream on the road this weekend. Monitor indicated a fully charged battery. We cooled the fridge using the LP setting, then when we hit the road we turned it over to 12V. About 3 hours into the trip, the LP detector started to sporadically beep, with the indicator light blinking back and forth between green and yellow. The generator wouldn't start (plenty of gas in tank), the fridge was no longer cold, and the Fantastic fan was slugglish on the '3' setting. The monitor indicated "Weak" for the battery charge. When we arrived at our destination, we plugged in and everything noted above started working fine. Within a couple hours the battery was charged and held the charge. We have an Interstate Workaholic Heavy Duty battery, C50-XHD; 600 CCA; 750 CA. Not sure what all that means, but that is what's on the battery. Don't know how old it is. My guess is that the fridge drained the battery, but I don't know why if we used it while driving. Any ideas?

One more thing...the LP detector stays on green now, but we took off the cover to get to the reset button when we had problems. Now whenever we try to put the cover back on, it won't stop the LOUD beeping. Any help on this one?

Thanks!

[skater]

In theory, the 12V fridge should not be running off the battery directly; it should only be running when the engine is running (because it will kill the battery - it draws 10 amps in 12 volt mode). I haven't actually verified that's how it's wired, and based on some other wiring things I've seen in mine I wouldn't be surprised to find they just hooked it to the coach's 12 volt system.

That said, while the engine was running, it should have been charging the coach's battery and powering the coach's 12 volt system, so that shouldn't be a problem in the first place. In mine, when the engine is running, the battery condition on the panel shows "charging" for that reason.

If that isn't happening, I would suspect the isolator in yours is bad. The isolator connects the two power systems while the engine is running but disconnects them when it shuts off so as not to drain the engine battery.

I don't have an LP detector so I can't help you there.

[rubyslippers6232]

Thanks Skater. Once the battery was charged again, the monitor did show it as "charging" while the engine was running, so I'm not sure what's going on. Will definitely keep an eye on it.

[rubyslippers6232]

One other thought. We did stop at a rest area and had lunch. Total stop time was probably about 30 minutes. If the refrigerator was on 12V, would it have drained the battery that quickly?

[skater]

One other thought. We did stop at a rest area and had lunch. Total stop time was probably about 30 minutes. If the refrigerator was on 12V, would it have drained the battery that quickly?

Wait, I just realized - do you actually have a deep cycle battery? The one you described sounds like a regular car battery. This page has some info on the C50 series of batteries from Interstate - it says "heavy duty", but I don't see "deep cycle" on that page, so I'm wondering if that's part of the problem.

To answer your question, I would've thought you'd get more than half an hour out of a good condition deep cycle battery, but I haven't run the numbers to figure it out. If you have a non-deep-cycle battery then that'll hurt, and of course any battery that's a couple years old is going to have lost some "life". However, keep in mind that it even if it was depleted, it should've charged again somewhat after you got back on the road.

[rubyslippers6232]

I did see that page but didn't know what to make of it. I'm guessing that what we have is not a deep cycle battery. Do you have a recommendation on which one to use as the house battery?

[skater]

I did see that page but didn't know what to make of it. I'm guessing that what we have is not a deep cycle battery. Do you have a recommendation on which one to use as the house battery?

The problem is that (as mentioned in other threads in this forum) our electrical system, when plugged into 120 volts, will just dump 13 volts or whatever into the battery. Which is fine while it's run down, but it then will kill the battery, unless you take precautions like disconnecting it when it's charged (or replacing the converter).

If you do take those precautions, I'd look at getting a decent battery like a Optima blue top (I think that's their deep cycle model) or something similar - they're more expensive but they're a better battery - more capacity, gel cells (no fluid to worry about), etc.

If you're more like me and likely to forget to disconnect the battery, consider getting a cheaper one because the electrical system will kill it if you leave the camper plugged in.

When I replaced mine right after I bought the camper (before I discovered the problem with the electrical system) I just went to Camping World and popped in whatever they sell. I think it was like $70. It's one that you have to watch the fluid level.

[Alaskan]

I suggest that if you don't know anything about your existing battery consider it suspect to start with...

Replace it with a good quality deep-cycle....in addition to what RJ suggested, Interstate and Trojan make good deep-cycle batteries frequently used for things like trolling motors, boats and RV's....

Using the frig on 12 volt is usually a pain in the butt btw...

Why are you not using it on propane while your on the road....?

[skater]

Why are you not using it on propane while your on the road....?

Many people do, but others worry about the the possibility of leaking propane if there was an accident.

For me, if I'm running the generator anyway, I'll switch the fridge to 110 volt power, since the generator is big enough to run our fridge and our A/C. If I'm not using the generator, I run it on 12 volt mode.

[rubyslippers6232]

This is really good information, thanks Alaskan and Skater. We read on other forums that when on the road, 12V is best for the refrigerator. But thanks to this forum we see that it's not the only way. We will use the propane, as that seemed the most efficient to start with. This is all a learning experience for us. When you say you run it on 110 volt power when the generator is running, would that be the "ELEC" setting on fridge? Also, we have an Onan 2800...is that powerful enough to run the AC and the fridge at the same time?

[skater]

This is really good information, thanks Alaskan and Skater. We read on other forums that when on the road, 12V is best for the refrigerator. But thanks to this forum we see that it's not the only way. We will use the propane, as that seemed the most efficient to start with. This is all a learning experience for us. When you say you run it on 110 volt power when the generator is running, would that be the "ELEC" setting on fridge? Also, we have an Onan 2800...is that powerful enough to run the AC and the fridge at the same time?

Yes, it is the elec setting, the same as what you'd use if you were plugged in somewhere.

Yes, the 2800 should be enough to run both the A/C and the fridge. The 2800 can start and run a 13,500 BTU A/C with 800 watts to spare. Our A/Cs are actually only 11,000 BTUs, so we have something like 1000 watts to spare. I'm not sure what our fridges draw (I keep meaning to test it but I don't have the tool), but I'd be surprised if the fridge draws more than 300 or 500 watts. (Like I said, I haven't personally checked this, but I believe the fridge is supposed to draw about 3 amps in 120 volt mode, so 3 * 120 = 360 watts.)