Question About Battery Monitoring

[Dawn Michelle]

So, the house battery for my RV is up in the engine. No monitor currently. I've been figuring I'd buy one of those inexpensive battery monitors and run wire and install in the dash (there's a place for it and such a small RV no issue checking it there). I know these aren't perfect but it would help me keep an eye on it so I don't run it past the 50-60% mark.

But while I was rooting around Amazon I see where you can get a plug in 12 volt socket (so ac to dc) and battery monitors that then plug into 12 volt sockets. Would this work when the house battery is on, and save me wiring as I'd just use the set up in an existing outlet?

[Rich Thomas]

If I'm understanding your question right,You are talking about a device that plugs into your AC 120 volt outlet that converts the AC to 12 volt D.C. then you plug in your 12 V DC battery monitor to that. The short answer is no. The AC and DC circuits are completely separate. Your AC outlets are only on when hooked to shore power or a gen set so when you are on batteries your AC outlets will no longer have power.

[Dawn Michelle]

Ah, see!  Am naive when it comes to battery power.  Assumed that's what the converter did, but the converter is the opposite of that right?  It converts shore power to 12 volt so it does run the lights, etc? Thanks Rich!

[Lakota Wolf]

A CONverter changes 110/120 V  A/C to 12 volts  . An INverter changes voltage from 12 V  -D/C to 110 v a/c    Those inverters like you see at truck stops and wlamart that plug into you cig lighter so you can use your laptop or small tv/  are INverter,,,, rated at 12 v.. 75 to 400 watt,,(even higher but pull some serious drain on the battery)

[Dawn Michelle]

I need a good mnemonic to remember that! I can't tell you how many hours I've read about solar and can't keep the basics straight about incoming and outgoing. Give me piece of nonsense code and I'll remember it next year. But, my brain is like a sieve when it comes to this. Maybe because up til now it's all been theoretical.

Okay, so how is the house battery replenished (right now unhooked and going to spend the winter with a battery maintainer in the basement - getting that this weekend). On the Bounder hooking into shore power meant the house batteries were maintained. Same here? The converter is part of the system that ensures, when the house battery is hooked up, it stays charged? There's not another piece of equipment I need to be running down and figuring out where it is?

We struggled with electrical systems in the Bounder (probably lucky we didn't burn ourselves down). I'm hoping not to make the same mistakes. And, be more respectful. Have gotten a circuit checker for the pole, external surge protector and even a cheap plugin meter to keep an eye on incoming shore power highs and lows.

[Lakota Wolf]

Some on board Converters trickle charge the cabin battery.,, and the older ones,, will give that battery a SLOWWW death,,, meaning they were not economical. They had a tendency to overcharge,, or constantly cook them to death, The newer Inverter/Converter units in RV's are built better and have a shut off as to not kill the batteries.

On my cabin battery. I use a solar panel set up, going through a solar controller (which has a digital display on the front showing voltage). The solar controller has a step down feature, which when the battery is low, it allows full current to charge the battery,, as the battery achieves its full charge, the controller reduces the current so to speak, and finally to a mode called *Maintain..I prefer this charging method over the on board inverter/converter charger built into the cabinet.

[Dawn Michelle]

How did you set it up so that the solar controller is in charge and not the converter? I haven't actually seen the battery hooked in (Rick took it out on the trip when he discovered it was trying to slide off its shelf) and haven't seen the hookups. I'm assuming there are two -negative and positive, but now that I think about it there was a third wire I saw. I guess there could be a third wire that manages charging? Or does the charging just go backwards through the two I would think of as output?

[Rich Thomas]

On the Palace I have one coach and one chassis battery. When I am on the road my coach battery is charged by the chassis circuit by way of a relay on the fire wall. When I am on shore power the battery is maintained by the power converter. I do not have a battery charge indicator. I assume your circuitry to be some what similar. So here's how mine works. The coach battery supplies all the DC while dry camping, there is no AC.  While on shore power the converter maintains the coach battery and supplies the 12 volt DC to the coach. AC from the shore power supplies the AC 120/130 volt outlets. This is the same when connected to a gen. set. while dry camping the coach battery can be charged by starting the engine and idling for a while. (not very economical though).   

[Dawn Michelle]

I suspect you are correct - I don't think there's anything fancy going on so mine is probably similar. The Bounder had a lot more bells and whistles, which made it easier to just flip switches and stuff just "worked". Which obviously had its downfalls because I didn't have to learn HOW it worked - and that led to some issues that could have been prevented (and been a lot worse). Okay, so I should try to identify a relay perhaps (for my own edumacation), as, if I'm understanding you right, the converter isn't doing anything when rolling down the road. This is helpful. I'm beginning to understand the limitations and prioritize my needs versus my wants - and against my abilities :-)

[Lakota Wolf]

I wired directly from solar controller to the batter(s), and watch the digital meter on front of panel for voltage reading. My newer 92 Terry 5th wheel had a fuse in the control panel for * batt charge*. I pulled that out and only use solar to keep cabin battery(s) maintained while hooked up to shore power.

[Dawn Michelle]

I like simple solutions :-)

I do want to add solar at some point, but work my way up to it. Right now, and for the foreseeable future I only see maybe boondocking overnight on the way somewhere and meeting those needs. Thinking I might just manage two systems. The house system as it stands now (you made me think I should probably replace the archaic converter that is there now) for what it already does, and then utilize one of those lithium battery with the built in sine wave inverters to charge up electronics (our big draw - computers, phones and tablets - no tv, coffeemaker, etc). My mac laptop can't charge via 12v and this would offer a fairly easy way to play with solar. Not the goal zero - that's a little pricey, but something along those lines. Dabble before I jump in.

Thanks both of you!!! You got my thinking a little further down the road -