Charging house battery

This charger is inside the engine compartment. It rides there all the time. The power cord is fed through the doghouse inside. If I need to charge this faster than the onboard setup I simply plug it in when connected to shore power.

Some folks will go nuts on this sort of thing but when you drive a '94 you mustn't be so tender (see what I did there?).

As for solar ... there is so much out there in the used market that putting something together is quite simple. Just be mindful of where you tap into your wiring. We went with a 750w set up (3 panels on the roof) but we are in here full time. My neighbor has a 55w panel and a cheap charge controller he just sold for $50 (our set up was quite a bit more but everything but the 5 batteries were purchased used).

Keep your eyes open.

All very useful info- I truly appreciate! Hmmm, now as I plan to do some boondocking dry camping, I need to look into solar, at least enough to keep a fantastic fan running, hopefully something super simple, maybe even portable, like a suitcase.... so many things to consider...

Battery voltage readings may be misleading. The condition/age of the battery, cleanliness/continuity of battery cable connections, and amount of loads on battery, if any, can affect voltage readings. I should have stated that a new/good house battery, when fully charged by, and still connected to the converter/charger, with no load on the battery from interior lights, 12 volt DC powered appliance controls, alarms and other devices, should read around 13.6 volts. When converter/charger is not connected to 120 volt AC power for some time, and engine is not running, house battery voltage should read around 12.7 volts after surface charge diminishes. When RV engine is running, it's alternator will charge the house battery, and starting battery, and both will read around 14 volts with no loads, after alternator has fully charged the battery and engine is still running. When engine is shut off, both battery's surface charge will diminish and voltage reading will gradually drop to around 12.7 volts. A new/good house battery and the engine starting battery, will gradually self-discharge to around 12 volts, even with no loads, when RV is parked disconnected from 120 volt AC power and engine is not run for a number of weeks. If you install a Trik-L-Start device or if RV is equipped with a BIRD device, the starting battery will be kept charged when the RV is connected to 120 vac shore power. At least the above is how I understand it.

Bordercollie wrote:
A 12 volt battery should read 13.6 volts when fully charged, when discharged/dead, it will read 12 volts or less. When you are plugged into shore power, it should read 13.6 volts if your converter charger is connected and working properly

When you the surface charge is gone after disconnecting from a charging source, a fully charged 12v will be 12.7 volts. A 50% charge is 12.2 volts. At 25% the battery will read 12 volts. Fully discharged is 11.9 volts.

Best not to run voltage above 15.4 with a portable or any charging source while the battery is connected to the RV. Remove one cable from the battery if you are unsure. Probably fine while connected for normal charging but reconditioning, restore charge or equalizing should be done with a cable removed unless you review and understand the voltage profile of the charging cycle chosen.

Anytime you expect the battery to get charge I would expect the switch should be in the "in-use" position so that battery is connected to the RV systems. Easy to check as you start charging the voltage on the battery terminals will pop up about 1 volt or more. So run through the systems and verify what works.

11-12 volts is not OK. 12.4 to 12.7 is OK. 12.2 needs to be charged. less than 12.0 is in desperate need of charge. 7 - 8 volts? Probably shot and is way over discharged.

Camping off-grid you should look at 2x group 27 as a minimum. A single group 24 is just for transit between pedestals.

If charging with a generator much you probably need to upgrade your converter.

The 12 Volt Side of Life

Battery life depends on:

depth of discharge
how long it is left discharged
how often it is returned to 100% state of charge
never have the plates exposed due to low electrolyte levels

If it is never taken below 12.2 volts, never left discharged (i.e. immediately recharged) and returned to 100% state of charge you may get 9 to 11 years of service. A good way to accomplish this is a decent solar charging system. For my detailed thoughts on adding solar surf here: https://freecampsites.net/adding-solar/

Your battery has been taken to 7 volts repeatedly. It is dead as a doorknob by industry standards.

Homestead or Bust wrote:
Another basic question- about how long should my house battery last?
Duracell 24DC RV MARINE. I think it's about 4 years old. SO maybe thats just to be expected at this point.

I guess I'll start with checking the cells for water just in case, and then maybe take the battery out and have it tested. Then look at other components...

Also, any recommendations on a good battery that doesn't break the bank? The above okay?

WOW! Thanks for such detailed responses. Thank you!

Particularly nice to have such and extended one from another that has a unit similar to mine, Thank you DrewE!

Another basic question- about how long should my house battery last?
Duracell 24DC RV MARINE. I think it's about 4 years old. SO maybe thats just to be expected at this point.

I guess I'll start with checking the cells for water just in case, and then maybe take the battery out and have it tested. Then look at other components...

Also, any recommendations on a good battery that doesn't break the bank? The above okay?

Your battery is almost certainly dead, as the others have said. It may have a shorted cell accounting for the low voltage. I'd also suggest checking the battery cables carefully; they sometimes tend to get corroded internally and look OK but not make a good connection.

Regarding question 1 -- generally you can connect an external charger to the battery in situ. I would be cautious about doing so with an actual equalization charge (as in around 15V or so) as some of the 12V things in the RV would not appreciate that hight of a voltage and a few appliance circuit boards or other things may be damaged.

Regarding question 2, what charges when the disconnect switch is on and off and so forth: there is some variation there in what the disconnect switch disconnects and what it does not. The unit that charges the house battery (and so also provides 12V power when connected to 120V AC) is called a converter, and it would operate identically from shore power and from generator power. Often the converter is connected to the "other" side of the disconnect switch from the battery, so having the battery disconnected while on shore power means that it will not get a charge. This is not universal, however, depending at least partly on what is more convenient to wire up.

Usually the battery will charge from the alternator if the disconnect is switched off, though I don't know why you'd care to be driving the RV around with the house battery disconnected.

On my '98 Coachmen Santara 315QB, the converter connects to the battery side of the disconnect switch, so it will charge regardless of the disconnect state (but it will not power the house 12V loads when the battery disconnect switch is off). The battery connections are actually fairly easy to suss out, as they're all assembled together next to the battery under the entrance steps. There's a main battery fuse of I think 175A, which connects to the isolation relay (to charge from the alternator and also to provide the emergency start function) and the connection to the generator starter. There's also a connection to a little bus bar with spaces for a few of the little rectangular shortstop circuit breakers. Originally one of these (a little 6A unit, I think) is for the dash radio clock and memory circuit. One (20A manual reset) is to power the entrance step mechanism. One (40A) connects to the house loads and to the converter, with two separate wires attached to the load side. There's room for a fourth breaker, but none installed.

I modified that setup a little on my motorhome, putting in separate 50A breakers for the converter and the house connections, and adding a little fuse panel fed by a third breaker for the loads that are not disconnected: the entrance steps, the radio memory, a battery voltage sense line for a meter I put in, and possibly an LSL Trik-L-Start unit in the future.

A 12 volt battery should read 13.6 volts when fully charged, when discharged/dead, it will read 12 volts or less. When you are plugged into shore power, it should read 13.6 volts if your converter charger is connected and working properly . When the engine is running, voltage at house battery should read around 14 volts. It shouldn't hurt anything to connect a charger to the house battery without disconnecting the battery. It should charge faster with house battery disconnect switch in "off" setting. Your converter/charger may not be working or it may have become disconnected from the battery, check the connections at the converter charger. Disconnect battery connections and clean them and battery terminals, reconnect ALL wires including small gage wires to battery terminals. Check electrolyte levels in battery, add distilled water to cover the plates inside using a bulb type battery filler. Your converter/ charger and/or house battery may need replacement. There is also a solenoid switch that is part of the house battery disconnect circuit which may need replacement. Might be good to find an RV service to troubleshoot your house battery system, rather than just replacing things.

Yes, yes and no.

Shore or genny requires the disconnect to be on.

But the battery is already toast.