Hello all, I was wondering what you all do for keeping your coach battery charged? My RV didn't come with any charging for the coach battery when on shore or generator power. The coach battery always seems to go dead after a couple weeks, so I want to find a way to charge it when on shore power. Right now, I just use a battery charger plugged into the 120 and then into the cigarette lighter. But I want to install something out of sight. I am not sure what would be better. Installing a 120 volt charger and running a 12V line to the battery, or just running a 12V line from the house battery to the coach battery with a diode and a solenoid to disconnect during starting. What do you all recommend?

Moved to Tech Issues forum from DIY.

Your lifestyle (time spent off grid) type and number of batteries, is critical information which can only be supplied by your response on this forum.i.e. Do you spend time disconnected from a power pole?

Go buy a battery tender. Connect it when your parked for more than a few days.

A maintainer charger can go under the hood out of sight and be plugged into the 120 outside. Just use the clamps set of wires instead of the cig plug set.IMO having its own charger like that is better than paralleling the starting battery with the house battery in case they have different specified floating voltages.

Oh, I forgot to mention, the reason I want to wire the house and coach batteries is because I want to be able to turn on the car radio and listen to it for extended periods. At present, the battery charger does not provide enough amps to do this alone, so the battery still drains. Not worried about the float voltages as the house battery is a smart battery, and also the alternator charges the house battery when driving. Currently, the charger I have is 2 amps which is higher than most battery tenders.

Coach battery charger/tender. | Good Sam Community

mlo166
Explorer
Nov 12, 2018
To bfl13: here , we have the E-450 Coach House 231 (23 ft) with a 80 amp battery isolator (abt $70) installed from the charger. In other words, the shore powers the charger then splits to the chassis battery and to the coach battery. Most OEM shore powered chargers will max out at 45 - 80 amps anyway. Use at least the same gauge wire (as from the charger) to the chassis battery from the isolator. Simple. Hope this helps for an alternative solution. Tom
wa8yxm
Explorer III
Nov 07, 2018
Two things. Battery tender you can get all over everywhere but this takes 120 volts.

Trick-L-Start (google it) Simple 3 wire hookup. provides teh reverse charge for the isolator system. Same as rigs with B.I.R.D.s have so the house converter does the job. No outlet occupied.
pnichols
Explorer II
Nov 07, 2018
This is what I've used 24/7 during storage to maintain our motorhome's engine starting battery for years - and as needed on our residence backup generator starting battery and on our garden sprayer's battery: https://www.amazon.com/BatteryMINDer-Model-12117-Maintainer-Desulfator/dp/B000P23HZS
pianotuna
Nomad III
Nov 07, 2018
My trik-l-start has behaved flawlessly since 2013. It is a diode based product. If the amp-l-start had been available, I would have ordered it.

I blame the ten year lifespan of the marine starter battery on the trik-l-start combined with solar based charging.
Cydog15
Explorer
Nov 07, 2018
time2roll wrote:
+1 for Trik-L-Start (or Amp-L-Start)

Keeping my truck battery charged from the trailer solar power for many years now.

Noticed most vendors have stopped selling them. Something going on. When I saw Best stopped selling them, and rvupgrades, I knew something was up. I got one and it quit working.
RJsfishin
Explorer
Nov 06, 2018
When in storage, I have always parallel them all (L/A) together,....let the PD take care of it.
time2roll
Nomad
Nov 04, 2018
+1 for Trik-L-Start (or Amp-L-Start)

Keeping my truck battery charged from the trailer solar power for many years now.
beemerphile1
Explorer
Nov 04, 2018
Works best if you use common nomenclature;
starting battery is the chassis battery
the RV battery is the house battery

Commonly the charging system of a MH does not charge the chassis battery.
CoeyCoey
Explorer
Nov 04, 2018
Janss wrote:
I've had Trik-L-Start on my coach for a few years. That's the little brother to Amp-L-Start recommended by pianotuna. It works great! I stay multiple months plugged in at one RV park and when ready to leave, the engine starts right up. Keeps the engine battery at 12.6 or 12.7 all the time.

That will probably do me. The radio draws less than 5 amps, so I should be good with the Trick L start.
BFL13
Explorer II
Nov 04, 2018
I would ask the Li guys on here if it is ok to parallel one with some other battery. (Balancing?)