hey all. we have a 2004 coachmen freelander 3100so with the ford e-450 super duty engine.i recently replaced both coach and house batteries (we bought the rig 1.5yrs ago and these were simply old and wouldn't hold much charge), with new interstate 12v agms. house got a group 27 and coach got (if i remember correctly) a group 24.now the house battery is part of a solar charging system. 2 100w panels through a 30amp pwm charge controller maintain the house battery, and this has been working like a champ for the 10 or so months this has been in place.however, the coach battery is a different story altogether. even though nothing is running, it runs down entirely within a week or so of sitting. i suspect that the alternator is bad, but don't want to dig in and see what's going on just yet (don't have the skills *yet*).i'd like the solar panels to charge both house and coach batteries if possible, and am considering two options:- one, add a positive wire between both batteries (assuming they're grounded to the same setup) so any overage from the house battery trickles down to the coach battery- two, change the momentary battery boost button to an actual toggle (and leave it on), assuming that this won't screw up the larger converter or other systemsany advise is appreciated... if i'm clear to go option one (which i prefer), is there a shorter path to connect both batteries together instead of routing an 8gauge wire between house steps and engine bay?thank you!

It sounds like you may want to find out what is drawing on your chassis battery that's causing it to drain like that before going through any mods. A chassis battery should not discharge completely in a week. Something is drawing it down - a light left on, the radio etc. You could (or should) install a disconnect on the chassis battery and shut it down prior to putting the RV away for any length of time. Granted an alternator could be part of the problem but it sounds like it's going dead in a week of sitting and not running in which case neither is the alternator. You did mention you just replaced the batteries. Did this problem occur before you replaced them?If you wanted to try to see if a solar charger would help, try a stand alone model for little cost before running any wires. Car solar charger

Plug a 2a maintenance charger that has a 12v plug into the dash cig lighter socket Run that from inverter on house Not efficient but who cares with solar

You have a drain someplace. Use a battery shutoff on the coach battery. Here's an example

BFL13 wrote:Run that from inverter on housethanks, but I don't have an inverter on the house battery; only a converter / charger.

hornet28 wrote:You have a drain someplace. Use a battery shutoff on the coach batteryagreed totally, there's a definite drain somewhere. but a shutoff means i'm wasting the excess solar power that's generated for free, and i'll just be that bit closer to having the engine battery work better... but not quite.thanks!

connect coach and house batteries? | Good Sam Community

MNtundraRet
Navigator
Mar 18, 2022
I would not recommend having the chassis battery(s) connected "full time" to the house batteries. The Chassis (starting batteries) are not deep cycle. They will draw down first before the deep cycle batteries if any 12v device is in use.

The temporary hold button is meant to use when needing help starting the engine.
wa8yxm
Explorer III
Mar 17, 2022
If you connect the two HARD. then if you do something stupid (And you will, we all do) like leave the headlights on.. You are... In trouble.

So there is a device called a "Trick-L-Start" 3 wire hookup at the battery isolator solenoid.. one lead to HOUSE. one to MAIN. and ground.

IF the house batteries are charging/charged. it will "Connect" the chassis to keep it charged as well.. IF NOT or if the voltage drops below some point.. it Isolates.. So you still have power in one of the batteries you can use to crank up Mr. Onan's contribution to your RV (or whatever generator you have).
altblank
Explorer
Mar 17, 2022
hey all. thank you for your very valuable replies. there are a bunch of great suggestions, which i will take up over the next few days:
- find out parasitic draw
- fix the root cause of the chassis battery's discharging

in addition, i'll pick up a 100w solar panel and plug it in to the chassis battery, just to be sure it will never die on me. will also replace the battery; i'm sure a few months of sitting at 0 is likely not very good for its longevity ;)

i already have a bunch of cables and a spare charge controller (picked up 2 full sets earlier and connected both panels to a single controller that maintains the house battery), and have the remaining pieces still lying around.

i'll respond in detail once i've had a chance to test the parasitic draw off of the battery, and will check individual fuses to figure out what exactly may be going on. thanks!
MrWizard
Moderator
Mar 17, 2022
Just a tip, extend the steps turn off the step switch, some have a light. That will be on, many steps are wired.to chassis battery , double.check your storage compartments lights are off , also entry/porch and security/docking lights
I have seen lots of weird mods done to RV wiring
Gjac
Explorer III
Mar 16, 2022
I would just disconnect the neg cable on your chassis battery set your HF multimeter to 10 amps and put the leads between the neg post and neg terminal and see what your parasitic draw is. Post that number here and we can tell you what to do next. To see if your chassis battery would charge when connected to the house batteries just turn your key to the ACC position don’t start the eng and take a reading on both batteries they should read 13 + volts .
pianotuna
Nomad III
Mar 15, 2022
KD4UPL wrote:
What you need is called Trik-L-Start.

I love my Trik-L-Start

There are also voltage sensitive relays. I use one on my generator battery and I'm well please by it.

Do make the effort to find the parasitic load.
Ed_Gee
Explorer II
Mar 15, 2022
KD4UPL wrote:
What you need is called Trik-L-Start.

What KD4UPL said. Works great on our coach too, letting our solar or shore power harge both house batteries and coach battery..
theoldwizard1
Explorer II
Mar 14, 2022
Lwiddis wrote:
Matt's right. Get it fixed right. It will never fix itself and makes your vehicle undependable.

AGREE !!

Start by buying an amp clamp meter. Under $75. Make sure it does DC amps. Simply clamp it on either the positive or negative battery cable in the engine compartment. You might get a reading for a couple of minutes after turn off the engine before it goes to very near zero.

It you me getting a reading, you will need to do more investigation. This can be a bit daunting for a novice but there are a lot of videos on YouTube.
KD4UPL
Explorer
Mar 14, 2022
What you need is called Trik-L-Start.
CA_Traveler
Explorer III
Mar 14, 2022
altblank wrote:
i'd like the solar panels to charge both house and coach batteries if possible, and am considering two options:
- one, add a positive wire between both batteries (assuming they're grounded to the same setup) so any overage from the house battery trickles down to the coach battery
This will initially cause the higher voltage battery to discharge to the lower voltage battery and then solar will charge both during the day and both will discharge at night due to whatever is causing the excessive drain.
- two, change the momentary battery boost button to an actual toggle (and leave it on), assuming that this won't screw up the larger converter or other systems This will add the additional drain of the solenoid to the above.

any advise is appreciated... if i'm clear to go option one (which i prefer), is there a shorter path to connect both batteries together instead of routing an 8gauge wire between house steps and engine bay? Yes the battery boost solenoid.
thank you!
I also have full battery disconnect switches on both battery bank posts. That does leave battery self discharge which is low.