1991 ford coachmen battery and chassis electrical

[Rhianntp]

Hoping someone has some experience and advice. When I bought this RV last fall it had a dead house battery and a dying engine one. I replaced the engine battery and working on what to get for a house set up. My question is other than the house potentially having the ability to drain the engine battery are there other downfalls to having the house battery connected in someway to the engine/alternator? I'm going to be relocating the house battery from under the steps to a better location with more room for solar equipment and so on eventually. Currently the wiring under the steps does lead back to the engine compartment where it is able to be charged I presume. My initial plan is to keep them separate and only charge the house battery from shore power, solar, or a generator. Is that foolish to not take advantage of the power produced by the engine in some way ? Is there something else I would need to do other than just use a new set of cables that do not lead up front?

Thanks :shy:

 

[bass_sears]

Get an isolator or a DC to DC charger. House battery will get a charge from the alternator when alternator is running, will be isolated from the engine battery when engine is not running. -- Bass

 

[Rhianntp]

How can i be sure it didn't already have something like that under the hood? Do they wear out if its old? Thanks

 

[B and C]

Most RV's already have a battery isolator that will charge the house battery when your engine is running but won't allow the engine battery to drain the house battery. They do not wear out as far as I know. I've only seen one bad one and it was because it had been damaged. Look for something that has three separate battery cables on it, one on each lug.

 

[Rhianntp]

Mind if I share a few pictures of what's under the hood when I get a chance?

 

[highdesertranger]

I much prefer solenoids over isolators. however that is a mute point because you probably already have one installed.

to check to see if it's working,
disconnect the house battery, do not let the positive cable touch anything metal.
with the key off, check for power at the positive cable it should read zero
with the key in the run position check for power again, it should read battery voltage about 12.6
start the vehicle and check again it should read charge voltage about 14.2.

if it fails any of these come back and let us know and we can help you through it.

highdesertranger

 

[Rhianntp]

Thanks! Will do ?

 

[Rhianntp]

Those were pretty much the exact voltages I measured as you suggested. Here are some images of driver and passenger side under the hood as well as under the step. Thanks   :shy:

 

[Rhianntp]

Today someone bought me a brand new FVP M27-7DC Battery in lieu of payment for work I did for them. I wasn't expecting it, but it happened so I installed it under the stairs today. The old battery was a group 24 this is 27.. it fits in the box though.. kind of a tight squeeze on the sides, but about 1/4" of room around the side vents of the battery. So far so good. Any concerns about a tight fit in a battery box? Do they expand and contract or is that not an issue? Thanks for all the advice

 

[wayne49]

A solenoid is in the passengersize.jpg image. That looks like a fuse in driverside1.jpg There's another fuse in understep.jpg

 

[Rhianntp]

Thanks Wayne It all seems to work well with the new charger/converter I installed. That thing is so quiet compared to the old one.

 

[Rhianntp]

Just an image of the converter/charger I mounted, and the space where a generator could have been from the factory. Eventually I'm thinking of using that space for batteries, inverter, and other items for solar. The big red wire wrapped in white protection sleeve goes right over to the batter box and connects to one side of the fuse. I assume this is how the generator would have charged the battery? Would I be able to just connect a solar panel and charge controller to that wire? How about connecting an inverter to that wire to draw power out of the battery vs putting it in?
:idea:

 

[Yohan]

What's the best way to connect two positive cables together on one battery post? Can I just put the ring terminals on top of each other or do I need to put a nut washer etc between them?

 

[bass_sears]

Right on top of each other (make connection as best you can by offsetting the wires, especially if they're larger gauge). No washers or anything, they actually just introduce more resistance and heat, not more connectivity.

Per ABYC (governs best practices in boats, certainly applicable to our bouncing around vehicles) no more than 4 wires on one post (if more than that use a bus bar), critical that you have the right diameter ring terminal, and use real nuts not wing nuts to secure the ring terminals to the posts.

-- Bass

 

[highdesertranger]

yes you can sack one on top of the other, or you can use military batteries terminals.

https://www.bing.com/shop?q=militar...&originIGUID=F5BDFD5892004046AB032B2B81266B4F

highdesertranger

 

[Yohan]

Right on top of each other (make connection as best you can by offsetting the wires, especially if they're larger gauge). No washers or anything, they actually just introduce more resistance and heat, not more connectivity.

Per ABYC (governs best practices in boats, certainly applicable to our bouncing around vehicles) no more than 4 wires on one post (if more than that use a bus bar), critical that you have the right diameter ring terminal, and use real nuts not wing nuts to secure the ring terminals to the posts.

-- Bass

Thanks! I've been researching the internet forever on this.

 

[Rhianntp]

I have another question please about my original post. In the under stair battery compartment large battery cables come from the engine compartment and then after a fuse and battery the same size cables exit to what appears to be the generator compartment which has no generator. I don't see where they connect in some way to the converter/charger which plugs into an AC outlet and takes 8 gauge wires back to the distribution panel. I don't see any of those huge battery cables anywhere in the RV. The largest I can find are the 8ga. Everything works though. What am I missing? Do those huge battery cables somehow attach to something under the chassis that then converts them into 8ga for connection to the distribution center?