Can House Batteries Be 14 Feet Apart?

[Spicoli]

My class b rv was designed for only 1 house battery ([font=Tahoma, Verdana, Arial, sans-serif]group 30h). It is located [/font]outside behind driver door. In August I put in a new Mighty Max 12v 100ah deep cycle agm battery. Now I would like to add 2 identical batteries but the nearest location is about 14 feet of wiring away (in an enclosed space under the bed against the back wall). Is that OK to have them that far apart? And if so - are there any special things to consider (besides wire gauge)? After that I plan to add 2 rooftop 160w solar panels. Thanks!!

 

[MrNoodly]

Is there room to put all three batteries under the bed? Remember, AGM batteries can sit on their sides or ends, so there are more ways to fit them in a space.

 

[Trebor English]

You can put them 14 feet apart but there are problems. 

The long wire ensures that the resistance from the charge sources to the 3 batteries will be unequal leading to unequal charging.  Similarly they will get unequal discharging.  That unequal treatment doesn't kill them but it does make one cycle more deeply and die sooner taking out the others.

Every wire should be protected from too much current at every point where power is applied.  That means the 14 foot wire should be fused at both ends.  If the 14 foot wire chafes and the insulation is cut on a sharp edge a fuse at one end doesn't protect the wire from too much current from the other end.

 

[Spicoli]

Is there room to put all three batteries under the bed? Remember, AGM batteries can sit on their sides or ends, so there are more ways to fit them in a space.

Absolutely brilliant! Duh. Why didn't I think of that!?  Sometimes I am my own worst enemy LOL!!  :blush:   

Yes! I need to remove the bed and measure in that compartment to be sure - but I think I may be able to fit all 3 there (2 for sure).

Thanks!!! 

 

[Spicoli]

You can put them 14 feet apart but there are problems. 

The long wire ensures that the resistance from the charge sources to the 3 batteries will be unequal leading to unequal charging.  Similarly they will get unequal discharging.  That unequal treatment doesn't kill them but it does make one cycle more deeply and die sooner taking out the others.

Every wire should be protected from too much current at every point where power is applied.  That means the 14 foot wire should be fused at both ends.  If the 14 foot wire chafes and the insulation is cut on a sharp edge a fuse at one end doesn't protect the wire from too much current from the other end.

Thank you for this insight esp the about fusing both ends of the long run. If I am able to fit all 3 batteries in the back then maybe I can forgo having them separated (see above).

 

[DLTooley]

Another option would be separate charge controllers for each bank.

I’ve been looking at Alibaba for lifepo4 batteries. There are lots of 100-300ah products. Prices are great, but shipping is steep. Who knows about QC, etc.

 

[mpruet]

Generally it's not a good idea to mix an old battery with a new battery.  What is the condition of the existing battery?

 

[Spicoli]

Generally it's not a good idea to mix an old battery with a new battery.  What is the condition of the existing battery?

Sorry I did not see your reply till just now! The battery is fairly new. Late August this year I installed a new Mighty Max ML100-12 AGM/SLA. I've only used it during a 6 week trip and rarely let it drop below 12.5 VDC. Since then I've had it out of the RV and in my garage connected to a BatteryMINDer 2A Charger Maintainer Desulfator. It should work fine with 2 brand new identical ones? Right?
.

 

[highdesertranger]

lots of misleading info in that Amazon ad. I am not going to go into all the contradictions but that is NOT a 100Ah battery. companies that try to mislead you are not to be trusted. also a ton of bad reviews. highdesertranger

 

[Spicoli]

Awesome. Thanks!

 

[Spicoli]

Ok. I think I have things figured out now. The 17+ year old Dometic fridge recently went kaput so instead of repairing it I decided to replace with with the 50 Qt Alpicool C50 and that left me just enough space under it for the 3 house batteries. Now I just gotta make decorative cover(s) to finish the job.