U-320-42 Battery relocation

Topic: U-320-42 Battery relocation (Read 796 times) previous topic - next topic

U-320-42 Battery relocation

January 04, 2022, 09:51:38 am

I would like to relocate the engine batteries to the propane tank compartment. We have removed the propane tank. The current location behind and below the tag axle defies any logic that I have ever seen in 50 years of working on motor coaches.
Has anyone done this?

Re: U-320-42 Battery relocation

Reply #1 – January 04, 2022, 10:28:07 am

Have not done this, but you need to consider the distance from the start batteries to the engine starter and the alternator. It is generally best to keep that distance as short as possible. You will need to upgrade the battery starting cables and alternator charging cables to a much larger gauge. May be difficult running the heavy cables the length of your coach. Not a lot of spare room in the utility trough.

You might get with Roger and discuss your project. He has made extensive modifications to his electric system, including removing his propane tank and installing extra house batteries. May have some ideas.

A Second House Battery Bank, Solar Panels, 2 New Inverters

Re: U-320-42 Battery relocation

Reply #2 – January 04, 2022, 10:32:31 am

Erniee,

I thought the same thing when I saw the first coach with the batteries mounted there. That was dumb as dirt for that location especially if you have a battery fail while setting at a campsite.

I don't see why it wouldn't work as long as you figure the proper size cabling you need to carry the amps required for the job.

Mike

Re: U-320-42 Battery relocation

Reply #3 – January 04, 2022, 11:33:50 am

I have noticed these batteries are red in color. Is this brand specific to this coach?

Re: U-320-42 Battery relocation

Reply #4 – January 04, 2022, 12:07:21 pm

No they are just what comes with the coach. They are AGM's

Re: U-320-42 Battery relocation

Reply #5 – January 04, 2022, 12:10:38 pm

Quote from: erniee – January 04, 2022, 11:33:50 am

I have noticed these batteries are red in color.

Probably Optima RedTops. Lots of marketing hype but there are other brands as good or better.

REDTOP® Batteries - Best AGM Starting Battery | OPTIMA Batteries

Re: U-320-42 Battery relocation

Reply #6 – January 04, 2022, 12:22:39 pm

I'll chime in with my 2cents. Although I'm not a big Walmart shopper. They have good prices on oil and batteries.

Best price.
Best warranty
They are everywhere,, if you need to change them out.
And maybe the handiest,, you can park there and maybe even overnight.

Re: U-320-42 Battery relocation

Reply #7 – January 04, 2022, 11:24:06 pm

Ernie,

If the LP tank has been removed there should be plenty of room for a set of start batteries. I put 4 6 volt FullRiver batteries in that space. These may not be the best start batteries but the idea is the same. You will need a sufficient steel battery rack and adequate hold-downs.

Pay attention to weight distribution.

Figure out what the maximum current for starting will be, maybe 400 amps for a very short time, I am not sure.

Use a wire size calculator like this one. Interactive Wire Size Calculator

Put in the maximum current, round trip length, 12 volts. If you put in 400 amps, 90 ft round trip, and 12 volts, 4/0 cables are never going to work. If you use 200 amps you still get a nearly 8% voltage loss. 3% is the max you should allow.

Even at 100 amps this length with 4/0 cables you will see a 3.8% voltage drop. Maybe a pair of 2/0 cables instead of a 4/0 set would keep the voltage loss acceptable.

So scaling up to 400 amps means 8 2/0 positive cables and 8 2/0 negative cables. And bundling all these cables reduces the ampere capacity (ampacity). For these assumed start loads the cable size needed for these lengths is prohibitive.

Cutting the distance in half would make a big difference.

This is probably a workable task, it just needs a better location, keep looking.

One might wonder how I was able to do this with two sets of house batteries. There is a pair of original 3/0 and a pair of added 4/0 cables for the two house battery sets. The charge and discharge loads on either battery set were rarely over 80 amps from the front to the rear. The distance from the batteries to the inverters was much shorter, generally, 6-8 ft each way or less.

The hardest part is getting the cables over the water and waste tanks and through the bulkhead and then over the diferential, tag and transmission to the engine bay end of the bed. Any place a positive cable is in a carrier or there is a possible rub point the cable needs to be protected with a corrugated cable cover or something similar. This was a tough and dirty job.

Once you are wiring things up be sure to include load monitoring. At least a clamp-on amp meter to confirm your assumptions were correct. And On/Off switches on both plus and minus sides and fuses on the plus side close to the batteries.

At the back end there would be not too much to change, just rearrange cables, probably add new common posts.

Roger

Re: U-320-42 Battery relocation

Reply #8 – January 05, 2022, 08:33:02 am

Whew- this all sounds above my pay grade. I think I will let someone replace these with new and keep them in the same crummy location. Thank you all and Happy New Year

Re: U-320-42 Battery relocation

Reply #9 – January 05, 2022, 11:35:38 am

Just thinking out loud here...

In Ernie's coach, where are the house batteries located? In the middle of the coach hidden in a storage bay?

What if the house battery bank compartment was repurposed to hold the engine start batteries? Then a new house battery bank location could be set up in the empty propane tank compartment, similar to what Roger did on his coach.

This would get the start batteries out of their present undesirable location, but still keep them closer to the engine. Some weight would be transferred from the extreme rear of the coach up to the front - probably not a bad thing.

What say the experts?

Re: U-320-42 Battery relocation

Reply #10 – January 05, 2022, 11:54:28 am

AHUH, AHUH!! I like your thinking, Chuck!
Sometimes it takes a variety of suggestions to "tickle" a practical solution into existence.
I used that gambit many times when trying to come up with solutions to design problems during a team meeting.
I found that everyone has something to contribute to a matter under discussion, even tho the contribution may not be feasible or even practical for the application.

Re: U-320-42 Battery relocation

Reply #11 – January 05, 2022, 11:59:13 am

Shortest distance from chassis battery bank to starter is a winner.

Not in a hot or wet area are pluses.

Re: U-320-42 Battery relocation

Reply #12 – January 05, 2022, 12:01:53 pm

Then why are most batteries installed in the engine compartment? Doesn't it get hot in there?

Re: U-320-42 Battery relocation

Reply #13 – January 05, 2022, 12:07:50 pm

How about a battery box.

Re: U-320-42 Battery relocation

Reply #14 – January 05, 2022, 12:09:21 pm

If Ernie's coach has the rear washer/dryer/closet, why not put batteries in the closet above the engine?

Re: U-320-42 Battery relocation

Reply #15 – January 05, 2022, 12:10:18 pm

Sometimes the simplest solutions are the best.

Re: U-320-42 Battery relocation

Reply #16 – January 05, 2022, 12:11:10 pm

Quote from: rbark – January 05, 2022, 12:09:21 pm

If Ernie's coach has the rear washer/dryer/closet, why not put batteries in the closet above the engine?

If sealed/AGM that would be OK. What is distance from there to starter vs current chassis battery location?

Would also want to verify that the floor was designed for that kind of weight.

Re: U-320-42 Battery relocation

Reply #17 – January 05, 2022, 12:11:29 pm

Quote from: nitehawk – January 05, 2022, 12:01:53 pm

Then why are most batteries installed in the engine compartment? Doesn't it get hot in there?

I suppose most starting type batteries must be designed to handle a reasonable amount of heat. After all, the start battery on MOST vehicles is traditionally located in the engine compartment. This Is The Way!

BUT, doesn't mean there isn't a better way. Just requires a little ingenuity.

Re: U-320-42 Battery relocation

Reply #18 – January 05, 2022, 12:16:15 pm

Brett, for sure sealed batteries, not sure of distance but would be much closer than the middle of coach somewhere. Just a thought.

Re: U-320-42 Battery relocation

Reply #19 – January 05, 2022, 12:30:36 pm

House batteries in a 2000 U320 are located in the first bay behind the driver's side front wheel. In a 42, it maybe different. FT switched to the middle-of-the-basement house battery location in 2002.

The 2000 U320 42 floor plans have a NS bed all the way to the rear. No room back there for batteries. I would have to think quite a long time before putting batteries inside the coach.

There are still lots of opportunities in a 42' coach for this move that keeps the start batteries closer to the rear. Conventional thinking has to give way to find a creative solution.

Re: U-320-42 Battery relocation

Reply #20 – January 05, 2022, 12:57:13 pm

Ernie, not that I am an expert by any means on batteries, but exactly where are your start batteries located?

I know you have a 2000 U320 non slide 42 foot coach. Mine are just behind the passenger rear wheels. I would think that is where your batteries are located as well. With them down low just off the ground, it does not get hot there from what I can tell. I am getting ready to pull my start batteries out and have the battery rack enlarged to allow Group 31's to be installed.

Re: U-320-42 Battery relocation

Reply #21 – January 05, 2022, 01:01:54 pm

Quote from: juicesqueezer – January 05, 2022, 12:57:13 pm

Ernie...exactly where are your start batteries located?

Not Ernie, but see the first post in this thread:

"The current location behind and below the tag axle defies any logic...

Re: U-320-42 Battery relocation

Reply #22 – January 05, 2022, 01:12:53 pm

Quote from: Chuck & Jeannie – January 05, 2022, 01:01:54 pm

Not Ernie, but see the first post in this thread:

"The current location behind and below the tag axle defies any logic...
you ain't wrong.
My house batteries are in the 3rd compartment on street side, which is exactly opposite of the now empty propane tank compartment. Ours has the washer/dryer in the kitchen.

Re: U-320-42 Battery relocation

Reply #23 – January 05, 2022, 01:48:36 pm

Maybe not so far. Post a picture of the passcside showing front wheel to rear wheel with bay doors open so we can get some perspective.

Re: U-320-42 Battery relocation

Reply #24 – January 05, 2022, 04:04:09 pm

Probably too far to route cables. I'm going to buy new next month. A friend will help with installing. They should be good for another 5 years and I will pay someone to install new. Besides, i have a large area for the sewer hose—

Affiliate Notice