House Battery Replace?

[Gary RV_Wizard]

as long as they are still functional for what you need, keep them.

That's the key point...

 

[Scarypat]

Just for your info - all installed, connected and everything works!

 

[Scarypat]

I did not read all the posts. But, here's my take on your house battery. (been there, done that... actually done this!)

I knew my batteries were getting weak because the house lights would dim when unplugging from shore power. I didn't care what voltage was still available on the batteries, all I knew was, they still functioned.

Well, the day came they didn't function any more, unless plugged into shore power. When that happened, I got new batteries.

We are always hooked up to shore power, even when the camper is not in use. But, once the battery becomes problematic, then it's time to replace.

My opinion, as long as they are still functional for what you need, keep them. Once they become problematic, THEN change them.

As long as you do minimal maintenance, such as topping them with water, if only to prevent damage to your inverter or your alternator…

 

[CharlesinGA]

Evidently you either took pics, made drawings, or really knew the layout of the cables. SO, SO many people will come on this or other forums and say they changed the batteries and something doesn't work, because they didn't keep track of the batteries' positive and negatives before they removed them, or they didn't take pics of the cable routing.

Glad it all worked out for you.

Last year was my year for batteries. My car battery was getting hesitant cranking when the first cold weather came thru, so off to Walmart for a Group 35 AGM.

My diesel truck which I do not often drive, was also getting hesitant cranking. It had Bosch AGM's I installed in March of 2018 when I bought it (the ones I took out were the 15 year old, original Damiler-Chrysler batteries with date code stickers of 12/02) Anyhow, the Bosch batteries were definitely slower cranking than they had been. Again, off to Walmart for a pair of Group 65 AGM batteries..

Then I noticed after restoring power to the trailer, that the battery in it was suddenly bad. I normally leave it on and connected to shore power but disconnect it when storms come thru. The battery that failed was in the trailer when I bought it in November of 2019, no date code so no idea how old it was. It worked well for me considering it is simply a Group 24 marine/RV deep cycle. This time off to Batteries Plus to get a Group 24 AGM marine/RV deep cycle, and I paid for it online and picked up at the store and got a discount, 17% I think it was.

All told, $725 plus taxes. Yep, expensive.

Charles

 

[Scarypat]

Evidently you either took pics, made drawings, or really knew the layout of the cables. SO, SO many people will come on this or other forums and say they changed the batteries and something doesn't work, because they didn't keep track of the batteries' positive and negatives before they removed them, or they didn't take pics of the cable routing.

Glad it all worked out for you.

Last year was my year for batteries. My car battery was getting hesitant cranking when the first cold weather came thru, so off to Walmart for a Group 35 AGM.

My diesel truck which I do not often drive, was also getting hesitant cranking. It had Bosch AGM's I installed in March of 2018 when I bought it (the ones I took out were the 15 year old, original Damiler-Chrysler batteries with date code stickers of 12/02) Anyhow, the Bosch batteries were definitely slower cranking than they had been. Again, off to Walmart for a pair of Group 65 AGM batteries..

Then I noticed after restoring power to the trailer, that the battery in it was suddenly bad. I normally leave it on and connected to shore power but disconnect it when storms come thru. The battery that failed was in the trailer when I bought it in November of 2019, no date code so no idea how old it was. It worked well for me considering it is simply a Group 24 marine/RV deep cycle. This time off to Batteries Plus to get a Group 24 AGM marine/RV deep cycle, and I paid for it online and picked up at the store and got a discount, 17% I think it was.

All told, $725 plus taxes. Yep, expensive.

Charles

Well, first of all, creatug two banks of 12V from 6V is not a big thing. And yes, I took the time to separate house and chassis wires AND took pictures prior. I am only partiallyout of the wood, as I think the batteries interconnectors might be too small - I bought those used in golf carts, but from pictures I found on the internet, people are using a much bigger cable size. I do have two much bigger cables (those that were used to link the 12V in parallel) linking the two banks, so I think I can get away with it until I build bigger links.

 

[Kirk]

Well, first of all, creatug two banks of 12V from 6V is not a big thing.

Nothing is difficult if you know and understand how it's done. Obviously, you do and that makes assistances less difficult.

I think the batteries interconnectors might be too small

The primary issue in interconnections is voltage drop and generally, the bigger the better. You do reach a point of diminishing returns though. The higher the current drawn the larger the conductor needs to be in order to minimize voltage loss.

 

[Scarypat]

Hey guys, still need some input on wire size. Suggested by the auto part store where I bought the batteries were those 4 gauge wires to create the 12V cells from the 2 6 volts, and I reused the two jumpers that were on the original 2 x 12V to link the the two cells in order to give me 2 x 225Ah. I think that the #4 are good to go within each created 12 volt cells as they stay at 225Ah, and the two big jumpers linking both cells link the big load. Am I correct in my assumptions?

 

[Mark_K5LXP]

The battery Ah doesn't have a direct relationship to wire size. It's your peak loads. I think the jumpers on mine are 2 gauge which is plenty for the tepid loads I have - nearly always under 25 amps. Something like an inverter can put a 100A or more load and too small a cable can cause a time and current limiting voltage drop. So identify your peak currents and see what gauge you can use that both fits and is a tolerable voltage drop.

Mark B.
Albuquerque, NM

 

[Scarypat]

The battery Ah doesn't have a direct relationship to wire size. It's your peak loads. I think the jumpers on mine are 2 gauge which is plenty for the tepid loads I have - nearly always under 25 amps. Something like an inverter can put a 100A or more load and too small a cable can cause a time and current limiting voltage drop. So identify your peak currents and see what gauge you can use that both fits and is a tolerable voltage drop.

Mark B.
Albuquerque, NM

BTW’ I’m sorry to pepper you with my questions!

I just bought an hydraulic crimper so I’ll be able to go bigger. The image is what I have so far. Had to split the load on both terminals of each bank, but those terminals are also linked together so I think I’m good. The house cables are big ass cables and so are the banks’ links, so I actually kind of prefer this connection as it share the mechanical stress of those big cables on 2 studs instead of installing a bus on each of the end terminals.

 

[Mark_K5LXP]

Ideally this is what you want:

Depending on currents this might be picking nits but taking power from the "opposite" poles of the bank will help keep currents more balanced. Ideally too is you want the jumpers the same gauge and length.

Pepper us with all the questions you want. You're the one that's going to end up doing all the work, not us...

Mark B.
Albuquerque, NM

 

[OldWEB]

Ideally this is what you want:

View attachment 1108969

Make a mistake and you will get this....

 

[Scarypat]

Make a mistake and you will get this....

Ohhh I did. I almost created a welder. Out of shear stupidity I closed the circuit on the same bank of batteries - posi to nega… Did a great spark. Luckily it was just a glance and the RV was not hooked up. Still, I know now that I could weld something with this set up!!!

 

[Adventurous Traveler]

Good Luck.

 

[Gary RV_Wizard]

Hey guys, still need some input on wire size. Suggested by the auto part store where I bought the batteries were those 4 gauge wires to create the 12V cells from the 2 6 volts, and I reused the two jumpers that were on the original 2 x 12V to link the the two cells in order to give me 2 x 225Ah. I think that the #4 are good to go within each created 12 volt cells as they stay at 225Ah, and the two big jumpers linking both cells link the big load. Am I correct in my assumptions?

Very short lengths of 4 gauge wire can handle a continuous 95 amps, which is probably sufficient unless you have an inverter drawing a sustained 1200 watts (e.g. a microwave running minutes rather than seconds). In a series connection battery bank, ALL the current passing thru that battery bank runs thru the connecting cables, so the load on the connectors is the same as the primary load & ground cables. So if you actually need larger primary cables, you also need larger connectors.
If you have an inverter as one of the loads, I'd choose a minimum of 2 gauge and suggest 1/0 gauge as an improvement..

 

[Scarypat]

Very short lengths of 4 gauge wire can handle a continuous 95 amps, which is probably sufficient unless you have an inverter drawing a sustained 1200 watts (e.g. a microwave running minutes rather than seconds). In a series connection battery bank, ALL the current passing thru that battery bank runs thru the connecting cables, so the load on the connectors is the same as the primary load & ground cables. So if you actually need larger primary cables, you also need larger connectors.
If you have an inverter as one of the loads, I'd choose a minimum of 2 gauge and suggest 1/0 gauge as an improvement..

Since I’ll make the links from scratch, I can go 1/0. It’s just harder to bend to reach the battery studs.