I have a four battery bank that is charged by a Xantrex PS2000 pure sine wave inverter charger. I have 4 12v large deep cycle batteries bought at Sam's Club. I think you call them 31 size (not sure but they are the biggest they have). Anyway they are a little over six years old, and I had to leave my trailer unplugged for about 12 hours, and the charge was way low after that. My warning lights for low batteries were blinking. I have kept water in them with those easy fill contraptions attached, and I periodically have equalized them. So I think my batteries are on the way out. The inverter only had to run the residential frig. Everything else was off. They did charge back up after I plugged in but I'm concerned that such a large bank discharged so quickly. Anyway, how do I go about changing the batteries? Do I need to shut off the inverter charger? Can I just transfer wire for wire or is there an order I should follow? Anything special I should watch out for? Any help is appreciated. I'll probably do it next week.

Unhook the chassis ground before you touch anything else and hook up last. Make sure you hook them up exactly the same way, take a picture before you start pulling cables and note + and - posts. And don't drop a screwdriver or wrench across the posts, this is really important.:)

Shut down all power, unplug the RV. If you have solar pull the fuse/turn off the breaker. Take good photos of the wiring and if at all possible label the wires. Remove the ground (-) to the coach first then the other negative wires off the bank. At that point you should be safe. Clean all the cable ends with a wire brush. Reverse the process to install the new batteries and spray the terminals with anti corrosion treatment (found at auto parts stores). The last connection is the main negative/ground wire to the RV.

FIRST ALWAYS FIRST BEFORE STEP NUMBER 2WEAR SAFETY GOOGLES AND GLOVES!Take at least four images of batteries with cable wiring intactDisconnect negative cable ends, one by one and wrap with black electrical tape for ID and shorting proofingDisconnect positive cables one by one and use masking tape on the metal for ID and shorting proofingThe best lifting device I have used is a lever clamping assembly with grip pads and bicycle handlebar lifting gripI have made lift ropes by squeezing on cable lug ends that were first dipped in GOOP®Protect your spinal discs while lifting DO NOT SWIVEL your back while liftingBefore placing first new battery review your images to get placement orientation correctWhen all batteries have been replaced recheck your images before connecting cables - you will not get a second chanceThen smear a healthy dose of silicone dielectric grease on all shined-up metal surfaces, battery posts and lugsAll electrical metal should gleam like newSmear a gob of dielectric grease on hold-down studs and nutsTake your time! A reversed polarity mistake can cost a fortune

I haven't had any experience running a residential refrigerator using an inverter and batteries. I would expect after 12 hours the refrigerator would significantly deplete the batteries.

Just be aware that the replacement battery from SAMs CLUB or anyone else even with the exact model number may be different where the BATTERY TERMAINALs are located.Observe which cables are one which terminals identified by the the word POS or NEG or the symbols = or - stamped into the battery case.The NEG or "-" cables always goes to frame ground on the 12VDC batteries...SAMS CLUB also sells 6VDC batteries so be sure you have one or the other. This is a typical wiring lay out for both 6V and 12V batteries...Use your CELL PHONE CAMERA to document the wiring of the terminals before removing them... If there is a bunch of wires I would use RED FINGERNAIL polish on the ones that connect to the POSITIVE TERMINALS...Roy Ken

Time to replace batteries. How? | Good Sam Community

Almot
Explorer III
Jun 03, 2016
pianotuna wrote:
Neither diagram is balanced wiring.

x2.
pianotuna
Nomad III
Jun 03, 2016
I would look seriously at LI batteries. No more watering, no more need to recharge to 100% each and every cycle, more capacity, more cycles, less weight, and SUPER voltage support--i.e. almost no puekert effect. Cost per cycle is cheaper than AGM.

or

Go to used cell phone surplus acid AGM. I'm delighted with mine--and Mr. Wizard has been torturing his for some years.
pianotuna
Nomad III
Jun 03, 2016
Neither diagram is balanced wiring. See Smart Gauge page for proper wiring diagrams.

RoyB wrote:
Just be aware that the replacement battery from SAMs CLUB or anyone else even with the exact model number may be different where the BATTERY TERMAINALs are located.

Observe which cables are one which terminals identified by the the word POS or NEG or the symbols = or - stamped into the battery case.

The NEG or "-" cables always goes to frame ground on the 12VDC batteries...

SAMS CLUB also sells 6VDC batteries so be sure you have one or the other. This is a typical wiring lay out for both 6V and 12V batteries...

Use your CELL PHONE CAMERA to document the wiring of the terminals before removing them... If there is a bunch of wires I would use RED FINGERNAIL polish on the ones that connect to the POSITIVE TERMINALS...

Roy Ken
MEXICOWANDERER
Explorer
Jun 03, 2016
My Vestfrost units have been trouble free. Only issue is they use Freon 12 and would lose a lot of capacity if it was substituted.
pnichols
Explorer II
Jun 03, 2016
I don't know what's inside this refrigerator, but it seems like it's internals may be unique -> operating off either 120V AC or 12V DC (maybe it has a built-in inverter?):

http://www.thetford.com/product/de-0061ev-0061/
Almot
Explorer III
Jun 03, 2016
MEXICOWANDERER wrote:
http://aspencompressor.com/

By the time they will start making affordable DC fridges - and many different models in 6-12 cf size - diminishing resources and exploding population will make RVing obsolete.

Would be interesting to compare side to side with Danfoss compressors though.
MEXICOWANDERER
Explorer
Jun 02, 2016
http://aspencompressor.com/
Almot
Explorer III
Jun 02, 2016
Res fridge is a hell of a draw, but... With 4*12V battery bank, when ONLY the fridge is running, any fridge should cycle at least 20-30 hours before battery drops to 50%.

There is still a possibility that battery was not fully charged at the beginning though.
MrWizard
Moderator
Jun 02, 2016
the bear II wrote:
I haven't had any experience running a residential refrigerator using an inverter and batteries. I would expect after 12 hours the refrigerator would significantly deplete the batteries.

12hr time span
should be about 6hrs run time for the compressor
maybe less, depends on the temp and ventilation in the RV

his batteries are aged and need replacement

i'm been shopping around to replace my 5 yrs old high rate 139AmpHr
agm ups batteries

they run my fridge approx 14 hr overnight, plus lights, tv use , pc, etc and are still at or above 50 percent most mornings

and i'm ready to replace..before there is total failure
Almot
Explorer III
Jun 02, 2016
Charge way low after 12 hrs of fridge, warning lights blinking. You are a psychic or maybe expect others to be psychics.

What was voltage under load or open circuit? What was the initial capacity of new batteries or what does it say on the label, how full was it before those 12 hrs, what was the fridge current?