Adding additional batteries - how much additional fridge time?

[wingnut60]

Since the OP doesn't know even the brand of fridge (label inside should show amp rating) he/she needs a lot of help in this, and probably not going to get it right from a dealer.
More batteries
New, matched batteries
True deep cycle batteries
Turn off the ice maker
Use the gen to run an auto battery charger connected correctly to the battery set will do much better in charging the batteries than the converter itself in a short time.

Lots of homework for them to do to educate themselves...

[pasdad1]

Originally Posted by NewToRVinNJ

We ordered our rv so it wasn’t sitting on the lot.

If the batteries were allowed to go dead even once, it damages them and they won’t hold a charge as long as they should. Battery abuse is very common.....you should get 4 new ones all at the same time for best effect.....then monitor them closely to be sure voltage never goes below 12.0 volts (a fully charged battery reads about 12.7)

[NewToRVinNJ]

Originally Posted by pasdad1

If the batteries were allowed to go dead even once, it damages them and they won’t hold a charge as long as they should. Battery abuse is very common.....you should get 4 new ones all at the same time for best effect.....then monitor them closely to be sure voltage never goes below 12.0 volts (a fully charged battery reads about 12.7)

Thanks for that info. The batteries did go dead once when we first got the rv as we didn’t know we were supposed to press the button to put it in “store” mode I think it is. As you can tell we are new to rving. I think then it’s best to get 4 new ones. Thanks!

[nutcker]

I went through something similar a couple years back, Denali National Park in Alaska has very limited generator hours as most national parks do I think. so in my battery tray was two 12 volt batteries at 105 amp hrs. each, I added two more for total of 420 amp hrs. I could not duplicate this amperage with 6 volt batteries due to limited space not to mention the cost would have been more for six volt batteries, I wish I had solar panels to help with charging but that will have to wait till spring, I think you need to add as much amp hrs. as you can and have them charged as much as possible at bedtime, might be difficult with two or three hrs, of afternoon generator.

[Cowpie1]

Originally Posted by pasdad1

If the batteries were allowed to go dead even once, it damages them and they won’t hold a charge as long as they should. Battery abuse is very common.....you should get 4 new ones all at the same time for best effect.....then monitor them closely to be sure voltage never goes below 12.0 volts (a fully charged battery reads about 12.7)

This is why my next battery purchase will be two Greenlife Lithium Ion batteries. They can be taken down to zero every time and recharged. Full voltage right down to the bottom, unlike LA batteries that voltage depletes as they are used. Will deliver full voltage for well over twice the length of LA batteries and even when fully depleted, no loss of capability when recharged. A minimum of 2000-3000 full charge cycles, and considerably more if taken care of. Sure, they are a wallet buster for initial buying, but they are as much or more cost effective over time along with none of the hassles of LA batteries. And they only weigh 30 lb each.

[griz326]

There may be exceptions, but coaches with in-home style refrigerators aren't very good at boondocking. The heating element in them draws quite a bit of power from a battery bank. I get 5-6 hours out of a bank of 8 deep-cycle D4 batteries. However, my refrigerator dates back to 1989.

If you add two batteries to two old ones, the old ones drag the new ones down to their level (forgive personification).

[Dranoel]

FWIW according to Kill-A-Watt, my 2013 25 cf Whirlpool uses about 150 AH per day if I turn the icemaker off. We use another 50 AH or so when boondocking.
-Len

[YooperVer]

Originally Posted by griz326

There may be exceptions, but coaches with in-home style refrigerators aren't very good at boondocking. The heating element in them draws quite a bit of power from a battery bank. ...

The heating element is to warm the door seal and prevent frosting at the seal. Often there is a "econ mode" or similar named switch or menu option that can turn off these heat strips and reduce refrigerator's electrical consumption.

[twinboat]

Originally Posted by YooperVer

The heating element is to warm the door seal and prevent frosting at the seal. Often there is a "econ mode" or similar named switch or menu option that can turn off these heat strips and reduce refrigerator's electrical consumption.

Not enough to kill 8, 180 AH batteries in 6 hours. You can run an AC for that long, with that much capacity.

The guys batteries must be shot.

[griz326]

Originally Posted by twinboat

The guys batteries must be shot.

That was my initial thought, however, they passed a load test.

My coach has quite a few heavy power consumers and my renovation will eliminate the most grevious offenders. It might even require updating my aging inverters.

[twinboat]

Originally Posted by griz326

That was my initial thought, however, they passed a load test.

My coach has quite a few heavy power consumers and my renovation will eliminate the most grevious offenders. It might even require updating my aging inverters.

You are saying that your " heavy power " items are drawing more then, a constant, 100 amps DC. That's what it will take to run that battery bank down to 50% in 6 hours. OK then.

[griz326]

Originally Posted by twinboat

You are saying that your " heavy power " items are drawing more then, a constant, 100 amps DC. That's what it will take to run that battery bank down to 50% in 6 hours. OK then.

That's not what I am saying.
What I am saying is that in 6 hours the low battery alarms go off.

My tech is investigating the cause. The prime suspects are the frig and two high pressure pumps used in the webasto because those were the big power consumers when the alarms went off. My gut tells me that the inverters, now pushing 30 years old, are at end of life and may be part of the problem too; that old tech is not nearly as efficient as the new gear. It is also possible that there are wiring faults because previous owners hacked at the wiring. Another possible problem could be improper battery connections; serial/parallel hybrid wiring might have been the root problem. I haven't talked to the tech since he started work on the wiring.

I can testify to what happens with my coach; it was a common complaint with the early all-electric coaches.

[griz326]

I talked with the tech today. He confirmed that one of the two heart inverters is not functioning. He continues to find hacked wiring that not only could have shortened the time-to-recharge but may have caused collateral issues as well.

Now I'm shopping for a 2500-3500 pure sine wave 24 volt charger/inverter replacement. We are discussing if the bus should have two units or if one larger inverter will be sufficient now that the electric frig and electric stovetop are gone. I appreciate redundancy, but for the extra $2k or so, I might learn to do without a backup charger/inverter.

The only remaining power hogs onboard are the microwave, the Webasto, and the washer/dryer. We haven't decided whether or not to wire the electric water heater into the inverter since the only time that it is needed is for showers and laundry. The washer/dryer is a new amenity for the missus so it was not part of the initial problem.

[nothermark]

I would not hook up the electric water heater to the Inverter. You have propane for when it is not plugged in.
When looking at inverters keep in mind that you will draw ~10 Amps @ 12 VDC for every 1 Amp at 120 VAC. Make sure your battery bank is happy supplying that much current.

Given efficiency losses I would be inclined to use a 500-1000 watt inverter for the fridge and TV that was on all the time you are not on shore power. Save the big inverter for when you are trying to avoid the generator with big loads and quiet time. The big one can also be a combination inverter/charger while the small one just needs to bypass when 120 VAC is present.