Coach Battery

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Tiercel

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I am only casually familiar with RV power systems. I just pulled dug into the battery system to see the configuration and age of the batteries. Something I read or saw made me think I would find 6-volt batteries connected in a series. The second thought is maybe I would find 12-volt batteries connected in parallel. Instead, I found one 12 volt deep cycle battery. It seems this could drain pretty fast with just a few lights on. I am switching most of my old filament bulbs out with LED bulbs thinking that will draw less power.


Is this considered pretty inadequate for battery power in an older RV of fairly common?
 

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DonTom

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Is this considered pretty inadequate for battery power in an older RV of fairly common?
Look at the AH rating of the battery.

But that is a Marine battery. You would be better off with an RV battery that has no mention of Marine Starting Amps or Cold Cranking amps. You want what is NOT at all designed to start an engine. You want what is called a true deep cycle battery, not a "Marine" deep cycle.

It will cost more and be even heavier.

-Don- Reno, NV
 
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uchu

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I'm not familiar with your class C motorhome, but I would say that one 12V deep cycle battery wouldn't be quite enough for your coach needs.
 

Tiercel

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The thing is that I guess it has to be enough because other than upgrading as DonTom indicated, there is not much more I can do. I cant just cram another battery in limited space.


I guess the 12v system supplies:
lights
starter spark for all propane appliances
Tank meters and smoke and carbon monoxide detectors
Maybe water pump ???
Maybe heater blower ???
 

NY_Dutch

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A lot depends on your intended style of RV'ing. If you primarily plan to stay in RV parks with power hookups, then one deep discharge battery will most likely be fine for the limited use needed between parks. If you plan to spend a lot of time off the grid though, then you'll need to work out a way to add more battery capacity. How much will depend on your intended loads and the available space and weight capacity. How to charge the batteries while off grid would also need to be addressed.
 

DonTom

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ghts
starter spark for all propane appliances
Tank meters and smoke and carbon monoxide detectors
Maybe water pump ???
Maybe heater blower ???
Yes, all of above. But the starter spark could be mechanical in the stove.

The six volt true deep cycle batteries will not be as long and you may be able to squeeze in two in series. The idea is to put in as much true deep cycle battery as you have room for but still be at a total of 12 volts.

Or if you really want to boondock, do what I did here.

I also added a 2nd battery system to my new RV using the same type of battery. See message #59 here.

The above batteries can be mounted anywhere as they have no need to be vented. And they are clean--cannot corrode your cables. And last forever (almost). Can be mounted in any position, even upside down.

If you spend a lot of time at RV parks with electricity, don't waste your money on such expensive batteries.

But if you want to boondock with no electric hookups for many days or weeks, then it is more than worth the expense.

With the help of my inverters, I can run my MW oven as long as I need and much longer without running my generators, with no shore power. In either of my RVs.

-Don- Reno, NV
 

uchu

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Look at the AH rating of the battery.

But that is a Marine battery. You would be better off with an RV battery that has no mention of Marine Starting Amps or Cold Cranking amps. You want what is NOT at all designed to start an engine. You want what is called a true deep cycle battery, not a "Marine" deep cycle.

It will cost more and be even heavier.

-Don- Reno, NV
True that. If my reading glasses are not deceiving me, the discharge rate in that battery label is 175 min @ 23 Amp.
 

Tiercel

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Arch, no, not yet, but I will check the water tomorrow before putting it back in the battery compartment. I think it is working fine. I just pulled it out to see what I had, check the terminals, etc.

DonTom, that is one crazy amount of battery you have on your link. Looks fantastic, but as you said, I could never justify it. I will probably be mainly on shore power anyway, although boondocking does have some appeal.

I might be missing something but since the battery mainly only operates lights I would probably buy a bunch of LED lanterns before paying over $1000 for a battery.

I think I will calculate what switching my old filament bulbs out to LED bulbs will save in energy consumption.
 

DonTom

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I might be missing something but since the battery mainly only operates lights
My battery is used to make coffee, use the MW oven, my ham radio stuff and anything else I could need. A lot more than lights, in my case.

I rarely use my generator.

-Don- Reno, NV
 

Ernie n Tara

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Actually, the most demanding consumer of 12 V current is probably the furnace blower followed by the incandescent light.
Replacing the lights with LED's will certainly help.

Ernie
 

Gary RV_Wizard

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You got some good advice here, but maybe leaning toward perfection rather than "good enough". That marine battery is what is called a battery hybrid, a standard starting battery design enhanced a bit for use on boats & RVs, where the power usage pattern is different than cars. It's adequate if in decent condition.

Typically a Class C like yours would have two 12v batteries, one to start & run the engine and related vehicle chassis stuff, and a second and separate one to operate the "house", e.g. lighting, appliances, etc. Two 6v batteries in series could be substituted for the house 12v, but that is not common on Class C coaches like yours, simply becasue of limitations on space & weight. I'm pretty sure you have a second battery for the engine, so look around for it.

Yes, a single 12v like that is typical and barely adequate for an evening or maybe overnight without shore power. It has enough stored power to handle lights (yes, leds help a lot!) and water pump, and to operate the fridge and water heater circuit boards for 16-24 hours before you need to use a generator or find a shore hook-up to recharge. It needs to be in good condition, though, with adequate water in the cells and not abused with frequent excessive deep discharges. An overworked battery loses its ability to store power, so that 175 minute reserve power rating might have dropped to 125 or less. There is no fixing that once it happens - battery would have to be replaced.
 
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Kirk

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I might be missing something but since the battery mainly only operates lights I would probably buy a bunch of LED lanterns before paying over $1000 for a battery.
While the battery does supply power to the lights when not connected to shore power or driving, that is neither the largest or the most important thing that it supplies. To me, the most important thing is the refrigerator. An RV refrigerator uses 12V power to operate the control circuits and that is what allows it to be able to automatically switch between propane and 120V shore power. If you deplete the battery voltage below 11V it will soon cause the refrigerator to stop working. In addition, the furnace uses 12V for control and to operate the blower which is the largest current user. It also supplies the control for the water heater and that also will not work without it. Your water pump also is powered from 12V.

Your RV has a converter and that takes 120V power when available and converts it into 12V to supply your 12V power needs and to recharge the coach battery. Given time it will recharge the battery but the time required will depend on what you are using.
As Gary said, it is pretty typically found in all but the most expensive class C RVs but I doubt that it came with a marine battery but it was replaced with that one by a previous owner. The marine batteries are far more readily available and many retail people will tell you that it is the same thing, just to sell what they have. If it is working satisfactorily now there is really no need to replace it but go with a deep cycle battery when you do so.
 

JayArr

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Fans and pumps are the big users of your battery power. The water pump isn't on very much so it's not a big factor and the range hood and bathroom fan can be counted in minutes per day but the furnace fan can be a huge draw depending on how often it comes on during the night. Set your thermostat lower and use more blankets to save battery power.

Your RV is a little older so you should investigate your various appliances. Get the model numbers of your fridge, hot water heater and stove and then search the internet for the manuals, most are easily found. The older appliances don't actually require 12VDC to run but the newer ones do.

Older HW heaters for example - if you have to manually light it by pressing a pilot button and using a match then it will run without 12V. Same with the fridge, there are some models of fridges by Dometic that will light the pilot using 12V (from a button inside) but also allow you to light it manually if the 12V is unavailable. This type will stay running if the pilot is lit and the 12V is removed. Older stoves and ovens are sometimes manual pilot and require no 12V. The furnace will not operate without 12VDC.

Switch all of your lights from incandescent to LED to start. If you want to have more power and can't fit two batteries you can buy and charge a second battery before you leave home and swap it out on the second or third day of a boondocking weekend.
 

Tiercel

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Fortunately, my BiL gave me all the manuals except for the generator (it was for the wrong model). I will check them out to see if they have a manual lighting option without 12VDC. I do know that they have electronic ignition IF you have 12VDC.
 

Isaac-1

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The other thing you could do is what I am doing at the moment, and upgrading to Lithium Iron Phosphate batteries, I am going from a pair of 185 AH 6V batteries, of which only about 95-100 amps is usable, to a pair of 210AH LiFePo4 batteries giving me a total of about 340 are usable without significantly shortening the battery life, all for under $2,000 ($1492 for the batteries, $250 for a DC-DC MPPT charger, plus bits of battery cable, bus bars, fuses, etc.) all for the about same amount of total weight as my GC2 6V batteries..

p.s. the service life expectancy on the LiFePo4 batteries is about 3-4 times that of the lead acid batteries they are replacing.
 

Tiercel

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While a generator supplies full power by producing AC and enabling the converter to supply DC to charge the battery, it seems it would be best to charge a house battery faster running the alternator for a hour before you go to bed to top off the house battery.
 
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