Coach batteries toasted?

[oyly]

Can't run the cabin heater through the night without draining the batteries down. Seems very strange that it would need so much power. Should only be the electric fan that needs the electric power?

Anybody have similar experiences?

[BobR]

I can run my furnace all night in 20F weather and have power left in the morning. I do set the temp to 60/65 during sleeping time. The coach batteries are two 12 volt deep cycle batteries.

[hanko]

are you confused now?

[pianotuna]

Another way to look at it.

You have 100 amp-hours available for a 24 hour time period.

That means about 4 amps per hour.

That is just two 1156 light bulbs.

[jerseyjim]

I have 2 6V in series...and have found that they will hold the furnace all nite (F30 and below)...but in the morning, they are kinda weak...and have to be re-charged. No problem for me, since that only happens when I'm on the road.

[Dale_Traveling]

The blower in the furnace takes a lot of power and add in the other 12VDC items, that individually do not consumer much but collectively they are another hit to your storage capacity, and by 3AM your batteries are getting pretty low. As best you can recharge as much as possible before turning in for the might.

To help extend my over night battery capacity I run an electric blanket (135 watts per side) off a small invertor that sips power and set the thermostat to a lower over night temperature. I also cover the sleeping area windows with reflective insulation to reduce heat loss. If temps really get low I'll cover all the windows and pull the slides in. If you can't increase your storage capacity you can reduce the heat loss and run time of the furnace.

[scrubjaysnest]

100 Ah battery; 50% usable = 50 Ah. 50 Ah / 6 amps = 8.3 hours of run time. Going below 50% reduces the expected life of the battery. True deep cycle although a little more tolerant of going below 50 % will drop from an expected life of 8 to 10 years down to between 4 to 6 years on average. Big caveat here, your results may be different.

[Golden_HVAC]

Hi,

Each battery will hold about 100 amp hours of power. If one is the engine starting battery, and the other is for running the coach, then only the 1 battery can supply power to run the furnace and lights, water pump, ect.

If you discharge that battery to much to many times, then yes it will require replacement. 12 volt batteries are more tempermental about being discharged to much. A pair of 220 amp hour golf cart batteries are more likely to come back from being discharged all the way - at least a few times, though they are not idiot proof.

And you might not have space to install 2 coach batteries. Golf cart batteries are like one huge battery in two easy to install 67 pound parts. You wire battery 1 ground to the frame, and the other terminal is +6 volts, that goes to the negative post of battery #2, then that +6 is added to the first battery, so it makes it +12 that is connected to the wire that had been connected to the 12 volt battery +12 terminal. My first set of golf cart batteries lasted 13 years with good care, and lots of attention, adding distilled water every 2 months. My second set only lasted 6 years. The best I ever got out of 12 volt batteries was about 2 years.

It is the very best care of the battery to fully charge it as soon as you can after discharging it. My wheelchair has lead acid batteries in it, and by recharging it nightly, the battery has lasted well into 3 years of daily use, about 25% to 50% is used daily. IF we where to skip a night of recharging, not only would the battery be down to 75% used up, but the low voltage would activate, leaving the wheelchair stranded. And it is hard on the plates, can cause them to warp, and that shorts them out, causing replacement right away.

6 volt batteries not only have more space between the plates, but also have more cooling water so warping is much less likely.

You do need to determine if you have 2 coach batteries and another battery under the hood for the engine, or not. That way you can upgrade to golf cart batteries if you have the space.

If your current battery is group 24, then it is only rated at about 75 amp hours, while a group 27, 31 would be around 100 AH.

Your RV will consume 35 AH daily just running the CO meter, propane leak detector and refrigerator. Add a couple of hours of lights, and then run the 6 amp per hour furnace, it will quickly discharge a group 24 battery or a weak group 27 battery.

Best thing for this trip? Do you have a generator? Run it for a while before going to bed, to both charge the battery and also run the furnace off the generator / converter charger power, not the battery for that first hour before going to bed. You can then set the thermostat from say 74 to 65, (or 60)and leave it there all night long. Then when you get up in the morning, start the main engine, and run the furnace for say 20 minutes, then shut both off. This way the already nearly dead battery has a chance to recharge while the 130 amp engine alternator is supplying the power to both recharge the battery, and supply the 15 amps of power the RV is consuming while getting breakfast.


If you are using a inverter to run a laptop, and that is coming off the coach battery, it might also be what is discharging your coach battery. It is best to run the inverter while driving, or charge from the generator, and save the battery power to run the furnace.

Even if the battery was in 'great' shape, cold nights will cause it to lose capacity greatly. Being 32F outside, a 100 AH 'Lab rating' will only put out say 50 AH before going below 11.5 volts.

IF you need to mount a second battery or even a pair of golf cart batteries from your frame, there are battery boxes called "Hidden Power" by torqulift and they are designed to be mounted under vans or pickup trucks, near the rear axle, where there is actually plenty of space for a battery, but it is not used because it is so difficult to get to to check the battery water 3 times a year. ..

Good luck,

Fred.

[SCVJeff]

That fan could easily be drawing 8-10A. Depending on how much it cycles and the size of your battery bank could drain them before morning

[Trackrig]

Yes, the furnace fan takes 12V power, but do you know if you're using 12V batteries or 6V batteries? If you're not sure whether or not there are two batteries, have you ever checked the water level in them? If they're 6V batteries, they may be way too low on water from charging them the last two years and not refilling them. And, since you're unsure how many batteries there are, have you ever cleaned the terminals to insure they're actually being charged?

If you're plugged in at an RV park the invertor, not the batteries directly, should be supplying power to run the furnace fan. If you're not plugged in, then the batteries are supplying everything such as the lights, water pump, control power to the refer, CO and LP gas detectors, TV, etc.

If the batteries were in good condition, with clean terminals, two good batteries should handle the furnace for one night, possibly two nights depending on your other power usage.

Bill

[oyly]

JR45 wrote:
Are you hooked up to power or are you running on the inverter. How many batteries how old are they what make of coach.
JR

Neither. Just 12V battery power. That's what the heater needs, plus of course LP.

It's a 2014 Winnebago Via. Think it has two batteries, and these have been well drained a few times.

[JR45]

Are you hooked up to power or are you running on the inverter. How many batteries how old are they what make of coach.
JR