New Deep Cycle Coach battery draining at a fast rate when dry camping

[Sportsdad]

Hi all,
We just did our first dry camping with this E350 Class C 1990 Fleetwood MH.
Last fall, I installed two new batteries, one for the chassis and one for the coach. The latter was a Deep Cycle Marine application battery.

We just returned from a ski trip where we had no electrical hook up. The generator appeared to charge the chassis battery when ran for 2 hours. Green indicator light. But after only 4-5 hours, running ONLY the furnace fan, on low temp setting (around 60 deg), the battery discharges completely. This battery should last longer than that with only the furnace fan shouldn't it? There is not enough battery power to crank over the generator so I have to start the MH in order to start the generator.

I might add, I have the MH connected to a 220 outlet at home, about once a month, for a couple of days.

I'm considering adding 2nd battery but first I want to understand why this is discharging so fast before going through the arduous task of A)Finding an area for the 2nd battery and vent box and B)running the long leads to the 1st chassis battery under the hood.

Thanks!

 

[Ned]

What is the AH rating of the battery?  How many amps does your furnace fan draw when running?  Where there any other loads like lights at the same time?

I have the MH connected to a 220 outlet at home,

I hope you meant a 120V outlet.

 

[bigskymt]

  If the battery is too low to turn over the Gen. it seems unlikely you're getting a full charge in 2 hours.
 

 

[John From Detroit]

Well, it takes around 200 amp hours of battery to run our furnace all night along with minimal other stuff (lights and such)

2 hours is not enough to fully charge a battery,  At most you had around 80% charge on it when you shut the generator down.. A full charge takes at least 6 hours, of not 12. (There is some agrument and a lot depends on your converter)

With some converters a full charge takes days

I see someone else ask how big a battery you have,, If it's is a group 31 or smaller (24,27,29) I might suggest a pair of Golf Car batteries, and possibly a converter upgrade

Or at the very least a 2nd 12 volt

I'm not too pleased with the marine/deep cycle either.  These are mostly starting batteries and if you run 'em down too far they do not recover well.. they loose a lot of capacity.

The golf car batteries 1: Have more capacity to start with and 2: Seem to be a little more "Hardy" if accidently run too far down...

Though you can not get 12 volt batteries that are Deep Cycle with no mention of "Marine" on 'em  I know Wall Mart sells one, I think it's a G-31 but am not sure.

However that said, It does not mean much in terms of how long they will last before needing re-charge.

It's more about how long they last before needing replacement.

 

[LindaH]

As others have indicated, at a minimum you should add a second 12-volt battery (two 6-volts would be better).  However, the forced-air furnace is a huge battery hog (not to mention propane hog).  Since you have a generator, you might want to consider changing out your inefficient converter to one that will charge the batteries quicker...something with a 3-stage battery charger such as this one (there are other brands, too).

 

[Sportsdad]

Thanks all for the replies.
The battery is a 100 amp hour battery.
As research this morning shows, the furnace fan is indeed a big draw on power.
And it appears that running the generator 2 hours in the morning, and 2-3 hours in the evening is not enough to charge the battery up.

We do not want to 'invest' more into the MH than necessary, as we only plan on owning this class C at the max another 4 years before we upgrade to a newer Class C or Class A. That means spending $200 or more for an upgraded inverter is currently out of the question for the rare one or two trips a year where we are forced to dry camp.

My biggest PITA is going to be finding room for a 2nd battery. Currently, the only place I can think of is putting it in the basement on the driver's side, then running battery cables over to the passenger side engine compartment, where the chassis battery is, and run them in parallel.

 

[Gary RV_Wizard]

Buy yourself a 10 amp car battery charger at Northern Tool or Harbor Freight for $50-60 and use that on the house battery when you run the genset. Or even leave it hooked up all the time, so it charges when you are on shore power too. Probably a better charger than the OEM one in your 1990 rig, but it's an additional source of charging in any case.

 

[Carl L]

You need more amp-hours that you are getting from that single dual purpose Marine unit.  Double up.  Next time consider going for a single purpose deep cycle like the Lifeline RV series.

 

[Mexray]

First, don't be fooled by the 'Marine' labeling...if your battery is a 100 amp hour rated Deep Cycle battery, it's the same battery inside, whether the label has 'Marine Service' or 'RV service' on the label - there's just no difference...

Some 'Marine' batteries note for 'Deep Cycling and Starting' - well, guess what - Deep cycle batteries will START things also - they just don't have as high a CCA rating because their plates are thicker and fewer of them, than a pure STARTING type battery in the same size case...

Beware of some 'marine' battery labels that note 'for marine starting only' - as this is a STARTING battery (and won't hold up to deep cycling) with dual terminals on top that look like many Deep Cycle batteries!..Starting batteries typically have higher CCA ratings, but lower amp hr ratings than deep cycle batteries of the same case size...

Sorry, got of track there...as others have mentioned above, it sounds like you're going to need more Amp Hours to 'get you through the night' with the furnace blower motor...another battery, perhaps...also, you have to make sure you battery is fully charged before trying to run the furnace all night - colder weather will of course cause it to run longer...there's just no free lunch here - the longer you have to run it, the more battery capacity you'll need...

Ray

 

[Sportsdad]

Thanks all, picked up a 2nd battery from Sam's, RV/Marine 850 CCA and 180 ah reserve.
Bought a vented battery box and installed in the basement. It turns out the house battery is on the same side as the basement, so I ran the two in parallel. Ran 9 feet of #4 battery cable protected by the crinkle hose, back to the basement and then vented basement with 2" hole and screen for the battery box. Putting a final trickle charge on the newer coach battery and will test it tomorrow with furnace and volt meter, observing.

I also piced up a Battery Tender Junior 12V Battery Charger.

 

[Gary RV_Wizard]

Thanks all, picked up a 2nd battery from Sam's, RV/Marine 850 CCA and 180 ah reserve.

The "reserve" figure is in minutes of use @p discharge rate, not amp-hours.  I suspect this battery has around 100-110 AH. And an 850 CCA is a high number, so my conclusion would be that this is more of  a starting battery design than a deep cycle. Should boost your capacity nicely, though.

 

[John From Detroit]

I don't know how much good adding the 10 amp charger someone suggested will do.. I do not recall the capacity of your existing converter and it's your desire to run it longer at night

That means more battery... And a 2nd 100 amp hour unit would be a good choice

Just remember to vent the battery compartment so that you don't get a build up of potentially dangerous and damaging battery fumes.

I agree with Gary, it is a starting battery,, All the Marine batteries even if they say "Deep cycle" are starting batteries... though in truth this does not mean much in terms of "How long will it run my furnace between recharges"

100 amp hours is 100 amp hours.. No matter the battery type

And 100 amp hours will run my furnace.. about 1/2 night.

Now..... The difference between DEEP CYCLE and Marine/Deep cycle is when you need new batteries.. The ones you have, with proper care and feeding should last till trade in so even that's not a factor here.  And by the time the new owner buys it they will have reasonably priced 12 volt DEEP CYCLE ONLY out there (with no mention of Marine)  In fact Wall Mart has one now I think.

I'd just double up on the battery

Note.. If you wish.. You could get the Wally-world Deep cycle. and set it in a battery box on the ground, and hook it in via jumper cables when dry camping...  That way you don't need to worry about mounting at all.  I have done that.  Just use a "Battery Minder" or "Battery Tender" type product on it when not using it camping....

NOTE 2: With the minder/tender type (1 amp 2-stage (Absorption/float) chargers it won't gas enough to make storage in the spare room in your house a problem (how I stored one) and ..... You can hook up a 12 volt trouble light so you can see to go to the ..ur.. little room.. when the power company fails to light up your life at home!!!.. Very handy (or even a small inverter for the radio or a small portable TV)

 

[Gary RV_Wizard]

The starting battery design (more, thinner plates) simply doesn't last as long in RV usage. But as long as the battery survives, amp-hours is amp-hours.

 

[Carl L]

Thanks all, picked up a 2nd battery from Sam's, RV/Marine 850 CCA and 180 ah reserve.
Bought a vented battery box and installed in the basement. It turns out the house battery is on the same side as the basement, so I ran the two in parallel. Ran 9 feet of #4 battery cable protected by the crinkle hose, back to the basement and then vented basement with 2" hole and screen for the battery box. Putting a final trickle charge on the newer coach battery and will test it tomorrow with furnace and volt meter, observing.

Be sure that you have good top ventilation from that basement compartment.  Charging batteries out-gas hydrogen, a light, non-toxic but highly flammable/explosive gas.

 

[bigskymt]

  I've been reading all the posts about adding batteries and the explosive gases in an unvented area really concerns me now.
  I found a good spot to move our two deep cycle boat batteries to for supplemental/winter use/never plugged to shore power. It is a 7 cu.ft. non vented area that includes the inverter. I would connect them to the inverter inputs and disconnect them when not in use. Charging would be limited to solar and engine running only.
  An option would be charging them with the door open, disconnecting them for driving then connecting them for use and solar charge.
  I'd appreciate any comments or suggestions, thank you

 

[Mexray]

Lead-acid, flooded cell batteries should only be housed in vented compartments - they emit hydrogen gas when charging AND discharging!

The easiest way is to cut a hole(s) in the compartment door and cover with louvers or screens - check some existing installations in other RV's...

constantly hooking and unhooking your batteries for use, storage, travel, etc., is a real PITA...find some way to install suitable switches for the amperage you'll be using..IMHO
Ray

 

[Jeff]

Another option is using a sealed, vented battery box like this. http://www.jegs.com/p/JEGS/JEGS-Sealed-Battery-Box-with-Vent/756199/10002/-1

If you want even higher quality (and more expensive) use an aircraft box like this. http://www.aircraftspruce.com/catalog/elpages/battracks.php

 

[Sportsdad]

Update: I haven't got my digital VOM from harbor freight yet, but from the idiot light indications after my test yesterday, things are looking good!

I made sure both batteries were completely charged up. Then hooked them in parallel. The temp outside was 40 in the morning, and 45 during the day. (During ski camping, I realize that the battery life won't be as forgiving with temps around 20-25 deg.)

I ran the furnace at 75 deg (which means the temp inside is really 70 deg), as well as two coach lights. This means the furnace was coming on about every 15 minutes, and running for 5 minutes before cycling.

I checked the idiot light above the range every 2 hours. Never did it change from green.  I finally shut everything off at 10pm last night so it went 12 hours and the green idiot light was STILL on! (This idiot light would drop down to dull yellow after just 4 hours when ski camping over this past week-end).

Then I popped the batt caps and am trickle charging them back up to 100% this morning to get ready for the next ski trip on Jan. 10th (but odds are, we'll have an elec hook up since the holidays are over).

Thank you all for your feedback.

And for the nervous nellies (that is a good thing, cause I am one too!), the compartment where the 2nd house batt is secure IS indeed vented.

 

[John From Detroit]

The starting battery design (more, thinner plates) simply doesn't last as long in RV usage. But as long as the battery survives, amp-hours is amp-hours.

Roamer says a lot here.. .There is a lot of confusion..

Starting batteries as he says have more thinner plates for greater peak amps... This has no effect on the amp hour rating. but it does affect the life of the battery.. As a battery charges and discharges metal on the plates enters solution with the acid, and then is re-deposited on the plates... This is normal.. Sometimes it's put back where it came from.. Sometimes in a different location.

The problem is.....  The thinner the plate the fewer times this can happen before plate failure.

The thicker plates in the DEEP CYCLE only battery will still start an engine (more on that in a second) but can take more discharge cycles, and occasionally deeper cycles. before they fail.

Now.. As for starting.......

In my younger days I could carry a 240 pound load on level ground and carry a 180 pound load up a ladder.. I can and have carried 100 pound Propane bottles (that's about 180 pounds when you count the bottle) on my own.

So imagine a load my wife is straining to carry.. I pick it up with one hand.

Same with batteries.

Take a small battery, say 90 amp hours. pull 900 amps off it, that's 10 times it's amp hour rating.

Now take a pair of U-2200's (220 amp hours) and pull 900 amp hours off them.. That's just over 4 times the amp hour rating.. Naturally they will both crank the same engine.  But the larger 220 amp battery is not even working half as hard.

However if you pulled 2,000 amp hours off it.. there would be greater voltage drop.. (I do pull 200 amps off them on occasion, in fact peak draw is 400, but only for a fraction of a second, when the inverter kicks in)

 

[Sportsdad]

Incidently, now that we have some extra juice, the wife is asking about a power inverter to run the coffee pot in the early AM so as to not fire up the generator at too early of a time (we are early risers, like 4 or 5am)  I understand coffee pots will use alot of watts, now I have to go out and research power inverters! Those things are not cheap, so whatever I buy, I'll be removing when I sell this MH!   I'm thinking 1500 watts pure sine should be fine for the coffee pot , 19" LED TV and occasional laptop for short periods in the morning.