Why does my battery die so fast?

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rice40

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May 4, 2015
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I have a 2006 Fleetwood Santa Fe Pup that we've had out on 4 trips now.  This is my first camper and I've got everything pretty well figured out except for one thing.  My battery drains really fast.  It was over four years old and not taking a charge anymore so I installed a new group 27 deep cycle marine/rv Interstate battery from Costco.  However, the new battery dies quickly as well.  I run the fridge off of propane and make sure the 12 volt and 110v switches are off.  We run the interior light at night as well as the porch light and the water pump  here and there.  That is really about all we use so with our light usage I would expect the battery to last a few days without needing to be charged.  I've been running the generator and a 40 amp smart charger direct to the battery for 2-3 hours a day and I still hear the carbon monoxide detector beep early in the morning from a low battery.  My last thought was to turn the water pump switch off when not using water which seemed to work.  After turning the switch off, the battery started to hold a charge.  It's my understanding that there shouldn't be any current draw unless the pump is actually pumping water and the pump does turn off when you shut off the faucet. 

My other question is whether the battery should charge when being towed.  I have a 2003 Ram quad cab with factory tow package and round rv connector which I thought was supposed to slowly charge the battery.  I was hoping it would charge it enough to be able to keep the fridge running since it always blows out when running on propane. Does anyone know if this is right or how much amperage the vehicle gives to the trailer battery?  I drove it for about 3-4 hours and it didn't seem to charge much if any.

Thanks for the comments!

Any thoughts?
 
The battery life sounds about right. The fridge uses 12 volts for the controls when on propane, and those lights draw quite a bit of power. The pump doesn't draw any current unless actually in use, other than the lighted switch.

Changing your light bulbs to LEDs will make a huge difference in battery life. You don't need to change them all at once, just a couple to use while boondocking.

Charging the battery for a couple of hours doesn't really do all that much. It will probably take 8 to 12 hours to charge the battery. A marine battery isn't a true deep cycle battery and isn't the best choice for this application. I can't speak to the charging circuit from the truck, but again, a couple of hours charge time isn't going to do much.

If you do a lot of boondocking, a portable solar panel would be a good investment. Also, it's probably the LP detector you're hearing on low battery, not a CO alarm.
 
A group 27 is around 95 amp hours.. Since it's a MARINE/deep cycle you can use about 30 percent of that or roughly 30 amp hours.

Had you gone with dual GC-2's (Taller and slightly smaller at the base) you'd have 220 amp hours give or take and since they are TRUE DEEP CYCLE you can use half of that or 110 amp hours.

Next: we have your converter.. Any converter from a Magnetek 6300 to a Progressive Dynamic 9200 will very quickly put what is called a SURFACE charge on a battery.. this will cause a volt-meter to show "FULL" but...... it's not.

A battery so charged will quickly die.. now eventually the Magnetek will get the thing filled,, ,,, Sadly it just keeps charging (That's called OVERcharging and it boils your batteries dry and kills them)  might take a couple weeks to get to full charge since it only puts a few amps into the batteries.

The PDI 9200 on the other hand, if properly sized will hit 90% in around 2 hours, and full charge in 6 (the last 10 % takes a while) then it will switch to FLOAT and not boil your battereies dry (How good is it at not boiling them.. I put in new DEKA G-20's last year (2014) in the Spring, long about March or April.. As of last week they were not begging for water yet (When last I checked)  I blew the engine in July last year so it's been pluigged in ever since)

Hope this helps.
 
Same thing happened to me with my Ford F-150, it was set up to charge but fuse was in glove box. They do not install them at the factory. This won't help with the quick discharge but will help keep them at full power while traveling and without shore power.
 
John has pretty much hit the issues for you. Suggest you read parts 1 and 2 of the 12 volt side of life - do an internet search for the two articles. Lot to this should you decide to step up.
 
I have run our trailer with a grp 27 95 Ah battery for years and have never had it go low over night. How are you charging before the trip? I take our battery off and put it on a auto charger right after a trip for a few days, once a month in between trips for a day and then a few days before a trip just to make sure it is topped off. A few hours a day on the trip using the gererator kept us going but it certainly didn't fully charge the battery.

A few inexpensive LEDs for the main light inside and your porch light would make a huge difference.
 
In addition to what RodgerS said.... That would be "The 12Volt Side of Life" by Mark Nemeth.... and can be found here:

http://www.marxrv.com/12volt/12volt.htm

One fairly sure way to know if your truck is charging the trailer battery is to get out your multimeter or voltmeter and test!! (You do have one, right?? ;) )    Measure across the battery terminals with no hookups and engine not running you should read in the range of 12-12.6 V. Connect the trailer and hookup, start the engine and measure again. If the truck is charging the battery as you expect it should, you will read 13.2V at least. If not, no charge is reaching the battery. From there, using the voltmeter check at the plug centre pin and the wiring into the trailer for correct wiring (and of course that fuse in the truck itself!!) You can do the same check before plugging into shore power and again after, just to be sure the converter is doing it's job. Be sure to leave any battery cutoff switch in the ON or working position or your charge system may not work correctly.

Voltmeter or multimeter,  an invaluable tool, don't leave home without it!!! ;) And, by the way 1-2 hours is insufficient to charge a battery. 12.0V is considered close to dead and 8-24 hours using a good 3 stage charger would be a more reasonable charge period required . These "marine deep discharge" batteries should not be discharged  more than 50% and doing so will shorten their expected life considerably. "GC" batteries or "Golf Cart"  style batteries, mentioned above, are a true deep charge type and can do much better.
 
I think a single Group 27 battery, even a marine type, should easily last a weekend in a pop-up, but it's hard to gauge the impact of those lights. Each one draws a steady 1.0-1.5 amps, so can be quite a drain over the course of an evening.

I disagree that only 30% of a marine battery's amp-hours is usable. Something like 65-75% of the amp hours should be deliverable before the voltage gets low enough to cause low voltage warnings from a CO detector. Discharging it below 50% may have a negative long term effect on battery life, but the amps are still usable.

I'm unclear what you mean by having the "12v & 110v switches off". Are you referring to individual lights & devices, or some sort of control panel switch?  Also, is your camper plugged into 110v (shore power or generator) when this happens? Obviously no 110v is involved if not.  You also mentioned a separate smart charger. Is the camper's own charger working? Have you checked the actual battery voltage with a voltmeter? A cheap Harbor Freight or Walmart VOM can tell you a lot about what is happening.

Your comment about the water pump is indeed strange. The pump cannot use power unless actually pumping, and you state that it does shut off.
 
Thanks to all for the great information!  I thought about doing two golf cart batteries but didn't think I needed quite that much power and didn't want the added cost or tongue weight.  As it is with two propane tanks and one battery, my tongue weight is already about 350 lbs.  I wish I could find a true deep cycle 12 volt battery so I could just run one.  I'm sure they exist but bet they're expensive. 

Gary, when I said that the 12v and 110v switches are off I was referring to the fridge.  I assume that the power draw is minimal this way.  I use an external charger off a generator to charge because the onboard converter only charges at 10 amps and my external charges at 40 amps and I don't want to run the generator anymore than we have to.  I would think that running a 40 amp charger to the battery for an hour would be long enough to keep a decent charge.  Don't want to make too much noise for the neighbors.  Do the lights really draw a lot of power?  I assumed that being such small bulbs, even though they're incandescent, wouldn't draw much.  Is it worth upgrading to led bulbs?  Is that even possible or would I have to replace the light fixtures?  I agree that it's weird that the pump would draw power when not pumping, but for some reason this seemed to make a difference.

As far as charging with the vehicle, does anyone know of a diagram for the fuse box so I can see if it's installed?  I do have a multi-meter and will look into this soon.

Thanks for all the help!
 
I'm more with Gary on the available juice....

My personal opinion is that there is a lot of mis-information thrown about re. this....

The general rule of thumb always tossed about is don't discharge below 50% to avoid harm to a marine type battery.  I honestly have yet to look for or find the credible source for this number. 

My wallet can attest though, than letting a marine type drop to zero will kill the battery in short order..... as in one or two cycles down near zero will have you buying a new one.  I've killed several in my old popup and in my boat, simply from self discharge while disconnected in storage!

For a true deep cycle, such as a Trojan Golf cart battery, their manual says something like 20% as the minimum level to avoid harm..... so that means 80% of the juice is available for routine operation.
http://www.trojanbattery.com/pdf/Trojan_QSG_Flooded.pdf

But they also suggest maintaining the battery above 70% when stored....

So,
I suggest getting a battery hydrometer, a temperature compensating one, and testing your battery after a full charge and proper rest (follow the directions).
Then you'll know if your battery is still good.
I'd bet that it's partially degraded......

Then, your question regarding charging from your truck.
I don't know about Dodge, but my 2006 Silverado with factory tow package was wired for it but it did not come with the fuse for the circuit.  I think it was a 40Amp fuse I had to buy, then it worked.
With your multi-meter, check for voltage at pin 4
https://www.etrailer.com/static/images/pics/q/u/qu41784_800.jpg
Some trucks are wired always on, and others are powered only with the ignition key "on".

One of my dead popup batteries was from switching the fridge on 12VDC right before leaving the driveway.... but then some sidetrack with the kids caused us to delay departure for a couple hours and I forgot to turn it off.  Killed my truck battery and the popup battery.

Now, I'm a big fan of disconnect switches hardwired at my batteries to completely isolate them....
and i have this on my boat
http://www.batterymart.com/p-022-0186-dl-wh-power-tender-12v-5a-charger-ca.html?utm_source=google&utm_medium=cpc&utm_term=022-0186G-DL-WH&utm_campaign=PLA&gclid=CjwKEAjw1f6vBRC7tLqO_aih5WISJAAE0CYwaybtYP-A5Xbo0Czjb6ZYCtS_S6or7vUbeTOap3MYDxoCKqfw_wcB
 
oh, one more brainstorm thought I had....
if the water pump is discharging the battery, even when not being used... two possibilities come to mind
1) there is a pressure leak in your plumbing, so that the pump cycles every now and then to get the pressure back up.  It could be as little as one or two pump strokes per hour so it might be easy to miss it..... but odds are that you would have eventually heard this
2) The only other far out idea I can come up with is a partial short in the pump circuit, bleeding a bit of voltage to ground....
 
The general rule of thumb always tossed about is don't discharge below 50% to avoid harm to a marine type battery.  I honestly have yet to look for or find the credible source for this number.

Not just a marine battery, but any lead-acid battery.  Lifeline recommend sizing an AGM battery bank to twice the required load, i.e. if you need 100AH then the battery should be 200AH.  This limits the discharge to 50% that greatly increases the number charge/discharge cycles.  The RV battery section of the Lifeline web site has lots of good information on their AGM batteries.  In particular, the documentation section has some excellent technical papers.  I've attached the diagram from the technical manual that shows how depth of discharge relates to number of cycles.  Note that the vertical scale is logarithmic.
 

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12V golf cart batteries should be readily available if you search. My golf cart has 6 of them and it was built initially in 2009. At one time they were generally available only in 6V and 8V versions but no longer. They are heavy!!!
 
Ned said:
Not just a marine battery, but any lead-acid battery.  Lifeline recommend sizing an AGM battery bank to twice the required load, i.e. if you need 100AH then the battery should be 200AH.  This limits the discharge to 50% that greatly increases the number charge/discharge cycles.  The RV battery section of the Lifeline web site has lots of good information on their AGM batteries.  In particular, the documentation section has some excellent technical papers.  I've attached the diagram from the technical manual that shows how depth of discharge relates to number of cycles.  Note that the vertical scale is logarithmic.

Well I suppose when i think about it that curve makes sense, Ned.
5,000 cycles if you never let it drop below 90% charge...
1,000 cycles at 50%
550 cycles at 80%/20%
so it becomes a question of utility vs life

BUT then as I dig deeper, the graph falls apart....
No battery I have ever owned could survive 375 or so cycles to 100% discharge. 
Nope, I've replaced way too many batteries from dying after just a few deep discharges to believe that this data is even close!

Still, the premise of the curve makes sense..... a question of utility vs life

Only going by the Trojan literature i have seen, they're among the battery experts & recommend the 80%/20% number in the link I posted earlier..... I'm pretty sure the larger manual I received with my golf cart batteries had 70%/30% recommendation.... same ballpark

I know there are are lots of other variables that come into play in addition to pure discharge levels..... but one things for sure I suppose, the deeper you go the shorter the life.
 
That graph applies only to Lifeline AGM batteries but other brands would have a similar one.
 
I would think that running a 40 amp charger to the battery for an hour would be long enough to keep a decent charge.

You might think so, but batteries aren't water barrels and don't simply fill up, nor does a charger func tion like a water hose. I seriously doubt it your battery ever gets that full 40A charge rate. And most so-called 40A chargers can't really produce that amperage anyway, except in a laboratory environment.

A battery resists being charged unless it is totally dead, so as the charge begins to rise the resistance increases and the rate of charge slows. Depending on the battery and the sophistication of the charger, you might get anywhere from 50%-80% in an hour. A full charge probably takes 16-24 hours, regardless of the charger used.

The fridge uses about the same amount of 12v power (amps) in either gas or 120v electric mode. If it has a 12v run mode, THAT would be a major power draw. Otherwise, the 12v usage is tiny and not worth worrying about.

I already explained that incandescent light bulbs use a fairly hefty amount of amps. The types used for RV lighting are typically in the 1.0-1.5A range, so one bulb would consume one amp-hour per hour or more. The common 1141 bulb uses 1.5 amps.  Count the bulbs and do the math. Leds are about 1/10 that for a similar amount of light.

You need to put an amp meter on that pump. My guess is that something else is on that circuit and robbing power.
 
Ned said:
That graph applies only to Lifeline AGM batteries but other brands would have a similar one.

Oh I missed that it was AGM....I have no experience with those.....
 
If that the ornigal battery from 2006.  I would start their.  Most deep cycle batters last 5 year max. Unless you have I very high quiltly one
 

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