My 2004 Ford E-350 V10 Class C has developed a problem with charging the house batteries. I have a Xantrex Battery monitor. My house batteries are 2 Group 24 batteries brand new, 2 weeks old. because I thought they were not charging when driving. Found 2 bad cells and they were 42 months old.So the house batteries were replaced. I was at a full hookup camp ground for 3 days and the batteries should have been fully charged. We left yesterday and drove 2 1/2 hours to another CG with full hookups. The Xantrex battery monitor showed full when we arrived. This morning after a night hooked up to shoreline power, I disconnected the shoreline power and went in to check the Xantrex battery monitor. It showed 85% and 12.4 volts. I hit the wall panel tanks/propane and battery switch and it showed 2/3's. that's crazy, it should be full and 12.6 volts. I started the engine and it showed 14.2 volts and 10 amps on the Xantrex battery monitor and full on the wall panel of gauges. I drove for 6 hours and when I got home, it was 12.6 volts, fully charged.Before I changed out the batteries, It would be fully charged when I pull out of my driveway and be down 10-15% after getting to the CG 6 hours later. Do I have a bad switch somewhere or could my converter charger which is an Intelli Power 45 amp with the charge wizard be the problem? How do I test?

Do you have a handheld digital multimeter available?

Yes, a clamp-on amp multimeter and a cheap Harbor freight one. Both are digital.

Sagecoachdriver wrote:I started the engine and it showed 14.2 volts and 10 amps on the Xantrex battery monitor and full on the wall panel of gauges. I drove for 6 hours and when I got home, it was 12.6 volts, fully charged.It's always 14-something when alternator is running. Aldo, red-green Christmas lights on that wall panel I suggest you disregard, they are not to be relied on.Also, it should be 12.6 or 12.7 not when you have just finished charging, but 24 hours later and in absence of any loads. Take the cables off the battery, wait at least overnight and check the voltage in the morning. With multimeter like Mex said. It's too early to tell anything yet. Could be faulty battery, or faulty converter, or a short somewhere.

Could the Intelli power converter with the charge wizard be allowing the 110v shoreline to work for the 110 volt appliances like fridge(switches off propane), microwave and not let the 12volt system stuff get anything from the converter part. thus any 12volt thing used like furnace or lights would draw off batteries. When I am dry camping on nothing is on except the fridge and parasitic drain, I have a draw of .6amps.How would I check?

Very confusing to know how much the OP knows. Assuming nothing, not to insult, sorry, etc. BUT the main thing is that while charging you can't use the voltage to estimate state of charge. It can look "full" even though it is half full, because the voltage is over 13 while charging and 'full' is 12.7v.IMO ignore all gizmos that claim to report the state of charge. Just got to be a bunch of BS.So the usual problem is the batts were not fully charged when taken home from the store (shelf life they lose SOC), not top charged, run down more, not fully charged, and they are still in limbo.Or maybe not. Need more info from the OP who is no doubt, not as clueless as all that! Sorry again! :(

Problem charging House Batteries | Good Sam Community

38 Replies

MEXICOWANDERER
Explorer
Nov 17, 2014
It's the meter that is schizophrenic if it disagrees with specific gravity, and you've satisfied yourself with discrete component testing. Verifying the accuracy of an amp hour meter on a cruising sailboat is a challenge. The saving grace there is battery banks are so huge, extracting 1 kWh does not lead to a huge change in resting voltage, so a 16 or 24 ampere incandescent light bulb test (amperes X hours) proves to be quite valid. I uncovered a disturbing number of instruments with 5.0% or greater ampere hour error. This gets hysterically complicated when batteries are VRB, sealed, and precludes the use of a hydrometer. This is where an extremely precise shunt and meter are required.

http://www.farnell.com/datasheets/67361.pdf

I do not trust a regular panel meter. I use a 4-1/2 digit digital multimeter to establish voltage drop across the shunt. Amperage measurement accuracy is amazing (AAA)

Shunt NERD FOOD (PDF) Link To National Institute of Standards & Technology paper

http://www.nist.gov/calibrations/upload/single-range-current-shunt.pdf
SFVdave
Explorer
Nov 17, 2014
I thought the battery solenoid that may be the problem. I called a RV repair shop and they said it maybe the problem and to check to see if there is voltage from the ignition on the center post of the solenoid. I ran the test. Engine off the voltage to house was 12.7v, voltage from engine battery was 12.6v and from ignition was zero as it should be. I started the engine and did a recheck. The house battery post was 14.1v, the engine battery post was 14.0v and the center ignition was 14.1v. So the battery solenoid is not the problem. But perhaps, I should remove the battery solenoid and clean up all the contacts. Then look at the converter charger and test that. However, everything seems to be up to the right voltage and amp levels.
MEXICOWANDERER
Explorer
Nov 17, 2014
Appreciate your efforts. But the fact remains, if they lose not .01 point of gravity despite your meter's argument, you need to focus on how to "cure" or minimize the misimpression your meter is trying to con you with. Fully ten percent of the cruising sailboat complaints I hear are associated with disparities between meters and hydrometers.

Yes, it is a PITB to measure, but you need to do the AFTER hydrometer test ONCE in order to settle the matter. You already know what the hydrometer says BEFORE you drive, right?

Confirm reality, be it what it may, and then folks here can concentrate on helping you resolve the actual problem not a false flag ruse.
SFVdave
Explorer
Nov 17, 2014
Mexicowander. I understand what you are saying. It's a pain removing the house batteries as they are in a compartment in the side of the MH. Not like the ones under the step. I have to undo the strap, Remove the wing nuts and then the cables and pull them out being careful not to have the cables hit the posts. Then test with the hydrometer and put them carefully back in. Took 10 minutes yesterday when I tested them as requested.
MEXICOWANDERER
Explorer
Nov 17, 2014
I can surface charge a battery to 13.4 volts. If voltage is used as a parameter to mistakenly determine level of charge, when a perfect battery loses the charge and settles into a 100.00000% level of charge of 12.7 volts, seemingly SEVEN TENTHS of a volt is "lost". I have seen overcharged batteries show 13.8 volts or more when freshly disconnected from a charging source. Just because the voltage level decreases to resting voltage does not mean it is losing capacity fullness.

This is a perfect example of how and why abstract charge measurements are so invalid. When the hydrometer says the battery acid density is 100.00000% it is telling you the truth. If you start out your voyage and the hydrometer shows 1.280 density and arrive at your destination with half a volt less, but still showing cell density at 1.280 the batteries have "lost" nothing. If density drops to say 1.275 then start looking for a charging problem.

This is fundamental battery and charging analysis. If you choose to ignore it, then may the force be with you...
SFVdave
Explorer
Nov 17, 2014
Mr Wizard, if I charge up the engine battery before I leave for the CG, shouldn't the house batteries stay fully charged then?
MrWizard
Moderator
Nov 17, 2014
the lower amps in the engine compartment
is because the engine aka chassis batteries are at a higher state of charge than the house batteries

the engine batteries don't get as much power drain during the camping as the house batteries
the isolator applies the same voltage to both outputs house and chassis
power absorbed by any battery at the voltage applied depends on the battery chemistry
the house batteries take more ..because they are lower SOC and need more

Sagecoachdriver wrote:
This morning's testing results
sat over night on house batteries only for power.
....................morning...................engine running.............Shoreline power
Engine.........12.61v .5amps..........14.3v 2.2amps............13.3v 0.0amps
Bat Monitor..12.7 v .6amps...........14.3v 12.1amps..........13.6v 4.4amps
House batt...12.43v .6amps..........14.02v 12.8amp...........13.29v 4.5amps
converter.....12.41v .5amps..........14.05v 0.4amps...........13.49v 4.8amps

nothing stands out to me. The lower amps in engine battery while engine is running is probably because the alternator is putting the amps to the house batteries.
Note that the engine is producing to the house batteries 14.02v and 12.8amps, while on shoreline power, the converter is producing 13.29v and 4.5 amps to them. Alternator is out performing the converter big time.
SFVdave
Explorer
Nov 17, 2014
I went to IRV2.com and did a winnebago search. This is a common problem. Seems the alternator will first charge the engine battery. With running the Air conditioner and charging cellphones and iPads while we drive, it takes longer for the engine battery to reach the point where it will start charging the house batteries. Plus, while camped, the engine battery gets further discharged because of the steps which are on the engine battery circuit and not the house battery. Yes, we pull out the steps and turn them off.
That forum says the battery isolator often go bad and they are $30 from Lichtssen winnebago. For $30, it's worth a try.
So, I have to keep the engine battery charged up while camping. I have a Battery Minder that I can plug in if we have hookups, or I also have a Vector 40amp charger that I can hookup to the engine battery when I run the generator. With the engine battery fully charged, the alternator should charge the house batteries while driving.
BFL13
Explorer II
Nov 17, 2014
Sagecoachdriver wrote:
hydrometer says all are 1300+
Still no answer to the question why fully charged house batteries lose 10-15% of there charge while driving for 5-6 hours.

Not sure, but it seems like maybe you think if the voltage drops that means you have lost capacity, but all that is really happening is when charging the voltage is up and when you stop charging the voltage drops.

After the 6 hr drive take another hydrometer reading. That will tell the truth about the actual SOC.
MEXICOWANDERER
Explorer
Nov 16, 2014
FORGET the lies the meter is whispering in your eyes. You can not get more than 100% into the batteries. This means FIX THE METER. Any possibility the meter is registering positive amp hours then zeroing itself?

This the way the first sentence reads

"My 2004 Ford E-350 V10 Class C has developed a problem with charging the house batteries. I have a Xantrex Battery monitor"

This is the way the first sentence should read

"My 2004 Ford E-350 V10 Class C has developed a problem with monitoring the house batteries. I have a Xantrex Battery monitor"

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Problem charging House Batteries

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