Battery Issues

[aswbe]

My batteries are are dropping from fully chg'd (checked w/voltmeter) to 10v in 24 hrs with the batteries disconnected by the switch. I did not have this problem a few months ago. I took the batteries in to battery store and they checked them good and fully charged (that's before I had a voltmeter). By the time I got them to the store at the current rate of discharge they should not have been fully charged if it was just a battery problem I believe.

Here are some possibly relevant facts: When I turn the battery switch back on the radio turns on. But only if the switch has been off for a min or longer. Same result when I hook to shore power with the battery switch off...radio turns on. The batteries are not original but by the date on the battery they were purchased a 1.5 yrs after the trailer was bought by PO. Indicating to me the previous owner had battery problems. Lastly I noticed before these problems started that wires from the brake breakaway switch and electric jack where badly crimped between propane cover and frame.

How should I proceed from here? and can anyone explain the radio turning on. My next step was to recharge the battery and then unhook them and monitor the discharge to possibly isolate the problem as battery related or not.

[ROBERT CROSS]

Try taking the radio face plate off, it may be wired directly and not thru the switch. Will it turn on with the switch off?

[bryanl]

Measuring voltage in close proximity to a charge effort can be misleading.

Charge the battery for a good 12 hours or more with a multiple stage smart charger.

If the voltage of the battery drops to 10v in 24 hours after it has been charged like this, it means that you have a 60 watt or so load on the battery (assuming typical 100 AH or thereabouts RV battery) or the battery has a bad cell.

Do make sure to measure voltage only after the battery has had no significant charge or discharge for at least a half hour. Keep in mind that a freshly charged battery will have a surface charge so it will show a voltage well above 12.8v until it is discharged a bit. A battery that is run down to 10 volts resting is a high risk battery that is likely to have suffered some damage.

Also, check electrolyte level if you can. The modern converters in Airstreams aren't as bad as the old ones when it comes to overcharging but they still don't charge or maintain batteries in any reasonable way. One of the best things you can do for your batteries is to upgrade to a converter that knows about multiple stage charging and also has a maintenance mode that uses a technique to inhibit sulfation.

[68 TWind]

If it is going down to 10V you have a problem with the batteries. Just because they are relatively new doesn't mean they weren't "abused" by the PO. bryanl is correct on the surface charge. I think you have a dead cell. If the batteries are lead acid, get a hydrometer and check the specific gravity of each cell. That will tell the tale. If they are not, any good auto parts place can put a load on the battery and check the discharge rate. My local NAPA store has a small computer now that analyses batteries.

[Darkspeed]

Are your electric brakes activated and you don't know it ?

[Bill M.]

Take the positive lead off and use the amp meter function of your meter to determine if there is a draw on the batteries with the switch off. Fix the damaged wires. Could be a short there. Unhook the radio for a while. Taking the fuse out of the hot lead will do that. Probably the batteries are bad again from being discharged heavily. But you ought to fix the problems before feed it new ones. What kind of batteries? Are they deep cycle?

[aswbe]

Thanks all for the suggestions.
I checked the battery again 24 hrs after posting message and it is still 10.8V and with the battery switch left on over night.

In answer to questions they are Sears deep cycle batteries.
The radio will not work with the fuse pulled.
When the cycling of the switch turns it on I now see it almost sparks with light and turns on to the setup mode. Normal manual turning it on it opens with the clock displayed. It will not turn on in any combination with the front opened up. I am guessing that what ever the problem is the radio is a separate issue from the battery...?

I have had trailer brakes locked up so I know what that is like and I am sure that this is not the issue.

I will purchase a Hydrometer and check the cells. The battery has been charged by shore power for days at a time, I was not aware of the overcharging potential when I did that. The PO had the trailer in storage for over a year but I don't know if it was plugged in. I ran the heater frequently on cold nights on battery only so the problem must have started in the last 2 months. I do not have a multi stage battery charger I was relying on shore power and driving to keep them charged. I have a cheap charger maybe I need to invest in a good one. I will let you know the results of the cell test.

[Gene]

You can disconnect the cables to the battery (take neg. off first) before or right after charging them. If they hold a charge, then you will know it is not them, but something in the trailer such as a short.

Gene

[Beginner]

Divide and conquer!
1. Remove the batteries.
2. Using a known good automatic battery charger, place each battery on charge for 48 hours. No smoking and do this in a well ventelated area away from any open flame. The charging process produces hydrogen (reference the Hindenburg)
3. Disconnect the charger.
4. Let sit for 72 hours. This will dissipate the surface charge.
5. Measure the voltage across the battery terminals. If is still 10.5 then yes you have a bad battery.
Do this for each battery individually.
If the Battery voltage is 12.5 or higher then the battteries are probally still in good shape.
I assume you have two batteries.
Insulate the positive battery cable in one of the compartments. Tape it, put it in a section of old bicycle tube, place it in a water bottle with the top cut off, whatever, just insulate it.
If both batteries are good by this test then reinstall one of them in the other battery compartment by hooking up the positive terminal first with the battery switch turned off .
HooK up a 12 volt light bulb between the negative post and the negative battery cable. Start with an 1157 or 1156 then if the bulb does not light drop down to aa 904 (side marker bulb).
If either the 1156 or 1157 bulb lights then you have a short somewhere. Dont bother with the 904.
That short is running the batteries down.
If either fails to light then place an ammeter between the negative post(negative lead of the ammeter) and the negative cable (positive lead of the ammeter) on its highest range and range down to the lowest range looking for a current.
If current is flowing you have a short and as I said before that is what is running the batteries down.
This is time consuming but very reliable.
Beginner

[bryanl]

re: "get a hydrometer and check the specific gravity of each cell."

this is not needed and really won't tell you anything you can't get from the voltmeter about the battery as a whole.

Hydrometry requires hazmat procedures and has a risk of cell contamination. There can also be a problem just in getting access to the batteries. It just isn't worth the effort these days for most RV situations.

Beginner has a good detailed description of a load test that isn't that hard to do.

Do fix any wiring problems such as you noted at the propane tank.

[Skater]

Gah, I had a reply but it disappeared.

Beginner's tests are good, but I think in the end you'll find your batteries are toast. Electronics can do weird things when the voltage is low - like the time I was driving my Cougar and the charging system wasn't working...all kinds of weird things were happening, like random lights lighting up. My recommendation is to invest in a good three stage converter and good AGM batteries...then you won't have to worry about them for years.

I did just that in my B190 in 2008, and since then I haven't had to touch the electrical system at all. The battery is still very strong, despite leaving the camper plugged in for weeks on end.

Our new trailer has three batteries, of the same age as the one in the B190, but they can't hold a charge for more than a few hours - i.e., the ONE battery in the B190 holds better than the THREE in the trailer. The only thing keeping it from being a major headache in the trailer is the fact that it has 3 solar panels on top recharging the batteries daily. But I'm already planning a replacement converter and batteries for it... expensive but I know I won't have to worry about it for a LONG time when I'm done.

[reo]

As 2 the radio coming on when you go from store to use on the battery disconnect switch, mine does the same thing and always has. (factory installed)It's a 2007 Bambi.

[davidz71]

After you have found your problem, you might want to consider a separate on/off switch for your radio. The PO of my '86 Sovereign installed one just above the radio which disconnects the hot wire when not listening to the radio. This way there is no draw when the radio is on standby.

[68 TWind]

A hydrometer will tell you instantly which cell is dead. As for hazmat, are you kidding me. I have had used them for 40 years, just don't get acid on you. It isn't rocket science. Wash the thing with distilled water before you use it, contamination is not an issue.

[aswbe]

Bought a cheap hydrometer batterys sat all night on shore pwr and read approx 12.8 when I switched off. 45 min latter 12.6/12.4. Pulled batteries out and 1st cell borderline red 3 more solid green and one off the chart red. 2nd battery no better. At the end of test one battery was down to 12.37 and falling the other holding at 12.42. Bad batteries... best guess cause overcharging.

Also some cells appeared to me to very low on water the old instructions from my youth to fill to bottom of extended lip is no longer on batteries but the level here was very much below that level but not below the cells. Any point in filling w/water and re-checking?

Recommendations on new batteries? Should I trouble shoot for possible drain w/new battery or old.
Is a new converter really necessary or should I just be more careful with shore power?
Should I always disconnect when on shore power?
Again thanks for all advise...my experience to date has been just w/tractor and RV w/o converter batteries and battery charger was just to get vehicle started.

[Bill M.]

I use the Interstate deep cycle batteries. Formerly use the Walmart deep cycle. I manage with the converter ( I guess I am stubborn and cheap). One thing you can do is put the trailer on a timer and just run the power 1 or 2 hours a day to keep the batteries up without boiling them as fast. Would not hurt to still check for draw. Ampmeter or perhaps as simple as looking for a spark when you hook the last positive up. Or you can leave the trailer hooked up and put just the converter on a timer. My trailer has a switched outlet for the converter.

[ROBERT CROSS]

aswbe..

Do you NEED a new converter, no.
But if you use the AS a lot and and want more peace of mind when using shore power it would probably make sense.

Do you NEED expensive AGM batteries, no.
But if the freedom to go without shore power, extended run time, longer service life and the convenience of a sealed battery is important. It's worth considering.

I replaced the OEM converter with an IOTA IQ4 55a and the batteries with two Lifeline AGM grp 27 100a.

No regrets.

[bryanl]

yes a hydrometer will tell you which cell is dead ... but all you need to know is if the battery is bad or not and that can be done with a voltmeter.

As for hazmat precautions and contamination, no I am not kidding. I know very well how sensibilities for such things have changed over the last 40 years and I also know about the sort of events that have caused folks to re-think the need for proper procedures when dealing with caustic acids and batteries.

I do not think it wise to dismiss or ridicule hazardous materials caveats and cautions.

Used to be that acid holes burned in clothing was no big deal. Neither were a few facial scars or maybe even a lost eyeball. Things are a bit different now. (we used to chase mercury blobs from broken thermometers around the floor, too. Now that's a school shutdown even)

The plain fact is that, for most RV needs, a voltmeter will suffice just fine.

[pmclemore]

bryanl make a good point...I have been in the habit of using the hydrometer because that was the way it always was done. But the fact that it shows a bad cell, therefore a bad battery, does not help you. You can't fix it anyway. Testing the battery for the ability to hold a charge tells you the same thing. If it's bad, it's bad.

So - anyone want my hydrometer, cheap?

Pat

[Gene]

I think a hydrometer is still useful. It tells you when a cell is becoming less good even though the battery is still holding a charge and allows you to read all the battery threads, price batteries and be ready for new ones.

Pat, keep your hydrometer. It's still a tool and a lot easier to use than checking charge over a period of days and disconnecting and re-connecting the batteries.

Gene