I just spent 4 days at a racetrack campground and our house battery drained each night. I just figured it was time for a new one but it charged up on the way home and held the charge for 2 days so far. I connected a DVM to the battery between the battery ground and the disconnected ground wire. Proceeded to pull fuses then found one of my lighting circuits seems to be the culprit.I should say here we are dealing with a '94 Tioga Arrow and there are 2 lighting circuits. The green one seems to be at fault. I disconnected all my lights and switches and can't seem to find the problem. 2 recent repairs I've done were the bath fan replacement (on the green circuit) and a new water pump (different circuit, I think). We did have an issue with the refer failing to spark right away when we left for out trip but I unplugged it during my search and it seemed to be ok.Now sitting in the driveway the refer and the water pump are off and the battery is holding a charge (probably aided by a small 12" square solar cell).What would the experienced electrical sleuth do next to find the issue?Thanks-Calisdad

Were you plugged into shore power at the campground?

Sounds like a classic converter problem. Check the voltage at the battery terminals to make sure it's charging when you have it plugged into shore power versus unplugged. If it's not charging, pull the converter out of the housing (be careful with exposed voltage). Check to see if the reverse polarity fuses have been blown. They are typically on the side or back of the converter where you can't see them unless you pull it out.If the fuses are good, carefully plug back into shore power and check the converter where the 12v wires exit the converter with your meter. If the converter is not providing DC voltage, you'll need to replace it.

Verify that other items are not on the circuit.Water pump may have a relay setup that turns water from multiple locations. Most are diode based and could be bad.Is your gas detector connected to this circuit.Is there any exterior lights connected? Maybe in compartment.

Are storage area lights on? It could also be smoke detectors and/or other electronic equipment.

I would use a DC clampon ammeter to find out and track down what is drawing amps from the battery and how much.

Any Electrical Wizards Out There? | Good Sam Community

59 Replies

YC_1
Nomad
May 28, 2014
I think you are a bit discombulated friend. Too many contradicting readings you do not understand. This is fine and I am glad you are learning but I suspect you really would like to put this to rest.

If your new charger is installed then put your best lead acid battery in the rv and let it charge over night. Measure the voltage across the battery. Forget measuring current at this time. Putting a voltmeter across a pulled fuse is absolutely useless and I stated that early in this thread. Again, just your body in series with a voltmeter can cause full battery voltage. A useless measurement for current since it takes micro amps to get a reading.

So get the good charger in place and a decent battery. Then when you Boondock without shore power your generator will bring your battery up in a couple of hours.
tenbear
Explorer
May 28, 2014
Calisdad wrote:
tenbear the ammeter didn't get a reading because it didn't read below 1 amp. I'm really not following your statement that the 1.4v reading is meaningless. Are you saying current is NOT flowing thru the circuit? Because I did use an ammeter (albeit a cheap one) and it didn't give a reading one would have to assume it was less than the meters capabilities, or the meter didn't work- which it does (I tested it on an extension cord, separated and running a light bulb at the time).

Current is flowing thru the circuit. The voltmeter placed across the fuse contacts makes a circuit with the meter in series with the circuit powered through the fuse. If no current was flowing thru the circuit you would measure zero volts.

Edit: The current flowing thru the circuit is very small. If the resistance of the circuit was smaller, meaning that more current would be flowing, the meter would indicate close to the applied voltage, 12+ volts. Ohms law - current thru a resistor = voltage / resistance. Your DVM probably has a resistance of over 1000 ohms so the current would be 1.4/1000+ Amps. Very small.

The current you measured with the extension cord is AC. The current flowing thru the fuse is DC. Is your clamp-on ammeter a DC meter or only an AC meter? Usually an AC/DC clamp-on meter would be more expensive.
Bobbo
Explorer III
May 28, 2014
Calisdad wrote:
I'm really not following your statement that the 1.4v reading is meaningless. Are you saying current is NOT flowing thru the circuit?

He said measuring volts across the fuse connections is meaningless because measuring volts across the fuse connections IS meaningless. You can measure amps that way and get a meaningful number. To measure volts, you need to measure from the hot side of the fuse contact to ground, not to the other side of the fuse contact.

Current flow is measured in amps.
CA_Traveler
Explorer III
May 28, 2014
Probably. Yes if it's a good 3 stage charger.
Calisdad
Explorer
May 28, 2014
So I should charge it in the RV with the new converter?
CA_Traveler
Explorer III
May 28, 2014
I would have thought a new battery would charge up higher than 13.2volts. I took 2 days to charge it. My charger has a 6volt and 2 volt switch so I'd trickle charge it for a couple hours, let it set and do it again, probably giving it 10 hours of charge in 2 days.
This is not the best way to charge a battery and in fact the battery may not be completely charged with this method.

You need a charger that will kick the battery into bulk charge, then absorb mode then float mode. There may be some variation depending upon the battery SOC. And AGMs have a different charging algorithm. That's why I said you need a new charger.

I agree that it does sound like you placed a voltmeter in series with the refer circuit. But incorrect application of test equipment or cheap/useless equipment can lead to confusing results. I'm still not sure what the 1.4V represents.
Calisdad
Explorer
May 28, 2014
Yes- thank you CA Traveler. It is the amp switch and it was early, I was just trying to post without getting up. I really don't see why I need a new charger.

tenbear the ammeter didn't get a reading because it didn't read below 1 amp. I'm really not following your statement that the 1.4v reading is meaningless. Are you saying current is NOT flowing thru the circuit? Because I did use an ammeter (albeit a cheap one) and it didn't give a reading one would have to assume it was less than the meters capabilities, or the meter didn't work- which it does (I tested it on an extension cord, separated and running a light bulb at the time).
tenbear
Explorer
May 28, 2014
Calisdad wrote:
It has a 1.4v drain on the system.

Reading this and subsequent posts I think you put your voltmeter across the fuse contacts and it read 1.4v.

That is pretty much meaningless. It indicates that there is a path to ground of some undetermined resistance. If you know the resistance of your voltmeter you could calculate how much current is flowing thru the voltmeter and the circuit in series, which is also pretty meaningless.

If you have an ammeter you could put that across the fuse contacts and that would tell you how much current is being drawn. If the current is greater than your meter can handle it could damage your meter.

I'm surprised your clamp-on ammeter didn't give you a reading.
CA_Traveler
Explorer III
May 28, 2014
Most likely a typo and he meant 6 and 12 volt switch which is common on chargers.

OP From your description you need a new charger. You can get a decent multi stage auto charger that will charge both flooded and AGM batteries for about $50.
DiskDoctr
Explorer
May 28, 2014
Calisdad wrote:
YC 1 wrote:
Sick batteries, (found even when new, can die internally in a couple of days with that much draw. I suspect your solar panel cannot actually keep up with the draw.

Testing my understanding here. Did you measure "volts" across the contacts of the fuse. Measuring current is fine this way. Trying to understand your statement about 1.4 Volts.

Yes- I measured the current by putting the pin contacts in place of the fuse. All the rest gave me little to no reading but the green lighting/refer circuit read 1.4volts.

I would have thought a new battery would charge up higher than 13.2volts. I took 2 days to charge it. My charger has a 6volt and 2 volt switch so I'd trickle charge it for a couple hours, let it set and do it again, probably giving it 10 hours of charge in 2 days. For reasons stated I'm not going to mix wet and AGM batteries. I do have another good wet battery that I'll install with a battery switch but I have to make a place for it outside. Having said that you don't suppose my red top chassis battery will be an issue? It's separated by a solenoid and charged by the alternator.

Ebay says my new light switches are sitting in my PO box. They will get changed out this week. I got lighted ones so we will know if we left something on like the porch lite. That's the one light usually left on if one is.

6 volt an 2 volt? It really sounds like you are having difficulty keeping volts and amps straight. You do NOT want to charge a 12 volt battery with 6 or 2 volts. I suspect you meant 6 AMPS and 2 AMPS?