HELP! House battery not charging. Any advice?

Nutsy_squirrel · 10-04-2019, 04:41 AM

Hey all.

I recently had my van out. I have a 1994 Pleasure Way STW. Everything was working well the first few days and then I noticed that the house battery wouldn't charge off the van's alternator. I plugged in overnight and it charged okay. The next day I plugged in again, wouldn't charge.

I took the battery out and had it tested. Tested out fine. Alternator test too, fine but at the lower end of passing. I will probably replace the alternator next season along with the oil pump.

Never had any issue with the house battery charging before. Any suggestions as to why it might not be charging?

GallenH · 10-04-2019, 07:33 PM

My 97 PW has a breaker between the alternator and the battery. 40A I believe.
It's in the compartment under the pass side bed in the rear. Your breakers might be in a different location. There's a reset on the breaker. Maybe that's your problem with no alternator charge. Maybe not.

booster · 10-04-2019, 09:14 PM

Breakers, yes to that, and also do you know if the van has an isolator in it, which would be the one way connection to the coach from the engine charging?

Nutsy_squirrel · 10-05-2019, 04:31 AM

Thanks for the inputs, both of you. I know in the glove box there is a fuse panel but that is different. Would the breaker for the house electrical systems be in that electrical enclosure by where the shore power cord is on the driver's side? I know there is a metal grill and some kind of fan there since I hear the fan kick on when I hook up shore power.

Far as an isolator, I'm not sure what that is. Can you elaborate?

GallenH · 10-05-2019, 04:50 AM

Hopefully this will help although, again, it's from the manual of a 1997 PW. Note that the breakers are not in the location of the dash fuse box nor in with the convertor/charger (where the shore cord is). On my model there is a small door under the rear end of the passenger side bed. The isolator is up in the engine compartment (at least that's what the diagram says). It sends alternator power to both the engine battery and the house battery but prevents the house battery from draining the engine battery.

IMG_6115.jpg

GallenH · 10-05-2019, 04:51 AM

Click on the image for a large view

booster · 10-05-2019, 01:54 PM

If you have an isolator it would be under the hood somewhere and would have battery size cables to it. One probably #6 or #8 wire that goes to the coach battery in the back, through the breakers that have been mentioned. Another cable would be from the starting battery to the isolator. A third wire would be from the alternator to the isolator.

All the power has to go through the isolator to charge the coach battery so if it fails no engine charging of the coach battery.

Nutsy_squirrel · 10-05-2019, 03:17 PM

I will for sure try the breaker. From the schematic it looks very similar to my van, though the coach battery is on the driver's side for my year. Which breaker is it? Is there a way to tell?

I will also look at the isolator as well. Can anyone tell me what that isolator is doing? Is that a Dodge component or something that comes from PW?

Final question...I know the battery charges off the alternator. Does it also charge off of shore power as well?

booster · 10-05-2019, 03:31 PM

The isolator is a one way pass though for power from the engine to the coach battery. It only allows power to go through it to the coach when the engine is running and also prevents the coach battery from being able to discharge the van starting battery when the engine is off. Basically it is a big diode switch. It is not a Dodge part and was added during the conversion.

Your coach battery should charge when on shore power and when the engine is running. The van starting battery will charge only when the engine running, if you have an isolator.

avanti · 10-05-2019, 03:46 PM

Note that there are two different kinds of "isolator". One is the "one-way" diode kind described by Booster. The other is a mechanical relay that is closed whenever the engine is running (or sometimes when the ignition is turned on). They both accomplish the same job, just in completely different ways. The relay is a mechanical device, and makes a click sound when it is activated.

The relay style is more common, I think. Given that the diagram shows three terminals on the device labeled "isolator" with the center wire coming from the alternator, I am guessing that this vehicle has the mechanical style. If so, it can be diagnosed with a voltmeter as follows:

1) Check to see that there is 12V at the center terminal when the engine is ON, and 0V when it is OFF. If not, there is a fault in the control signal coming form the alternator.
2) Check for continuity across the two outside terminals. There should be no continuity with the engine OFF and full continuity (i.e., ~0 ohms) when the engine is running. If not, the isolation relay itself is faulty.
3) With the engine OFF, measure the voltage at each of the outside terminals. They both should be approximately 12V, but in all likelihood slightly different (since one should be showing the chassis battery voltage and the other the house battery). If either of them is zero volts, then the wiring between that terminal and its respective battery is faulty (or there is a tripped fuse or breaker somewhere).

booster · 10-05-2019, 03:56 PM

Quote:

Originally Posted by avanti

Note that there are two different kinds of "isolator". One is the "one-way" diode kind described by Booster. The other is a mechanical relay that is closed whenever the engine is running (or sometimes when the ignition is turned on). They both accomplish the same job, just in completely different ways. The relay is a mechanical device, and makes a click sound when it is activated.

The relay style is more common, I think. Given that the diagram shows three terminals on the device labeled "isolator" with the center wire coming from the alternator, I am guessing that this vehicle has the mechanical style. If so, it can be diagnosed with a voltmeter as follows:

1) Check to see that there is 12V at the center terminal when the engine is ON, and 0V when it is OFF. If not, there is a fault in the control signal coming form the alternator.
2) Check for continuity across the two outside terminals. There should be no continuity with the engine OFF and full continuity (i.e., ~0 ohms) when the engine is running. If not, the isolation relay itself is faulty.
3) With the engine OFF, measure the voltage at each of the outside terminals. They both should be approximately 12V, but in all likelihood slightly different (since one should be showing the chassis battery voltage and the other the house battery). If either of them is zero volts, then the wiring between that terminal and its respective battery is faulty (or there is a tripped fuse or breaker somewhere).

I think I am missing what you are saying about the relay style isolator/charge relay/separator (called lost of names). My understanding is that the the relay style will have two big connections only on the charging line stuff, and then small connections for the coil activation. The alternator connection would go on the same connection as the big cable to the starting battery. The center tap for the alternator wire is usually the input from the alternator to both batteries that goes through diodes to those batteries and that is why it is on a separate input to the isolator. The drawing seems to show the alternator as a discreet input, so wouldn't that mean diode isolator?

avanti · 10-05-2019, 05:18 PM

Quote:

Originally Posted by booster

I think I am missing what you are saying about the relay style isolator/charge relay/separator (called lost of names). My understanding is that the the relay style will have two big connections only on the charging line stuff, and then small connections for the coil activation. The alternator connection would go on the same connection as the big cable to the starting battery. The center tap for the alternator wire is usually the input from the alternator to both batteries that goes through diodes to those batteries and that is why it is on a separate input to the isolator. The drawing seems to show the alternator as a discreet input, so wouldn't that mean diode isolator?

You can't really tell the difference from the diagram. Sometimes, the relay-style's center terminal is picked up from the "IG" terminal of the alternator, which is powered by the ignition switch, but is conveniently available under the hood. But, yes, it could also be the diode style. We need a picture.

BTW: on Sprinters, there is a "engine running" signal generated by the ECM and available in the "EK1" connector under the driver's seat. This signal only goes high when the engine has been running for several seconds. This is typically used to control the relay in Sprinters.

Bertiboo · 10-15-2019, 03:46 PM

Older style solenoid isolators look like the picture attached, do fail occasionally and are quite cheap to replace. (max $30 to $40 on amazon). Like mentioned above, their job is to prevent your house system depleting your auto battery, so you can still start your unit the next morning after a long cold night using the furnace or other electrical items. If they jam in the open position, the power won't go the other way from the alternator to the house battery, after you start the van. I wouldn't replace the alternator if it is still charging your auto battery, but not your house battery; as mentioned, the problem is more likely between the alternator and your house system. You can either test the isolator as above, or just replace it, since it's likely 25 years old.

Gary (bertiboo)
Shawnigan Lake, BC

Nutsy_squirrel · 10-17-2019, 07:21 PM

Quote:

Originally Posted by Bertiboo

Older style solenoid isolators look like the picture attached, do fail occasionally and are quite cheap to replace. (max $30 to $40 on amazon). Like mentioned above, their job is to prevent your house system depleting your auto battery, so you can still start your unit the next morning after a long cold night using the furnace or other electrical items. If they jam in the open position, the power won't go the other way from the alternator to the house battery, after you start the van. I wouldn't replace the alternator if it is still charging your auto battery, but not your house battery; as mentioned, the problem is more likely between the alternator and your house system. You can either test the isolator as above, or just replace it, since it's likely 25 years old.

Gary (bertiboo)
Shawnigan Lake, BC

That's probably it. When they fail do they "partially" fail or go all at once? Also, how do I get a part number to buy it off of Amazon? I assume the isolator is a PW installed part? Do I need to contact PW for a replacement?

Bertiboo · 10-17-2019, 10:18 PM

If it looks like that picture I sent with three terminals and chrome housing, it’s completely generic and you can get one at your local auto or RV parts store or Amazon. The 3 pole one I found on amazon Canada was the tow ready 118665 but any 3 pole one will work. Search “battery isolation solenoid”.

One way to check it is to tap it (the housing, not a terminal) lightly with a hammer with the engine running. The terminal that has no voltage when the engine is off, might produce voltage when you tap it. The internal switch might be weak or stuck.

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