Battery Isolator Question

[eric1514]

If you're plugged into shore power, should the battery isolator relay be hot to the touch. I would think it should be cold since its job is to prevent current from passing through it. I also get the same voltage reading on either side of it when I measure at the large terminals to a ground.

TIA

[cruising7388]

Originally Posted by eric1514

If you're plugged into shore power, should the battery isolator relay be hot to the touch. I would think it should be cold since its job is to prevent current from passing through it. I also get the same voltage reading on either side of it when I measure at the large terminals to a ground.

TIA

What is the make and model of your isolator?

[mikeehlert]

If it’s hot it’s closed and conducting electricity to or from the batteries. That the voltage is the same on either side is further proof it’s closed and conducting electricity.
Generally you want it closed when parked and using it.

Open when stored.

If it’s too hot to touch you have a problem, bad or overloaded.

[eric1514]

Originally Posted by mikeehlert

If it’s hot it’s closed and conducting electricity to or from the batteries. That the voltage is the same on either side is further proof it’s closed and conducting electricity.
Generally you want it closed when parked and using it.

Open when stored.

If it’s too hot to touch you have a problem, bad or overloaded.

I thought that the only time it would be allowing current through itself would be when the alternator is running so that the alternator would charge the chassis battery and the coach batteries. I thought that it would prevent shore power or generator power through it to the chassis battery. That's why we install Trik-L-Starts.

[eric1514]

Originally Posted by cruising7388

What is the make and model of your isolator?

I'm not sure. I can't get my head in there to see. Here's a pic. It's the top silver canister.

I was going to replace it with a Cole Hersee 24213.

[mkguitar]

Is that a solenid switch?


could be hanging up


smack it with the heel of your palm




If this was every operated with low voltage the internal contact disk could be carboned up and need cleaning


mike

[cruising7388]

Originally Posted by eric1514

I'm not sure. I can't get my head in there to see. Here's a pic. It's the top silver canister.

I was going to replace it with a Cole Hersee 24213.

I think what you have is a bi-directional separator setup rather than a uni-directional isolator. When the alternator is running , the relay (silver canister) is activated and is charging both engine and coach batteries. During shorepower operation, (unlike a basic isolator), the relay is also active to permit the battery charger to address both batteries.

So seeing an active relay during shorepower operation is to be expected and the fact that battery voltage is the same on both batteries verifies this.

These relays do run fairly hot and it isn't helped when they don't have a heat sink like a fender well. They eventually jam in either the open or closed condition. IMO, the arrangement is working as it should but if you intend to replace the relay, a Cole Hersee product is the only way to go.

BTW, what battery terminal voltage are you seeing during shorepower?

[eric1514]

Originally Posted by mkguitar

Is that a solenid switch?


could be hanging up


smack it with the heel of your palm




If this was every operated with low voltage the internal contact disk could be carboned up and need cleaning


mike

I’ll try hitting it tomorrow. I’m sure it was operated with low voltage. The previous owners knew less about batteries and maintenance than I do. Even if smacking it works, I’m probably going to have to replace it as it doesn’t look like it comes apart.

I just wanted confirmation that when parked and plugged in to my house 1) It should not be hot and 2) I should read different voltages at each end.

[eric1514]

Originally Posted by cruising7388

I think what you have is a bi-directional separator setup rather than a uni-directional isolator. When the alternator is running , the relay (silver canister) is activated and is charging both engine and coach batteries. During shorepower operation, (unlike a basic isolator), the relay is also active to permit the battery charger to address both batteries.

So seeing an active relay during shorepower operation is to be expected and the fact that battery voltage is the same on both batteries verifies this.

These relays do run fairly hot and it isn't helped when they don't have a heat sink like a fender well. They eventually jam in either the open or closed condition. IMO, the arrangement is working as it should but if you intend to replace the relay, a Cole Hersee product is the only way to go.

BTW, what battery terminal voltage are you seeing during shorepower?

Thanks, that's a different set-up than I'm used to. The lower canister clicks when I push the "boost" button in the cab.

As far as voltages, the coach has a Progressive Dynamics converter so the voltages vary with time but when I checked it last, I was around 13.47 on both sides.

[cruising7388]

Originally Posted by mkguitar

Is that a solenid switch?


could be hanging up


smack it with the heel of your palm




If this was every operated with low voltage the internal contact disk could be carboned up and need cleaning


mike

These type of solenoids are sealed units and there is no easy way to access the power contacts.

[mikeehlert]

Originally Posted by eric1514

I thought that the only time it would be allowing current through itself would be when the alternator is running so that the alternator would charge the chassis battery and the coach batteries. I thought that it would prevent shore power or generator power through it to the chassis battery. That's why we install Trik-L-Starts.

I misread your initial post. Isolator relay Should be cold and voltage across it when engine is off.

Stuck or miswired.?

[mikeehlert]

Originally Posted by eric1514

I’ll try hitting it tomorrow. I’m sure it was operated with low voltage. The previous owners knew less about batteries and maintenance than I do. Even if smacking it works, I’m probably going to have to replace it as it doesn’t look like it comes apart.

I just wanted confirmation that when parked and plugged in to my house 1) It should not be hot and 2) I should read different voltages at each end.

Right. Not hot and voltage across it because it should be open.

[eric1514]

Originally Posted by cruising7388

These type of solenoids are sealed units and there is no easy way to access the power contacts.

That’s what I’m thinking. I’ll just replace it for piece of mind. Thanks for your help.

[eric1514]

Originally Posted by mikeehlert

I misread your initial post. Isolator relay Should be cold and voltage across it when engine is off.

Stuck or miswired.?

No problem. I thought it should be cold also but cruising7388 has introduced a new wrinkle. He thinks this might be a bi-directional situation and therefore should be warm/hot when I'm plugged into shore. So it's either that or it's stuck like you suggest.

[cruising7388]

Originally Posted by mikeehlert

I misread your initial post. Isolator relay Should be cold and voltage across it when engine is off.

Stuck or miswired.?

I don't think anything needs fixing. Seems to me the setrup is working as it's supposed to

[eric1514]

Originally Posted by cruising7388

I don't think anything needs fixing. Seems to me the setrup is working as it's supposed to

I'm unplugged right now and I'm trying to draw down the house batteries overnight by running the vent fans. Tomorrow I should see different voltages on either side of that solenoid because it should be keeping me from running down the chassis battery. If that's what happens then it's probably as you think. If I still see the same voltage on both sides, then I probably have a faulty solenoid.

That seem like a good test?

[cruising7388]

Originally Posted by eric1514

I'm unplugged right now and I'm trying to draw down the house batteries overnight by running the vent fans. Tomorrow I should see different voltages on either side of that solenoid because it should be keeping me from running down the chassis battery. If that's what happens then it's probably as you think. If I still see the same voltage on both sides, then I probably have a faulty solenoid.

That seem like a good test?

If it is a bi-directional separator setup it typically works this way. When shoreside charging starts the separator will only charge the coach battery until it reads a predetermined voltage (typically 13. at which pointy the separator will combine all batteries for charging. When shoreside power is disconnected, the batteries remain combined until the coach battery voltage drops below 12.8 volts at which point the coach and engine batteries separate.

So, your test should verify if that is the case. It doesn't take much battery load to reduce its surface charge voltage sufficiently to see different terminal voltages on the engine and coach batteries. If the voltages remain identical, that would warrant further testing of the solenoid.

What make and year model is this coach?

[markopolo]

The upper canister (no label) is a solenoid. The lower canister (with label) looks like an Intellitec battery disconnect.

Intellitec battery disconnects only use power while switching.

The solenoid uses power to stay closed so they'll get warm. Google search: RV Solenoid Hot - https://www.google.com/search?source...v+solenoid+hot

If the solenoid is functioning automatically as a bi-directional relay when it senses a charging voltage from any source then it is being triggered somehow (my understanding). You might find a "smart" device in the coach such as a Battery Isolator Controller or a Bi-Directional Isolator Relay Delay.

[eric1514]

Thanks folks,

Here's what I found. This morning after being unplugged all night and having 2 vent fans running my batteries where like this.

Chassis-12.84
House-12.35

I plugged in and after a couple of minutes

Chassis-13.56
House-13.56

Unplugged and engine on

Chassis-13.74
House-13.61

The coach is a 2006 Dynamax Isata 250. I know, it's a class C but you guys are smart about this stuff so here we are.

I'm leaning towards a faulty solenoid. I can't think of any test that will confirm that I have a bi-directional system vs. a broken solenoid. The age of the coach and my not being able to find any other "smart" components leads me to believe the solenoid is stuck although it does seem to isolate the batteries when I'm not plugged in.

I guess I'll buy a replacement and swap it out and see. If nothing else, I'll have a replacement.

Thanks,
Eric

[eric1514]

Quick update. According to someone at Dynamax who haunts the Forest River forum, it is indeed a bi-directional system.