Chassis Battery not charging

[dyates773]

I own a 1987 Fleetwood Bounder, 7.4L (454) V8 on a P30 Chevy Chassis. Only 21,500 miles and runs well except the alternator is not charging the battery. After some troubleshooting when starting the engine their is only 12.65 volts at the battery but 14.6 voilts at the alternator. I've traced the problem to a "mystery" device on the fire wall:

The top terminal connects to the house battery, the center terminal to the alternator, the bottom terminal to the chassis battery. Their are two additional smaller wires one on the top terminal, one on the bottom.

Any ideas what it is? No markings, no labels, no nameplate.

[f14av8r]

I don't recognize that particular device but I bet it is some electronic version of an Isolator Relay Delay. See this link for a version made by Intellitech - Battery Isolators - Battery Switches - Intellitec MV

Your alternator can't just be connected to both your chassis and coach batteries simultaneously. You need some sort of interface to make sure it charges the right battery at the right time. I'm betting this device, whatever it is, is not working properly.

[bruceisla]

Originally Posted by dyates773

I own a 1987 Fleetwood Bounder, 7.4L (454) V8 on a P30 Chevy Chassis. Only 21,500 miles and runs well except the alternator is not charging the battery. After some troubleshooting when starting the engine their is only 12.65 volts at the battery but 14.6 voilts at the alternator. I've traced the problem to a "mystery" device on the fire wall:

The top terminal connects to the house battery, the center terminal to the alternator, the bottom terminal to the chassis battery. Their are two additional smaller wires one on the top terminal, one on the bottom. Attachment 37356

Any ideas what it is? No markings, no labels, no nameplate.

Doesn't look familiar. With Alternator, Chassis bat, and House bat connections it "sounds" like a BIRD (bi-directional relay device). The separate terminal at the end might be a pick or signal ... does it have voltage applied? However, a BIRD is usually parallel and not serially in the bat/alternator chain. Can the black material be removed for a peek at what's under it?

[whem2fish]

Same in my 1985 I had bad connections there cleaned them it worked ok then they can go out

[gt350ed]

Originally Posted by dyates773

I own a 1987 Fleetwood Bounder, 7.4L (454) V8 on a P30 Chevy Chassis. Only 21,500 miles and runs well except the alternator is not charging the battery. After some troubleshooting when starting the engine their is only 12.65 volts at the battery but 14.6 voilts at the alternator. I've traced the problem to a "mystery" device on the fire wall:

The top terminal connects to the house battery, the center terminal to the alternator, the bottom terminal to the chassis battery. Their are two additional smaller wires one on the top terminal, one on the bottom. Attachment 37356

Any ideas what it is? No markings, no labels, no nameplate.

Here is a picture of a Cole Hersee Isolator. This particular one is specific to the type of alternator I'm running...a CS series Delco on my 901/2 Bounder. I just ordered this this morning. There are variations of this particular one.

The one in YOUR photo looks to be a copy or at least similar.

[dyates773]

Ed, you got it! I checked the upper small wire on the unit & it is switched to the ignition. Where did you find the isolator? Cost?

[gt350ed]

Originally Posted by dyates773

Ed, you got it! I checked the upper small wire on the unit & it is switched to the ignition. Where did you find the isolator? Cost?

On ebay...search this...
200 AMP COLE HERSEE MULTI BATTERY ISOLATOR EXCITER NEW

$101...free shipping. American made by the way.

[ga traveler]

What you have is a battery isolater. It is a heatsink with three large diodes.
it allows voltage to go into the battery but not out. You need to check the small leads for voltage. Maybe someone who has the paperwork can give you advice on checking it out. If the diode is burned out, it will have to be replaced.

[ga traveler]

If you want to do a quick check, crank the engine, check the center lead for 13+ voltage. check the small wire for 12 volts. Then check the outer large wires for 13+ volts. If you have 13 volts on the center wire and 12 volts on the small wire and no voltage on the two outer wires, the diodes are bad. If you have no voltage on the small wire, the isolater is not turning on. All you need to do is get 12 volts to the small wire.

[cimplexsound]

Question??? Do you have a power converter with both breaker switches and fuses? If so you might check to make sure a fuse hasn't blown or breaker switch didn't trip. Usually located in your overhead cabinets by the drivers seat.

[cimplexsound]

You might also have bad isolator.