testing battery isolator

[sailorboy1]

How do you test a battery isolator? Does a diode block voltage or only current? Can I just apply voltage on the outlet side of the diode and check the supply side, and if there is voltage the diode is bad?

[velero]

Don what brand/model number isolator/combiner? Is it an isolator or a combiner?

IIRC my 410 had an isolator that looks like a selenoid in your car starter motor - a cylinder with 2 large bolts on top and two small ones on the side.

If you have an isolator there are no diodes. you apply a voltage to the small bolts and that engages the selenoid combining the 2 large bolts. Use the continuity/ohms funtion on the volt meter to determine if its working. On my 410 the selenoid was activated by the engine start switch or when the charger was on otherwise the isolator was off, isolating the house and starting battery banks.

[Blue Stocking]

Originally Posted by Don Lucas

How do you test a battery isolator? Does a diode block voltage or only current? Can I just apply voltage on the outlet side of the diode and check the supply side, and if there is voltage the diode is bad?

Off the top of my head, I can think of 4 types of battery isolation devices. Each serves its purpose by different means.
Can you post a photo?

[DeepFrz]

Don, if its a diode isolator you test it with an ohmmeter with no battery connected. The resistance should be low in one direction and high in the other. Connect the leads, take a reading, reverse the leads, take a reading. You should have one high and one low resistance reading. Then with the batteries connected you can measure the voltage drop across the diode. It should be somewhere around .3 to .7 volt depending on the diodes used. (Don't forget to switch the multimeter to volts for the second test). Hope that helps.

[sailorboy1]

Originally Posted by velero

Don what brand/model number isolator/combiner? Is it an isolator or a combiner?

IIRC my 410 had an isolator that looks like a selenoid in your car starter motor - a cylinder with 2 large bolts on top and two small ones on the side.

If you have an isolator there are no diodes. you apply a voltage to the small bolts and that engages the selenoid combining the 2 large bolts. Use the continuity/ohms funtion on the volt meter to determine if its working. On my 410 the selenoid was activated by the engine start switch or when the charger was on otherwise the isolator was off, isolating the house and starting battery banks.

I have not found it on the boat yet (going to look for it today). On the Hunter drawing there is a soleniod that is engerzies from the engine start circuit as you say.

AND there is an isolator that the drawing shows as having a set of diodes. This in turn as an output to the house batteries via the inverter selector switch (charges whatever battery is selected to the inverter), and an ouput to the start batery (which also has the feed from the little solar panel).

There seems to be a few different electrical arrangements for the 410: 1-standard Battery charger, 2-inverter charger, 3-high output alternator

I have a combo of 2&3 and Hunter has not been able to find a drawing for this. Apparently the alternator feed point is different for the high output alternator system.

Looks that I'm tracing wires and circuits today!

[sailorboy1]

Originally Posted by DeepFrz

Don, if its a diode isolator you test it with an ohmmeter with no battery connected. The resistance should be low in one direction and high in the other. Connect the leads, take a reading, reverse the leads, take a reading. You should have one high and one low resistance reading. Then with the batteries connected you can measure the voltage drop across the diode. It should be somewhere around .3 to .7 volt depending on the diodes used. (Don't forget to switch the multimeter to volts for the second test). Hope that helps.

Thanks!

[velero]

Don mine was located under the breaker panel. There is a removable inspection panel. If not there follow the alternator red wire and it should be at the other end IIRC. If the selonoid is not working I would recomend you get a blue seas batterry combiner 7610. I have this combiner on my 49, its a lot better than the selonoid type. All solid state no moving parts.

[cal40john]

Originally Posted by velero

Don what brand/model number isolator/combiner? Is it an isolator or a combiner?

Use the continuity/ohms funtion on the volt meter to determine if its working.

You have to disconnect the battery to use the ohms function. With the engine running and the batteries reasonably charged, around 14 volts on one side of the solenoid and less than 12.6 volts on the other would indicate that the solenoid is not functioning.

Originally Posted by DeepFrz

Don, if its a diode isolator you test it with an ohmmeter with no battery connected. The resistance should be low in one direction and high in the other. Connect the leads, take a reading, reverse the leads, take a reading. You should have one high and one low resistance reading.

Most DVMs have a diode testing setting, most do not apply enough voltage to forward bias a diode in the ohms settings.

[sailorboy1]

Couldn't really tell anything about the isolator be testing it. But I did find it and it is a Guest 2430 (took a lot of disconnecting stuff to find this).

I never found that soleniod switch and don't believe it is in the system.

The alternator feeds the isolator. On the same lug as the alternator is line to the inverter switch (just like a 1, 2 both, off switch) and on another lug is a line to the start battery.

Now when I got to the boat the inverter switch was off. The start battery was reading 13.2 V because it was being charged by the trickle solar panel, the house battery was reading 12.8V (beczause I motored 4 hours to get in the other day and everything has been off since then).

I turned on the stereo and 20 minutes later the house battery reads 12.2V. This is my "good" battery and it believe has lost the war (got new batteries for both house banks on the way home). The "bad" battery is less than 11V but is competely disconnected.

I turned the inverter switch to 1 (the only house battery) and the start battery voltage drops to 12.2V. I turn it back off and the start battery slowly goes back up to 13.2V.

So near as I can tell that inverter switch is connecting the house and start batteries. And the only way to do that is though the isolator.

Since the start battery powers the windlass; I'm thinking it is much less trouble to replace the isolator that to redo the power to the windlass in order to use some echo type charger.

Thoughts are welcome!