I just installed a new pair of 6V batteries and rewired everything pretty much the same way, except for wiring them in series. Everything's working great except for the isolator that is supposed to give me a charge from the alternator. It's not giving me any juice when the engine is turned on anymore. The generator is providing charge just fine, although it's on the cabin side of the isolator.Here's a quick diagram of my basic wiring:Do I have everything wired correctly? If so, maybe my isolator has gone bad. I did accidentally touch it with a wire when I was removing the old batteries and it gave off a few sparks.

Isolators come in different flavors. What does yours look like?

Hi pNuker,If it is a relay that is energized when the key is on have someone else turn on the key while you listen for a "clunk". If you hear the clunk then check for power on both "sides" of the relay. If there is no clunk check to see that the small wire has power when the key is on. Mine had a fuse before the relay that I've caused to be replaced by auto reset circuit breakers.Relay type isolators do fail and contacts do burn. My Ford OEM one lasted less than a year, in spite of it being rated for 100 amps. The contacts were in poor shape. The "intelligent" design folks put the relay down below the starter battery so the battery has to be removed to service or check the relay. Of course you can't check it with no starter battery. The one I used to replace it is a lot better made. I would not put my inverter through a shunt. Too much chance of a surge taking out the shunt and leaving me without cabin power. I would have a heavy duty manual switch on the inverter as well.

Hey there Mex, here's a pic of it. It's a Camdec 97226-wr.

Is the chassis battery being charged from the alternator? If so check the wiring against the pictures that you hopefully took before the new batteries. The n check the two small control terminals (if it's a solenoid) on the isolator. Once you got the sparks then the isolator or something else could have been zapped. BTW There are several good reasons to disconnect the negative battery cable first and connect it back last. Prevents those sparks is one reason.

Pianotuna's diagnostic procedure is right on the money...I h-a-t-e those solenoid type isolators. I much prefer the Essex type bi-directional "smart" solenoid. They can rate the can solenoid for a billion amps but they'll only carry 60. I even tried the 11880 solenoid with silver contacts years ago and they too were junk.Someone else will chip in about the smart solenoids. Again I love the new stuff. They protect themselves and do not need an ignition signal wire to work.

Battery Isolator Not Working | Good Sam Community

79 Replies

pianotuna
Nomad III
Dec 10, 2012
Hi pNuker,

Go to Napa and get a perko switch--rated at 100 amps--1000 amps contacting.

pNuker wrote:
I'm also looking for a method to divert the charge from the isolator to my extra backup battery (damaged agm battery discussed over here) when it needs. I was thinking about getting one of those marine battery switchers to manually switch to it when my main cabin batteries are already charged up. Something like this:
http://www.amazon.com/gp/product/B000K2MCR2/ref=ox_sc_act_image_1?ie=UTF8&smid=A1UNWS4MSNTF2A

It looks like the perfect switch dual rectifier would accomplish this, but like I said it's way too pricey...
pNuker
Explorer
Dec 10, 2012
Aren't voltage sensing relays solid state?
jumpshowhigh
Explorer
Dec 10, 2012
pNuker wrote:
I guess I'm not sure what everybody means when they say "solid-state". Is the one I currently have solid state (see pic at beginning of thread)? Got any recommendations?

solid state means no moving parts
tenbear
Explorer
Dec 10, 2012
pNuker wrote:
I guess I'm not sure what everybody means when they say "solid-state". Is the one I currently have solid state (see pic at beginning of thread)? Got any recommendations?

The one in the photo is an electro-mechanical solenoid. That's just a high power relay.
pNuker
Explorer
Dec 10, 2012
I guess I'm not sure what everybody means when they say "solid-state". Is the one I currently have solid state (see pic at beginning of thread)? Got any recommendations?
jumpshowhigh
Explorer
Dec 10, 2012
It's mechanical solenoid so it will definitely be inexpensive. Why not just use a mechanical relay that gets energized with the ignition and get de-energized when you shut the RV off. Then apply your solar charger output to your house bank. The issue with the voltage sensing relays is they tend to cycle constantly if the batteries approach the voltage where they engage/disengage. Add in the additional resistance of the contacts as it wears and a cheap and easy option makes your head want to explode with the constant slapping open and close of the contacts. Forget that. I go solid-state with the lowest voltage drop I can find. More spendy but more reliable and less aggravation.
pNuker
Explorer
Dec 10, 2012
I was looking at the perfect switch, but it looks like it's pretty expensive. I'm leaning towards this one:
Sure Power 1314 200 Amp Battery Separator

It's unidirectional, but if I'm not mistaken that's what I actually want for my setup. If I'm understanding things correctly, the bi-directional isolator would charge the cabin batteries when the alternator is on, and then charge the engine battery when the solar is coming in.

I want to completely maximize the amount of charge from the solar to the cabin batteries and don't want any of it getting sucked up by the engine battery. I drive around quite often and never have any issues with it starting, so I don't really see any benefit to bi-directional.

I'm also looking for a method to divert the charge from the isolator to my extra backup battery (damaged agm battery discussed over here) when it needs. I was thinking about getting one of those marine battery switchers to manually switch to it when my main cabin batteries are already charged up. Something like this:
http://www.amazon.com/gp/product/B000K2MCR2/ref=ox_sc_act_image_1?ie=UTF8&smid=A1UNWS4MSNTF2A

It looks like the perfect switch dual rectifier would accomplish this, but like I said it's way too pricey...
jumpshowhigh
Explorer
Dec 09, 2012
The old-school diode isolators do suck, but the MOSFET based units like Perfect Switch are the cat's meow. I'll take that over a sloppy solenoid any day of the week.
MEXICOWANDERER
Explorer
Dec 02, 2012
A large percentage of constant duty solenoid failures occur when solenoid coil power is removed when a lot of current is flowing through the power contacts. With monster 385 amp 24 volt 50 DN alternators powering a half dozen batteries I added a "Delay on Break" timer to the solenoid control circuit. The engine was shut down, the alternator stopped charging and 5 seconds later the solenoid disengaged. What a difference in lifespan. Engage disc contacts before current is applied, disengage after current is removed. Magic.
YC_1
Nomad
Dec 02, 2012
scroll down to #15

At this link scroll down and you will see a picture of a defective relay. There are several PDF's you can review as well.

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Battery Isolator Not Working

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