ChrisGalipo Posted June 14, 2009 Share Posted June 14, 2009 How do I know if my battery isolator is working? How can I test it? Thanks. Quote Link to comment Share on other sites More sharing options...
Maineah Posted June 14, 2009 Share Posted June 14, 2009 Check the voltage at each battery while the engine is running should be about 13.2 - 14.2 volts. Quote Link to comment Share on other sites More sharing options...
ChrisGalipo Posted June 14, 2009 Author Share Posted June 14, 2009 Check the voltage at each battery while the engine is running should be about 13.2 - 14.2 volts. Ok, cause I just checked it and I don't get more than 12.50 at the coach battery... I disconnected the coach battery completly and when the engine is running, I get like 12v at the coach battery connection... you think my isolator is broken? Quote Link to comment Share on other sites More sharing options...
Maineah Posted June 15, 2009 Share Posted June 15, 2009 What kind of voltage at the truck battery? Do you have the isolator that looks like a starter relay or one with cooling fins? Quote Link to comment Share on other sites More sharing options...
ChrisGalipo Posted June 15, 2009 Author Share Posted June 15, 2009 What kind of voltage at the truck battery? Do you have the isolator that looks like a starter relay or one with cooling fins? I get 14v at the car battery when engine is running. I think it's the one with cooling fins, it's blue with 4 bolts on it. Quote Link to comment Share on other sites More sharing options...
Maineah Posted June 15, 2009 Share Posted June 15, 2009 OK that's a solid state one. So what you need to do is check the voltage (truck running) at the terminals of the isolator that have the bigger wires attached. One goes to the truck battery and the other to the coach. In the middle is the alternator wire (marked "A") if you have the same voltage at both of the battery terminals the isolator is fine. If one is lower the isolator is toes up. If you check the alternator voltage is will be more by about .7 volts that's OK. If the output is fine you need to have a look at all of your connections most likely there is a breaker in line in the wiring some times they go bad if you have voltage on one side and not the other it's bad. Beyond that is just a matter of looking at all of the connections and wiring clean every thing up and see what happens. Quote Link to comment Share on other sites More sharing options...
ChrisGalipo Posted June 16, 2009 Author Share Posted June 16, 2009 OK that's a solid state one. So what you need to do is check the voltage (truck running) at the terminals of the isolator that have the bigger wires attached. One goes to the truck battery and the other to the coach. In the middle is the alternator wire (marked "A") if you have the same voltage at both of the battery terminals the isolator is fine. If one is lower the isolator is toes up. If you check the alternator voltage is will be more by about .7 volts that's OK. If the output is fine you need to have a look at all of your connections most likely there is a breaker in line in the wiring some times they go bad if you have voltage on one side and not the other it's bad. Beyond that is just a matter of looking at all of the connections and wiring clean every thing up and see what happens. Ok yeah, I don't have the same voltage on both sides... I have like 14v on the engine battery side and 12.50V on the coach battery side... I even disconnected the coach battery and I was getting 11v when engine was running... I guess it's toes up. I'll go buy a new one and try it. By the way, is it ok if I plug 2 batteries on the coach side? I bought a second one and I want to connect both to my motorhome. Quote Link to comment Share on other sites More sharing options...
Maineah Posted June 16, 2009 Share Posted June 16, 2009 Did you check your voltage right at the isolator? If so it is toes up. I run two coach batteries in mine with no problems. Quote Link to comment Share on other sites More sharing options...
ChrisGalipo Posted June 16, 2009 Author Share Posted June 16, 2009 Did you check your voltage right at the isolator? If so it is toes up. I run two coach batteries in mine with no problems. Yes, right at the isolator... I'll go buy a new one this week and try it. I'll let you know! Quote Link to comment Share on other sites More sharing options...
Gulfstream Greg Posted June 16, 2009 Share Posted June 16, 2009 Have you checked to verify the isolator is wired correctly? Quote Link to comment Share on other sites More sharing options...
ChrisGalipo Posted June 16, 2009 Author Share Posted June 16, 2009 Have you checked to verify the isolator is wired correctly? Yes it is, I'll double check... Quote Link to comment Share on other sites More sharing options...
ChrisGalipo Posted June 20, 2009 Author Share Posted June 20, 2009 I replaced the battery isolator and now it's working. Quote Link to comment Share on other sites More sharing options...
wetboy Posted November 18, 2009 Share Posted November 18, 2009 One thing to keep in mind if you are replacing your Isolator...If you are adding batteries (I have 5- 120 Amp hour bats in my 85 Toyo), you will need to make sure your Isolator has an Amp rating AT LEAST that of the full power of the Alt. Really, you should go over by 30 or 40 amps so they are not working at their Max all the time. Most Coach builders put the least powerful isolator they can get away with. Fine for one battery (usually), but not a several. Those batteries, when depleted, will suck the Max power from your Alt. On that note, make sure your Alt can handle the extra demand too. A lil 30 or 40 amp alt will be straining to keep up with Engine, lights, radio, and wiper demands going down the road while trying to charge a hungry pack in the back. I went to a monster 160 Amp Alt that puts out 90 amps idling, and my piddly old 30 amp contact isolator was replaced with a 200 amp solid state one. Quote Link to comment Share on other sites More sharing options...
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