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MXdad · 03-29-2022, 03:44 PM

Riddle me this. Brand new house batteries. 1 year old chassis battery. I’ve kept chassis on trickle charger when not in use. Starts up fine. When on a trip I can be parked for a day or several days. Go to start RV and nothing. Dash completely dead and nothing lights up, no clicks nothing. Always hooked up to shore power or running generator. Put cables on to jump start and starts right up. I can remove cables and shut off and Rv starts right up. No issues. I’ve had battery checked and it’s good. Can leave it for a couple hours and still starts so I no it’s not a charge or voltage issue. Also cannot use emergency start as k have in the past. Could it be isolator(BIM160) causing issue? Connections are all tight and show no corrosion.

Julia2005 · 03-29-2022, 05:57 PM

A few things to check would be the battery connectors. They may look good but could have corrosion on the inside that you cannot see. Also, if it is a wet cell lead acid battery, try testing each cell with a specific gravity tester. I know you said the battery checked out, but how was it tested? I have had batteries sitting on trickle chargers over a long period of time and the battery has failed. I would also test the alternator to make sure it is really charging. at 1500 RPM you should get 13.8 to 14.2 volts at the battery. You can also see what the battery voltage is when you try to start it. I don't think you want much below 10 or 11 volts on start up.

theroc · 03-29-2022, 07:07 PM

From what you've written, can we interpret that the chassis batteries hold a charge when directly hooked to a separate trickle charger but when on shore power for a few days, the chassis batteries are dead? I don't know how long you're leaving it on shore power but could the parasitic draw be draining them to a point where there's not enough juice to start? If so, maybe install a Trik-L-Start? ...or keep the trickle charger you have hooked up too when on shore power?

I don't own a Thor but from what I've read in the past, they don't charge the chassis batteries on shore power. That's why I've talked to several Thor owners who have installed an ISL Trik-L-Start (or Amp-L-Start).

The ISL product seems to be the most popular but you could also use a similar products such as a Xantrex Echo-charge, etc.

But again, I'm not sure how your coach is set up or if I'm even interpreting your explanation correctly.

Trik-L-Start

Amp-L-Start

Xantrex echo~charge

Jabber Jaw · 03-31-2022, 11:48 AM

Gad a friend with a 2019 Thor....similar issues!

Two different Dealers, 18 months of working on it!

His Solution: He SOLD the dang thing!

Problem solved!

A sad but true story! He got so disgusted that he will not even consider another "RV", of any type!

twinboat · 03-31-2022, 01:36 PM

Some of the BIM160 are wired improperly.

Download the instructions get a volt meter and see if it's correct.

If I remember, the ignition wire is on the wrong post.