Trickle charge the chassis battery

[waynetaylor55]

My solar system keeps the house batteries nicely charged, but has anyone set up a solar system to keep the chassis battery charged?
I run the genny and drive our FW 28A once a month, but for the chassis battery, it doesn't seem enough.

[DavidEM]

Do you have a Precision Circuits BIM 160 in your coach. If so it is supposed to connect the coach and chassis batteries together to charge one if the voltage on the other is 13.5+V.

If you have the BIM 160 then it is probably wired backwards as Thor is won’t to do. Wire it right and it should keep your chassis battery charged.

See the attached spec sheet and wire it like the diagram at the bottom.

David

[Dan-sr@perra-us.net]

Originally Posted by DavidEM

Do you have a Precision Circuits BIM 160 in your coach. If so it is supposed to connect the coach and chassis batteries together to charge one if the voltage on the other is 13.5+V.

If you have the BIM 160 then it is probably wired backwards as Thor is won’t to do. Wire it right and it should keep your chassis battery charged.

See the attached spec sheet and wire it like the diagram at the bottom.

David

This diagram does not show where the charging connection(s) is/are supposed to be.

[waynetaylor55]

Originally Posted by DavidEM

Do you have a Precision Circuits BIM 160 in your coach. If so it is supposed to connect the coach and chassis batteries together to charge one if the voltage on the other is 13.5+V.

If you have the BIM 160 then it is probably wired backwards as Thor is won’t to do. Wire it right and it should keep your chassis battery charged.

See the attached spec sheet and wire it like the diagram at the bottom.

David

I assume I do have the BIM 160. I'll be able to check after what appears to be rain (in So. California) has stopped.

After looking at the Solar PDF from THOR, it looks like the solar system should be charging the chassis battery through the BIM.

After two years, I'm just now having voltage issues with my chassis battery.

Thanks for your help!

[DavidEM]

Originally Posted by Dan-sr@perra-us.net

This diagram does not show where the charging connection(s) is/are supposed to be.

Hmmm! The diagram at the bottom is pictorial. It shows the chassis + connected to the lower left terminal. The coach + is connected to the lower right.

Thor often reverses these, leading to the problems you are experiencing.

David

[Pete'sMH]

Originally Posted by waynetaylor55

My solar system keeps the house batteries nicely charged, but has anyone set up a solar system to keep the chassis battery charged?
I run the genny and drive our FW 28A once a month, but for the chassis battery, it doesn't seem enough.

There is a simple little device (just 3 wires) to connect the two batteries so that the solar will keep both the chassis and house batteries called a Trik-L-Start. Works great.

[waynetaylor55]

Originally Posted by Pete'sMH

There is a simple little device (just 3 wires) to connect the two batteries so that the solar will keep both the chassis and house batteries called a Trik-L-Start. Works great.

If the BIM is doing its job, that shouldn't be necessary.

Wayne

[Dan-sr@perra-us.net]

One thing no-one has pointed out is that the Battery disconnect must be "ON" in order to charge the coach batteries. I think this may be a catch 22 issue. If the coach batteries are too low will there be enough power to operate the switching relay? So, what is the procedure to boot strap charging if there is not enough power to trip the master battery relay?

[waynetaylor55]

Originally Posted by Dan-sr@perra-us.net

One thing no-one has pointed out is that the Battery disconnect must be "ON" in order to charge the coach batteries. I think this may be a catch 22 issue. If the coach batteries are too low will there be enough power to operate the switching relay? So, what is the procedure to boot strap charging if there is not enough power to trip the master battery relay?

That is not true for solar. Solar will charge the house batteries and, supposedly the chassis battery through the BIM, with the Battery Disconnect in the OFF position.

[Dan-sr@perra-us.net]

Originally Posted by waynetaylor55

That is not true for solar. Solar will charge the house batteries and, supposedly the chassis battery through the BIM, with the Battery Disconnect in the OFF position.

The statement on page 15 of the TMC Electrical system guide states

" The Master Battery Disconnect Switch must be ON in order to charge the Batteries by any on-bord method described in the following sections."

Solar battery charging IS one of the following sections. I would post the doc but I suspect that would not be allowed for copy right issues.

[waynetaylor55]

Originally Posted by Dan-sr@perra-us.net

The statement on page 15 of the TMC Electrical system guide states

" The Master Battery Disconnect Switch must be ON in order to charge the Batteries by any on-bord method described in the following sections."

Solar battery charging IS one of the following sections. I would post the doc but I suspect that would not be allowed for copy right issues.

In my 2021 FW 28A, with the Main Battery Disconnect set to the off position, my solar system charges my house battery.

On page 6 of the "TMC QSG, Solar Panels and Charge Controller" PDF, it shows the charge controller on the house battery side of the Main Battery Disconnect switch.

[MJC62]

Here's the $20 question, is the coach battery any good? Did I read on one the posts the coach battery is two years old. Which would mean if it is the OEM battery it is at least three years old or older.
My coach is a 2018. Mid-summer 2020 the battery Thor installed took a dump. It wouldn't hold a charge. After a load test it was determined to have a bum cell.
I would be surprised if Thor is installing a coach battery with more than a 36-month warranty.

[Dan-sr@perra-us.net]

Originally Posted by waynetaylor55

In my 2021 FW 28A, with the Main Battery Disconnect set to the off position, my solar system charges my house battery.

On page 6 of the "TMC QSG, Solar Panels and Charge Controller" PDF, it shows the charge controller on the house battery side of the Main Battery Disconnect switch.

The TMC Electrical system guide also states that it does not account for factory or local mods. So how your unit is wired is not necessarily the way all units are wired. I also suspect that you would charge the coach batteries from solar you might need to have the battery disconnect on to also charge the Chassie battery.

[Lt Keefer]

Originally Posted by MJC62

Here's the $20 question, is the coach battery any good? Did I read on one the posts the coach battery is two years old. Which would mean if it is the OEM battery it is at least three years old or older.
My coach is a 2018. Mid-summer 2020 the battery Thor installed took a dump. It wouldn't hold a charge. After a load test it was determined to have a bum cell.
I would be surprised if Thor is installing a coach battery with more than a 36-month warranty.

This is what I was thinking. OEM factory batteries frequently fail after 3 or 4 years.

[16ACE27]

Originally Posted by Dan-sr@perra-us.net

The TMC Electrical system guide also states that it does not account for factory or local mods. So how your unit is wired is not necessarily the way all units are wired. I also suspect that you would charge the coach batteries from solar you might need to have the battery disconnect on to also charge the Chassie battery.

No. The chassis/house battery interconnection does not go through the house battery bank disconnect.

[waynetaylor55]

Originally Posted by MJC62

Here's the $20 question, is the coach battery any good? Did I read on one the posts the coach battery is two years old. Which would mean if it is the OEM battery it is at least three years old or older.
My coach is a 2018. Mid-summer 2020 the battery Thor installed took a dump. It wouldn't hold a charge. After a load test it was determined to have a bum cell.
I would be surprised if Thor is installing a coach battery with more than a 36-month warranty.

This is a very good point. I'm almost excited to have my OEM batteries fail so that I can upgrade!

[DavidEM]

Not sure that failing coach batteries would affect charging of your chassis batteries. Maybe if the plates became shorted the coach batteries would draw all of the available charging current so their voltage would ne ver get high enough to trigger the connection to the chassis batteries.

BTW, did you ever determine if you have a BIM 160?

David

[waynetaylor55]

Now where to find the BIM. I've looked in the battery compartment and in a void under the refrigerator where a lot of wires come in. I've also looked in the engine compartment, under the driver's seat and under the dash on the driver's side.

Also to note, I ran a meter across the wires for the Emergency Switch and got 0 readings.

Anybody have any other ideas?

Wayne

[waynetaylor55]

Originally Posted by DavidEM

Not sure that failing coach batteries would affect charging of your chassis batteries. Maybe if the plates became shorted the coach batteries would draw all of the available charging current so their voltage would ne ver get high enough to trigger the connection to the chassis batteries.

BTW, did you ever determine if you have a BIM 160?

David

Still searching for it (see previous post)

[Chateau_Nomad]

Try looking on the firewall on the driver's side. Mine was hidden behind a plastic reservoir (I think washer fluid). I had to practically stand on my head to see it... and I'm over 6' tall. It's buried down behind it. Maybe same on yours?