Electrical problem and weird noise

[EdInArk]

We have hit a problem where we have little or no 12-volt power when unplugged from shore power. We're OK when plugged in, and we managed to complete our trip like that. But sometimes the 12-volt is so weak the pump won't even work.

Batteries check 12.7 volts or thereabouts when not on shore power and the switch is in Store mode. I have not yet disconnected and checked batteries individually.

What I'm really asking about is this noise coming from the battery compartment. The noise happens when the switch is in Use and not when it's in Store. It's coming from a devise labeled "BIS160" which Googles to a Battery Isolation Manager. I've recorded over 9 minutes of it, and this noise happens almost precisely every 2 minutes and 5 seconds. I'm wondering if this device itself might just be bad or if it could indicate a different problem.

The 9-minute audio file is too large to attach, so I've sent a snip of a few seconds containing the sound. It's very much like a relay not making good contact to me -- like a horn relay or starter relay.

[Skip426]

I didn't listen to your audio file ; but from you description , I believe the BIM is bad ; here's a file on troubleshooting .

[keymastr]

Agree with Skip, good luck!

[BCam]

Originally Posted by keymastr

Agree with Skip, good luck!

Me, too. I did listen to the audio and it definitely sounds like a solenoid to me. Solenoids are often used as battery isolators. Once you ID the offending unit, it should be an easy replacement.

[Ray,IN]

You have checked liquid level in all batteries, right?? Liquid level below the plates can cause all manner of 12V issues.

[twinboat]

Its a " BIM " 160 battery isolator and that's a normal sound of it activating and de-activating.
I have the same exact device in my Thor and it cycles every few hours.

Why its doing it every 2 minutes is the question.

First, the BIM is not your low battery problem. It only connects the " charging " house battery to the chassis battery, while on shore power.

Are you leaving your battery disconnect in " Use " mode ? You should be, unless the RV is sitting in storage with NO shore power.

If your camping or driving, leave it on so the battery gets charged.

I think the BIM is cycling due to bad house battery or bad battery connections.
It has a delay built in and that may be what takes a 2 minutes.

Its closing the connection to charge the chassis battery, but with the bad house battery or connection, the voltage drops out and it disconnects. That's what it's supposed to do.
Now the voltage climbs during the delay and it does it over again.

Fix the battery problem and the BIM will work normal.

[twinboat]

Here is its operation and wiring.

You can see that it's basicly a jumper cable between batteries and not between the house battery charger and house batteries.

The Use Store switch is, leave it on.

[EdInArk]

Originally Posted by Ray,IN

You have checked liquid level in all batteries, right?? Liquid level below the plates can cause all manner of 12V issues.

Yes, I do check the level periodically. Batteries both show 12.6 volts or thereabouts.

Originally Posted by twinboat

Its a " BIM " 160 battery isolator and that's a normal sound of it activating and de-activating.
I have the same exact device in my Thor and it cycles every few hours.

Why its doing it every 2 minutes is the question.

First, the BIM is not your low battery problem. It only connects the " charging " house battery to the chassis battery, while on shore power.

Are you leaving your battery disconnect in " Use " mode ? You should be, unless the RV is sitting in storage with NO shore power.

If your camping or driving, leave it on so the battery gets charged.

I think the BIM is cycling due to bad house battery or bad battery connections.
It has a delay built in and that may be what takes a 2 minutes.

Its closing the connection to charge the chassis battery, but with the bad house battery or connection, the voltage drops out and it disconnects. That's what it's supposed to do.
Now the voltage climbs during the delay and it does it over again.

Fix the battery problem and the BIM will work normal.

Thanks for the reply. As I told Ray, the batteries both show 12.6 volts, but I know that doesn't mean they're good. They're the ones that came in the coach and have labels that say they were shipped in 2016. I suspect it's time.

It stays plugged in most of the time, and the switch stays in Use. The only exception is when the RV is just sitting with nothing on and not plugged in.

[twinboat]

What is the voltage when its plugged in ?

House batteries should be 13.6 or more and the chassis should show the same at least during the time the BIM is connecting.

Another reason for the BIM to cycle is a very low chassis battery. It connects and then cuts back out, if the weak chassis battery draws down the house battery more volts then the charger can maintain.

[EdInArk]

Originally Posted by twinboat

What is the voltage when its plugged in ?

House batteries should be 13.6 or more and the chassis should show the same at least during the time the BIM is connecting.

Another reason for the BIM to cycle is a very low chassis battery. It connects and then cuts back out, if the weak chassis battery draws down the house battery more volts then the charger can maintain.

Unplugged this morning at battery -- 12.64
Plugged in it jumped to 13.27

Oddly, unplugged this morning the onboard battery gauge showed 2/3 full. Plugged in it shows full.

I started it to see if my jacks would work, and all five lights flash, which indicates voltage below 10 volts even though my voltmeter shows 12.6 at the batteries.

And .... my dash radio doesn't even turn on. It is on the house batteries.

Thanks for all the feedback. I need to take the batteries somewhere that can load test them for me. Today, I've got other projects I need to get one while it's not raining, though.

[HarryStone]

If, when you are putting a load on the batteries, and they still show 12+, and the leveling system shows less than 10, you have a wiring problem. Either a bad positive connection, or a bad ground.

[Piros1]

Originally Posted by EdInArk

Unplugged this morning at battery -- 12.64
Plugged in it jumped to 13.27

Oddly, unplugged this morning the onboard battery gauge showed 2/3 full. Plugged in it shows full.

I started it to see if my jacks would work, and all five lights flash, which indicates voltage below 10 volts even though my voltmeter shows 12.6 at the batteries.

And .... my dash radio doesn't even turn on. It is on the house batteries.

Thanks for all the feedback. I need to take the batteries somewhere that can load test them for me. Today, I've got other projects I need to get one while it's not raining, though.

Ed since you have not reported back I thought I would throw this out. When you get batteries load tested they need to be fully charged. A discharged battery won’t give you an accurate load test or that has been my experience and how I was directed by commercial battery suppliers in the past.

If one of your batteries is bad it will discharge the other batteries. If your batteries are very old and one is bad I would recommend you replace them all as a set I’m talking over a year old.

That said it seem strange that your jacks are not working on shore power or did I miss something in your post. Anyway if you get your battery situation figured out and your jack still have issues I would start checking your wiring especially the ground connections. Just a thought. I did not notice the jack manufacture mentioned but they should be able to supply you with a diagnostics procedure to help with that as well.

[EdInArk]

Yeah, I thought it was really odd that the jacks wouldn't work on shore power or with the engine running as well.

I appreciate all the input. I dropped the RV by the RV repair facility this morning. I'll report back what they find.

[THenne1713]

Hmmm ... My coach RV/ MARINE battery was 6-yo (2012-2018) when replaced, and chassis battery is dated 2011, still going strong..