Battery Isolation Manager at work again

[Sagecoachdriver]

When we left Yosemite for the 6 hour drive back to LA, the Battery Monitor said down 39.9 amps. When I got home, it said 29.3 amps down. The Battery Isolation manager will only charge the house batteries for 1 hour while driving unless the voltage drops down to a certain level or it's reset. If the engine battery is in need of a charge, it will charge that first. Since I have 200 watts of solar on the roof, and drove for 4 hours with full sunlight, why didn't it charge it up. The DW left the fridge off for 4hrs after fueling, too. The BIM charges bi-directional and I wish I could somehow select what gets charged myself.

[RamblerGuy]

I can't help fix your problem but I can suggest a workaround. I had a similar problem in that the BCC would connect the chassis 12 volt system to the coach 12 volt system just fine when I checked it out in the driveway but would sometimes not do its job when we were on a trip. As a temporary fix on the road I disconnected the 12 volt feed from the BCC to the relay and fed it from a 12 volt accessory receptacle when I was driving.

I planned to feed it with a toggle switch, but the relay failed so I assumed it had been intermittent all along. With a new relay installed, I've not had a problem.

You could install a toggle switch with two wires going to the emergency battery booster switch on the side of the driver's seat. The booster switch is a momentary contact that engages the relay. With a toggle switch you can select when you want 12 volts to continuously go from the chassis system to the coach system. It would be nice to install an indicator light that comes on when the relay is engaged to remind yourself that it's powered and to not let it kill the chassis battery when you're not driving.

[Sagecoachdriver]

The system is designed by Precision Circuits here is the manual.
http://www.precisioncircuitsinc.com/...anual-RevA.pdf

Note the points in which the system isolates the house and engine. Crazy that the house batteries don't get charged while driving more than 1 hour for fear of over charging them. Just checked my solar and it's only charging at 3.5amps. Guess it's because of the low winter angle and the fact that the panels are flat on the roof. When we drove up to Yosemite, the batteries were fully charged at 12.7volts and 1300 SG. When we pulled in to our campsite, it was down 8 amps on the Battery monitor. We stopped a few times to let our dog do it's business, lunch and to refuel. We were down 45amps the next morning. Solar was useless with all the trees and had to use the generator.

[Snowman9000]

I could not agree more. I contacted a tech guy at the manufacturer. It was clear to me that they do not understand the needs of a RVer who dry camps. Neither does FR in this matter, I would have to say.

My recollection is that when I pulled out of camp and stopped 10 minutes later to buy gas, upon resuming the thing would not charge the house batteries because they had enough of a surface charge that they still presented voltage > 12.60. Then after driving a while, the resting batteries would drop < 12.60, and charging would begin. But you are right, it never lasted long enough either.

This system is the answer to a question that nobody asked.

Our previous 2005 B+ had one of those famous BIRD systems. I have to say, it did what I wanted.

Since I have added solar, I will likely just live with this system's problems. Otherwise, I'd be looking at gutting it or just bypassing it with a more basic isolater relay system.

edit: I have a troublshooting sheet from them, carrying the same basic date in the file path as the manual above. It shows how it won't charge a battery unless it is showing below 12.6v. That's what the guy told me, too.

http://www.precisioncircuitsinc.com/...e-Shooting.pdf

[Snowman9000]

By the way, you can email them your thoughts and suggestions at: tech at precisioncircuitsinc dot com.

Please do.

[Sagecoachdriver]

Originally Posted by Snowman9000

I could not agree more. I contacted a tech guy at the manufacturer. It was clear to me that they do not understand the needs of a RVer who dry camps. Neither does FR in this matter, I would have to say.

My recollection is that when I pulled out of camp and stopped 10 minutes later to buy gas, upon resuming the thing would not charge the house batteries because they had enough of a surface charge that they still presented voltage > 12.60. Then after driving a while, the resting batteries would drop < 12.60, and charging would begin. But you are right, it never lasted long enough either.

This system is the answer to a question that nobody asked.

Our previous 2005 B+ had one of those famous BIRD systems. I have to say, it did what I wanted.

Since I have added solar, I will likely just live with this system's problems. Otherwise, I'd be looking at gutting it or just bypassing it with a more basic isolater relay system.

edit: I have a troublshooting sheet from them, carrying the same basic date in the file path as the manual above. It shows how it won't charge a battery unless it is showing below 12.6v. That's what the guy told me, too.

http://www.precisioncircuitsinc.com/...e-Shooting.pdf

Thanks Snowman9000 for the update.
So does the alternator charge go directly to the BIM and then back to the engine battery for charging when needed? Or does it go to a voltage regulator under the hood and to the battery? My understanding is it's redirected to the BIM and then back to the engine battery.
They should have some sort of user control to allow an increase in charging time for the house batteries like 1,2 or 3 hours. If it's regulating the charge and direction, why would the house batteries get over charged? Isn't it doing it's job?
Does it really need to be bi-directional anyway? I never had an issue with my 2004 Winnebago and never had to use the engine battery boost.
I recall that when I spoke with them last year, they said that after an hour when the BIM stops charging the house batteries, turn on every light in the motorhome until the voltage drops down to the re-activation voltage of 12.6v. That's not do able especially at night. Can you imagine driving down the road with every light on?
Also, that was a reason why I added the solar on the roof. But it was shady in Yosemite and once I got out of the valley, I thought it would recharge the house batteries as it's direct to the house batteries. Sunny for at least 4 hours.

[Snowman9000]

I don't know for sure, but I would be very surprised if the chassis self-charging was routed through the BIM. I would say the BIM is in parallel with the chassis self-charging. So if it detects house voltage less than 12.6, some of the alternator charge is routed to the house. But no, it cannot route alternator charge back to the chassis battery.

I agree with you that the voltage regulator should be allowed to regulate the house charging. The batteries will only accept what they accept, as long as the voltage is kept under control.

You might never need bi-directionality, but the industry likes it. Some people must run down their chassis battery. In some cases the genset starter is fed by the chassis. (Not in ours.)

[Snowman9000]

Your experience with shaded solar are points well taken. On an overcast day, the solar will still be making the system show more than 12.6v, but almost no amps will be flowing. That will cause the BIM to cut off the charging. Then you drive somewhere, and your batteries have not been charged.

This was my experience too, on at least one travel day.

[Sagecoachdriver]

Snowman9000, going to send you a PM. Want to run something by you.

[Sagecoachdriver]

Just a thought, when leaving the campground for a long trip home, the BIM will allow the engine alternator to charge the house batteries for 1 hour. Then if and when the house battery voltage drops down to 12.6v it will start up again for 1 hour. But won't the voltage from the solar panels prevent that from happening. Low light winter sun won't produce enough current to fully charge the house batteries back up to full either.
I need to pay closer attention to my scangauge as it has an engine volt reading. I have noticed it starts off at 14.2v and drops to 13.9v and 13.5v. This could well be the indication of the BIM starting to charge both batteries and only charging the house batteries and then back to normal engine battery.
Also consider the fact that the nav radio, the power ports that we use for USB charging cellphones and iPad and my Garmin all run off the house batteries. Plus the fridge and other parasitic drain bring the draw up to 3.2 amps while driving.
This wouldn't be an issue if we camped with hookups, but 90% is dry camping like Yosemite, Rincon, Morro Bay, Death Valley and Quartzsite. We want to get to the campground with fully charged batteries.

[Snowman9000]

Yes to the solar question. I mentioned that above, it happens to me.