Interstate charging system - BIM confusion!

[wayneskid]

This is a very long and convoluted story but basically my Interstate charging system does not charge the house batteries from the Sprinter alternator. I have spent countless hours (including 2+ days of my recent 2 week vacation), dozens of emails with AS and Precision Circuits, and several phone conversations with the same key players. I have gotten conflicting and confusing information from AS and information from Precision Circuits that contradicts what AS is telling me. To make matters worse, I am unfortunately hampered in troubleshooting this problem by the fact that I’m in AK and the Interstate is in OR where I go to use it when I can. I do have a couple of advantages that have so far failed get me to the root of the problem: 1) I have a solid background in electronics and DC and AC systems; 2) I have installed a TriMetric battery monitor so I can see exactly what is happening with my house batteries.



So, for those of you with MY2010 or newer Interstates (I mean the model year of the Interstate, not the Sprinter) could you kindly tell me:

1. The Model Year of your Interstate?
2. Does you Interstate have a switch on the dash (just below the headlamp switch) to engage the Engine Start Assist feature? This is mentioned on page H-14 of the 2013 Owners Manual.
3. Does your Interstate have the Precision Circuits BIM #00-10021-000? If not, what kind of BIM do you have?
4. Is there a wire connected to the DASH SWITCH terminal of your BIM? If yes, what color and does it have a marking like ST or some other marking?
5. Can you say with certainty that your house batteries get charged reliably from the Sprinter alternator? How do you know this?
6. Can you verify that your Sprinter battery gets charged when you are plugged into shore power?

This has been an extreme case of the blind leading the blind and confused. Your input could be a real help.


Thanks in advance,
Wayne

[gmillerok1]

Originally Posted by wayneskid

So, for those of you with MY2010 or newer Interstates (I mean the model year of the Interstate, not the Sprinter) could you kindly tell me:

1. The Model Year of your Interstate? 2011
2. Does you Interstate have a switch on the dash (just below the headlamp switch) to engage the Engine Start Assist feature? This is mentioned on page H-14 of the 2013 Owners Manual. No
3. Does your Interstate have the Precision Circuits BIM #00-10021-000? YES. If not, what kind of BIM do you have?
4. Is there a wire connected to the DASH SWITCH terminal of your BIM? NA. If yes, what color and does it have a marking like ST or some other marking?
5. Can you say with certainty that your house batteries get charged reliably from the Sprinter alternator? YES, provided the inverter is turned off. How do you know this? Because they stay fully charged.
6. Can you verify that your Sprinter battery gets charged when you are plugged into shore power? Yes, absolutely.

This has been an extreme case of the blind leading the blind and confused. Your input could be a real help.


Thanks in advance,
Wayne

See answers above. One issue that you may need to be aware of is that if your inverter is on, the house batteries will discharge as you drive. Turn it off while driving and see if they stay charged.

Gerald

[wayneskid]

Thanks Gerald, If you have a chance sometime, could you look at the BIM and see if there is a wire on the DASH SWITCH terminal. Mine has a gray wire marked ST. AS tells me this should connect directly to the starter solonoid. Precision Circuits tells me if there is no dash switch there should be NO WIRE connected to this terminal on the BIM. The PC founder/owner was very emphatic about this. He is to contact AS to resolve the conflict. Can't wait to hear what they come up with.

[Protagonist]

Originally Posted by wayneskid

So, for those of you with MY2010 or newer Interstates (I mean the model year of the Interstate, not the Sprinter) could you kindly tell me:

1. The Model Year of your Interstate? 2012
2. Does you Interstate have a switch on the dash (just below the headlamp switch) to engage the Engine Start Assist feature? This is mentioned on page H-14 of the 2013 Owners Manual. No. Not mentioned in the 2012 manual, either.
3. Does your Interstate have the Precision Circuits BIM #00-10021-000? If not, what kind of BIM do you have? No idea. Never looked.
4. Is there a wire connected to the DASH SWITCH terminal of your BIM? No idea here, either. If yes, what color and does it have a marking like ST or some other marking?
5. Can you say with certainty that your house batteries get charged reliably from the Sprinter alternator? Yes. How do you know this? Started the fridge two days before a trip so it would be cold when I loaded food. House battery display showed 80% charge when I started my trip. It showed 100% charge by the time I reached my destination.
6. Can you verify that your Sprinter battery gets charged when you are plugged into shore power? Cannot verify either way. Longest time hooked up to shore power has been 8 days, and since I was camping at the time (Viper alarm system turned off) that wouldn't be long enough to deplete the chassis battery anyway.

This has been an extreme case of the blind leading the blind and confused. Your input could be a real help.


Thanks in advance,
Wayne

Responses inside the quote, in bold.

[wayneskid]

Thanks Protagonist,

You said "House battery display showed 80% charge when I started my trip. It showed 100% charge by the time I reached my destination."

Does the monitor panel provided by AS give you SOC as a percentage or do you have another type of battery monitor? Mine just gives me volts and I can deduce SOC from that, but it isn't very precise.

Wayne

[Protagonist]

Originally Posted by wayneskid

Thanks Protagonist,

You said "House battery display showed 80% charge when I started my trip. It showed 100% charge by the time I reached my destination."

Does the monitor panel provided by AS give you SOC as a percentage or do you have another type of battery monitor. Mine just gives me volts and I can deduce SOC from that, but it isn't very precise.

Wayne

Solar panel charge controller gives a percentage readout, but only for the house batteries, not the chassis battery. By the way, on that aforementioned trip, it was raining for much of the drive, so it wasn't the solar panel that did the recharge.

[gmillerok1]

Originally Posted by wayneskid

Thanks Gerald, If you have a chance sometime, could you look at the BIM and see if there is a wire on the DASH SWITCH terminal. Mine has a gray wire marked ST. AS tells me this should connect directly to the starter solonoid. Precision Circuits tells me if there is no dash switch there should be NO WIRE connected to this terminal on the BIM. The PC founder/owner was very emphatic about this. He is to contact AS to resolve the conflict. Can't wait to hear what they come up with.

It may be awhile before I can physically take a look, but the schematic shows the dash terminal should be connected with a "ST (GRY/Blu) wire to the dash switch on the 2011. I don't recall seeing any switch so I'll go take another look and see if they just ignored that part. If there is no switch, I would think there would be no wire on the isolator on the dash terminal. I think whoever you talked to was confused. There is a terminal labeled "IGN" that should be connected to the ignition signal and is labeled "15 (WHT/Brn)". This should not be wired to the dash terminal on the isolater.

The manual for the isolater can be viewed on the Yahoo Interstate group site if you are interested in seeing it.

Gerald

[wayneskid]

Originally Posted by gmillerok1

It may be awhile before I can physically take a look, but the schematic shows the dash terminal should be connected with a "ST (GRY/Blu) wire to the dash switch on the 2011. I don't recall seeing any switch so I'll go take another look and see if they just ignored that part. If there is no switch, I would think there would be no wire on the isolator on the dash terminal. I think whoever you talked to was confused. There is a terminal labeled "IGN" that should be connected to the ignition signal and is labeled "15 (WHT/Brn)". This should not be wired to the dash terminal on the isolater.

The manual for the isolater can be viewed on the Yahoo Interstate group site if you are interested in seeing it.

Gerald

It will be very interesting to hear what you find on yours. Looking at the Interstate Owner Manuals, the first mention of the dash switch for Engine Start Assist is in the MY2013 manual.

I have the schematic also. My copy indicates the ST wire connected to the Dash Switch terminal of the BIM is GRY/blu. The wire is there but it is solid gray with no blue stripe. AS told me to look for the other end of this wire under the driver's seat, which I did for a couple of hours (working along with an AS tech at the dealers shop) to no avail. Later AS told me this wire was connected directly to the Sprinter starter solonoid. I have not crawled under the Sprinter to look for it there. The other terminals on the BIM are wired as indicated on the schematic and voltages measure what you would expect under various modes of operation. Except the voltage to the house batteries never raises to the 13.4v charging level when running the Sprinter engine. i.e. the BIM contacts don't appear to close under this situation. So yes, confusion reigns.

[gmillerok1]

Originally Posted by wayneskid

It will be very interesting to hear what you find on yours. Looking at the Interstate Owner Manuals, the first mention of the dash switch for Engine Start Assist is in the MY2013 manual.

I have the schematic also. My copy indicates the ST wire connected to the Dash Switch terminal of the BIM is GRY/blu. The wire is there but it is solid gray with no blue stripe. AS told me to look for the other end of this wire under the driver's seat, which I did for a couple of hours (working along with an AS tech at the dealers shop) to no avail. Later AS told me this wire was connected directly to the Sprinter starter solonoid. I have not crawled under the Sprinter to look for it there. The other terminals on the BIM are wired as indicated on the schematic and voltages measure what you would expect under various modes of operation. Except the voltage to the house batteries never raises to the 13.4v charging level when running the Sprinter engine. i.e. the BIM contacts don't appear to close under this situation. So yes, confusion reigns.

If there is a grey wire connected to the dash terminal on the isolater, and no dash switch, I would disconnect it. It wouldn't do any harm. I would go with the manufacturer's installation instructions. That is the only thing that terminal should be used for. If it is not connected to anything, I guess it would be the same thing as disconnecting it, though. If it is connected, on the other hand, to something other than a switch or has shorted out, and it shouldn't be, then it shouldn't be connected at all. My schematic refers to another page for the switch (95295S4). There is a reference for a "future install" for a dash switch on that page. So my guess is the harness has the grey wire built-in, and they connected it, but it likely isn't connected on the other end to anything. The switch has another (probably hot) purple wire from the EMS panel display. My guess is the harness is located on overhead the drivers seat to the "future" switch. Another guess is that when this switch or the circuit is closed, it causes a relay in the isolator two link the house batteries to the chassis battreries for a boost. I would not think it likely would cause any issue related to charging the house batteries, whether it was closed or open. But to be safe, it should be open normally, so I would disconnect it if I had no switch and see if it makes a difference. It can't hurt anything. There is also a possiblity that the isolator is defective. In any event, a dealer should be able to troubleshoot and correct the issue if you can ever get it to one for service.

Gerald

[gmillerok1]

Here's the instruction on how the isolater should be working:

Detailed Operation:

1) Relay is turned on if:
a) ignition is on for 20 seconds &
i) 2 minutes have passed since Relay last turned off &
Coach Battery less than 12.6V &
Chassis Battery is greater than 13.2 &
Chassis Battery is Less than 15.5V &
Generator is off
b) Ignition is off &
i) 10 minutes have passed since Relay last turned off &
Chassis Battery less than 12.6V, &
Coach Battery is greater than 13.0V &
Coach Battery is less than 15.5V
c) Generator is On & Ignition is On then the Alternator and Battery charger are fighting each other and Relay should be turned off.

2) Relay is turned off if:
a) Ignition goes from on to off state
b) Relay has been on for 1 hour
(prevent overcharging and allow to view separate voltages)
c) Anytime Ignition and Generator are both on.
d) Anytime either Battery goes above 15.5 volts for 30 seconds
e )Coach battery charge can drop to support the engine, in start and stop situations)

While the Ignition is on, the time the Relay will remain on is Voltage dependent

i) High end of time 12.8volts = 40 minutes
ii) Time is scaled between above and below values
iii) Low end of time 11.8 volts = 5 seconds

f) (Thou shalt never discharge Chassis battery for Coach functions)
While the Ignition is off, the time the Relay will remain on is Voltage dependent and shorter than while the Ignition is On
i) High end of time 12.8 volts = 10 minutes
ii) Time is scaled between above and below values
iii) Low end of time 11.8 volts = 5 seconds

3) Relay Coil will be driven with approximately 4Volts DC. The Solenoid will be turned on hard with full battery voltage, and then the voltage will be throttled back to reduce battery power and Relay heat.

Maybe this will help you troubleshoot the issue.

Gerald

[wayneskid]

Gerald,

Thanks for the info. I had the BIM "manual" already; I should have mentioned it. In any case, your suggestion is exactly what I had decided to do the next time I can get my hands on the Interstate; disconnect the gray ST wire from the Dash Switch terminal. That is unless the folks at AS and PC manage to reach agreement on a better plan. I'm still waiting to hear something from them. At least now I know enough about how things are supposed to work AND have what I need to monitor what is going on with the system. I'm hopeful this will be an quick fix; can't wait until June to have a go at it.

Thanks again,
Wayne

[73shark]

My 2011 answers are essentially the same as Gerald's except when they replaced my BIM, they installed this one from Sure Power. Not sure if the original was the Precision Circuits one. They replaced in a failed attempt to fix the constant relay clicking when the solar panel wasn't charging. Now they are going to replace the solar panel controller.

Also my alternator charges the house batteries w/ the inverter on or off.

[wayneskid]

Originally Posted by 73shark

My 2011 answers are essentially the same as Gerald's except when they replaced my BIM, they installed this one from Sure Power. Not sure if the original was the Precision Circuits one. They replaced in a failed attempt to fix the constant relay clicking when the solar panel wasn't charging. Now they are going to replace the solar panel controller.

Also my alternator charges the house batteries w/ the inverter on or off.

The BIM from Sure Power looks very similar to the PC one; main differences I see are 1) lower current capacity; 200 vs 225, 2) the Sure Power BIM lacks the inputs from gen set and ignition switch.

Charging from the alternator whether inverter is on or off; I think this is how it is supposed to work. Someone correct me if I'm wrong on this.

Although I have no solar panel, I will be interested to see the final results of your experience.

By the way, AS just informed me that their electrical engineer is discussing my issue with the founder/owner of Precision Circuits. Hope they come up with something difinitive.

[Protagonist]

Originally Posted by wayneskid

Charging from the alternator whether inverter is on or off; I think this is how it is supposed to work. Someone correct me if I'm wrong on this.

That's the way it works on mine. House batteries charge from engine alternator while driving, with the inverter switched completely off, on "charge only" or on "auto/invert."

[Boxster1971]

Info on my BIM below as requested:

1. The Model Year of your Interstate? 2013 on 2012 Sprinter van
2. Does you Interstate have a switch on the dash (just below the headlamp switch) to engage the Engine Start Assist feature? This is mentioned on page H-14 of the 2013 Owners Manual. YES
3. Does your Interstate have the Precision Circuits BIM #00-10021-000? If not, what kind of BIM do you have? I think so, but I'll have to look closer to see the number
4. Is there a wire connected to the DASH SWITCH terminal of your BIM? If yes, what color and does it have a marking like ST or some other marking? I'll have to check on this detail
5. Can you say with certainty that your house batteries get charged reliably from the Sprinter alternator? How do you know this? Yes, just completed a 6 day trip to Michigan with fridge on all the time and no hook ups. Driving each day keep the coach batteries charged.
6. Can you verify that your Sprinter battery gets charged when you are plugged into shore power? Not sure never checked -- I use the van a regular family hauler when not camping

Sorry I couldn't be more definite on details I'll try to check on them later this week.

- - Mike

[wayneskid]

I installed the new BIM sent by Airstream and initial tests indicate the charging system is working as specified. At least the coach batteries are charging from the alternator. I will be testing the other charging modes over the next few days. The new BIM was installed without connecting the gray ST wire to the "Dash Switch" terminal. I hope to find the other end of this wire and rig up my own dash switch as that function could come in handy should I inadvertently discharge the chassis battery.

It's great having the Trimetric monitor; it allows me to see exactly what's happening with the charging system and the state of both the coach and chassis batteries.

Happy Camper, so far!

[dirklohry]

Interstate 2012 Mercedes 3500. Since it was purchased February 2012, the engine never would charge the house battery no matter what was switched. There is no dash switch. I think the 2013 model might have that. Frustrating and time consuming to solve problem. I had the local RV expert test everything but got no solution. Could not get any help from AS. Authorized service center is too far away. It was a serious problem when a couple of times when overnight the battery would run down so far that the generator would not start. The manual said to run the engine to charge the battery. That did not work. So on the isolation relay I wired it with a toggle switch. Now it charges when the switch is on. I just have to remember to turn it off so the engine battery would not run down. Probably not good advice, but I was desperate, the battery would run down on long trips and I would not have water pressure and the fridge would warm up.

[cjrdad]

Originally Posted by Boxster1971

Info on my BIM below as requested:

1. The Model Year of your Interstate? 2013 on 2012 Sprinter van
2. Does you Interstate have a switch on the dash (just below the headlamp switch) to engage the Engine Start Assist feature? This is mentioned on page H-14 of the 2013 Owners Manual. YES
3. Does your Interstate have the Precision Circuits BIM #00-10021-000? If not, what kind of BIM do you have? I think so, but I'll have to look closer to see the number
4. Is there a wire connected to the DASH SWITCH terminal of your BIM? If yes, what color and does it have a marking like ST or some other marking? I'll have to check on this detail
5. Can you say with certainty that your house batteries get charged reliably from the Sprinter alternator? How do you know this? Yes, just completed a 6 day trip to Michigan with fridge on all the time and no hook ups. Driving each day keep the coach batteries charged.
6. Can you verify that your Sprinter battery gets charged when you are plugged into shore power? Not sure never checked -- I use the van a regular family hauler when not camping

Sorry I couldn't be more definite on details I'll try to check on them later this week.

- - Mike

Didn't mean to resurrect this old thread, but does anyone know for sure if the chassis battery gets charged when plugged into shore power? I'm currently using a plug-in trickle charger to charge the chassis battery when not starting engine for a couple weeks or longer. Just wanted to know if this was necessary. Oh, I also have the 2013/2012 3500 EXT. Thanks!
BTW, I'm a newbie and have been doing a lot of reading here. Been very helpful! Hopefully, I'll be able to contribute someday...

[toskeysam]

I have a 2013/2012 Airstream Interstate EXT. The chassis battery does indeed charge while on shore power.

[cjrdad]

Good to know, Thank you!!