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Chassis battery powering coach loads
I was surprised to discover that with the coach batteries disconnected and solar controller disconnected there was still power to the coach. I assume the chassis battery is the power source.

I expected there was a chassis battery-to-coach connect/disconnect mechanism that connected the chassis battery only when the engine was running. Can someone shed light on this mystery?
2013 27’ Mid-Bath
2005 Honda CR-V
Re: Chassis battery powering coach loads
Reply #1 –
Something is going on.   I doubt it was wired from the factory that way.  Either someone changed something, or the batteries/solar weren't really disconnected, or there is another power source somewhere (converter, generator - are you sure it wasn't plugged in to 120v?).

Rich
2003 MB
Re: Chassis battery powering coach loads
Reply #2 –
In that vintage, there is an underhood relay that connects the batteries together for charging from the alternator. If the contacts have frozen together, it would connect the chassis battery to the coach battery compartment. At that point, it would depend on how the coach batteries are 'disconnected' as to whether the 12V would connect to the power center.

Steve
2004 FL
2013 Honda Fit
Re: Chassis battery powering coach loads
Reply #3 –
Quote
there is an underhood relay that connects the batteries together for charging from the alternator.

They get pretty corroded. This is what mine looked like when I got this Southern California rig.
jor
09 27' MB
10  Suby Forester
Re: Chassis battery powering coach loads
Reply #4 –
I concluded that my problem was also that relay. I removed it and it bench tests as working normally. Since I went to the effort of buying a replacement, I replaced it anyway, figuring that maybe it occasionally sticks.

Nope. The Huine solar charger that I installed to replace the Amp-L-Start is the actual culprit for supplying voltage to the coach when the coach batteries are disconnected and solar is disconnected. I triple checked the connections, and the battery lead is indeed connected to the chassis battery, and the panel lead to the coach electrical system. Possibly the Huine has failed, although its LEDs look like it’s working normally. I am going to replace it with the Xantrex Auxiliary Battery Charger.
2013 27’ Mid-Bath
2005 Honda CR-V
Re: Chassis battery powering coach loads
Reply #5 –
I don't think you will find many here familiar with this unit, but I have never heard of any such problem with the more established brands. I would contact their technical department to see if this is an issue they are familiar with and have an answer. Good luck!

Steve
2004 FL
2013 Honda Fit
Re: Chassis battery powering coach loads
Reply #6 –
Quote from: Steve  - 
I don't think you will find many here familiar with this unit, but I have never heard of any such problem with the more established brands.

We had the same issue with the old Heliotrope solar controller that was in our current coach.
Re: Chassis battery powering coach loads
Reply #7 –
Hi Keith S.; I am using a Huine charger to keep my chassis battery charged (lead acid) and to power the CB, entertainment radio, TPMS, GPS, USB port and one power point on the dash, The Huine draws power from the Lithium house battery system.
    I tried to use my old Trik-L-Start, but it didn't work with the LIF voltages. Tried to use an Amp-L-Start, but it had a feed back issue with the chassis battery when the engine was running. The Amp-L-Start sent me the 'fix it kit' but I was trying to 'shoe horn' it into a small place, so the Huine fit better and so far has been working well.
    With solar and LiF batteries, and the Huine always on, the chassis battery is always a bit high voltage, but at 3 years, seems to be OK. I'll check out the system to verify that the Huine isn't back feeding the house.
       A heavy duty diode in series with the Huine output, may reduce it's output voltage a bit, and ensure that nothing back feeds through the Huine.  That might upset the operation of that unit though if it can't sense the WLA voltage properly.     RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Chassis battery powering coach loads
Reply #8 –
Quote from: RonB  - 
Hi Keith S.; I am using a Huine charger to keep my chassis battery charged (lead acid) and to power the CB, entertainment radio, TPMS, GPS, USB port and one power point on the dash, The Huine draws power from the Lithium house battery system.
    I tried to use my old Trik-L-Start, but it didn't work with the LIF voltages. Tried to use an Amp-L-Start, but it had a feed back issue with the chassis battery when the engine was running. The Amp-L-Start sent me the 'fix it kit' but I was trying to 'shoe horn' it into a small place, so the Huine fit better and so far has been working well.
    With solar and LiF batteries, and the Huine always on, the chassis battery is always a bit high voltage, but at 3 years, seems to be OK. I'll check out the system to verify that the Huine isn't back feeding the house.
       A heavy duty diode in series with the Huine output, may reduce it's output voltage a bit, and ensure that nothing back feeds through the Huine.  That might upset the operation of that unit though if it can't sense the WLA voltage properly.     R

I also had installed a Trik-L-Start a few years back but now have LiF house batteries. I haven’t noticed any problems yet but it’s only been a few weeks. Wondering if I should change anything?
Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264
Re: Chassis battery powering coach loads
Reply #9 –
The Trik-L-Start is appropriate for Lead-Acid House battery type. The Ampl-L-Start is for Lithium. Both are orphaned products since the death of the principal in 2022. The Ampl-L-Start has a higher voltage threshold to turn on charging the Chassis battery, to match the higher voltage typical of Lithium House batteries. The disadvantage of Trik-L-Start with Lithium is it will charge the Chassis battery even without charging input to the House batteries, so the House batteries will be (a little more) drained to keep the Chassis battery charged. Not such a bad thing, just not what was intended, which was to use excess solar input to charge the Chassis battery.
2013 27’ Mid-Bath
2005 Honda CR-V
Re: Chassis battery powering coach loads
Reply #10 –
Hi Keith, My house batteries are always charged so far just with solar. So the parasitic drain to keep the chassis battery charged up isn't a problem. I want the chassis battery always topped off. Especially if I forget to turn off the manual back up camera, or CB radio. (BTDT). The Huine defaults to a lead acid charge profile, appropriate for the chassis battery. If for some dire reason the LiF batteries got too low, the BMS's would shut them off, and the chassis battery should be fully charged. The Huine has the LFi battery/(solar pv supported) hooked up as the PV inputs. It thinks it is charging a lead acid battery and it is. I don't see how it could back feed the house any more than it would try to let power back into a solar panel.. On my set up the load output on the Huine isn't hooked up to anything. Per RV Tito's you tube example.  RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Chassis battery powering coach loads
Reply #11 –
I also assumed that the Huine wouldn’t or couldn’t, thus wasn’t, feeding Chassis side to House side. It came down to a simple test where power was present on House side with House batteries disconnected and Solar disconnected, and Huine showing its middle LED solid green. Disconnecting the Huine House wire immediately shut off power on the House side. I interpret that as a misbehavior (not what I desire to happen) at least, and probably a malfunction (not what anyone would expect to happen).

The Amp-L-Start and the Huine were connected to the posts on the solenoid in the engine compartment, and mounted close by in the engine compartment. They are both weatherproof. The Xantrex is connected to the same place, although it wants to be protected from the weather. It may not last long in that location, but I didn’t want to lengthen the leads to reach the coach interior. It can produce 15A charge current, and it recommends keeping the leads short.
2013 27’ Mid-Bath
2005 Honda CR-V
Re: Chassis battery powering coach loads
Reply #12 –
Ron - I should have started by confirming that my thinking agrees with everything you wrote, and my Huine connections agree also. The Huine Panels lead goes to House side (Lithium, Solar), Huine Battery lead goes to Chassis side (Lead-acid Starter battery), Load is not connected. The rear most post on the solenoid goes to Chassis side, and the front most post goes to the House side. Thanks for your information and help!
2013 27’ Mid-Bath
2005 Honda CR-V
Re: Chassis battery powering coach loads
Reply #13 –
Quote from: HiLola  - 
I also had installed a Trik-L-Start a few years back but now have LiF house batteries. I haven’t noticed any problems yet but it’s only been a few weeks. Wondering if I should change anything?

Greg
Doesn't your LD have a Blue Sky 3000i solar controller? If so, it can charge the starting battery and the coach battery. I believe the Mothership wired the 3000i so charging the starting battery was part of the changing system.

Our LD has a 3000i, which keeps the starting battery fully charged and has increased its lifespan. I used to get 2-3 years out of a Costco battery; now, they last twice as long.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Chassis battery powering coach loads
Reply #14 –
Quote from: Larry W  - 
Greg
Doesn't your LD have a Blue Sky 3000i solar controller? If so, it can charge the starting battery and the coach battery. I believe the Mothership wired the 3000i so charging the starting battery was part of the changing system.

Our LD has a 3000i, which keeps the starting battery fully charged and has increased its lifespan. I used to get 2-3 years out of a Costco battery; now, they last twice as long.

Hi, Larry. Yes it does. The Blue Sky displays an Aux battery charge which I believe is the chassis battery. So does that make the Trik-L-Start unnecessary? And, can the Blue Sky recognize the difference between the lead acid chassis battery and the lithium house batteries, as far as charging voltage?
Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264
Re: Chassis battery powering coach loads
Reply #15 –
Hi Greg;  the Aux light means that there is an output ready to be connected. Page 10, figure 5 details how it should be hooked up. You would need to look at that connector on the back of the SB 3000i to verify a wire is connected. A voltmeter could tell you at the chassis battery if charging voltage was there. Current measures could tell you if any charging was happening.  You probably can't use the Trik-L-Start, as Keith and I experienced. It doesn't like the higher voltages of the LiF batteries.  The voltage out at the R3000i, adjusted for LiF batteries should be the same voltage at the AUX output, and might not be so good for the Chassis battery. But the chassis battery does experience even higher voltages when being charged by the alternator.  My chassis battery floats at 13.2 volts all the time according to my BalMar monitor system and hasn't been harmed so far (2 1/2 years), that I can tell.
    I believe Larry W has a Lithium battery for his chassis also. I have a lead acid (AGM).      RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Chassis battery powering coach loads
Reply #16 –
Quote from: RonB  - 
I believe Larry W has a Lithium battery for his chassis also. I have a lead acid (AGM).      RonB

Nope, still running a Costco lead-acid battery under the hood for starting. lithium batteries do not belong in engine compartments, it gets too hot and there is no way to keep the battery from shutting down if camped in very cold conditions without running a battery heater.
Lithium batteries have very narrow operating ranges compared to lead-acid batteries.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Chassis battery powering coach loads
Reply #17 –
Larry makes a good argument against Lithium starting batteries that are not temperature-controlled.

I understand that Lithium batteries have a typical low temp limit for charging of 32F. But for discharging, the low temp limit is -4F. I can see that this is not a useful difference, since even if the battery can start the engine at -4F, it would be seeing charging voltage a few seconds later with the engine running while still cold - long before engine heat would warm the battery.
2013 27’ Mid-Bath
2005 Honda CR-V
 
Re: Chassis battery powering coach loads
Reply #18 –
Sorry Larry;  I also use a 'DieHard' what used to be a Sears brand lead acid.  Maintenance free, otherwise known as non removable caps.  Expensive enough it could have been AGM, but maybe just a wet battery.
    What ever, it starts the engine. If it didn't, I can use that 600 Amp Lazy Daze relay that was donated to me from a member that had another type of "shorting relay" installed with his solar package. One button push to connect the LiF's to the chassis battery momentarily.    https://www.supplyhouse.com/White-Rodgers-586-108111-Solenoid-SPNO-15-VDC-Isolated-Coil-Normally-Open-Continuous-Contact-Rating-200-Amps-Inrush-600-Amps?gclid=Cj0KCQiA0eOPBhCGARIsAFIwTs4gQws6LzxHDOujEFj9i1F0ccfuzbDUgO1hi70607__L02wturKK7kaAju_EALw_wcB     
     RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB