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Topic: Boost Circuit * Something doesn't Make Sense * (Read 1010 times) previous topic - next topic

Boost Circuit * Something doesn't Make Sense *

Today I brought the coach home for sanitation, washing, etc.  I went through my routine (much quicker now that I installed the Cole Hersee battery disconnects).  But, after turning on the genset and turning on a few appliances to consume some wattage upon inspection, the boost circuit was not functioning.  The gel coach batteries were at 12.8 VDC and the Optimas were at 12.6 VDC so not big deal.  I crancked up Forrest and away we went.  After plugging the coach to 120 VAC, upon checking the solenoid (Beth was home so she turned the boost switch on/off), the boost circuit is now functioning.  No this is not a Click & Clack quiz... :-X

Thanks for your thoughts on this one.

Peter
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Boost Circuit * Something doesn't Make Sense *

Reply #1 –
Next time it fails to work, you will need to see if the signal terminal of the boost solenoid is getting 12 VDC positive when the boost switch is on.  If so, the solenoid is bad.  If not, need to find out why not.

Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Boost Circuit * Something doesn't Make Sense *

Reply #2 –
Brett,
Thanks.  Hope it was a fluke, but these symptoms usually signal some impending failure.  The solenoid is 6 years old.
Peter
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Boost Circuit * Something doesn't Make Sense *

Reply #3 –
Peter,

It will take a few yards of wire, but run a wire from the signal terminal up into the coach.  Use either a test light or voltmeter from that wire to ground.  Easy to see whether the solenoid is starting to stick.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Boost Circuit * Something doesn't Make Sense *

Reply #4 –
Peter,

Had a lot of trouble with wrong isolator installation and bad boost solenoid when I bought my U300. I installed a couple of digital voltmeters on my instrument panel, one for house and engine respectively. Now I can hit the boost switch and if both voltages change to read the same, it's working. Don't have to stick my head out the window to listen for the click.  Works for general electrical system health as well. Search for my previous posts for photos if you are interested.

If your isolator/boost solenoid panel is in the same location as mine, it's a wonder there is not more trouble than there is.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Boost Circuit * Something doesn't Make Sense *

Reply #5 –
Quote from: wolfe10 –
Peter,

It will take a few yards of wire, but run a wire from the signal terminal up into the coach.  Use either a test light or voltmeter from that wire to ground.  Easy to see whether the solenoid is starting to stick.

Brett
Brett,
For clarity...the signal post at the solenoid when boost switch is "on" should read 0 VDC if operating properly?  So, if I have a helper, the wire is really not needed?
Peter
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Boost Circuit * Something doesn't Make Sense *

Reply #6 –
Peter,

NO. The signal terminal is the one that gets a 12 VDC positive signal from the boost switch.  So when the boost switch is turned on, you should have 12 VDC between that terminal and ground AND the voltage on house bank and chassis bank should equalize, since they are now both connected.

If no 12 VDC when the boost switch is on, you have a problem between fuse, boost switch or wiring to the solenoid.

If you have 12 VDC to the signal terminal, but the two battery voltages to not read the same, the solenoid is bad.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Boost Circuit * Something doesn't Make Sense *

Reply #7 –
Quote from: wolfe10 –
Peter,

NO. The signal terminal is the one that gets a 12 VDC positive signal from the boost switch.  So when the boost switch is turned on, you should have 12 VDC between that terminal and ground AND the voltage on house bank and chassis bank should equalize, since they are now both connected.

Brett
Got it.  (I thought so)
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Boost Circuit * Something doesn't Make Sense *

Reply #8 –
Maybe I'm reading it wrong.....but if your gen is running the house batteries should have been +13.2, the charge rate. If at 12.8 there is a different problem.
1994 U280, Build 4490
Deming, NM.

Re: Boost Circuit * Something doesn't Make Sense *

Reply #9 –
Quote from: Twig –
Maybe I'm reading it wrong.....but if your gen is running the house batteries should have been +13.2, the charge rate. If at 12.8 there is a different problem.
Perhaps I was not clear.  My reason for running/excercising the genset is to ensure the alternator is not overtaxed when initially starting the coach after unplugged storage.  The coach battery read 12.8 VDC & the start bank read 12,6 VDC prior to starting the genset.  I always take a reading of the battery banks prior to start-up after storage.
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Boost Circuit * Something doesn't Make Sense *

Reply #10 –
For what its worth, I haven't had to use my boost circuit since I installed a trik-l-start
Ultra TRIK-L-START Starting Battery Charger/Maintainer

It works wonderfully and keeps my starting batteries happy even after sitting for weeks (on shore power of course).
Steven M
98 U270 WTFE 36'
Houston, TX

Re: Boost Circuit * Something doesn't Make Sense *

Reply #11 –
Quote from: smillner –
For what its worth, I haven't had to use my boost circuit since I installed a trik-l-start
Ultra TRIK-L-START Starting Battery Charger/Maintainer

It works wonderfully and keeps my starting batteries happy even after sitting for weeks (on shore power of course).
I hear ya Steven.  Unfortunately, I do not have 120 VAC available at my storage facility.
Peter
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Boost Circuit * Something doesn't Make Sense *

Reply #12 –
Which battery bank powers the boost solenoid coil?

John Duld
1995 U320C SE 40'

Re: Boost Circuit * Something doesn't Make Sense *

Reply #13 –
Quote from: John Duld –
Which battery bank powers the boost solenoid coil?
John,
(edit)
I had to look this up when I was troubleshooting, but I don't remember, and I don't have the electrical drawings with me as they are in the coach in storage location.  My guess would be the start coach batteries.  Perhaps someone else can confirm.
Peter

(edit) p.s.  coach batteries makes more sense as you would want to have boost when the engine start batteries need additional amps to start the engine.  If the coach batteries have no charge, then the boost solenoid would not activate.
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Boost Circuit * Something doesn't Make Sense *

Reply #14 –
Peter is right the coach batteries.
niagarachip 
1997 U320  40'

Re: Boost Circuit * Something doesn't Make Sense *

Reply #15 –
Peter,

I also do not have access to shore power where my coach is stored (outside).  My solution was to get a portable solar panel, hook it to the house battery and let the Trik-L-Start keep the coach battery charged.  The only time I had an issue is when a connection corroded in two. If you are lucky enough to have sheltered storage may be you can mount a solar panel outside and run the wiring to the coach.
John Cooper
'91 GV 36'
Oshkosh chassis
Cat 3208T 300HP

Re: Boost Circuit * Something doesn't Make Sense *

Reply #16 –
Quote from: John Cooper –
If you are lucky enough to have sheltered storage may be you can mount a solar panel outside and run the wiring to the coach.
As luck would have it, because of the building orientation, its shadow covers a large area next to the coach.  If I were to move a panel out far enough it would be in the pathway for other vehicles.  Good thought though.
Peter
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Boost Circuit * Something doesn't Make Sense *

Reply #17 –
Peter,
On the shadow issue, I have many solar panels on machinery and some stay under sheds and as long as sunlight is present they work, they don't require direct sunlight.  This is the one I use in those applications and it has an indicator on it to show it is working.  It isn't big enough for what you need, but might be cheap enough to use to test in the shadow.......
NPower Solar Battery Maintainer — 1.8 Watt | Amorphous Solar Panels |
Steven M
98 U270 WTFE 36'
Houston, TX
 

Re: Boost Circuit * Something doesn't Make Sense *

Reply #18 –
Steven,
You just taught me something about solar panels.  Anyway, since my C8.3 is all mechanical, I just disconnect both battery banks when in storage.  I just recently installed Cole Hersee switches (1,800 amp rating) to disconnect the batteries and the job seems to be working just fine for me.  Thanks,
Peter
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH