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Topic: Newbie boost switch question (Read 873 times) previous topic - next topic

Newbie boost switch question

Today I forgot to turn the boost switch off after starting.  Drove for 6 1/2 hours with generator running and the switch on.  Did not notice it was on until several hours had passed while on 50 amp shore power at the camp site.

Any consequences to house/coach batteries and or alternator from having left it on?
Gary Mauck
Deerfield Beach, Fl.
2005 U320 40' PBGB

"Elks Care, Elks Share!"

Re: Newbie boost switch question

Reply #1 –
Shouldn't be any adverse issues. Just another alternative path for combining the battery banks for charging.  The alternator already charges both banks.  Your generator (through the inverter/charger) does charge the house battery and MAY also charge the chassis battery.

Foretravel used constant duty solenoids for the boost function, so no harm done to the solenoid itself.
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: Newbie boost switch question

Reply #2 –
Nope.  You are good.  In fact,  the chassis batteries are happy with a good,  well regulated charge,
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer

Re: Newbie boost switch question

Reply #3 –
Brett and Tom thank you so much for the quick answer to my question.  I'll sleep much better tonight!

Gary
Gary Mauck
Deerfield Beach, Fl.
2005 U320 40' PBGB

"Elks Care, Elks Share!"

Re: Newbie boost switch question

Reply #4 –
Does the light in the switch not work? It is changeable.
1994 U280, Build 4490
Deming, NM.

Re: Newbie boost switch question

Reply #5 –
I haven't tried yet, but how do you get to bulb to change it?
Steve DeLange
2005 U320T 40'
Pearland, Texas

Re: Newbie boost switch question

Reply #6 –
Quote from: sedelange –
I haven't tried yet, but how do you get to bulb to change it?
My recollection is that I pulled the panel in which the switches are mounted. From the under side of the switch, you have access to the tiny little bulbs in the switches.

I replaced some bulbs and rewired the "Aux Lights" to illuminate when the ignition switch and "Aux Lights" switches are both on. They were previously wired to require headlight to be on. I use the "Aux Lights" (fog lights) as daytime running lights.

I used to leave the Boost switch on for days in order to keep chassis battery charged. I now have a Battery Tender dedicated to keeping the house battery charge while on shore power or inverter power.
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: Newbie boost switch question

Reply #7 –
The boost switch does not control a latching solenoid but a solenoid that constantly draws juice. The boost solenoid gets almost too hot to touch after being on for an hour.

I would only use mine to start in an emergency as normal boost usage to start the engine gives no clue to engine battery condition. If the main engine has trouble starting in cold/freezing weather, either the batteries, cables or both need attention.

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

Re: Newbie boost switch question

Reply #8 –
sedelange, it pulls out the front of the panel. There are tines holding it in which you have push in on the back side. They are either on top and bottom or both sides of the housing. Once you pull it out, it pries apart and the bulb is exposed to replace. Common switch bulbs found at auto parts stores.
1994 U280, Build 4490
Deming, NM.

Re: Newbie boost switch question

Reply #9 –
I looked at that switch and looked at it and looked; well you get the idea. Accessing that little bulb is like opening one of those puzzle boxes. It can be opened... ;D
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

Re: Newbie boost switch question

Reply #10 –
My coach (2003) came with an 85 amp rated boost solenoid made by Pollack. When it started malfunctioning, I replaced it with a 180 amp Bosch solenoid.

When I had the boost solenoid problem, it started me thinking about the whole idea of using the boost to charge the chassis batteries. While it is true that the alternator charges both battery banks, it does it through an isolator. The alternator therefore charges each bank separately. The boost solenoid, on the other hand, puts both banks together and the charger treats them as one bank. To me, that's the same as putting 3 8D's and 3 Group 31's together and using them as one battery bank. But that is what the boost solenoid does.

So for piece of mind, I installed a dedicated 40 amp smart charger for the chassis batteries. I believe the chassis batteries are getting a full charge for the first time ever.
2003 GV320 4010

Re: Newbie boost switch question

Reply #11 –
Quote from: Ed –
So for piece of mind, I installed a dedicated 40 amp smart charger for the chassis batteries. I believe the chassis batteries are getting a full charge for the first time ever.
I installed the Battery Tender, which is a 5 amp smart charger, to charge the chassis batteries. It is a smaller than the 40 amp charger, but implements the same idea. I've been pleased with the results.

I always use the "Boost" for starting, but leave it off otherwise. I had been disappointed with starter performance for a long time. A "cheapie" battery tester showed that one of my chassis batteries had failed. After replacing that battery, starting performance has been good. Starting performance is still better with "Boost" engaged. Engaging "Boost" to start is not likely to hurt anything, and it does help.
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: Newbie boost switch question

Reply #12 –
Don't know if this any help on starting but an electric fuel pump makes starting much eaiser on a cold morning. At least it does on my old 3176 cat.
1995 U320 40', 2013 chevy sonic toad, my real love are corvettes have owned 30

Re: Newbie boost switch question

Reply #13 –
The reason the LSL Trik-L-Start is so popular, it keeps the start battery bank charged, and works 24/7 whenever the house battery bank is being charged, from Xantrex/Magnum etc or from solar. And this type of simple permanent diode connection from house to start takes advantage of house's smart charger's 3-stage, battery-temperature compensated charge-voltage. One of the best $50 we have spent, which has kept our RedTop start batteries lasting 9-years or more.
Ultra TRIK-L-START Starting Battery Charger/Maintainer

Dedicated chargers have their place, but often are not as smart as house charger, don't have charge voltage profiles, and always need 120-volts to work and may be difficult to mount & connect in a weatherproof area.

All multiple battery bank chargers have disadvantages as well as advantages, whether they be boost solenoid, dedicated, diode based, relay controlled, so there is no best answer. Good we are talking about charging start bank and encouraging others to add something. A volt meter reading on the start bank after coach has been sitting for a while will tell if a charger is in the system already.

Re: Newbie boost switch question

Reply #14 –
I agree, Barry (or Cindy), its a good discussion to have.

The Sterling charger I choose has 11 pre-programmed charge profiles and one user defined profile available. I also installed a battery temp sensor on the chassis battery bank.

I decided to go with it because it gives me a backup if the inverter/charger fails on a trip. I connected the cable to the chassis side of the boost solenoid. If needed , I just have to move it over to the house battery side of the solenoid. Or, since its a 3 bank charger, I could run a separate charge cable to the house battery connection.

The start battery bank must be happier getting 14.6 volts bulk charge for the first time. The alternator charges through the isolator that has a .4 volt drop through the diodes. I never saw more than 13.6 volts while the alternator was charging them. Or on shore power or generator the bank was paralleled with 3 8D's and I never saw them getting more than 13.8.

Your comments are always welcome.
2003 GV320 4010

Re: Newbie boost switch question

Reply #15 –
J.D. - The 5 amp Battery Tender was my first thought. So easy to plug it in to a 120v outlet in the coach and into the dash cigarette lighter that is connected to the chassis batteries. Done deal.

Unfortunately, the place I store the coach doesn't have any electric hook ups. So if it has been sitting a while I run the generator to charge. The 40 amp charger cuts down the running time.

Then there was the idea of having some charging redundancy on a trip. So once again, I turned a small project into a larger one.
2003 GV320 4010

Re: Newbie boost switch question

Reply #16 –
I try to keep charge voltages within battery manufacturer limits.  Notice that the difference between a cold battery and a hot battery is over 1 volt, so temperature steps are quite important and not always achievable with all battery chargers.

These AGM & Gel charts are from East Penn's attached publication.

We keep the Gel chart in our kitchen to check if voltages at various battery temps are ok.