Boost switch & charging

December 23, 2010, 10:46:15 am

Hi guys , moved on to another project, checking out the boost switch.
In the back on the driver side is the isolator board with the boost solenoid ,looking at the wiring diagram don't know much about isolator ,it's like a one way valve? which way does the power travel?
Boost switch ties the two sets of batteries together when on, so driving both sets get charged ?
When plugged in do they both charge ? how do I test boost to see if it works?
When it's plugged in the house Batteries read 13.8 volts, starter batteries read 12.6 volts if when plugged in if they both charge I would think both sets should read the same 13.8 volts? Thanks Art .

Re: Boost switch & charging

Reply #1 – December 23, 2010, 11:45:39 am

Quote from: prevostart – December 23, 2010, 10:46:15 am

Hi guys , moved on to another project, checking out the boost switch.
In the back on the driver side is the isolator board with the boost solenoid ,looking at the wiring diagram don't know much about isolator ,it's like a one way valve? which way does the power travel?

The center post is coming from Alternator to feed the 2 battery banks.

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Boost switch ties the two sets of batteries together when on, so driving both sets get charged ?
When plugged in do they both charge ?

You need the Boost Switch "ON" even when plugged in to charge engine batteries or use a device like a Ultra TRIK-L-START Starting Battery Charger/Maintainer trik-l-start.

Trik l start vs boost Thread

Boost Switch

Re: Boost switch & charging

Reply #2 – December 23, 2010, 12:25:14 pm

Quote from: prevostart – December 23, 2010, 10:46:15 am

Hi guys , moved on to another project, checking out the boost switch.
In the back on the driver side is the isolator board with the boost solenoid ,looking at the wiring diagram don't know much about isolator ,it's like a one way valve? which way does the power travel?

Yes, like a one way valve allows alternator output to charge both banks, but when engine/alternator off, the batteries are not connected.

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Boost switch ties the two sets of batteries together when on, so driving both sets get charged ?

While this statement is true, the isolator already allows both battery banks to be charged by the alternator. Said another way, a n y connection between the batteries will join both banks, but doing so is not necessary if the isolator is functioning properly-- it is the "automatic" solution.

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When plugged in do they both charge ? how do I test boost to see if it works?

Sounds like your inverter/charger only charges the house battery bank. This is the more common way it is done. As barry said you need to buy another device to charge the chassis battery bank. Your answer below is the test-- with inverter/charger on shore power if the chassis battery voltage is a volt lower than the house battery bank, you know the chassis batteries are not being charged.

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When it's plugged in the house Batteries read 13.8 volts, starter batteries read 12.6 volts if when plugged in if they both charge I would think both sets should read the same 13.8 volts?

Correct.

Re: Boost switch & charging

Reply #3 – December 23, 2010, 05:59:00 pm

Barry thanks for the tip on battery charger trick-L-start , read up on it and ordered one pretty cheap 47 bucks not bad Thanks Art.

Re: Boost switch & charging

Reply #4 – January 05, 2011, 11:42:37 am

Barry I went to install the Trick L Start that Barry said to install, so I thought I would check the Boost operation. First thing I did is to check Boost solenoid with my meeter and to house side read 13.8 Volts and starter side read 12.5 so I turned on the Boost switch and volts didn't change . I removed all cables cleaned ends and put on house side only, turned on Boost read again and house side read 13.8 and other side of solenoid ( with out) starter cable installed so power just going through solenoid on read 11.2 .

I removed solenoid and bench tested, put power to the coil wire side (small lug) and read the continuity between the two large post, and it read 18.56 should read 0 lots of resistance , solenoid bad . I went to Napa Auto and bought a new continence duty 80 AMP solenoid and installed , now with Boost off house side 13.8 volts and starter side 12.5, Boost on reads 13.8 on both sides Good to go, now I installed the new Trick L Start to the isolator easy install , 3 wires, Yellow to house side Blue to Starter side, and Black to ground, the green Light (Maintaining) on the unit came on after about 2 hours so starter battery's are now fully charged. another project done. Thanks Barry.

Art

Re: Boost switch & charging

Reply #5 – January 05, 2011, 11:54:31 am

Quote from: prevostart – January 05, 2011, 11:42:37 am

I installed the new Trick L Start to the isolator easy install , 3 wires, Yellow to house side Blue to Starter side, and Black to ground, the green Light (Maintaining) on the unit came on after about 2 hours so starter battery's are now fully charged. another project done. Thanks Barry. Art

Don't you love it when it works out that way.

On to the next project & may it be just as easy.

Re: Boost switch & charging

Reply #6 – January 06, 2011, 06:16:02 am

Quote from: prevostart – December 23, 2010, 10:46:15 am

Hi guys , moved on to another project, checking out the boost switch.
In the back on the driver side is the isolator board with the boost solenoid ,looking at the wiring diagram don't know much about isolator ,it's like a one way valve? which way does the power travel?
Boost switch ties the two sets of batteries together when on, so driving both sets get charged ?
When plugged in do they both charge ? how do I test boost to see if it works?
When it's plugged in the house Batteries read 13.8 volts, starter batteries read 12.6 volts if when plugged in if they both charge I would think both sets should read the same 13.8 volts? Thanks Art .

Looks like you found your problem with the solenoid. If your solenoid is working properly and your house charger is on solenoid on your house charger will charge both battery banks and maintain the charge. However you should not attempt to start your coach with the boost S/W on it will overload it (80 amp sol) all it will do is burn up your solenoid, Also keep in mind if you are running your coach on the house battery's (dry camping) with the solenoid ON you will be discharging your cranking battery as well.

Your automatic battery isolator where the cable from the Alt. comes to is a large dioad that allows current to flow in one direction, allowing the alt. to charge both sets of batts. when running. A simple way to check it is to check for voltage at the large cable on the back of the alt, or the center terminal of the isolator with the motor NOT running if you have voltage the isolator is bad, also you should not have any continuity between the two outside terminals on the isolator with the cables disconnected

Bruce Beane

Re: Boost switch & charging

Reply #7 – January 06, 2011, 08:25:59 am

Regards starting the engine using boost. No reason I can find not to do-so. The additional amperage is good for the starter and according to everything I've read and have been told, (including by James T at FOT) there is no harm to the boost-solenoid provided you DO NOT turn it on, or off, while cranking the engine. We've used boost on every start for the 5-years we've owned our coach.

Re: Boost switch & charging

Reply #8 – January 06, 2011, 10:34:16 am

The only reason I have had to use the boost switch is when my engine battery was low, that is before I got a Trick-l-start. Unlike the newer coaches my mechanical injection Cat 3208 starts very easy.

Re: Boost switch & charging

Reply #9 – January 06, 2011, 10:53:42 am

The other reason is James T recommends it to reduce wear on the starter.

best, paul

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The only reason I have had to use the boost switch is when my engine battery was low, that is before I got a Trick-l-start. Unlike the newer coaches my mechanical injection Cat 3208 starts very easy.

Re: Boost switch & charging

Reply #10 – January 06, 2011, 02:51:24 pm

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Chad's Quote: "Regards starting the engine using boost. No reason I can find not to do-so."

I have been told by several service people both at MOT, FOT and Encore to use the "Boost" when starting up the Cummins, especially in cold weather. Supposedly it is easier on the starter. Just remember to turn it off soon after starting the engine.

Re: Boost switch & charging

Reply #11 – January 06, 2011, 06:46:23 pm

I read Bruce's post to mean that the 80 amp solenoid is to small for the amperage that the starter draws. What size solenoid do they come with?

Re: Boost switch & charging

Reply #12 – January 06, 2011, 07:59:20 pm

Quote from: Gayland Baasch – January 06, 2011, 06:46:23 pm

I read Bruce's post to mean that the 80 amp solenoid is to small for the amperage that the starter draws. What size solenoid do they come with?

I think I replaced mine with an 80 amp continuous duty because it was readally available, and 80 amps is fine for charging. You can get momentary on sol. on up to 200A or so but they are not intended to be left in the on position very long. However, while not disputing MOT or FT or the Guru of Foretravel James T. think about this for a second, if your house battery's are in the front of the coach that means you have some where about 40' or more of cable back to the sol and on to the cranking battery's through an 80 amp sol, I doubt it will flow enough current (given the high amp draw of a starter motor) to make a difference anyway given that long of a cable run, you will have a voltage drop as well under that kind of load.

Just my humble opinion
Bruce

Re: Boost switch & charging

Reply #13 – January 06, 2011, 08:11:09 pm

Bruce,
When I start my engine with boost on it makes a noticeable difference in the crank speed on startup. I have new engine and house batteries.

Re: Boost switch & charging

Reply #14 – January 06, 2011, 09:32:03 pm

I also use the boost solenoid for starting. It makes a huge difference in turning the starter.

Re: Boost switch & charging

Reply #15 – January 07, 2011, 11:08:50 am

You guys are all rite, Caller Mark Harvey at Foretravel and he sells a 100 AMP continuous relay , He said the 80 AMP would work for a while if the battery's weren't dead . Art

Re: Boost switch & charging

Reply #16 – January 07, 2011, 11:57:05 am

Just got on computer and ordered a 100 AMP cont. duty solenoid from E-Bay , $ 18.95 Napa Auto couldn't get that style. Computer, aren't they great . Art

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