Community Forums

Quincy · 12-13-2017, 09:49 AM

I just got off the phone with Newmar and was asking the tech about the battery boost switch. He told me that I would have to hold the boost switch until the batteries equalized and that could take as much as fifteen minutes and I sould not necessarily hear the relay click.

I have had MH's before and all of the previous switches would click when the boost button was pressed and it was similar to a jump start where all I had to do was turn the key and the motor would start off of the coach batteries.

Can anybody please confirm weather or not the 1999 Newmar works differently than my previous experiences would lead me to believe?

Thanks in advance,

Q

Rotten-Red · 12-13-2017, 10:15 AM

Quote:

Originally Posted by Quincy

I just got off the phone with Newmar and was asking the tech about the battery boost switch. He told me that I would have to hold the boost switch until the batteries equalized and that could take as much as fifteen minutes and I sould not necessarily hear the relay click.

I have had MH's before and all of the previous switches would click when the boost button was pressed and it was similar to a jump start where all I had to do was turn the key and the motor would start off of the coach batteries.

Can anybody please confirm weather or not the 1999 Newmar works differently than my previous experiences would lead me to believe?

Thanks in advance,

Q

That doesn't sound right to me. It might be hard to hear a click since it all takes place in the rear and you are up front, but it should click. If your house batteries are charged you should not have to wait 15 minutes for the batteries to equalize. It should crank right away.

Sbrownstein · 12-13-2017, 10:20 AM

No different than jumper cables. Do you wait 15 minutes to start a car with a dead battery? Yes you should hear it click if you are close enough. Don't believe him.

Mr_D · 12-13-2017, 10:24 AM

Have had two DSDP's, a 2000 and 2002. Both needed the switch held down to connect the batteries. Usually only needed to be held down a short time to have enough voltage/amps to start, not 15 min.

Quincy · 12-13-2017, 03:53 PM

Thank you both for your help. At least I know now what to look for.

Q

Stuart W · 12-13-2017, 04:10 PM

Quote:

Originally Posted by Sbrownstein

No different than jumper cables. Do you wait 15 minutes to start a car with a dead battery? Yes you should hear it click if you are close enough. Don't believe him.

Right? Good point

harleyjt · 12-13-2017, 04:15 PM

All you are doing is connecting the house batteries to the chassis batteries in a parallel circuit - meaning you will still have 12 v circuit. Yes - its just like a set of built in jumper cables. If you have a gas rig, you can probably hear the relay click. If diesel probably not since its at the rear. Throw the switch and hold, hit the key and start. Voila!
jt

twinboat · 12-13-2017, 05:58 PM

You all are correct, that the boost relay is like a jumper between the house and chassis battery. With a modern boost solenoid, the heavy cables go directly to the batteries.

I think the problem with the older MHs, with battery isolators, is that they use the small 1/4" or 5/16" isolator terminals as the boost point. The boost relay jumps the house and chassis terminal on it.

If you don't wait for some current to transfer from the good battery to the dead battery, your drawing a few hundred amps thru the small connections. That could overheat them enough to burn them off.

15 minutes does seem like forever. 5 minutes may be enough.

The Brews Cruise · 12-14-2017, 08:01 PM

Will the battery boost work the other way? As in using the chassis battery to jump the house batteries? The generator starter operates from the house batteries and will not start if these are dead. I don't know if there is a blocking diode in the circuit which has would prevent this. My house batteries were dead and I had to jump them from my truck so that I could start the generator. Then I realized that I should have tried the boost switch with my MH engine running.

twinboat · 12-14-2017, 08:37 PM

The boost will work both ways.

Sbrownstein · 12-15-2017, 04:00 AM

I have boosted the house in just the same way to start the genny. Best to start the engine as well...

wa8yxm · 12-15-2017, 07:29 AM

There are relays and relays IF the boost overrides the isolator and uses the isolator relay then you can hold it like forever and no damage.

On the other hand if they use a STARTER relay 30 seconds is the recommended max time to hold.

How I use mine.
Press and hold for 30 seconds release for 30 seconds Press and hold again for 30 seconds. release

Press and hold while starting (For main engine)

For Generator boost
Press both BOOST and Gen Start hold till lights inside RV brighten as converter kicks in,

Sbrownstein · 12-15-2017, 08:47 AM

I have never seen a boost relay installation that didn't use the Battery Isolation Solenoid, which is a constant duty solenoid. It has to be there to charge the house with the engine and that has to be a continuous duty solenoid.

twinboat · 12-15-2017, 11:01 AM

Quote:

Originally Posted by Sbrownstein

I have never seen a boost relay installation that didn't use the Battery Isolation Solenoid, which is a constant duty solenoid. It has to be there to charge the house with the engine and that has to be a continuous duty solenoid.

I have one [emoji4] .

Under the hood of my Class C is a isolation relay. It activates by turning on the key. Its a continuous duty solenoid that connects the chassis battery to the house battery.

Back by my MH door is a switch marked " Emergancy Start ". It controls a solenoid under the side door step and when on connects the house battery to the chassis battery. I don't know if it was a continuous duty solenoid because its buried down under the battery switch and breakers for the generator and house loads.

Why they have two is beyond me, but they do. Because of that they also ran 2 side by side positive battery cables from the front solenoid to the rear one. One brings power from front to back and the other from back to front.

As a foot note: Both solenoid have failed years ago. I simply connected a Cyrix battery combiner to both sides of the under hood solenoid. The 300 watts of solar keep everything charged.

I also moved the generator battery cable to the chassis battery. Now I can run the house battery down real low and still start the generator.