how far can you drive with boost switch on?

Topic: how far can you drive with boost switch on? (Read 1376 times) previous topic - next topic

how far can you drive with boost switch on?

April 25, 2015, 06:40:43 pm

I'm 500 miles from Nac and my alternator is not charging the chassis batteries. Turning on boost there is enough voltage to start and keep the engine running but how far can I drive like this? Will I burn up the boost switch or break something else?

Any advise will be appreciated.

Re: how far can you drive with boos switch on?

Reply #1 – April 25, 2015, 06:42:49 pm

So, the engine is charging the engine batteries but not the house batteries? Run the generator with the boost switch on. Check and possibly replace the isolator. Boost solenoid is continuous duty. Won't burn up. If the engine alternator is not charging the engine batteries, the boost switch with the generator running will keep you going.

Pierce

Re: how far can you drive with boos switch on?

Reply #2 – April 25, 2015, 06:44:57 pm

I ran with the boost on from New England to nac, no problems.

Re: how far can you drive with boos switch on?

Reply #3 – April 25, 2015, 06:47:13 pm

I should add, with gen running.

Re: how far can you drive with boos switch on?

Reply #4 – April 25, 2015, 07:17:00 pm

I think the engine alternator is not charging the engine batteries at all. This morning after driving about 200 miles the check engine light came on. Pulled into Walmart and noticed the voltage gauge was below 12. The Drivers Info Center (DIC) indicated the engine batteries were at 12 volts.

So I turned on the boost restarted the engine and the engine batteries settled in at 12.6v. The check engine light was off. I then set off and drove another 250 miles but I noticed that the engine battery voltage had dropped to 12.2 -12.3 volts. I did not want the check engine light to come on again so I got off the road for the night.

Under those circumstances is that normal? How far would the voltage drop? Why did it appear that the boost was loosing its boost?

Re: how far can you drive with boost switch on?

Reply #5 – April 25, 2015, 07:26:05 pm

Quote from: Mark Benko – April 25, 2015, 07:17:00 pm

I think the engine alternator is not charging the engine batteries at all.

So I turned on the boost restarted the engine and the engine batteries settled in at 12.6v. The check engine light was off. I then set off and drove another 250 miles but I noticed that the engine battery voltage had dropped to 12.2 -12.3 volts.

Under those circumstances is that normal? How far would the voltage drop? Why did it appear that the boost was loosing its boost?

The voltage will continue to drop unless you start the generator because with boost switch on and the alternator not charging, you are now pulling the engine's 12V needs from the house batteries without replenishing their charge, either. If you don't find a means to keep a charge going the house batteries, you could drain them too far - to the point you can't get the genset started, either.

Start the genset to keep the house batteries charged and then turn on the boost to link the house and coach batteries when you need to drive (or if you're in a situation where you don't have electric hookups).

Re: how far can you drive with boost switch on?

Reply #6 – April 25, 2015, 07:32:19 pm

Quote from: Michelle – April 25, 2015, 07:26:05 pm

The voltage will continue to drop unless you start the generator...

Sorry Michelle and others - I did start the generator and left it running the whole time. Long day and not as precise as I should be.

Re: how far can you drive with boost switch on?

Reply #7 – April 25, 2015, 08:39:26 pm

Quote from: Mark Benko – April 25, 2015, 07:17:00 pm

...
So I turned on the boost restarted the engine (with the Generator running) and the engine batteries settled in at 12.6v. The check engine light was off. I then set off and drove another 250 miles but I noticed that the engine battery voltage had dropped to 12.2 -12.3 volts. I did not want the check engine light to come on again so I got off the road for the night.

Under those circumstances is that normal? How far would the voltage drop? Why did it appear that the boost was loosing its boost?

Also, I want to make it tomorrow to Cummins MidSouth in Little Rock which is about 200 miles in the direction I want to go. Anyone have dealings with that place?

Re: how far can you drive with boost switch on?

Reply #8 – April 25, 2015, 08:53:03 pm

Quote from: Mark Benko – April 25, 2015, 07:32:19 pm

... I did start the generator and left it running the whole time....

Mark,
We drove 1300 miles with the generator running and boost switch engaged (our alternator failed in Phoenix; we had it rebuilt in Kalispell, MT).
Grant

Re: how far can you drive with boost switch on?

Reply #9 – April 25, 2015, 08:57:32 pm

Thanks Grant. Did you happen to watch the engine battery voltage while driving?

Re: how far can you drive with boost switch on?

Reply #10 – April 25, 2015, 09:08:52 pm

Mark,
We have had very bad, bad, luck with Cummins in Little Rock. I would be very careful. They misdiagnosed when we had a CAC leak as a bad turbo. When they took the alternator off to fix turbo, they miswired it. Even after I told them how to do it. They swore up and down they knew how to do it. But that was 2 years ago so things may have improved. Can't tell you where to go in Little Rock, but you might try and give Dub a pm and he might be able to refer you to someone in South AR. We are headed to NAC in the morning let us know if there is anything we can do.

Re: how far can you drive with boost switch on?

Reply #11 – April 25, 2015, 09:44:28 pm

Thanks Ellen.

Re: how far can you drive with boost switch on?

Reply #12 – April 25, 2015, 09:52:29 pm

Quote from: Mark Benko – April 25, 2015, 08:57:32 pm

Did you happen to watch the engine battery voltage while driving?

As I recall it stayed close to 13V, well above 12V on the dash gauge.

Re: how far can you drive with boost switch on?

Reply #13 – April 25, 2015, 09:53:49 pm

Mark,

It might be worth a couple of minutes diagnosis time.

Start by raising the bed and verifying that there are no loose connections between alternator and battery isolator. Pay particular attention to the small "sense" wire from battery isolator chassis battery lug to alternator.

Start engine and raise RPM to about 1100. Check voltage at either alternator B+ terminal or center lug of battery isolator-- if 14.5+, the alternator is doing its job. If so, the isolator is the "likely suspect". Check voltage at the two outer lugs (the ones that go to the individual battery banks). Let us know what you find.

VERY easy work around if that is what you find.

Re: how far can you drive with boost switch on?

Reply #14 – April 25, 2015, 09:54:55 pm

Mark,
Really glad to hear there's a work around so you can get there Mark. We're here @FOT with tools and extra hands if it helps any...
Great info on this topic about the interactions of the genset, booster and house/chassis batteries. Thanks to all chiming with details, it's really useful for other folks just working through the learning curve. :-)

Ellen, if you're going to be in Nac Sunday/Monday look us up! We might be out doing a shake down camping trip Sunday, but we'll be back Monday for what we hope is the last bits and tweaks before we leave camp fore-ever-travel. ;-)

Re: how far can you drive with boost switch on?

Reply #15 – April 25, 2015, 09:57:15 pm

Thanks very much Brett for the info. I will start investigating in the morning. Too dark now and I'm too tired.

Re: how far can you drive with boost switch on?

Reply #16 – April 25, 2015, 10:43:34 pm

Will look you up we are going to be at Xtreme for a couple of days

then got to be at FOT the next week

Re: how far can you drive with boost switch on?

Reply #17 – April 25, 2015, 11:29:39 pm

Mark, we had the same problem happen on the way home from Texas. We were in the middle of Minnesota and had to get to central Wisconsin. The alternator wasn't putting out, the cruise dropped out when the voltage had dropped to around 10V. I started the generator and turned on the boost switch and let everything run until we got back up to 13V+. Then I would turn off the gen & run until voltage dropped again.

The problem turned out to be dirty contacts between the wire ends and the alternator posts. Everything was tight, but dirty. Unfortunately it cost me $145 to find out what was wrong.

You might want to clean your alternator connections and see if that may be the problem.

Re: how far can you drive with boost switch on?

Reply #18 – April 26, 2015, 05:33:28 pm

Mark,

About 6 months ago experienced the same problem you are having on our 05. From reading one of Brett's previous post on checking voltage at the isolator, while checking, I found the nuts on both outer posts had backed off maybe a thread or two. Tightened up, no problems since.

Re: how far can you drive with boost switch on?

Reply #19 – April 26, 2015, 09:15:58 pm

Mark,

Have you made it to Nac. yet are do we need to send out a rescue ranger?

Pamela & Mike

Re: how far can you drive with boost switch on?

Reply #20 – April 26, 2015, 09:34:09 pm

No rescue ranger needed! Thanks Brett and Mike for the calls today. You guys are the best. I'm absolutely sure you guys have forgotton more about FTs than I'll ever know. Thanks to everyone else who chimed in.

I made it down to Nac tonite and have an appointment with Bernd in the morning for a annual maintenance and a resonator. I will pass on everyone's much appreciated insights.

I did figure out the dropping voltage issue (driving down the road, generator running and boost on but engine voltage dropping to 12v). Turns out after x amount of time my charger goes from "charging" to "ready" state all by itself. When that happens it does not automatically go back into charging mode. At least not under theses circumstances. Under normal circumstances it keeps the house batteries charged.

Lastly, I"ll post the outcome in a few days.

Re: how far can you drive with boost switch on?

Reply #21 – April 27, 2015, 10:47:56 am

Hello Mark & Mary,
Glad you made it in without being stranded. Sorry we missed you guys! We were at the mother ship getting a small fiberglass crack repaired last week and will be in Canton later this week for the First Monday thing. Good luck with your repairs...I'm envious of your resonator install.
Safe Travels!
Bill & Donna

Re: how far can you drive with boost switch on?

Reply #22 – April 27, 2015, 10:16:25 pm

Thanks Bill. Based on Michelle's replacement of their Areo with a Magnaflow (I really do like quiet) it will be interesting to determine how this affects my coach.

Tomorrow I will find out the root cause of the charging problem. On a side note, Bernd is a standup businessman. He talked me out of a couple of things I thought I needed done and talked me into a few things that that should be done. This will be interesting.

Re: how far can you drive with boost switch on?

Reply #23 – April 28, 2015, 10:19:43 am

Another little nod here to solar panels. If it's daytime a reasonably sized solar array (say 500-watts or more) will put out a lot more power than you'd think. Ours (640-watts) put out 8-amps in dense fog when we were camped in the in-laws driveway. So even you're driving if you have a solar panel bank you can hit the boost switch and direct some of those amps toward keeping the rig running.

I turned off our charger/converter months ago. Even though we're parked with 50-amp service the juice needed to charge the batteries is something I don't need to pay for.

Craig

Re: how far can you drive with boost switch on?

Reply #24 – May 15, 2015, 09:38:00 am

Just to follow up and close out on my chassis battery charging problem. Bernd diagnosed a failed alternator. I'm guessing from age/heat. There was an exhaust leak on the turbo/manifold that probably contributed to its demise.

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