Help! Can't start my RV. Click link to video

[rolfesangel]

Hi,
This is my first time to visit.? Thank you for any help you may be able to offer.? My RV just won't crank.? It seems there is full power from the batteries and everything in the RV seems to work that runs on batteries either in the coach or the chassis.? The slide out works.? The headlights work. All of the 12 volt lighting system seems to be fine.? However, with the ignition on, but the starter not engaged, there seems to be several seconds of full power with headlights bright followed by several seconds of weaker power with headlights dimming without touching anything.? That cycle repeats itself continuously.? The links below show what is happening when the starter is engaged.? It sure acts like the batteries are weak, but they don;t seem to be, and it doesn't change anything when i try the "Battery Booster" switch.? Please view the links below and help me figure out what to try next or who to call to get me started. Thank you.
http://www.mesmerizer.com/rv/starter.mpg
http://www.mesmerizer.com/rv/clanging.mpg

 

[Jeff]

rolfsangel:

The noise you hear is one of the start relays engaging and disengaging. My guess would be low batteries, bad battery connection, or bad relay.

Doing easiest first would be to check battery voltage, check for loose or corroded battery terminals and then jump around the relay directly to the starter to see if starter is OK. On my Freightliner/Cat there are two relays in the starter circuit, one on the starter and another about 18" forward of the starter.

 

[Karl]

What is that topmost gauge that we see briefly, that appears to be fluctuating in sync with the starter/relay sounds?

Also, how long has it been since it was last run? Can you turn the engine at all with a socket wrench on the flywheel nut?

 

[rolfesangel]

Hi!? Thanks for your help.? I do not know how to turn the engine with a socket wrench, or where to put the socket wrench to try that.? That guage is the voltage of the battery.? It is all the way up to 12 volts until you hear that clank and that's when the voltage drops momentarily as if being drawn down by something.? Something else to note is that I am also unable to start the generator, which seems to put the focus back on the batteries not having enough power, but it doesn't seem to help at all when I use jumper cables to my car.? I may be in above my head here.? I do have Good Sam Emergency Road Service and I was thinking about trying to call them tomorrow to see if they can send a mechanic to get it started.? I did clean quite a bit of green corrosion off of the battery terminals and it has been about a month since it was started..

 

[Shayne]

Try recleaning the termials of the Starter Battery and recheck all cables.  When that is done try charging the battery to a complete charge and then try to restart.  Battery may not be very stable.

 

[Chet18013]

Sounds like a bad battery connection or bad ground. Remove bthe ends of the battery cable and clean it, especially at the starter.

Chet18013

 

[John From Detroit]

From that flucuating voltage guage I'm going to go with "Check all connections" as well, Check all the chassis battery connections that are on HEAVY cables, starting at the battery.  Two ways to test these, one is to measure from the post to the post on the other end of the cable, the other, which may now work in this case, is to feel the connction after cranking (Quickly after trying to crank) a bad connection will get HOT, (Very hot in some cases, you can get burned this way)

A better way is to simply clean all connections. Even if they don't need it

Other posibilities include bad starter, and a few other "Bad's" including bad battery

To check the battery use a voltmeter, Hook it to the battery POSTS (or hold the leads) and see if it flucuates like the dash meter while other-half tries to start engine.

 

[Jeff]

Hi!  Thanks for your help.  I do not know how to turn the engine with a socket wrench, or where to put the socket wrench to try that.  That guage is the voltage of the battery.  It is all the way up to 12 volts until you hear that clank and that's when the voltage drops momentarily as if being drawn down by something.  Something else to note is that I am also unable to start the generator, which seems to put the focus back on the batteries not having enough power, but it doesn't seem to help at all when I use jumper cables to my car.  I may be in above my head here.  I do have Good Sam Emergency Road Service and I was thinking about trying to call them tomorrow to see if they can send a mechanic to get it started.  I did clean quite a bit of green corrosion off of the battery terminals and it has been about a month since it was started..

It takes a while for jumper cables to have much effect if you connect them to the batteries. If you have GS that is your answer, they will give you a jump. I do have better luck using jumper cables for the generator by going directly to the gen connection if you want to try again. Charging the coach batteries which will make your emeregency start boost more effective.


How old are your chassis batteries? If they sit a lot without charging they may need replacing.

 

[Karl]

You may have a bad cell in one of the batteries. The voltage could read normal without a load, but quickly drop when you try to use significant power from it. Try disconnecting the positive lead from the chassis battery(ies) and use heavy-duty jumper cables and your auto battery exclusively. Check and clean all connections to the starter relay(s) and starter. It would be unusual for the battery boost switch to not have any effect unless it's a bad connection somewhere downstream from the battery bridge relay.
A closer look at the video shows that you may need a special spanner to turn the flywheel. Forget it; I was just trying to see if somehow the engine froze up, but that's pretty unlikely.

 

[rolfesangel]

These are excellent ideas which I need a helping hand with.  So I have called Good Sam Emergency Road Service to come out and help me today.  I might as well get their help since I pay for the service.  I will report how it goes and post information as to what happens.  It may be that their ability to jump the batteries will work whereas my attempts to jump using normal jumper cables to my Honda was inneffective.  They may be able to show me where the starter is, or the starter relays are.  So, stay tuned for the exciting conclusion to today's adventure!  Thank you all!

 

[Terry A. Brewer]

It's either your batteries or dirty/loose connections.
If your batteries are 3-5 years old I would replace them.

 

[rolfesangel]

OK.  The verdict is in and the RV is running.  It was the batteries.  Both failed the load test that they can put on at Midas.  To me it was a bit surprising, because I always thought you could start a vehicle with a jump from a good battery even if you didn't even have a battery.  It sure makes sense that you could.  I am still not sure why dead cells in a battery can keep a strong jump from starting the vehicle.  But, the Good Sam rescue truck came over, connected a jump and still didn;t make a difference.  I took the batteries in to Midas, he assured me they were shot, i bought new batteries and it cranked right up.  Thank you to all who helped me today.

 

[John From Detroit]

I always thought you could start a vehicle with a jump from a good battery even if you didn't even have a battery.  It sure makes sense that you could.  I am still not sure why dead cells in a battery can keep a strong jump from starting the vehicle.

There are a few ways that a jump start can fail with poor/dead batteries on the "dead" vehicle

1: (Not your problem) shorted cells.. If the batteries failed SHORTED they can actually pull down the "Good" battery

2: Bad connections.  When jumping you have 4 connections. I've never gotten all 4 down good on the first try, When using a "Jump Pack" you have 2 connections... it's odd I get them both 100% the first time either. Usually I have to make multiple attempts and it does work

3: Jumper cable size.. I have light weight (Good for Yugos) normal weight (Works with most cars) and heavy weight (Will jump start my motor home, or a 12 volt semi truck (or a 24 volt semi if you have a 24 volt jumper)

4: Alluded to in 3,  Some trucks need 24 volts to make VAROOM happen

and finally.. The jump battery has to be big enough... To jump start a Chevy 6000 Diseal I used a combination of 3 sources...1: Jump pack (1,000 amp peak) 2: 10 amp charger and 3: 30 amp "Booster" I also added in some time to bring up the not-very-good batteries on the truck, it was a 12 volt system... Took everything I had to make VAROOM happen.  If I'd have tried starting off my car .... Well, i'd be buying a new alternator (Again)
(NOTE: Car is a teenager, you expect to buy a new alternator every decade or two,,, More often if you give jump starts, which is why I have the jump pack)

 

[Ron]

Thanks for the update.  Glad you got it going again.

 

[rolfesangel]

Yep!  And, as Willie sung and we always chime as we drive away from our last camp site, "On the Road Again!"

 

[Gary RV_Wizard]

I am still not sure why dead cells in a battery can keep a strong jump from starting the vehicle. 

A "bad cell" can short circuit under load and effectively prevent current from ever reaching the starter. High resistance in another type of bad cell can also soak up a lot of the incoming "jump" power, with the same lack of results.  Load testing is the only way to get a real picture of the battery condition, though with flooded cell batteries a hygrometer (specific gravity) measurement of each cell is also a good indicator.