Author Topic: C7 won’t start  (Read 1099 times)

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Offline Captpar

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C7 won’t start
« on: February 15, 2020, 06:54:42 AM »
Tried to start engine got about 2 seconds of weak spin then nothing. Seemed like dead batteries but checked with multimeter and they showed 13.4.  Tried several more times during the day with same results. Went home for the night and tried again this AM  same results weak spin then nothing Inverter is showing absorb charging right now at  14.6    Chassis batteries are 6 months old.
Really in a bind since rv is backed into my covered storage parking space and can’t open battery bay door all the way due to rv parked next me that is a junker and hasn’t been moved in over 5
Years. Generator started right up. Does it start off the chassis or house batteries? Really need some help here. Thanks
2007 Sport Coach, C-7, Freightliner XL

Offline Brett Wolfe

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Re: C7 won’t start
« Reply #1 on: February 15, 2020, 07:07:35 AM »
What happens when you use the boost/combine switch?

You say voltage at the chassis batteries is 13.4.  Check it when someone else turn the key to try to start it. If voltage drops below 12.0, bad batteries.  If little or no drop, suspect poor connection at batteries, starter (positive) or ground. Yes, there could be other causes such as bad starter, but at least it will give you a place to start.

BTW, very few coaches charge the chassis batteries from shore power/generator.  Said another way, the converter or inverter/charger usually only charges the house bank.  Sounds like yours is wired to charge both banks-- a good idea.
« Last Edit: February 15, 2020, 07:42:55 AM by Brett Wolfe »

Offline Captpar

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Re: C7 won’t start
« Reply #2 on: February 15, 2020, 07:12:08 AM »
More info rv was on shore power while parked 50 amp. When I turned off gen to leave it still was on absorb charging at 14.55 went back to shore power it showed float charging  at 13.6.what happened to the 14.55?  Boost switch switch made  zero diff
2007 Sport Coach, C-7, Freightliner XL

Offline Brett Wolfe

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Re: C7 won’t start
« Reply #3 on: February 15, 2020, 07:16:33 AM »
You say voltage at the chassis batteries is 13.4.  Check it when someone else turn the key to try to start it. If voltage drops below 12.0, bad batteries.  If little or no drop, suspect poor connection at batteries, starter (positive) or ground. This is a good diagnostic procedure. Yes, there could be other causes such as bad starter, but at least it will give you a place to start.

And, if boost switch/solenoid is working (easy to verify, as voltage is exactly the same at both banks), that is another indicator that there is a bad connection,
« Last Edit: February 15, 2020, 07:42:33 AM by Brett Wolfe »

Offline trekker01

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Re: C7 won’t start
« Reply #4 on: February 15, 2020, 09:32:25 AM »
Note that the boost switch must be held throughout the process.  It is a momentary switch.  Push it and hold it for about 30 seconds before attempting to start.  Keep it held until you either get a failure (as you have been experiencing) or the engine starts, then release.  I would suspect you have a bad/poor connection between the battery bank negative terminal and the chassis, or between the chassis and the engine.  What brand coach?  What year? 
Gary
1998 Safari Sahara 300 Cat

Offline Brett Wolfe

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Re: C7 won’t start
« Reply #5 on: February 15, 2020, 09:36:10 AM »
Yes, the boost switch COULD be momentary (must hold it in the on position to work) OR it could be a regular switch closing a constant duty relay.

Indeed, depends on how the coach is wired.

Offline Captpar

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Re: C7 won’t start
« Reply #6 on: February 15, 2020, 03:26:33 PM »
Update. Went to rv this AM with help and a battery charger with engine start feature,hooked it up and one first try engine spun regularly,but no start on 3rd try it fired up. Let it fast idle for one hour before shutting down also moved it so I can fully open bay door to access batteries easily. Now why did batteries show full charge when it’s apparent to me that they were depleted . Also while idling the gauge showed 14.4 charging,but when I switched to shore power charging rate went to float  13.7. Is the magnum not providing enough amps to provide full charge?
Monday will loosen and clean check all connections ((assuming it will start)
2007 Sport Coach, C-7, Freightliner XL

Offline Brett Wolfe

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Re: C7 won’t start
« Reply #7 on: February 15, 2020, 03:52:06 PM »
If you plugged in immediately after batteries read 14+ VDC from alternator charging, it would be  reasonable for the inverter/charger to go immediately into FLOAT mode.

What device do you have for the inverter/charger to charge the chassis batteries?  Again, rate on OE installations.

Offline Captpar

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Re: C7 won’t start
« Reply #8 on: February 16, 2020, 06:16:19 AM »
Magnum inverter/charger
2007 Sport Coach, C-7, Freightliner XL

Offline Brett Wolfe

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Re: C7 won’t start
« Reply #9 on: February 16, 2020, 06:19:17 AM »
Again, on most coaches the inverter/charger ONLY charges the house batteries, not the chassis batteries.

What device do you have to charge the CHASSIS batteries.

Let us know what coach you have as well-- that may assist us in helping you.

Offline David.e.atherton

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Re: C7 won’t start
« Reply #10 on: February 16, 2020, 06:55:26 AM »
Gentlemen, in relationships to this no start problems . Sounds like one battery is holding a surface charge
that battery is bad, than what happens the bad battery pulls down the good battery. A dirty connection to
Ground or as stated loose ground connection will put out the same picture. As stated use of house booster
Batteries is a very good practice because the starter needs to spin the engine. Remember the engine will
not start before 870 psi oil pressure is built up.  Ask Dave, Dave Atherton Retired Cat Mechanic

Offline Captpar

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Re: C7 won’t start
« Reply #11 on: February 16, 2020, 09:03:21 AM »
Thanks all for the info. Brett I was told that the magnum inverter charged both banks of batteries. Went to rv this AM and got out magnum book and couldn’t find anyway where it said it would charge both chassis and house batteries. It just it it would charge batteries. Will call them in morning to verify. In all the years driving this RV I never had a problem with chassis batteries not staying charged. How do I check for a bad battery if if multimeter is giving false reading. I will also check and clean all connections. I will buy new batteries if I have too but these are only 6 months old and I won’t be replacing  with same, got them at truck repair store. So I’ll probably have the eat the cost.
2007 Sport Coach, C-7, Freightliner XL

Offline Brett Wolfe

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Re: C7 won’t start
« Reply #12 on: February 16, 2020, 09:35:41 AM »
Your inverter/charger manual will NOT tell you how it is wired.  That is up to your coach manufacturer.

Again, most common is for it to ONLY charge the house bank.

But, very easy for you to determine this-- with coach plugged in, what is voltage at each battery bank? Two most common methods for charging chassis battery are "smart thief" devices like the Xantrex Echo Charger or a stand-alone small smart charger dedicated to only the chassis battery.

Yes, you can do a quick check on the batteries condition by charging them fully then monitor voltage while having someone try to start it-- covered several posts ago. Actually, when the key is turned to its first position, the intake manifold heater will come on.  That will be your first test of battery voltage. If the intake manifold heater drops voltage below 12.0 batteries are bad.

A better method is to fully charge them and take them to any place that sells batteries to have them LOAD TESTED.  The batteries will need to be separates so you can separate good from bad.

When you post voltage readings to questions posted in this thread, we can be of a lot more assistance.  Remember, a bad connection could cause 100% of your symptoms-- doesn't have to be a bad battery.

BTW, thank Gary for going in and changing your signature to reflect the coach you have-- at least the coach you mention in past threads.
« Last Edit: February 16, 2020, 10:31:30 AM by Brett Wolfe »

Offline Captpar

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Re: C7 won’t start
« Reply #13 on: February 17, 2020, 06:32:50 AM »
RV this AM  batteries read 13.4 turned key and waited for heater light to go out batteries now 13.1 started engine batteries went 12.00 monentarily then started charging as alternator kicked in. Engine start was sluggish . What do you think.
2007 Sport Coach, C-7, Freightliner XL

Offline Brett Wolfe

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Re: C7 won’t start
« Reply #14 on: February 17, 2020, 06:38:48 AM »
Normal readings.

What is ambient temperature?

I would still clean both ends of battery cables-- both positive and ground.

Offline Captpar

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Re: C7 won’t start
« Reply #15 on: February 17, 2020, 07:15:36 AM »
Temp 55 degrees
2007 Sport Coach, C-7, Freightliner XL

Offline Captpar

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Re: C7 won’t start
« Reply #16 on: February 17, 2020, 12:52:59 PM »
Ok all terminals checked and cleaned batteries charged. So what caused  this problem .RV set for 3 weeks without a start,could this have caused them to run down.never had before . I could take them out for a load test,but now I leaning toward them just being depleted from sitting. Thinking about a battery minder on them.
2007 Sport Coach, C-7, Freightliner XL

Offline Brett Wolfe

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Re: C7 won’t start
« Reply #17 on: February 17, 2020, 12:56:05 PM »
We still do not know what means/device your coach has for maintaining chassis battery charge, so it would be pure speculation as to what went wrong when on shore power while in storage for 3 weeks.

Offline trekker01

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Re: C7 won’t start
« Reply #18 on: February 17, 2020, 01:47:49 PM »
Captpar,
Are you getting your battery voltage readings from an installed gauge in your coach?  Or using a multimeter?  If an installed gauge, do you have a multimeter you can use directly at the batteries?  What is the chassis battery voltage reading directly off those batteries.  How old are the chassis batteries?

If you used the coach a month ago, any chance you left something turned on that is powered off the chassis batteries?  Radio?  Rear camera?  Heated side mirrors?  Not familiar with the wiring for your coach, but generally there are some things that get their 12v power from the chassis batteries beside the starter motor and outside lights.  The wiring diagram for your 12v systems might give a clue.                                 
Gary
1998 Safari Sahara 300 Cat

Offline Captpar

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Re: C7 won’t start
« Reply #19 on: February 17, 2020, 02:03:16 PM »
I assume no charger if as you say magnum only charges house batteries tried to call them today,but they closed for holiday. Batteries are 7 months old and I don’t know of anything left on since last trip. I did a cursory check but nothing leaped out to me.  Thanks all for the responses.
2007 Sport Coach, C-7, Freightliner XL

Offline Captpar

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Re: C7 won’t start
« Reply #20 on: February 17, 2020, 02:04:11 PM »
Used multimeter.
2007 Sport Coach, C-7, Freightliner XL

Offline Brett Wolfe

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Re: C7 won’t start
« Reply #21 on: February 17, 2020, 02:36:55 PM »
VERY unlikely that your inverter/charger manufacturer would know how it was installed in your coach.  If you bought it new and did not modify the 12 VDC system, your coach maker can tell you "WHAT DEVICE CHARGES THE CHASSIS BATTERIES FROM SHORE POWER".

But, even better is to look around for either a "smart thief" device that takes power from the house bank when it is above a certain voltage OR a stand-alone charger (120 VAC to 12 VDC).

Offline trekker01

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Re: C7 won’t start
« Reply #22 on: February 17, 2020, 03:31:25 PM »
I have been using Magnum Energy 2,000 watt inverters for over 15 years and they do not come with that capability.  However my current coach came with a Heart Freedom 2000D inverter from the factory, and the coach builder installed a Heart brand product that allowed the inverter charger output to be shared by both house and chassis battery banks.  I switched that coach over to a Magnum inverter in 2017 and kept the Heart device, so it continues to share the charger output with both banks.  Magnum has something similar they call a Smart Battery Combiner - see https://www.magnum-dimensions.com/smart-battery-combiner  - which could be on your coach somewhere in between the inverter/charger and the battery banks.  Lacking that, you may not have the capability. 
Gary
1998 Safari Sahara 300 Cat

Offline Brett Wolfe

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Re: C7 won’t start
« Reply #23 on: February 17, 2020, 03:53:28 PM »
Yup, and Xantrex's "smart thief" is the Echo charger.

http://www.xantrex.com/power-products/power-accessories/auxiliary-battery-charger.aspx

I have no favorites here, but our speculation on one will be irreverent (actually  MISLEADING) if you have something else.

Offline pfhays

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Re: C7 won’t start
« Reply #24 on: February 17, 2020, 04:09:08 PM »
You can make sure the chassis batteries are being charged if the boost switch is held on.  Most of those switches are a momentary switch and return to the off position when released.  Using something to jam the switch in the on position will keep the two sets of batteries connected and the charger will charge both sets of batteries.  I would only leave the switch jammed until the chassis batteries are brought up to proper charge state.