Home » Public Forums » GMCnet » Battery and/or starting issues
| Re: Battery and/or starting issues [message #189052 is a reply to message #189043] |
Sat, 03 November 2012 10:37   |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma:
|
Senior Member |
|
|
| Kerry Pinkerton wrote on Sat, 03 November 2012 10:06 |
Trying to work through a few issues on the new coach.
When we first looked at it, we had to hit the boost button to start it. NOTHING on the engine battery. Decided the mechanic had thrown the disconnect switch the wrong way.
When we went to pick it up, the engine battery was very weak and wouldn't start the coach. Charged it a while at the dealer and it made some noises but we finally just hit boost and drove it home.
Better noises when we got home after a 2 hour interstate run. Gauge showed 13V charging all the way.
Been plugged in to shore power since. Engine battery still won't start the engine by itself. My meter showed 12.5V on the battery so I pulled it and took it to my local Advance. They tested and said it was not fully charged but the result was iffy. I've had it on the charger all night and will let them test it again today. This morning, my charger says the battery is at 100%. Whether it stays at 100% or will take a load is the question.
The battery connectors looked clean and were tight. There is a large battery disconnect in the circuit that I have not bypassed to see if it is the problem. On the list to do.
The other thing I noticed is that they battery cables are these common 4 gauge things. I'm wondering if I should replace them with the heavier 2 gauge wires. There are several wires that would need to be replaced if I go this route. Advance sells some of the heavier cables I need but some will need to be fabricated. They sell the wire (clear insulation 2 gauge copper) by the foot with solder on connectors or crimp on connectors. I'm thinking I'll go the solder on approach with shrink tubing.
Since the house battery starts the engine fine, I assume that wiring is OK but I'll look at it also.
The house battery is a fairly new 12V. The engine battery is a 5 year old 950Amp top of the line from Advance. Based on what I've read while drinking from the GMC firehose here, the hot setup is to put two 6V golf cart batteries in series for the house battery. If my engine battery is bad, I can pull the house battery and move it up front and go with two 6 V for the rear.
Thoughts, suggestions, and comments please.
|
Kerry,
If a battery has been deep discharged or left in a less than full charge state for long, it will lose capacity. The fact is that the terminal voltage can be brought up to the 12.6 that a charged battery should be, but it can do that with no capacity behind it. Kind of like if you had an air tank that was largely full of water - there can be pressure there until you let out just a little air and then it is gone.
For starting a good 455, #4 cable is adequate, but (as I tell clients all the time), more copper never hurts and you only have to buy it once.
Before you do anything rash (as in spend money), and as a quick diagnostic, put the house battery in the engine position (you don't need to strap it down and everything, just make the connections solid) and see if you get a good crank...
If yes, you have answered the question.
If no, go looking for bad connections.
I have found that the best diagnostic tool is a light bulb with two long clip leads connected (how doesn't matter) to it. Put it places that either should or should not have any voltage and see if it lights. (Says the guy that owns several High buck meters and gives away HF cheapies to clients.)
=>One of my favorite is to put the light from the battery to the motor terminal on the starter.
It should light.
Hit the starter. It should out COMPLETELY. Even with your hands cupped around it so any glow at all would be visible. If it doesn't, you know you have a problem and now you know sort of where to start. Now do the same between the negative post and a good ground. This one should not light at all - ever. The same would be true between the positive and the battery terminal on the starter.
Gene's rewire of the starting circuit is not a bad idea, but do the complete diagnostic before you do it. If there is a defective piece in the system, you don't want to waste all that energy and then still have things not work right.
Your thought to move the house bank to the engine service is a very good plan, and along with making the house bank a pair of 6V golf cart batteries, you will have a much better overall system.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
|
|
|
|
Current Time: Sat Jun 15 21:54:12 CDT 2024
Total time taken to generate the page: 0.00687 seconds
|
GMCforum
Search
Help
Register
Login
Home
