I tried to start my coach a few days ago, a '93 U300 GV, and it wouldn't start. It cranked (with boost on) but after a short time the cranking slowed down. I shut the boost off, turned the key and nothing happened. I re-engaged the boost, heard clicking then gave up. I have 3-year old Optima Red Tops. The coach is stored indoors and plugged in. The chassis batteries have a trickle charger installed.
I connected a commercial heavy duty battery charger for 2 days. I tried to start it again today and everything happened the same way. I removed the batteries (3 of them) and a voltmeter showed about 10.6 on all 3 batteries. I took the batteries to Autozone and they passed a load test.
I have limited knowledge in this area. Is a normal load test possible if I got 10.6 on the VM?
The battery posts and clamps were clean.
Any suggestions? I do have 3 new batteries ready to go but I don't want to kill those.
Thanks all
I found one problem, could be material. In the middle of the bus bar, the clamp corroded and separated from the post. It was only kept on by the trickle charger clamp. You can see this above the middle battery in the photo.
(https://i.postimg.cc/DZN5HzM8/IMG-2616.jpg) (https://postimg.cc/r0SStqck)
After losing two sets of chassis batteries I copied the rest of the rv industry and installed a battery auto combiner.
I failed two different trickl chargers type units. Both failed from lack of enough capacity to charge low multiple batteries.
The trickl chargers green dot was on. No output. Failed internally.
I added a small solar which ALWAYS charges both battery banks though the combiner.
Unless cloudy for long times should fix things.
Works parked without a plug in that way.
As far as I know all new rv's use a auto combiner.
It's control switch eplaces the boost switch. No indicator light but the connecting click is audible.
ML-ACR Automatic Charging Relay - 12V DC 1A - Blue Sea Systems (https://www.bluesea.com/products/7620/ML-ACR_Automatic_Charging_Relay_-_12V_DC_1A)
Replaced the isolator at its old location
Great info Bob but that really doesn't help me with this issue.:+)
Jeff,
I would guess that bolt broken loose from the bus bar could certainly reduce voltage getting to the starter. Definitely need to correct that situation.
As to load test, I don't think a valid test can be conducted unless the battery is fully charged. 10.6 volts is a dead battery (or else a fully charged battery with a dead cell).
I would disconnect the batteries and try charging them independently. While you are doing that, you can get some new battery connector parts. Put everything back together with fully charged batteries and good clean solid connections, and see how it works.
Once the batteries are damaged the post moderm you are doing should show a physical issue.
If not the trickle charger failed internally. See if it works. The damaged cabling demanded more output than the small charger was designed to put out so like mine it failed internally killing the battery set.
Repair the wiring and replace the batteries.
Buy a new trickle charger.
Repeat cycle. Repeat cycle. If unlucky.
Or fix the basic issue with a 500 amp capable non fail no spark marine grade unit.
Adding the solar adds a additional level of backup power.
Three mk 8g8d's and three optima agm's That were installed new in ours were too expensive to damage them so a system upgrade was necessary IMO.
I am adding a desulfurization system to my optimas coming up. Not sure if it works with spiral wound
That bad clamp is a problem. I can't stress how to use a voltmeter right. Put one lead (any lead) on the battery post and the other on the clamp. Should read 0 volts. if it reads .2 volts you have a dirty connection between the post and clamp. Even under a load (like starting). I have even seen were the voltage drop was from the cable to were it goes into the clamp. Every joint must be measured.
More possibly helpful info:
3 Ways to Check for a Bad Battery – Tech Tips & Tricks | BatteryStuff (https://www.batterystuff.com/blog/how-to-tell-if-your-battery-is-bad.html)
Jeff, I would charge your engine start batteries while out of the vehicle if they are already out. Then when you reinstall them make sure that the terminals are clean and that the cables attached to the back side of the terminals are clean. (Mine had a ceramic type burn built up on these) that did not allow the proper voltage to charge the batteries nor could the batteries supply the starter with the proper voltage. also check the boost solenoid for proper voltage going across the two large terminals, if there is any loss there you will not be getting full power to the starter. I have found that most times when the engine fails to turn over properly it relates to a bad ground or corroded cables... Provided that the batteries are Good and Charged.... ^.^d
Jeff,
As several have said, doing a load test on a battery that is not fully charged is INVALID!
And, as you identified, make sure the cabling is good, solid, clean and TIGHT.
I also have a preference for having the positive off one end battery and negative on the battery on the other end (vs both in the middle).
The first thing to do is remove all battery connections, clean and file both sides of the cable connectors until they are flat and shinny. I installed all stainless hardware and installed an extra ground cable to the frame a foot or so away. It spins like a top in hot or freezing weather.
The photo is off group 31 batteries. They are turned around to avoid hot to ground possibility.
Pierce
I would not be surprised you will have one battery with a bad cell /short and it is taking the other batteries down. I do not know how may times I have had one battery in my truck, Coach, or boat take itself and the other one down.
I forgot to add that I NEVER use the boost and keep it in reserve for an emergency. If the engine cranks faster with the boost actuated, something is lacking in the primary starting circuit. A good way to check your batteries it to charge the three and then disconnect them from each other. Check the voltage at the battery then and the next day, repeat checking voltage.
Battery voltage is just about at the top of the list to monitor. I installed twin voltmeters in the dash but plug in digital voltmeters in the lighter sockets do just as good of a job I watch them for changes all the time while driving and while parked. If something is causing a drop over a short period of time, you can quickly see it. The voltmeters were only about $8/ea so no big deal. The plug in to the lighter socket are instant installation and cheap too.
Pierce
Thanks all, this is what I love about the forum. It's fullof folks smarter than me that we always willing to share their time and knowledge. I'll report back tomorrow.
Pierce, I tried to reach you before I posted this but your mailbox is full. :+)
It seems to fill all by itself. :)) Will empty it now.
All fixed and fired right up. It was the ground wire issue. I replaced the broken battery clamp and all is well.
Thanks all!
Were the batteries damaged?
It may be difficult to find a cigarette lighter connector that is powered from the house battery to plug a volt meter into. I had to add one near the dash I added a battery monitor in it that alarms when the battery voltage drops to the set point. The set point is variable and I set mine at 12.5 volts. It keeps me out of trouble as long as I take the time to look at it !! The GV is in the RV garage next to the house, so it isn't difficult for me as long as I remember to do it. Just for reference purposes, it takes a couple of weeks for the battery voltage to drop to the set point from fully charged. I don't know if that is good, bad, or in-different !! Have a great day ---- Fritz
There are two cigarette lighter connections on a 1993 U300. The first one, which is the most obvious, is the one by the ignition switch. The second one is in front of the navigator's station, UNDER the dash. That one may require a flashlight and some contortions to find, but it is there. One of them is connected to the house batteries and one to the start batteries, but I don't remember which is which.
Jeff
What EXACTLY did you do to correct the ground issue
Gleam, I replaced the corroded, broken clamp used to connect the ground wire to the bus bar. I also removed both bus bars and cleaned all surfaces to insure a good connection.
The end of summer is a good time to pull all the terminals, upgrade the fasteners, etc. Easy summer starting does not require near as much juice from the starting system and any high resistance between the bars and battery lugs can easily go unnoticed. Not only is it harder for the starter to turn the engine over, it may also have to crank for an extended time.
I melted a battery terminal in Yellowstone when the temp was 17 degrees, elevation 8000 feet and the block heater had failed. Detroits don't have the heated screen to warm the air either. I finally got it going with ether and many attempts.
Photos include melted terminal and before and after cable end cleaning.
Pierce
Pierce, that's what mine looked like. It had worn through previously as I found solder drips on top of the battery...a Mickey Mouse fix.