Bill & Judy Rouse <yahoogroups@...>
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is undersized. Why did you buy a Grp27? Your 54 came with a Grp31
The Grp27 battery you bought is 840CCA. Deka makes a Grp 31 1000CCA battery.
Did you replace your other batteries?
Do you have the 4 cylinder Onan, or 3?
If you are reading battery voltage in the cockpit, you must be reading it on a Volvo output panel, which means that you have the entire suite of Volvo electronics, 2 computers and various sensors powered-up as well as the 12VDC exhaust fans running. I am guessing 6-10 amps at 12VDC draw on your starting battery. This is NOT a way to test resting voltage, nor is it the thing to do before starting the generator.
In my opinion, you undersized the starting battery. This is especially significant when we are talking about the generator. The length of 12VDC wire from the starting battery to the starter is almost 7 meters from battery to starting motor. If everything is perfect, the wire that Amel uses for this is adequate, but, with an undersized battery, I suspect NOT.
Continue testing the "resting voltage," but at the battery. Continue to look for resting voltage of less than 12.8 volts, then see if you can determine why. Turning ON your Volvo systems and energizing the fans will drop the voltage and drain the battery. You did not say whether you "prime" the Onan when starting. This is pressing and holding down before starting. This should not be necessary for you unless the Onan has not started in a while. If you do this before starting, you will drain the battery.
Hopefully, you will learn why the resting voltage got as low as 12.4 volts (basically discharged), and hopefully your battery is OK. However, I think you need to plan on replacing that Group 27 starting battery with the correct size. BTW, if after running the Onan only for 1-2 hours the resting voltage on the starting battery after turning OFF the Onan should be 12.8-12.9 VDC at the battery...if it is not, the little alternator on the Onan needs attention.
I have forgotten the output of that little alternator, but see to remember something like only 10 amps.
On Mon, Nov 20, 2017 at 3:01 PM, Alex Ramseyer alexramseyer@...
So these are the answers to Bill's questions:
1. I read it from the display in the cockpit, which in the past showed the same numbers when I did it at the battery.
2. I went to IWW in St. Georges and the employee tested a battery in the shelf (they store them loaded), but I was stupid enought not to interfere when he took another battery from that same shelf when we went to the cashier.
Starting Battery Sealed 27M6 1050 MCA 12V
Marine Master starting batteries have calcium alloy frame grids and plates for minimum maintenance, deep pocket ...
4. This morning I saw 12,8V before starting and the genset started fine. But yesterday I had the main engine running for ca. 10 min
after I discovered the starting problem.
5. I own no load tester, but I will get one from a friend and uncircle the problem....
Thanks for your advice,
Alex / NO STRESS
It certainly looks like the alternator on the Onan is not charging the battery.
Lots of possible reasons...
As with anything electrical, start with ALL the connections. They are not always the most likely cause, but they are cheap and easy to fix, so it makes sense to test them first. Since the problem started after a service on the generator, it is quite possible you bumped a wire and broke a connection somewhere. Many times I have been working in the engine room and managed to bump the main power switch on the genset... "Why won't this darn things start???"
Be sure to NEVER disconnect the alternator from the battery when it is running. That will kill the diodes in very short order.
If it turns out the alternator is the source of the problem, it is almost certainly able to be rebuilt at a fr
action of the cost of a new one. That service is available all over.
Fort Lauderdale, FL
, wrote :
generator runs, I see 13,6V on the starter battery. When I turn the
ignition key of the engine in the cockpit the current goes down to 13,2V (maybe because of the
ventilator in engine room / generator is still running). When I start the main
engine the current goes to 14,4V.
servicing the ONAN and replacing the starter battery a short while ago, everything worked find
for a while, but this morning the ONAN only started AFTER I started the main
engine. The starter battery showed 12, 4 V initially. It showed 13,2 after I
run the genset for 2h and then 12,8 anoher 2h later. All observations come from the little display in the cockpit.
So what is
the conclusion of you fellow Amelians from this observations?
STRESS in Grenada