Three(ish) years ago. I installed a new isolator. It's a Sterling zero loss two batt marine rated model.
Events were that we arrived at our camp site after a four hour drive. We are plugged in. This morning we were awakened by a very loud alternating on and off buzzing. It was coming from the Sterling isolator. No led's were on. As they are right next to the iso, I disconnect the start batt. The buzzing stopped. Got out the multimeter and batteries were at 13.4V. Next thing I did was to turn on the starter key and reconnect the isolator. No buzzing. And the leds were as normal. Turned of the 'ignition' key and the buzzing commenced.
Maybe a bad isolator?
The house batteries are on the charger and were on float. I disconnected the pos cable and put the start batt on a charger just to make sure. After the charge cycle, I will hook everything back up and report what happens.
Give Justin at Bay Marine a call to help diagnose this.
FWIW your Sterling Zero Volt Drop battery isolator uses a relay to separate the batteries. So you should listen closely the next time it malfunctions and ask yourself if you are hearing an "AC Hum" or mechanical relay chatter. If you decide it's the latter, taking the Sterling out of circuit would be a good idea. If the former, something else handling DC power from the AC mains is failing.
Tried calling west marine. They are all working from home and the mothership in the UK is closed due to covid.
Even though the batteries were at 13.4V.
After having them on trickle charge all day. I connected the start batteries again. The iso unit didn't make a peep.
I will be at gracerace's (Chris White's) house on Monday. I'll touch base with him on this issue as well.
It's quite possible that, unless you have a loose connection somewhere, you found a bug in that 1,000 lines of code. If so, good luck reproducing the failure.
I am going to post again about the industry wide use of battery bank combiners replacing battery bank isolators.,.,
My experience is that one occurrence of not charging the chassis batteries correctly permanently lowers their capacity.
I think I have a bad start battery(s) or at least a dead cell. As a month ago the batteries passed a load test with flying colors. They are 5 years old and have been rundown 2-3 times from phantom draws during storage.
I noticed a new light on the sterling today after reconnecting the main neg cable on the start battery. The sterling was showing some feedback. Which according to the manual is indicative of a weak bank being charged by a second bank, But not to the point of the relay doing it's isolation duty.
This was after running a 10 amp charger to the start batteries and it showing full charge. The cold engine was def hard to start. Had to use the boost.
So off to Pendleton this week to pick up 3 new redtops.
May I respectfully suggest adding a auto combiner instead of a combiner?
That depends Bob. As it's seems the issue is a battery not the isolator. Yet. If the isolator is wonky. I want to go simple next time.
I killed 2 sets of redtops before the auto combiner install.
Once totally discharged batteries are never the same in my experience.
If you have power into the coach it's foolproof
Mine were dead because of phantom loads. I usually disconnect the start batteries when it sits for a long time now. Where I haven't in the past.
My old Xantrex 2500 only charges the house bank unless the boost switch is left on. But as I have heard. FT recommends a max of 24 hours of boost switch activation while charging.
In the meantime. I'm just going to replace the old start batteries with new ones and see what the isolator does.
The boost draws 3 amps and gets physically hot. The auto connect is magnetic latching and consumes zero power after engaged.
Every new coach has a combiner as far as I know. Close to $700 to kill another set of redtops as you well know.
Got tired of non 100% reliable. Where we are we have to have this run in a emergency. Not an option
I'm betting that your isolator goes back to normal. I like the idea of a battery combiner but I like the idea of my solid state isolator better. 4 or 5 down on my to do list is a second PD 9260 battery charger dedicated to the chassis battery because I like the idea of having 120A total boost from my generator set. Why? Because on a very cold night after a long day I did leave the headlights on and the furnace did run down the house batteries down leaving me with the gen set's dedicated battery. On our previous rig.
That's my thought as well. What threw me off was having each of the three batteries load testing within spec. But when I was in CDA visiting Gracerace. He mentioned that he had the same battery issue as me. Load test fine, But checked each individual cell via hydrometer. And a cell was bad.
And that is likely why every now and then. I get a generic low voltage fault code on my VMSpc. Even the guys at a large Cummins shop in Boise said that particular code number usually happens from a battery issue.
We will see.
I'll of course report back as to how it turns out.
Isolator does not work on shore power. Only divides up alternator. Hence the combiners invention