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Inspector 06-01-2019 06:59 AM

Agile battery separator
Our 2011 Agile sat for 16 days in the garage and when we went to start it, everything was dead. I had posted before about an earlier experience. I connected a charger under the hood to charge the starting battery. After about 15 minutes the battery separator started closing/opening every 20-30 sec. Shouldn't it remain closed or is it trying to share with the auxiliary batteries,as they are low too. I doubt it could keep cycling for the time it takes to fully charge the batteries with out over heating. Is this normal? Thanks

irvingj 06-01-2019 10:09 AM

Re: Agile battery separator
Not sure about your Agile, but we had a T@B camper for a few years... when the (only) battery was discharged heavily, the charging system --which went through the inverter-- would click & squeal for quite a while after it was plugged in to 120V. It would seem that charging a heavily-depleted battery through the inverter is not very efficient. But of course, it didn't have a starting battery.... which should in any case be separated from the coach batteries.

Sounds similar... perhaps the separator relay isn't operating correctly? By any chance, were the house batteries left ON while the vehicle was sitting? If that switch is left in the ON position, there are all kinds of parasitic drains that come into play, but I think that should have left your starting battery alone if the separator was working properly. It does sound as though, when you connected a charger under the hood, it was trying to charge both the starting battery and the coach batteries. Not sure how --or if-- the inverter could have become involved, however....

I don't know if yours is equipped with some sort of "sharing" ability; our 2015 is not, though I've read about some systems that can --when commanded to do so-- access the coach batteries to "jump" the starting battery.

Sorry to not be very helpful -- I'm just thinking aloud here -- please do let us know what you find out! Curiouser and curiouser....

autostaretx 06-01-2019 05:09 PM

Re: Agile battery separator
It sure sounds like you have a voltage-sensitive relay (VSR) between your Sprinter's native electrical system and the house batteries.

Such VSR beasties watch for the alternator to be running by sensing over 13 volts appearing on the Sprinter side.
When they see it, they "join" the batteries.
Your charger is lifting the Sprinter battery above 13v (more like 14.2).
In your case, the "join" may be dragging your charger down enough that it drops below the VSR's trigger voltage, so it disconnects.
Removing the "house load" allows the charger to rise above 13v, and the cycle repeats.

One would think/hope there was a manual beefy switch somewhere between the banks to avoid this.

--dick (you're seeing one of the reasons i prefer tapping the Sprinter's "alternator running!" signal instead of "relying" on a VSR)

BobLLL 06-01-2019 07:37 PM

Re: Agile battery separator
There isn't a manual disconnect, but you can easily disconnect the ground wire from the separator to stop the cycling. It's the small black wire on the separator. Once the starting battery is fully charged, connect your charger to the coach batteries before reconnecting the separator. You will probably find the coach batteries are extremely low. Once they are charged up, reconnect the separator.

Inspector 06-01-2019 09:09 PM

Re: Agile battery separator
I charged the coach batteries last night as the 2-6v batteries read 5.86v each, how they ran down is a mystery as we don't have anything turned on, the disconnect switch was in the off position. Once they got close to a full charge, I transferred the charger to the starting battery connecting to the posts under the hood. No more separator on-off. Thanks for the tip on the ground wire, I'm making note of it.
Now I need to figure out what drained the starting battery as I don't think a 16 day rest should have taken such a toll. Next I will check the alternator charging voltage. THANKS everyone! I will post what I discover with the alternator.

BobLLL 06-01-2019 10:33 PM

Re: Agile battery separator
The Tripp Lite charger/inverter draws about 0.25 amp even with everything off. 0.25 amp times 24 hours is 6 amp-hours. 6 amp-hours times 16 days is 96 amp-hours. About half of the coach batteries capacity is used, more than half if they aren't in like new condition or weren't fully charged when you parked.

This cycling of the separator is typical for this particular setup, if the coach batteries are heavily discharged before you start the engine. As Autostarext suggested, the separator is quite sensitive to voltage changes. The wiring from starting battery/alternator to separator to coach batteries is a rather long run, because it runs along the firewall from the driver side over to the separator on the passenger side, then back to the driver side to the coach batteries. And it is only 6 gauge wire, so the voltage drop is fairly large. Even with your alternator putting out well over 13 volts under load, the voltage at the separator can drop under the 12.8 volt disconnect trigger for the separator. It has happened to me a couple times, when I accidentally left the refrigerator on 12 volts overnight while dry camping. If this happens while camping, just keep driving -- the brief charging cycles while the separator cycles will eventually charge the batteries enough so the voltage at the separator rises and it stops cycling, if it doesn't drive you crazy hearing that clicking in the meantime. The best solution is to find someplace to plug into shore power.

BobLLL 06-01-2019 11:31 PM

Re: Agile battery separator
The starting battery will also run down over time, but not as fast as the coach batteries, usually. So yeah, time for a check of battery and alternator health.

Inspector 06-02-2019 01:23 AM

Re: Agile battery separator
Autostarext, I now understand about the voltage sensitivities of the separator, it didn't have enough to keep it made in the closed position. BOBLLL the explanation of how Roadtrek wired the coach sure explains why the DC voltage drop is so critical. I measured the charging system at start up and idle, it was 11.8 v, went to 15 v then settled down at 14.5 v. This was over a 45 second time span.

So the disconnect switch above the door on the monitor panel still leaves the inverter drawing juice even when off?

BobLLL 06-02-2019 05:17 AM

Re: Agile battery separator
The Tripp Lite unit is wired directly to the battery. It does not go through the disconnect switch. It draws 0.25 amp just checking to see if you turn on the inverter switch, I guess.

Inspector 06-02-2019 05:58 AM

Re: Agile battery separator
Now I'm a tad confused, probably a bit dense as well. If I turn off the monitor panel switch, I hear a solenoid operate, so I guess the only job the switch does is disconnect the rest of the 12v from the batteries. The inverter supplies the 120v but has no 12v disconnect ahead of it?

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