Forum Discussion

bronccat's avatar
bronccat
Explorer
Feb 05, 2016

Inverter / Charger Settings when Batteries Removed..

Coach has an Magnum ME2012, 4 6V Interstate U2200 House and 2 Workaholic Chassis batteries

I have the house batteries and one of the chassis batteries out because I am working on the tray (what a mess). I am hooked to 50 amp Shore power. I turned the charger to standby on the magnum remote since the batteries were disconnected. (Both battery disconnects are open to avoid a short)

I then noticed the the next night that the lights were dim. Remote was reading "charger standby 10.3v 26 amps" with charger off, inverter on and no batteries connected (WHAT was it reading??)

I hit the "charger on" button today and the heater fan sped up and the lights brightened.

Remote was then reading "absorb charging 15.0v 43a" inverter on (still no batteries connected)

So I assume the charger should be on even with batteries disconnected?

I assume the inverter should be off?

Second question:
How do I determine the total amp hours for the charge setting? I have 4 6v batteries that say:
"RC@75amp-122"
"20 amp hour rating-232"

Right now it's set at 400.

Third Question:

I opened the battery compartment door the other day and the batteries were all overflowing. Haven't seen that since we got the coach in November.

I checked the electrolyte (about 1/4" over the plates), checked with hydrometer (all good). There was some corrosion in the tray which I was told during the checkout was due to off-gassing, but once I got the batteries out it was clear there was a lot of liquid escaping historically. Once I got the mat out of the bottom of the tray, there was a ton of corrosion and liquid under there. I have added mineral oil for the time being, but don't know if there is another issue.

Thanks for your help. Just bought this coach in November and a lot to learn.
  • Reply from Magnum in response to basically this post (read from bottom to top)

    Mary:

    Yes that is correct.

    In all reality, your inverter shouldn't even be showing you power on the remote display, nor passing thru; you are experiencing that phenomenon I mentioned earlier.

    Me:

    I am still confused as to why everything seems normal with the charger on and starved without it. But you are saying turn it all off and bypass if possible. And by bypass you mean remove the AC in from the inverter.

    Mary:

    > As I mentioned, the inverter really shouldn't even be passing thru
    > with the batteries disconnected. It would be best to bypass the
    > inverter altogether if you're wanting to power your loads from shore power.
    >
    Me:

    > Thanks. I have the battery switch off if that metters. Why do you
    > think I am low on power with the charger off?

    Mary:
    >
    >> You will want to turn it to charger standby to help prevent excessive
    >> voltage from accidentally reaching those DC terminals.

    Me:
    Thanks.

    >> Should the charger be on or on standby? As noted below everything is
    >> very dim on standby which I don't understand.

    Mary:

    >> Leaving the shore power connected to the inverter and leaving it
    >> energized can leave you open for the possibility of energizing the DC
    >> terminals accidentally. This isn't too much of an issue as long as
    >> nothing is near those terminals and they aren't accessible for
    >> something to accidentally touch. Another phenomenon that I've seen is
    >> that the inverter will sometimes still allow for Shore power to pass
    >> thru in this situation, and an end user has come to expect that
    >> phenomenon... however, the inverter was designed to shut down and not
    >> allow for pass thru at all in the event batteries are disconnected.
    >>
    >> In short, no, you won't damage the inverter leaving it the way it is,
    >> but there's also not much point in doing so either.

    Me:

    >> Thanks Mary.
    >>
    >> Will it hurt anything to leave it connected and the inverter turned off?
    >> This is a short term problem, hope to have the batteries back in next week.
    >>
    >> Should I have the charger on standby or "on". The lights were really
    >> dim when it was on standby. Thanks again!

    Mary:

    >> Dear Shaun,
    >>
    >> If you still had shore power connected when you disconnected the
    >> batteries, you can still keep the internal circuitry powered in the
    >> inverter and it will read on the remote what it thinks it should be
    >> doing. The capacitors still have a charge in them, so the inverter
    >> thinks this is the battery voltage. In short, you're getting
    >> erroneous readings and it would be recommended to disconnect your AC
    >> input going to the inverter if you're going to disconnect the batteries.
    >>
    >> As for you battery size, with 4x6V batteries (assuming you've wired
    >> them into 12V), you would have 2 paralleled strings of batteries. To
    >> figure out your Amp-Hour capacity, you take the 20-hour rating and
    >> multiply that number by the amount of paralleled strings you have. So
    >> in your case, 232 x
    >> 2 - 464. Having your AH set to 400 is close enough and I would say is
    >> set properly.
  • The coach is plugged in because I work in there part of the time. I never imagined that removing the batteries would render the coach useless since I have battery disconnects and can turn off the inverter / charger.

    It's going to be a process to replace the tray hence why this matters so me. Between the weather and repairs it'll take a few weeks.
  • When our batteries did that (hot and boiling)on the road this past summer, it was because the the batteries had went south. The charger was fine, so a trip to the nearest Sam's Club and problem solved.
  • I agree..unplug the coach while doing that sort of maintenance. That said, from your description, it appears your charger is overcharging the batteries or maybe it keeps charging after they are fully charged. That is what is causing them to "boil" over. I would check your charging system to ensure it's working properly otherwise you will eventually destroy the batteries.....Dennis
  • When I had to change out the house batteries, everything was off and I was NOT plugged in to show power. To me that seemed like the only safe way to do the swap. I cannot think of any reason that I would have needed to be plugged in during the job...
  • Thanks. I looked through that last night and didn't find what I was looking for.

    I am receiving answers from Magnum, will post shortly.
  • http://www.allbatterysalesandservice.com/graphics/ME-Series-Owners-Manual.pdf

    Here is a manual

    Some one will jump in shortly who has your unit. My system if battery are remove then I turn off the unit.