Magnum charger over charging?

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SargeW

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I am out on a short 5 day trip, and stayed at a KOA for 2 days plugged in to 50 amp. No issues noted. While leaving this morning when I turned the key to retract the slides, I noted a yellow "MIL" light on the dash. Rig started and ran fine, no issues besides the MIL light.

Got to the next campground in AZ about 3 hours later and plugged in to 50 amp. After setting up I opened the VMSpc and checked the diagnostic history. The trouble code that was saved looked very familiar. 1081 31 Unknown Issue. I used to get that code all the time before I put the Amp-L-Start in the battery bay. It was due to the low voltage in the chassis batteries from the charging algorithm Spyder uses to charge the chassis batteries.

I looked at the Magnum remote above the seat and the State of Charge (SOC) of the house bank was 100%. Checking the status of the house and chassis batteries, the house bank showed charging at 14.8 volts, and the chassis was sitting at 13.8 volts.

Going to the house bank and checking the status of the Amp-L-Start mounted on the wall, two of the red LED's were blinking indicating "high voltage" from the house bank. Getting close to them I could hear the house batteries charging by the electrolyte bubbling rapidly.

Checking my Coach Proxy on my phone, the house bank still showed at 14.8 volts. I came in and checked and the Magnum remote was still showing 100% SOC. I pushed the "Charger" button on the Remote Panel, putting the charger in standby mode. Almost immediately the voltage on the house bank began to decrease. That was about 30-45 minutes ago, and the house bank is showing 12.6 volts and the chassis is at 12.9. When I went back to check the Amp-L-Start, the blinking red LED's were off, and the green "maintainer" LED was lit.

While outside I checked the network cables to the BMK and shunt, and all are tight and secure. Unplugging the network cable caused the LED on the BMK to start to blink. Reinserting the network cable caused it to glow solid.

I am at a loss to figure out why the Magnum was pushing so much voltage to the house bank. I recently watered and cleaned the battery connections before I went on a 4 day trip to Quartzsite dry camping. All batteries and systems worked normally. I checked the settings on the Magnum, and all seem to be set up normally.

Any guesses on where to look or what to try? I scanned the BMK manual, but saw nothing indicating what might cause that issue.
 

Gary RV_Wizard

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A high charge rate & high voltage usually means a battery has a shorted cell. The charger is valiantly trying to get the battery bank up to float state but the shorted cell keeps sucking the amp. That can fool the charging algorithm. Most newer chargers put a time limit on bulk or absorption charging as a way to stop "boiling" the batteries under these circumstances.
 

SargeW

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Thanks Gary, that helps a lot. I will check the cells with a hydrometer to see if I have a bad cell. If so I would say that 6 new batteries are in my future...
 

Gizmo100

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SargeW said:
Thanks Gary, that helps a lot. I will check the cells with a hydrometer to see if I have a bad cell. If so I would say that 6 new batteries are in my future...

If you find a bad cell you should be able to disconnect 2 of the 6 volt out of the setup. That will buy you some time until you can replace all the batteries. Of course you won't have as much amp hours to draw on but it will keep things running.
 

Mark_K5LXP

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Having cells gas at 14.8V is perfectly normal, they should be gassing a bit at that voltage.  Elevated voltage is standard protocol for periodic equalization and the Trojan equalization profile is 16.2V for 2-4 hours, so yours at 14.8V it's closer to a "strong" absorb voltage than equalize.  The $64K question is whether the charger is operating correctly and what mode it's in (14.8V may be "normal" absorb for this charger?), or if you have a battery starting to go south.  SG will be one indicator, if there's a bad cell or generally crappy battery and the charger is trying to bring it up the bad cell or battery will likely be getting warmer than the rest.  A capacity test will also reveal any one of the set that's starting to have issues.

Mark B.
Albuquerque, NM
 

SargeW

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Yeah, the big question in my mind was why it was charging at such a high voltage when the SOC of the bank was at 100%. I would expect the voltage at that point to be just at a "maintainer" level.

And when I went out to see if the Amp-L-Start was working, it was in by pass mode because of the high voltage in the house bank.

I checked the whole bank today with a hydrometer and all cells were perfect. And then I pulled the cables off and checked each battery one at a time for resting voltage. They were all perfect as well. The mystery continues...
 

Gary RV_Wizard

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I think most all the Magnum brand chargers use the same algorithm, but what series/model is it? I'm assuming that 14.8v is either bulk or absorption mode charging - float should be somewhere in the 13.3-13.6v range.
 

larryr

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I have a magnum MS2012 (or MS 2000)? I use the easy to program ME RC remote control. This makes it easy to set voltages and time for each stage of charging. Also sets a variable low voltage cut off to limit heavy discharging.
 

Lou Schneider

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The current coming out of the Magnum has to drop to a certain level (should be in the manual) before the charger will drop out of Bulk charging mode, i.e. dial back from 14.8 volts to the float voltage. This includes house loads - have you added anything that would place a parasitic load on the charger? If not, a battery cell that's going bad by continuing to draw current but not yet completely shorted is a possibility.
 

Henry J Fate

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There are several possibilities. If possible, connect the Magnum to a 12 volt battery about 80-85% charged and known to be good. Disconnect all other batteries and loads. This will provide real data of the charging personality. Once the charge personality is confirmed to be as it should, connect pairs of the 6 volt house batteries to confirm they are charging properly. I think you indicated you have 6 batteries and I assume in 3 sets each set in series. Apply the first set and if ok apply the 2nd set then the 3rd. This will indicate whether the house batteries are ok. If all that checks out, probably something in your power grid causing the problem. All batteries applied in the test should be about 80-85% charge state.

You could also disconnect a set one at a time to see if the problem goes away.
 
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