Unpleasant surprise

Stopped the boat after Thanksgiving weekend and no lights. Checked my battery monitor and only 1 red light. Checked the inverter and monitor states absorb charging no amperage. So I kicked on my backup 50amp Lamarche charger and the monitor shows positive 35amps. Magnum inverter still shows absorb charging no amperage. I check the inverter output and no current. So I kick the breaker off to the inverter and back on. Inverter monitor goes through, dead battery, bulk charging no amperage to absorb charging no amperage. What next, down in the engine room to turn the battery switch on an off to the inverter and check out put breakers. The Guest battery switch is stiff and possibly welded internally, after substantial force I get the knob to turn but I think the shaft may have broken in the switch. The breakers are not tripped. After three days of charging with the Lamarche 50 amp charger and the battery monitor indicates 3 and sometimes four lights. Still the inverter indicates absorb charging no amperage. Down in the engine room with a hydrometer, all four 8d house batteries show very low readings, basicly all have failed. The battery boxes and the tops of the batteries have water on them and in the bottom of the boxes. We apparently had a power failure during the 24 deg cold snap that lasted six hours or so. As a side note the two 8D start batteries that were installed at the the same time check out fine with the hydrometer and were able to start both engines in the cold weather with no problem. They are not ghost charged with the house bank. Is it likely that the Magnum inverter went crazy after the power outage and cooked the house bank. All the batteries are five years old and the same brand. All the cables were replaced and still in excellent condition. The Magnum inverter is capable of 125 amps during bulk charging. Any Ideas ?

was any cell dry?

Unlikely the batts froze, down in the ER near the water was probably warmer than air temp..


Most likely one failure drained all batts dead if they are in parallel.

If the inverter was on when a shore side power failed and there was a load then placed on the inverter which drew the batteries down. This is why I always turn the inverter off when on shore power. I suggest if shore power in back on that you move the battery switch to "all" to permit the start batteries to bring up the house batteries and the charger add to the charge. If this works then you can move the battery switch back to where you usually keep it. The Inverter you have has an optional control panel and if you do not have it I suggest you install one.

Sounds like a bad cell in the bank. You can set the inverter to cut off at any selected voltage, no need to turn it off, especially if it is powering something like a refridgerator.
Something like an ACR is a better idea than using a battery switch IMO, though typically for charging a start bank from an inverter bank or alternator.

I have the remote control panel, It refuses to turn the charger on or off. The inverter switch seems to work indicates that the inverter section is on, just no power. After three days of charging with my back up 50 amp charger, three of the four 8d's show failed specific gravity tests. The fourth 8d is marginal on a couple of cells and fails on the others. The battery switch to the inverter may have failed as well. it looks to me as though something caused all of the batteries to fail at once and possibly the switch. When I left nothing was on except the refer and engine room lights. The refer seems to have stayed cold. The refer runs on the inverter or shore power. It will normally run for several days on the inverter and battery bank. All of the dc systems seem to be working on the battery charger and whats left of the battery bank.I'm going to take the battery switch apart and check it out next and call Magnum to see if it's possible to run tests on the inverter.

Oh my, it does sound like a bigger problem then just inverter pulling the batteries down. Best wishes on the fix.

Magnum is usually quick to respond, this is a good test. BTW, do I understand correctly that 8Ds are the house bank? Are they optimum for a house bank?

Are they in parallel????

Steve, ceck and make sure that the switch between the batteries and the inverter/charger is not open or have a very high resistance.

The reason I say that is because without a battery bank connected to the inverter it coud do many of the things you derscribed.

Your house batteries might be toast. Hygromoters are pretty good, but I'd actually try them out under load berfore I got inclined to bulk replace them.

I have a 2000W Magnum Inverter/Charger with the remote control. Recently, after installing our new carbon foam Oasis batteries the remote said it was bulk charging, but no amps were being sent to the batts. Couldn't quite figure it out until I remembered that I had remotely put the charger on "stand by" before turning the unit off. Taking it out of stand by mode on the remote panel, it started bulk charging like normal...

I have a napa load tester

ksanders said:

Steve, ceck and make sure that the switch between the batteries and the inverter/charger is not open or have a very high resistance.

The reason I say that is because without a battery bank connected to the inverter it coud do many of the things you derscribed.

Your house batteries might be toast. Hygromoters are pretty good, but I'd actually try them out under load berfore I got inclined to bulk replace them.

Click to expand...

One of the first checks will be the battery switch, It feels broken when I turn it. No detent or resistance. it felt as though I broke it when I operated it checking turning battery power off to the magnum. Do you think my Napa battery load tester will handle an 8D battery?

I'll check this option out.

Moonfish said:

I have a 2000W Magnum Inverter/Charger with the remote control. Recently, after installing our new carbon foam Oasis batteries the remote said it was bulk charging, but no amps were being sent to the batts. Couldn't quite figure it out until I remembered that I had remotely put the charger on "stand by" before turning the unit off. Taking it out of stand by mode on the remote panel, it started bulk charging like normal...

Click to expand...

. I've been busy working on every one else's stuff lately that I haven't been able to jump on this, maybe tomorrow. I can't seem to control the charger as to off or on with remote control panel, Is this what you mean by standby or is there something more?. The Magnum is so intuitive and reliable I haven't had to learn all of the features.

I have 8D's; AGM type in my boat. NAPA load tester worked fine.

Thanks I'll follow up solution
If I find out what happened

The problem maybe solved

The guest 2102 battery switch between the inverter and battery bank was melted. After replacing the switch with a Blue Seas 3001 heavy duty switch the inverter seems to be working as well as the battery charging portion. I'm not sure as to why the Guest battery switch would fail. Possibly corrosion although the terminals appear fine. I had the inverter installed 6 years ago when I bought the boat. Replaced the original inverter which failed soon after I bought the boat. This switch was probably installed with the old inverter.

When the boat was built, thermal protection was not required within the first three ft of the the positive cable from the battery bank to the switch. Not required on the starting bank now. After looking at this switch I'm lucky to have a boat. Thermal protection on the house bank is my next project. My battery bank consists of 4 8D wet cells and the inverter is a 2000 watt, 125 amp Magnum. It's been a couple of months at the dock with my old LaMarche 50 amp charger maintaining the battery bank after the switch failed. My battery monitor indicates the battery condition to be normal, tomorrow I'll check with a hydrometer tomorrow. Maybe I dodged the bullet all around.

Guest 2102 - Continuous Amps: 230 Momentary Amps: 345


Should have handled the inverter even on max but pretty close...any other loads through the switch? Any signs of corrosion? (but the real question is what did the switch look like inside the housing?)


Maybe just a bad switch...over the years the Guest bottom line switches haven't given me a lot of confidence for as many bad ones I have replaced.

No other loads

psneeld said:

Guest 2102 - Continuous Amps: 230 Momentary Amps: 345


Should have handled the inverter even on max but pretty close...any other loads through the switch? Any signs of corrosion? (but the real question is what did the switch look like inside the housing?)


Maybe just a bad switch...over the years the Guest bottom line switches haven't given me a lot of confidence for as many bad ones I have replaced.

Click to expand...

Your not the first one to say this. I'm going to open it up this morning and see. The switch is probably 15 years old.

That is "scary".

High resistance in a device can cause overheat/fire even if amp draw is within spec. A condition like that is hard to protect against. A fuse would not help.

I set up my rig with all Blue Seas batt switches. My gut feel is that the quality is good, but really don't have anything to back that up.

Had to break it apart

The contacts are clean but the housing got hot enough to allow one of the posts and contacts to actually melt through the housing and move sideways 3/4 of an inch. Hard to tell what could have caused this. At this point I'm going to go back and see if something could have shorted out , something on one side of the switch or the other must have drawn a lot of current. There has to be a certain level of safety built into these switches. This wasn't just a couple of amps over the rating. I don't think the inverter has the ability to produce that much energy to melt the switch, No big smoke coming out of the inverter either. I'll have to see what Magnum says.

Scary said:

The contacts are clean but the housing got hot enough to allow one of the posts and contacts to actually melt through the housing and move sideways 3/4 of an inch. Hard to tell what could have caused this. At this point I'm going to go back and see if something could have shorted out , something on one side of the switch or the other must have drawn a lot of current.

Click to expand...

Scary...
See Steven Cyr's write up on batt'y sw problems - any chance this was a loose - hi res connection causing hi amp draw?

Don't want to insult your intelligence...but having a stainless washer or lock washer between the terminal end and the contact in the switch is also a no no.

A lot of stainless I guess has a very low conductivity rating compared to direct contact or brass/tinned stuff.

A poor post connection on the switch when your drawing high amps, that resistance will definitely heat it up a lot, enough to melt some plastics.
I have a new blue seas and an old switch made of bakelite which does not melt. That old switch is 45 years old, and still is fine. Done it's job from 1970. The old switch is twice the size of the new one.

A washer ought to be next to the nut. SS does have a higher resistance.

I would suspect the cable crimp, the switch lug will pass heat easily.

Blue seas

low voltage high amperage

After talking to Magnum techs, it's likely the extremely low voltage condition of my battery bank and the high amperage needs of the inverter may have started the melt down of the switch. An interesting thought that I intuitively would not have thought of.
The magnum inverter stops inverting at 10 volts, the amperage draw of the inverter at that voltage would have been over 200 amps. this would be close to the switch's rated capacity. Other factors like resistance in the cable from the switch to the inverter and the switch heating up may have increased the load as well.
After checking my batteries with a hydrometer they check just ok. they are five years old and a couple have cells that are marginal, the other four are in good shape. So I guess I'll get by with these for a while.
As to Thermal protection between the battery banks and the switch's there was none. I'm adding a 400 amp in line fuse as soon as it gets delivered.

A lot of stainless I guess has a very low conductivity rating compared to direct contact or brass/tinned stuff.

Its Called AMPACITY

Ampacity is a portmanteau for ampere capacity defined by National Electrical Safety Codes, in some North American countries. Ampacity is defined as the maximum amount of electric current a conductor or device can carry before sustaining immediate or progressive deterioration.
Ampacity - Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/AmpacityWikipedia

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Many boat hassles can be found with a digital thermometer .