House Battery Problem

CDACamper · 02-18-2024, 03:06 PM

I have a 4D house battery (Centennial installed Jan. 2020) that has been very well cared for. It is kept at 100% state of charge for storage and never drained below 60%. We are not heavy battery users and the battery didn't show any signs of being in decline. The van is in my shop during winter and I drive it for 30 minutes every 3 weeks or so. I have a charge wizard and plug the van in when the house battery monitor drops to around 12.6. I leave it plugged in for a couple of days and then unplug the van until the voltage drops again (it gets plugged in about once a month during winter).

Today I went to check the battery voltage and the voltage was at 0.1 volts. My eyes almost popped out of my head. I have never seen a battery get that dead. So now I am wondering if the battery just suddenly failed or if I have a draw from something. I have a battery monitor with a shunt on the negative. All loads that I am aware of go through the shunt.

I need to determine the cause of the issue. Is it possible that an otherwise healthy battery just suddenly died? Nothing has changed over the past few months with the van and it is in its winter storage mode (so not getting used other than a 30 minute drive here and there). Nothing was turned on that I could find. I wish there was because I would know the cause if the issue.

I have the battery plugged in now and it's charging. Is there any possibility of saving the battery after being drained so low?

Any suggestions on how to approach troubleshooting the issue?
W

1der · 02-18-2024, 03:23 PM

are you measuring voltage right at the battery terminals ?

CDACamper · 02-18-2024, 03:54 PM

No. The battery is under the van so I would need to drop it. I figured step 1 was attempting to charge it.

1der · 02-18-2024, 05:44 PM

Under the side step or behind the axle ?

High probability a connection has failed/ come loose. A battery with a TRUE reading of 0.1VDC is not going to charge or hold a charge.

You may "resurrect" the voltage but what you have really done is pumped enough current through the bad connection to overcome the resistance..... for a bit. The resistance problem will return.
I would check the connections prior to applying a charge.

Start, with a meter, checking the connections you can get to. If you have an inverter, check the connections there. If your inverter reads 12 vdc then you have a problem up stream, so work your way up to the volt meter. If 0.1 at the inverter then you are headed towards the battery. First check would be the grounds except normally that should be running to the shunt for the meter.

kbeefy · 02-18-2024, 06:00 PM

If it truly is 0.1v then it will never fully recover. You can get some charge back into it if it's not too badly sulfated or shorted internally.

Before worrying about that I would get an actual reading at the battery terminals. That will tell you if you need to fix a draw and battery issue, or fix something on the load side of everything.

CDACamper · 02-20-2024, 11:55 AM

1der, the battery is under the barn doors not behind the axle.

Well the battery took a charge and seems normal again. I was getting some odd voltage readings from my battery monitor where it would fluctuate up and down without any load so I am suspecting I have a bad battery monitor, a bad ground or a combination of both. After charging the battery, I am getting a little over 13 volts (measure by volt meter and battery monitor) after letting the battery rest overnight, so it is holding a charge. I also switched on lights and the voltage didn't dip drastically. I haven't load tested it yet.

Question: I currently have the negative ground going from the house battery to the ground shunt. Then from the shunt to the wheel well for the rear tire (grounding to the body (this is where Sportsmobile put the ground originally). The connection looks clean but I imagine that it's not an ideal location. I would rather not run the ground back down through the floor to the frame, but can if that would be advisable. Is there a better place for the main ground inside the van other than the wheel well? I have an e350 EB50.
I know there is a ground strap from the frame to body near my house battery that is the original. I now plan to replace it with a new strap and clean connection surfaces.

1der · 02-20-2024, 12:15 PM

Quote:

Originally Posted by CDACamper

1der, the battery is under the barn doors not behind the axle.

Well the battery took a charge and seems normal again. I was getting some odd voltage readings from my battery monitor where it would fluctuate up and down without any load so I am suspecting I have a bad battery monitor, a bad ground or a combination of both. After charging the battery, I am getting a little over 13 volts (measure by volt meter and battery monitor) after letting the battery rest overnight, so it is holding a charge. I also switched on lights and the voltage didn't dip drastically. I haven't load tested it yet.

Question: I currently have the negative ground going from the house battery to the ground shunt. Then from the shunt to the wheel well for the rear tire (grounding to the body (this is where Sportsmobile put the ground originally). The connection looks clean but I imagine that it's not an ideal location. I would rather not run the ground back down through the floor to the frame, but can if that would be advisable. Is there a better place for the main ground inside the van other than the wheel well? I have an e350 EB50.
I know there is a ground strap from the frame to body near my house battery that is the original. I now plan to replace it with a new strap and clean connection surfaces.

Good, seems like a a non-battery issue then and more in the connection/monitor area.

Battery Ground goes directly to one side of the shunt, that is correct, it is the only connection on that side of the shunt. Other terminal of shunt goes to a ground which, yes, SMB loves to use a bolt through the wheel well to ground to the body. As you saw, there are various ground connections from the body to the frame under the van to connect frame to body for ground continuity. Replacing a worn strap is a good idea but likely not the cause of the bad reading.

It would be better to also run a dedicated ground for the load side of the shunt to a bus bar that receives other ground connections from your loads. The battery monitor should have a direct connection to the shunt, correct?

You might be able to reach up and check the terminal connections on the battery to see if they are loose. You could also have a bad positive connection along the circuit.

CDACamper · 02-20-2024, 01:00 PM

1der, yes, the battery is connected to the battery neg. side of the shunt. Here is a diagram and picture of what I have.

Do you recommend a better location to ground a buss bar that is inside the van (under the seat area? Would one of the bolts that bolt down the goucho seat be better?

Scalf77 · 02-20-2024, 02:48 PM

The other question is where do you get the voltage for the reading for the battery monitor. Not a huge fan of the wheel well connection, but it works. Looks like possibly the monitor has a 3 wire power connection Common ground, Positive to power the monitor, and a positive to read the battery voltage.

CDACamper · 02-20-2024, 08:44 PM

Question. The diagram I posted shows the load side of the shunt is attached to the load negative and I also have this side grounded to the chassis. Is this not wired correctly? Does the battery not need a chassis ground when using the shunt? If I do this it would mean if there are any loads grounded to the chassis it would not work correct? So to be safe I should add another ground wire directly from battery negative post to the frame as a backup?