Fight: Water Pump vs. Battery

[rallypanam]

Originally Posted by rob_gendreau

I tend to think it's the 12.9 that is is the mystery. In other words, it's not accurate. And in fact your battery is shot.

What happens if you go out, measure 12.9 v, and stick another load on it through say a cig lighter adapter? Does it drop right away as well?

As another example, will the fridge run on DC for any length of time?

Fridge doesn't seem to like running.

12.9 comes from xantrex and Blue Sky solar controller - they match.

[Gooseberry]

I had this happen and it was the ground wire on the pump. Yours might be the battery ground to the frame or on the battery.

[daveb]

Originally Posted by rallypanam

Fridge doesn't seem to like running.

12.9 comes from xantrex and Blue Sky solar controller - they match.

Yeah but a solar charge can mask a number of problems and why I asked if you ran the inverter pulling a reasonable load. That is a fairly good way to test the battery and battery connections but as mentioned, too much load can cause a poor connection to bond from the high amp flow.

The issue from how I see it may be localized to a connection at the main 12v fuse center or ground strip if the inverter seems to run OK. If not it may be a bad battery connection at either end of the main battery buss wires. You can't rule out a bad battery unless you load test it but I always do the easy stuff first before dropping anything. During the day I'd isolate the solar and load test it with the inverter. Check voltage at where the inverter connects to the main buss, usually rated terminal lugs close to the inverter. At least on my build, both 4/0 battery buss wires go directly to the rated lugs under the bench seat. There is a ground strip that bolts to the chassis and a smaller 2 str wire running to where the 4/0 battery neutral terminates. One of the smaller hot wires runs from the positive lug where the 4/0 terminates (and inverter connects) to the fuse block and another goes to the separator.

With no charge and no load, if you see the battery drop below 12.4 or 12.6 overnight, the battery might be on it's way out. With no load or charge you should see 12.8 for several days. Then it would be time to drop it, charge it to full and do a real load test. There is always a possibility of a light short... probably the worst thing to track down. That's where a good amp meter really shines.

One other thing to mention is if you have more than one house battery in the loop and one is bad. The bad one will quickly pull the good one down.

BTW the Raiders won.

[rallypanam]

Originally Posted by daveb

Yeah but a solar charge can mask a number of problems and why I asked if you ran the inverter pulling a reasonable load. That is a fairly good way to test the battery and battery connections but as mentioned, too much load can cause a poor connection to bond from the high amp flow.

The issue from how I see it may be localized to a connection at the main 12v fuse center or ground strip if the inverter seems to run OK. If not it may be a bad battery connection at either end of the main battery buss wires. You can't rule out a bad battery unless you load test it but I always do the easy stuff first before dropping anything. During the day I'd isolate the solar and load test it with the inverter. Check voltage at where the inverter connects to the main buss, usually rated terminal lugs close to the inverter. At least on my build, both 4/0 battery buss wires go directly to the rated lugs under the bench seat. There is a ground strip that bolts to the chassis and a smaller 2 str wire running to where the 4/0 battery neutral terminates. One of the smaller hot wires runs from the positive lug where the 4/0 terminates (and inverter connects) to the fuse block and another goes to the separator.

With no charge and no load, if you see the battery drop below 12.4 or 12.6 overnight, the battery might be on it's way out. With no load or charge you should see 12.8 for several days. Then it would be time to drop it, charge it to full and do a real load test. There is always a possibility of a light short... probably the worst thing to track down. That's where a good amp meter really shines.

One other thing to mention is if you have more than one house battery in the loop and one is bad. The bad one will quickly pull the good one down.

BTW the Raiders won.

Thanks.

Plan tonight is to pull the fuse on the solar (disconnecting it from the system) and charge the battery (I have only one 4D). Then Sunday check voltage on battery, look for loose connections, put a load on it, etc etc.

[BUFFALO]

Break it down into different things to test.
Charge the battery fully and load test it. Take it to a shop and have them use a real machine.
With the battery disconnected, check the wiring, with a meter. All the wiring from the battery to wherever it goes. Both positive and negative cables. Check for opens, short to grounds and shorts to positive. Wiggle the connections when you are there. Make sure there is no corrosion and they are not loose. Continue through the circuit wiring until you find something that isn't right.
Look at it as lots of simple things to check. Not a big or complex system.

[Scalf77]

It looks like you have a Xantrex battery Monitor, other then I think you say it reports SOC of 100% all of the time, and the voltage is 12.9, did you check amps, and amphours. I expect SOC is derived from the amount of charge that was put back into the battery, if it never leaves 100%, then it would not have measured any current leaving the battery, while your solar may get you to 100% during the day, I would expect some drop during the night, especially if your running your fridge. (this assumes your not plugged in), Also you reading of 12.9 is odd, in that I would expect that to be changing also, I expect you would see a higher value when the Van is running, or when the solar charger is in float, or absorption.
Happy debug

[rallypanam]

Originally Posted by Scalf77

It looks like you have a Xantrex battery Monitor, other then I think you say it reports SOC of 100% all of the time, and the voltage is 12.9, did you check amps, and amphours. I expect SOC is derived from the amount of charge that was put back into the battery, if it never leaves 100%, then it would not have measured any current leaving the battery, while your solar may get you to 100% during the day, I would expect some drop during the night, especially if your running your fridge. (this assumes your not plugged in), Also you reading of 12.9 is odd, in that I would expect that to be changing also, I expect you would see a higher value when the Van is running, or when the solar charger is in float, or absorption.
Happy debug

Yes, I have Xantrex. No, I have not yet figured out how it works. I do see higher than 12.9 when running, normal 14.1, 14.2, so that sounds normal.

I will charge battery and load test tomorrow (I have access to a SnapOn load tester), then poke around Sunday.

[rallypanam]

Hmm. Disconnected solar, threw battery on charger. Charger seems to think the battery is full.

While on charger, everything works perfectly (water pump, fridge, etc).

Nothing noticeably loose on battery/shunt/etc that I installed (most likely screw ups).

I'll leave it on charger and load test tomorrow, and go from there.

[rallypanam]

Left it on battery charger overnight.

Battery still won't run anything. I think it's just kicked. Shows 12.8, but as soon as any load is put on it drops to under 10.

But why? Once I get the new battery installed, I need to do some troubleshooting and see if I can find a drain.

[daveb]

There might not be any drain and to think it reads fully charged and a light load takes it down to 10 volts either means there is a battery connection problem or the battery is no good. When most AGM's die, if left idle left w/o load they slowly discharge over a few hours and why a light charge from solar can keep the battery monitor showing good voltage. A heavy load from a carbon pile type tester will usually instantly show the battery is bad. If there is a heavy draw or short and the battery was subjected to nightly discharges to below 10v daily for a long period, it could do what you're seeing. AGM's can go fast in that situation. Also when a batteries time is up, it's up. Some just fail for mechanical reasons, being overcharged or age.
What kind of battery tester do you have Robb? It should have shown the battery as bad when hooked to the terminals. As mentioned the only way to test it is to pull it out, charge it and test it on its own.
After you get a new battery (If it is bad) you can check for an amp draw with a clamp on amp meter. Disconnect and check each circuit. You can also pull all the fuses, check amp flow and reinstall each fuse checking flow on each install.
You should also pull that separator out of the loop, especially if it's a Surepower.