House Battery Blues?

[boywonder]

Originally Posted by daveb

My thoughts still point to a dry cell but a combination of problems may have led to it's death.
Hard to tell w/o actually being there.

The OP has gone through 3 batteries.......may be pointing to a van problem.......I'm thinking chronic undercharging...

Mountainbikeroamer: Dave has some solid advice above, convince yourself the battery is good (or not...) then focus on why you may be killing batteries.

What is the voltage at the house battery with the van running and the motor revv'd?

[boywonder]

Originally Posted by MountainBikeRoamer

***directly testing the current across the terminals of the battery itself.*** Both numbers were very close....12.5 volts.

...that would be voltage.......

measure the voltage across the house battery with the engine revved up a bit.

Consider replacing your isolator with a Blue Sea Separator....won't suffer from the .7V diode drop and these don't have coils to heat up and burn power.


I used this one....basic...actually came with a manual switch as well...called an "add-a-battery" kit



The ML-ACR style ones are really popular here...they have a number of nice features/functions but are about twice the $$ as the one above

[MountainBikeRoamer]

Originally Posted by boywonder

What is the voltage at the house battery with the van running and the motor revv'd?

I'll answer you with two (or rather four) voltages:

1) When I *began to charge* the battery, it showed the following:
- At the battery terminals with electrician's voltmeter: 14.39v
- As read by the cheapo wall-socket house battery meter: 14.3v

2) *After 30 minutes of charging* (via the van's alternator), it showed:
- At the battery terminals with electrician's voltmeter: 13.85v
- As read by the cheapo wall-socket meter: 14.0v

Of note, however: at no point was I "revving" the engine beyond its normal idle.

Up next:
I'm planning to go and check voltage again via both methods in 30 minutes.....and then again in an hour.

Definitely planning to also charge the battery up, isolate it completely from the van's electrical circuits (unplug it), and then do some testing of the battery in a situation where (as you guys have mentioned) there's *only the battery* being studied.

Heading to Harbor Freight now to pick up a battery load tester.

[Gooseberry]

One question for you on this and that is have you checked the ground to the chassis on the house battery? I had that issue last spring while camping and when I checked the ground to the chassis it fixed it.


My issue was the battery getting a what looked like a voltage charge but no current and why I shut off the motor and turned on a light or the fridge it would drop to 11.2 from 12.7 and then not recover.

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[MountainBikeRoamer]

OK --- updates:

After the last posting --- when the battery appeared to be charged (following 30 minutes of idling van to recharge battery), I let it sit for a while and then checked the voltages twice over the next hour. (I left the house battery plugged in for this period of time, by the way.)

After 30 minutes, I read the following voltages:
- Electrician Voltmeter at terminals:12.69v
- Plug-in wall socket voltmeter: 12.8v

After 1 hour, these were the readings:
- Electrician Voltmeter at terminals: 12.66v
- Plug-in wall socket voltmeter: 12.8v

Not much change.

Next (I know I'm jumping around a bit here, but bear with me) -- I plugged in the "Battery Load Tester" that I picked up at Harbor Freight and proceeded to do three separate 5-10 second long "load tests" on the battery.

It's ridiculously simple, just a high-load heat resistor (to create the battery "load" on demand) and a reasonably precise analog needle-gauge meter. Powers itself via the 12-volt battery itself.



Here's the voltage reading it displays prior to testing, appears to be around 12.7volts, pretty much on par with what the precision electrician's test meter indicated as well:




And then here's what the gauge shows *during the 5-10 second load test*.



Did not notice anything hugely out of whack by the needle measurements, although since this is indeed a 1000 CCA battery, I'm reading the needle as being *right on the edge* of the "weak" zone when under load. No idea if this is normal to be that close to the yellow zone.

I did note:
After three of these 5-10 second "load tests" (each spaced about 5 minutes apart), the overall battery voltage had dropped to around 12.45volts...but then over the ten minutes or so it rebounded to about 12.55volts.

Anyway --- I've absolutely absorbed what you guys have mentioned today to do....in order to properly test the battery out. (Especially daveb!)

So....here's what's next:
Charged the battery back up fully using a 10amp bench charger.




And.....gonna let her sit (unplugged) for 24 hours.
Further load testing to commence then.
(As well as (firstly) the overdue "visual inspection" of the individual wet cells as you guys have insisted is necessary. I've also got a battery hydrometer on the way from Amazon...should be here by Tuesday.)

Thanks again tons guys --- hoping something becomes obvious that points to this indeed being a quirk with the battery (or, second best, the charging circuit), and not an endemic short or parasitic drain somewhere in the van itself.

[MountainBikeRoamer]

Originally Posted by Gooseberry

One question for you on this and that is have you checked the ground to the chassis on the house battery? I had that issue last spring while camping and when I checked the ground to the chassis it fixed it.

My issue was the battery getting a what looked like a voltage charge but no current and why I shut off the motor and turned on a light or the fridge it would drop to 11.2 from 12.7 and then not recover.

Thanks.....interesting you ask this ---

There are indeed *two separate wires* that hook up to the negative terminal on my house battery (the heavy-duty black one that runs to the fuse block (LATER EDIT/CORRECTION: this was incorrect, it is actually a ground wire directly connected to the chassis.), and a skinny, light-duty green one that runs off......under the carpet.....and......somewhere? Is that the chassis ground?)

I've run (and camped with) the van successfully over the last 2 years both *with* and *without* the green wire hooked up to the house battery (not on purpose, I think I accidentally unhooked the skinny green wire for six months....)....and it seems to charge (and hold a charge) identically well in both instances. No problems until recently.

How did you diagnose your chassis ground issue? And did you run a completely new wire to remedy the situation?

For what it's worth --- my battery truly *does* charge up successfully. (At least as measured, at the terminals, by the "resting voltage" it reaches once charged, around 12.7 volts.)

[boywonder]

how do you know when your battery is fully charged?

It's probably a good idea to leave the battery on the charger all night at "trickle charge" setting. Since that appears to be a dumb charger be careful not to overcharge on the other settings....

Have you checked the water level in all of the cells?

Also, if you know how to use your Craftsman multimeter in current mode you can easily check for parasitic draw from the house battery once you reconnect it. Use the 10A DC setting on the meter, and don't turn on any big loads. The meter has to be inline with either cable..ie remove a battery cable and use the meter leads to complete the connection. Plug the positive lead into the 10A socket in the meter.

[MountainBikeRoamer]

Originally Posted by boywonder

how do you know when your battery is fully charged?

It's probably a good idea to leave the battery on the charger all night at "trickle charge" setting. Since that appears to be a dumb charger be careful not to overcharge on the other settings....

Have you checked the water level in all of the cells?

Also, if you know how to use your Craftsman multimeter in current mode you can easily check for parasitic draw from the house battery once you reconnect it. Use the 10A DC setting on the meter, and don't turn on any big loads. The meter has to be inline with either cable..ie remove a battery cable and use the meter leads to complete the connection. Plug the positive lead into the 10A socket in the meter.

Super/Thanks .

My (retired engineer) Dad just suggested the same thing about checking parasitic current draw with the meter placed in series with the house battery. Great methodology to all of this! Love that these things can be sleuthed with reasonably simple equipment.

Good question you are asking about me knowing the battery is charged, by the way. In summary: I guess I don't truly know? This is a "semi-smart" battery charger, in that it shuts the 10-amp charge circuit down once it reaches a point it determines is "charged," and then throttles back to "trickle charge" mode.

(It did indeed do that --- dropped into the lower-amperage trickle charge mode....I suppose that I'm indeed showing my "should-know-better" battery naivety here by not allowing it to trickle charge beyond that overnight to fully charge the battery (we do that with the 7.2V NiMH batteries in our RC cars at work for maximum charge....)

So....with the caveat that perhaps it's not fully charged....(no overnight trickle charge....) : one hour after *believing my battery was charged*, and it reads 12.7volts.

I'm popping the caps on the battery tomorrow to peer inside the cells.

[Gooseberry]

Originally Posted by MountainBikeRoamer

Thanks.....interesting you ask this ---



There are indeed *two separate wires* that hook up to the negative terminal on my house battery (the heavy-duty black one that runs to the fuse block, and a skinny, light-duty green one that runs off......under the carpet.....and......somewhere? Is that the chassis ground?)



I've run (and camped with) the van successfully over the last 2 years both *with* and *without* the green wire hooked up to the house battery (not on purpose, I think I accidentally unhooked the skinny green wire for six months....)....and it seems to charge (and hold a charge) identically well in both instances. No problems until recently.



How did you diagnose your chassis ground issue? And did you run a completely new wire to remedy the situation?



For what it's worth --- my battery truly *does* charge up successfully. (At least as measured, at the terminals, by the "resting voltage" it reaches once charged, around 12.7 volts.)

You have your negative going to the fuse block?

The large wire on the negative should go to a frame point on the van so I'm assuming that on the fuse block it has another going to the frame or body. If not then that small wire is limiting the load to charge your battery from the alternator


To find it I started checking wires from the battery and I was able to move the bad connection just a little. I have used my van a bunch and this just happened on that trip.

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[MountainBikeRoamer]

Originally Posted by Gooseberry

You have your negative going to the fuse block?

The large wire on the negative should go to a frame point on the van so I'm assuming that on the fuse block it has another going to the frame or body. If not then that small wire is limiting the load to charge your battery from the alternator.

My bad? Yargghhh. Perhaps its the fat red wire that runs off to the house fuse block, and not the black one? It's late, and it's possible that my brain's electrical connections are as unreliable as my battery's voltage readings. Let me go re-check this.