South How to plan for BD

[ATownTX]

To get the true state of discharge you need to remove the load and let the battery sit for awhile. That say 4 hours. So 12.3 V may not be an unreasonable reading. I think you are doing the right thing in getting to know the characteristics of your batteries and monitor by testing them. IMO

[The Colonel]

Originally Posted by OTRA15

12.3 volts indicates that your batteries we about 40% depleted, which is sub-standard for only running a fan for 6 hours (assuming they were fully charged before). Please see Post #4 for some initial steps to take to research why the batteries have fallen so much. In my opinion, you are not in good shape to leave on a trip that involves any boondocking.

Peter

PS here is a good primer on RV batteries:

http://www.batteriesnorthwest.com/ba...ool.cfm?TID=10

Voltage percentages in the middle here:

http://www.batteriesnorthwest.com/batteryschool.cfm

And here:

http://www.batteriesnorthwest.com/ba...cfm?TID=5#ANC5

Thx, Peter, these were good reads.

[twobikes]

Here is a mod from Dick Mansfield's VERMONT BIRDER blog. A solution for the Dometic fridge's lack of a climate control.

http://www.vtbirder.com/power-drain-fixed/

[Al and Missy]

Originally Posted by The Colonel

Yep, grp 24. I'm running one fan, everything else is off. Been going 6 hrs and v indicator in AS shows 12.3, pretty much since I started this am. Not sure how good A measurement I get from that indicator. Shooting for 8 to 10 hours

It sounds like you may be reading the voltage while the fans are running. As ATownTX posted, battery voltage should only be used as an indication of state of charge when there has been no current going into or coming out of the batteries for some time. If you were reading 12.3 at the beginning and it stayed constant during your test it may just be due to the batteries having a load on them.

Al

[OTRA15]

Originally Posted by ATownTX

To get the true state of discharge you need to remove the load and let the battery sit for awhile. That say 4 hours. So 12.3 V may not be an unreasonable reading. I think you are doing the right thing in getting to know the characteristics of your batteries and monitor by testing them. IMO

Originally Posted by Al and Missy

It sounds like you may be reading the voltage while the fans are running. As ATownTX posted, battery voltage should only be used as an indication of state of charge when there has been no current going into or coming out of the batteries for some time. If you were reading 12.3 at the beginning and it stayed constant during your test it may just be due to the batteries having a load on them.

Al

Good points. Before checking the specific gravity, I would disconnect from shore power for a similar 4 hour period with the Use/Store switch on Store. Check the specific gravity of each battery cell, then put the Use switch back on, and check the battery voltage readout on the panel.

An improved report of battery condition will then be possible.

Cheers,

Peter

PS -- Just a reminder that only distilled water should go into the batteries, wear safety goggles and gloves when working on them, and wait another 4 hours to check SG if you add water.

[Adventure.AS]

Originally Posted by The Colonel

...Suppose to go BD this fall. ...

What is BD?

[OTRA15]

The original poster used that acronym so I guessed in Post #4 that he meant Boondocking.

The forum's acronym lists don't have it FYI:

http://www.airforums.com/forums/f138...ist-28713.html
http://www.airforums.com/forums/f483...ms-156815.html

[OTRA15]

Originally Posted by twobikes

Here is a mod from Dick Mansfield's VERMONT BIRDER blog. A solution for the Dometic fridge's lack of a climate control.

http://www.vtbirder.com/power-drain-fixed/

Thanks for the link, which shows helpful photos FYI, about disabling the 12-volt feed for the climate control with an inline quick-connect crimp fitting.

[Mattirs]

BD is boondocking.

[The Colonel]

Originally Posted by OTRA15

Good points. Before checking the specific gravity, I would disconnect from shore power for a similar 4 hour period with the Use/Store switch on Store. Check the specific gravity of each battery cell, then put the Use switch back on, and check the battery voltage readout on the panel.

An improved report of battery condition will then be possible.

Cheers,

Peter

PS -- Just a reminder that only distilled water should go into the batteries, wear safety goggles and gloves when working on them, and wait another 4 hours to check SG if you add water.

Thx, I'll do that is soon as I go get a hydrometer

[tjplus]

Good post. Thanks for the battery data. Question - if one watches tv via the pure sine wave inverter will the total load mean a dead couple of batteries in the AM?

[ATownTX]

As an example.

Your Television is 120 Watts (maybe), which is 1 Amp at 120 V.
Through the inverter it's pulling 10 Amps from the 12 V batteries. (10 A x 12 V = 120 Watts). There are some losses there, too, through the inverter but, for the simplicity, lets go with 10 Amps.

So, over 8 hrs you would use about 50% of the capacity of your Interstate batteries, which is fine. You would need to account for other 12 V items too. e.g., fans, lights, etc.

A good AC/DC clamp meter comes in handy to monitor your system.

[Mollysdad]

Through all of this I'm thinking, "Why not run the tow vehicle every so often to charge batteries or the generator?"
BD does not mean you're on the Moon.
Maybe it's challenging to know every bit of minutia about batteries.

[tjplus]

Thanks! I'm getting a generator after this chat.

[The Colonel]

Originally Posted by The Colonel

Thx, I'll do that is soon as I go get a hydrometer

Ok, pretty much did that, forgot to put in store. V at batteries was 12.92, V at inside indicator read 13.5. All cells but one at post end read 1.3, one cell read1.28~. I topped off with distilled water and put power on after a few hours I'll check the different cell again, but don't think there is too much of a problem right now. I sure hate dealing with acid.

[55AS]

Originally Posted by The Colonel

Ok, pretty much did that, forgot to put in store. V at batteries was 12.92, V at inside indicator read 13.5. All cells but one at post end read 1.3, one cell read1.28~. I topped off with distilled water and put power on after a few hours I'll check the different cell again, but don't think there is too much of a problem right now. I sure hate dealing with acid.

One of the many advantages of AGM...

[OTRA15]

Originally Posted by The Colonel

Ok, pretty much did that, forgot to put in store. V at batteries was 12.92, V at inside indicator read 13.5. All cells but one at post end read 1.3, one cell read1.28~. I topped off with distilled water and put power on after a few hours I'll check the different cell again, but don't think there is too much of a problem right now. I sure hate dealing with acid.

Thanks for the update. Be sure to wait an hour after you disconnect from the shore power, to measure the battery voltage. Before this waiting period you can get false high readings.

Have a great trip!

Peter