Battery Monitoring while Dry Camping

SocalHodaka · 08-29-2008, 08:46 AM

While camping at a California State Beach, a parking lot with no hook-ups for 4 days. I try to monitor my batteries from the levels monitor in my coach. Our inverter indicated low battery but the monitor show full charge. We were already in the camp quite time so I could not run the generator, but since the monitor indicated full I went to bed with no worries. About 4 am low battery buzzer going off, not enough juice to even turn off the disconnect to silence the buzzer. My question is, what is a good way to monitor the Batteries? cause I don't think the monitor is very accurate. Thanks Kelly

SocalHodaka · 08-29-2008, 08:46 AM

While camping at a California State Beach, a parking lot with no hook-ups for 4 days. I try to monitor my batteries from the levels monitor in my coach. Our inverter indicated low battery but the monitor show full charge. We were already in the camp quite time so I could not run the generator, but since the monitor indicated full I went to bed with no worries. About 4 am low battery buzzer going off, not enough juice to even turn off the disconnect to silence the buzzer. My question is, what is a good way to monitor the Batteries? cause I don't think the monitor is very accurate. Thanks Kelly

John_Canfield · 08-29-2008, 09:11 AM

Sounds like your monitor isn't working properly.

MrTransistor · 08-29-2008, 10:57 PM

Hi SocalHodaka,

You say, "-I don't think the monitor is very accurate.". What type of monitor are you looking at? I thought the ˜OnePlace' on all Winnies had a 2 and ½ digit digital voltmeter readout for the coach and chassis batteries.

If you are looking at the digital readout, be aware that the reading can fluctuate as a function of what loads are placed on the circuits. The meter is not a remote sensing meter i.e. it does not have measuring wires that run directly to the batteries. Instead it just reads it's own supply voltage and as such is subject to voltage drops on the line.

Each coach is different so I can't tell you what errors will occur with what loads but I see drops of up to .6 Volts.

Same applies to most inverter setups. They will tell you what voltage is at their own terminals but can't and don't tell you what the voltage is right at the battery.

The best way to get an accurate battery voltage reading is to run two separate wires directly from the batteries terminals up to the ˜OnePlace' and connect them to a couple of banana jacks (one red and one black) mounted conveniently on the panel. Then get yourself a good 4 and ½ digit readout voltmeter with a pair of test leads with banana jack tips. Now all you have to do is plug in at the ˜OnePlace' to get a very accurate battery reading.

I did this for both coach and chassis batteries when I installed the Auto Generator Start unit from Onan called an Energy Command 30.

Ride safe!

MrTransistor · 08-29-2008, 11:12 PM

Hi SocalHodaka,

Ahhhh, I see now. You have an idiot light that reads ˜F', ˜2/3', ˜1/3', and ˜E'. If they don't work very well at all for the tanks, why does Winnebago think they will work for the battery? And yes, it will be sensitive to loads the same way that the digital display is.

I'd suggest calibrating the readout, but calibrate to what? I'm sure there is a potentiometer (or two) inside to set the thresholds of the display but without seeing a schematic, I can't even guess what the threshold spread would be. And that's up to the designer of the circuit.

Is it anything over 12.8 Volts is ˜F' and anything under 11.9 Volts is ˜E' who knows.

Install the remote meter, then you will know for sure.

I wish I still had my 1967 Triumph Bonneville! It was a sweet ride but guess what, the 2007 is sweeter!

SocalHodaka · 08-30-2008, 07:10 AM

Mark, thanks for the reply. Yes I have the idiot lights. So far they seem to work fine on my tanks, they read empty when I dump them. I think I will use your idea and mount a hook-up to use a Volt meter to monitor the batteries easy.
Thanks Kelly

NoMoreAZ · 08-30-2008, 05:17 PM

If you have the inclination, install a Xantrex Battery Monitor. Not too hard to do. Tells you everything you need to know about your battery bank. I would not be without it. Search the Xantrex web site for additional info.

As a side note, my One Place meters show a .7 volt drop for each bank, chassis and coach.

Indy Itasca · 09-01-2008, 06:32 AM

We just have the Christmas tree idiot lights as well. I bought a small digital read out VM that plugs into a 12V socket. It has both a digital read out and 3 led lights that show the charge state. When we dry camp I plug it into either the bedroom 12v or the one by the dinette. I get a much better idea of whats going on. I think it was less than $20 at CW. I see RV Upgrade has them even cheaper:
http://www.rvupgradestore.com/index....OD&ProdID=2065

SocalHodaka · 09-01-2008, 06:53 AM

Hey, everyone thanks for the reply's. I have some great options. Thanks for the help. Kelly