voltage drop

[boisesmith]

We have been boon docking for a few weeks and find an overnight voltage drop to about 11.3 volts. This is according to the number of lights on the panel and as shown on my "Nature Power" solar charge controller. The solar panel seems to charge the batteries during the day and running the generator certainly does. I recently installed two new 27 series Interstate batteries. Where do I start to find the voltage loss?

[PNW Fireguy]

Do I understand you correctly that you are relying upon the 4 light OEM battery indicator and readout on your charge controller? If your system does not have a current shunt these are approximations based upon the voltage curve of the PbSO4 interstates you have. With PbSO4 this method of measurement is acceptable due to the nature of the chemistry's voltage curve. However a shunt measures with a high degree of accuracy the amps in and out of your batteries. All that being said I am wondering if your charging methods are actually getting through the absorbtion phase of the charge curve. Specifically with solar this is usually a significantly lengthy phase when charging PbSO4. Also bear in mind that there can be significant parasitic loads through the night hours that are draining your batteries as well. Since you state the Interstates are recently new I would start with making sure you are getting a full absorbtion charge cycle with your generator. Check the voltage at the cells with a volt meter to verify.

[DQDick]

Even running the frig and hot water heater on propane, the controls for all your appliances including the frig are still drawing 12v. Propane detectors etc. will also be drawing current in addition to things you are actually running like fans, lights Tv's etc.

[mtheo]

Problem with this newer rigs is that there are a lot of parisitic leaks. Everything from the radio on standby, to the fantastic fans, to the TV antenna booster, and who know what else.

[jcurtis934]

Televisions also are in standby mode when turned off... If you added two new interstates to old batteries already in the unit, the old batteries will vampire the new ones, which is why you always change all batteries at the same time.