Engine battery and house battery questions.

klutchdust - Have any new devices been installed that run off 12 volts? Then you need to determine which battery it would effect.

I connected up an OBD II and loved it, but 2 months later my engine battery was dead. Unplugged it and now the engine battery stays fully charged from late September to late May.

You can measure your parasitic current draw with the use of a inexpensive multimeter like this http://www.harborfreight.com/7-function-multimeter-98025.html.

Just like the website that IAMICHABOD mentions. You should get a milliamp reading less than 20-30.

When you disconnect the engine battery and place the multimeter in series between the battery post and the battery cable, make sure you do not open doors causing interior lights to come on or have under the hood lights on etc. You will quickly exceed the range of your setting. It might even let out the smoke. :)

Another popular remedy that works well is the LSL Trik-L-Start (or its bigger brother, the Amp-L-Start). These little gizmos are DC powered battery charger/maintainers: when hooked in, they divert a little of the charging current from the converter (or solar, if you have it) to the chassis battery to keep it charged. They're not too expensive, easy to install, and work reliably.

Of course, if you don't have anything to charge the house battery with, the chassis battery won't get/keep charged either with these devices.

One bad thing about the newer vehicles is Parasitic Drains that occur.

I had the same problem with mine at first but neighbor,a retired ASE mechanic teacher,explained it to me. The only to stop it was to disconnect the battery when not in use for a period of time or keep it plugged in if you have a Bird
like I have or put a battery maintainer on it.

Paul, you are correct about the generator and alternator charging the house batteries. Using shore power is the same as using the generator, both feed through the Converter which converts the 120VAC to 12 VDC.

You can use a DMM or an analog VOM to check for current flow, you do have to place the meter in series with the load to check for amperage. Some of the Better DMMs can read when in parallel but not all will.

Normally when your chassis battery is good, it will be charged by the engine alternator and when it reaches a SOC somewhere around 12.6 to 13 vdc, it will then switch and charge the house batteries.

You can check the BIC(battery isolator controller) and see when the two potteries are charging in parallel. The voltage going to the house battery will jump up to about 13.5 volts. It's really cool.

I might add you can put a center off switch in place of the switch that allows you to use either the chassis or house batteries. That would eliminate the vampire draw of the clock and such.

The engine should charge both sets of batteries when running. If not there might be a problem with fuses or solinoids between charging and the batteries. I also have a radio switch that is either travel or park so it can run off the coach batteries when engine off.

The radio switch can be in either position to operate it. However the memory ids normally off the chassis battery