batteries went dead.

[Captain Newell]

The last time it was in storage for about 6 weeks the 2 house batteries and the engine battery went dead. I recharged all 3 at home, but now worry about a repeat. At this time I am disconnecting one of the cables for each system when I store the MH. When I touch the cable to the battery post there is a spark. This indicates to me a draw on the batteries. How do I measure that current to determine if it is excessive and will run the battery dead again? Should I simply add a battery isolator switch and turn it off when stored? The MH has a house battery connect switch which I turned off, but there is still a spark when I touch the cable to a post.

[Bob Fetters]

A spark when connecting battery cables is not uncommon. Vehicle alternators will always bleed a little current backwards through the diodes. When new, this is a low enough drain that starting batteries will go a considerable time before discharging to the point of not starting the vehicle. As the diodes age through use, this drain typically increases. Occasionally, one of the diodes will fail, draining the battery fairly quickly when the engine is not operating. Frequently, the other diodes will operate correctly and the system will charge the starting battery while driving, masking the fact that the alternator is bad. It is not unusual for a starting battery in an alternator car to go flat in a couple of months if it is not charged. I assume your Newell has a larger starting battery and that should last longer against diode drain. As a rule of thumb I consider replacing alternator diodes when I find drains beyond 0.2 amps.

Sometimes there are condensors, coils or the like that will cause a spark while they "charge" up. If you connect and notice a spark and then disconnect and re-connect quickly the lack of a spark the second time will tell you that something was charging up and a short is not likely.

I have found our 93 Newell has things like a digital L.E.D. clock and other 12 volt accessories that run all the time. These are not huge drains, but over time, they will run the house batteries down. Our House Battery master switch actually powers a solenoid so the swithch it self and things like the clock continue to have power even though the lights and other major items are shut down.

Shortened capacities are sometimes the result of low battery acid and or sulfated battery plates.

Let me know what you find.

Bob