Battery switch question

skennelly

This past weekend I was out on the lake anchored for a few hours....went to pull up and start engines and just got clicks.

Switch was on both...changed to battery 1 and clicks....changed to battery 2 and was able to start.

My question wasn't BOTH able to start?  

chamberb

Both should have started it you are correct. Sounds like battery 1 discharged faster than 2. When you're out for the day leave switch set to 1 or 2 to avoid having this problem again. 

Michael T

Without seeing your wiring, if one battery is really dead and then switched so that it is  hooked-up to a good battery it will scavenge enough power from the good one to drop the minimum cranking amps too low to start the engine. BTW When anchored I only have the battery selected to house. If it's on both systems, house and start (is that what you meant?) then you can kill everything. If you had it on house and killed that battery then I would not parallel them I would select only crank to start or the depleted house (as I mentioned) could draw the good one down. Paralleling the batteries is usually reserved for a "hail Mary" situation IMO.

skennelly

Thanks for the feedback.  I'm going to replace the batteries to get a fresh start.  I'll be sure to flip the switch to a single battery while anchored from now on.

Michael T

Yes, put it on the house battery. that will save your starter battery. If you are sure both batteries are not good - a load test will determine that. You may wish to look at Two series 31 AGM batteries for their extra durability. Also the new Thin Plate Pure Lead AGMs may have come down in price to where they are somewhat reasonable. They are real beasts.