dual battery and perko switch question

This has got me stumped, maybe somebody out there has some idea about this? I have recharged both of my batteries, they are in parallel, but I disconnected them and recharged them separately anyway. I have also recharged them together as well. They are both the exact same type, purchased at the same time, etc. I have an onboard charger. With the perko switch set on all, the engine cranks right up, with it set on 2 it starts up, but set on 1 it just makes the clacking sound like the starter is not getting enough juice. Despite the fact that that battery by itself tests OK, like 13. something to 14. Any ideas as to what could be up with this? BTW I usually leave the perko switch set on "all"

Assuming your No. 1 battery is in good order, then I highly suspect that one or both of the cables coming off battery 1 is corroded internally, OR the relevant contants on the Perko are corroded. Swing the Perko switch around between positions a bunch of times to see if that clears the problem. If not, suspect the cables. Easiest and best procedure is to replace those cables.

I don't think lead-acid batteries can possibly develop a memory like some dry cell rechargeable batteries can.

There should be no reason that you cannot charge both batteries simultaneously with the Perko in the "ALL" position, if both need recharging. However, if one battery is significantly more discharged than the other, then you should charge one at a time, or as Kim implied use an isolator, especially if you are relying on a trickle charger. You can hook up an additional set of leads to the Perko to interface with a charger, so that when the switch is in the "1" position, only No 1. battery will be charging, and if the switch is in the "2" position, only No. 2 battery will be charging.

....a third possibility is that you have a bad starter. i once ran across this where the starter had such an amp draw that the two batteries "masked" the bad starter. i know it is a reach.....have both batteries load tested, then have a starter test done to see how many amps it is drawing.

crankbait said:

....a third possibility is that you have a bad starter. i once ran across this where the starter had such an amp draw that the two batteries "masked" the bad starter. i know it is a reach.....have both batteries load tested, then have a starter test done to see how many amps it is drawing.

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I'll check the starter, my boat is famous for starter problems.
thanks all