Hi, I have a 1900 Pro-V with a 101 Terrova and am getting an uneven draw across the three batteries. The middle one always ends up dead first. Usually have 25% charge at the end of the day on the other two but middle is always dead. Any ideas as to this or should I be concerned.

What size batteries do you have and how are you measuring the amount of remaining charge? I was taught that marine deep-cycle batteries are designed for a maximum of 50% discharge. If you are running the batteries down to 25% or less remaining charge, you may be over-discharging them and shortening their lifetime. It sounds like the middle one is already on its way out.

Are the batteries the same age/brand/group size and RC rating? If so, try moving two of the batteries in rotation so the one that has had the most discharge isn't in the middle. If it still shows more discharge, replace that battery. The amount you discharge your batteries each time you use them can have a longevity effect on your batteries. The less you discharge them each time, the more cycles you will get in the long run. There is no 50% rule, but you should avoid killing them so dead that they will not turn your trolling motor. If you do this, your onboard charger may not want to start charging. If that ever happens, you may need to put a manual charger on each battery to provide enough charge that your charger will work. (sounds goofy doesn't it?)

Thanks for the suggestions. They are all the same size and make ( series 27 interstates) and usually at the end of the day the two others have 25% left but the middle tends to draw first, I know this because the Pro-V's have a battery indicator that allows you to check the level of your trolling batteries individually. They all charge up to full, but the middle just draws out faster...may be it is on it's last legs.

Curious how old are the batteries ?

Also I usually use #29 Batterries, hold more reserve than 27's

Things to consider:

1. Your middle battery is not being as fully charged as the other batteries, or
2. Your battery gauge is faulty, or
3. Your middle battery has lost capacity to hold charge- more so than your other batteries, or
4. Something is draining charge from the middle battery, but not the other two.

So, like Boatnut said...

Swap the positions of the middle battery and one of the other two. Does the problem move with the old middle battery? If it does, it's the battery. If not, then suspect the charger or the gauge... or look for something draining charge from the battery installed in the middle position.