Battery question: best battery for the job: small+1hour life

[HOUSE]

Hey guys, I'm modifying an inflatable boat to use on some rivers and I have to row about 1-2 miles to a spot which takes about an hour upstream depending on the river flow (and only 30min downstream if I can get a friend to go and bring a second car). I'm looking for a light weight/inexpensive option to power a 30# thrust Minn Kota or a 40# BPS Prowler.

I had a brand new atv/jet-ski type battery which I tested in my garage running each motor separately. I should have probably filled a bucket with water to simulate the river, but I tested them dry and got 3+ hours on a full charge both times. However, when I used them on the water (on 2 separate trips) the 30# Minn Kota died 30minutes upstream and the Prowler died 45min going downstream after fading in and out 20minutes in. This isn't a deep-cycle battery so I expected both motors to fade in and out along the way which they did, but I still thought I could get a good 1-2 hours out of it. I'm guessing I got less life out of them because of the water resistance? Are there any tricks out there that would allow me to get more juice out of this particular battery or am I looking at buying a deep cycle? I need to keep the size down since I have to carry all of this stuff with my boat.

Any ideas?

-House

edit: I just read in another post that a wheelchair battery might work. Anyone have any experience with those?

 

[Sawdust Farmer]

I know you are trying to keep the size and weight down, but I think you are going to have to go with a deep cycle battery.

ATV/PWC batteries just don't have the capacity to run a trolling motor for any length of time - plus they don't handle deep discharges well.

Just my opinion,
sf

 

[Frogman Ladue]

A number of snowmobiles run larger lead acid batteries. More weight and size over the motorcycle/atv iddy-biddy batteries, and not quite the size of a car battery. They have to be bigger for use in snow and adverse weather. I would think that they're in the mid 20lb spectrum...and have the "big lugs". I'd think they would be better than the small AGMs from power sport apps. For the price yer gonna pay, you can get a small car battery cheaper. I'm still thinking that a deepcycle is the way to go. Group 24's start around 40lbs...they still have the same case as the 27's...just less guts, power, and weight.