Trolling Motor Battery

Hi all,

As part of this lithium journey, I want to somehow replace my super heavy lead-acid battery that I use with my trolling motor on my portable fly fishing pontoon.

The motor is a 30 pound thrust Minn Kota that runs a 12v motor andhas a maximum draw of 30 amps continuous. The Minn Kota website says the motor is not able to handle lithium chemistry (3s is too low voltage, and 4s is too high).

I was thinking about trying LiFePo4 cells since they have a lower nominal voltage, good safety, higher drain,and cycle count.

I'd like to make a roughly 100 Ah battery.

Does anyone have any experience doing something like this? Any thoughts, or suggestions? Sources for LiFeP04 cells?

Thanks.
Eric

There are boost/buck converters you can use to adjust the voltage to match what your motor needs.

I use a 20A Buck converter from 7s lithuim (29V) down to 12V Now I'd rather have a programmable output version as I'd like 13.5 V instead of 12.1V But it works great for my camper and I have seen 40A versions

Yep, was gonna suggest the same thing. Go with a higher voltage pack and use a buck converter to drop the voltage to what you need. Plenty of high amp ones out there, or you could parallel 2 together to balance the amp draw if you want. No need to go LiFePo4 if you don't have to. (nothing against LiFePo4 chem, just if you already have LiCo's and gear, why spend the extra $$ to get LiFePo4 cells/equipment just to run one device)

I am building a trolling motor pack for a gentleman over in Nashville as we speak...small world...

The motor will not care about the chemistry of the battery..makes no difference at all where the current comes from, as long as the source can provide the constant 30A draw you seek...the motor just wants current, it doesn't know what you have hooked up providing that current..could be a crack head pedaling a bicycle sprocket, that's turning an alternator...

but I did have an issue with a UPS pulling more current than my pack could steadily provide once. Easy remedy was to use cells that are designed to allow a high/large current outflow, like those rated in the 10-20C range and it that solved the annoying beep ( anyone who has owned an APC UPS knows the beep)...common sources for high current flow 18650's are power tool packs (not laptop) and portable vacuum packs as well...LG has a line of 18650 dedicated to the high current needs, ill try to find and tag the datatsheet.

I wasn't so worried about chemistry, more the voltage. LiFePO at 4s is a bit closer to 12v than LiCo at 4s. Buck converter may be the way to go along with powertool batteries.

Crack head on a bike behind my pontoon....now that's an image

Any thoughts on 'wet proofing'?

EricKoshinsky said:

I wasn't so worried about chemistry, more the voltage. LiFePO at 4s is a bit closer to 12v than LiCo at 4s. Buck converter may be the way to go along with powertool batteries.

Crack head on a bike behind my pontoon....now that's an image

Any thoughts on 'wet proofing'?

Click to expand...

a buck converter is the way to go mate and they are not hard to build yourself. but remember you have the entire range ofusable voltage 3.0-4.2v as well and can run more in parallel to increase the run time at lower state of charge too..use the LM7812 and itll put out exactly 12 from a 4s,5s pack too...if you do find a lead on the "cheaper" LiFePo4 let us know... for higher current maybe don't use the linear chips, if so a few LM338 in parallel will do it, not the LM7812

im working out the water proofing for the build now...I am handy with gelcoat and fiberglass and the client wants a nice enclosure, so ill probably fab up a dry box and use outdoor utility access panels (like they use for normal outdoor AC power at the house) for the entry exit points. im haven't finalized it. I am going to a couple boat dealer this week to see what the pros have done. ill post the pics on my built thread once I get it all built and wired, I can tag them here too