Trolling motor and charging

[Syversens]

Hey all, last weekend the mrs and I went on a nice sail without the kids. We did a nice row along the beach in the inflatable without taking the beast 10HP off the rails and hooking up gas and all that, too slow for the kid and not really much room to row... So a kayak took off with electric trolling motor to check on pots, it looked like the perfect slow propulsion and since we have electric start for outboard the battery is already there.

So... anyone have experience using the smallest (30 pound trust) troller and a small battery, 35 amph, in a dinghy for just tooling around the boat? also curious how I'd charge the portable battery, just plug it into one of my cig outlets or does it need some sort of DC to DC charger?

If we stay for significant amount of time or need speed we'll use the 10hp for sure but for $100 it's a good rowing alternative... or so it seems.

 

[Chief RA]

You would need a size 34 deep cell battery w/ the little battery as emerg. backup. for a 30lb electric motor. They will not go far on the small batteries. Jumper cables for charging off your boat batteries but you better have a good charging source for your battery bank or it will eat you up! Use conventional charger when in port. Chief

 

[gleason99]

You would need a size 34 deep cell battery w/ the little battery as emerg. backup. for a 30lb electric motor. They will not go far on the small batteries. Jumper cables for charging off your boat batteries but you better have a good charging source for your battery bank or it will eat you up! Use conventional charger when in port. Chief

I have used a Torqeedo for the last 5 years and have had zero problems and have saved hundreds in gas particularly in the Bahamas !

 

[Chief RA]

gleason99: Whats your point? I didn't say it can't be done. His proposal takes a nice size battery to do. You should know. What size gen are you using and how much gas does it use? Did you consider how much you spent on your motor as well? Solar costs? I am an Industrial Engineer. None of these options are free! Chief

 

[Syversens]

Appreciate both inputs but my 10hp will be primary mode of propulsion for anything but in harbor short trips.

Chief, I think I saw a site saying 100 Ah would get 3.5 hours so a 3rd would be one hour, that sound about right on slowest speed?

Think I'll try it out, if I'm liking it I'll get a bigger battery. The stater battery I have is AGM and was darn expensive, I don't really want lead acid as I take it off an on when needed...

Cheers!

 

[Chief RA]

Its not a problem using wet cell batteries in a dinghy. Just buy a battery box for it. I tested a motorcycle battery and it lasted about 15 minutes. I have a 3.5hp Tohatsu (2015) that weighs 41lbs and will run an hour on a quart of gas! It cost less than $1k. Chief

 

[Syversens]

yikes, 15 minutes eh, I was hoping for more than that. thanks for all input!

 

[Chief RA]

Remember, it was just a medium sized motorcycle battery, not the fancy one you have. Let us know on the run time. Chief

 

[Syversens]

Will do, if I get one. I'm also looking at charging, might be over thinking this but just connecting it to the batteries probably won't charge well since the voltage will be low. I'm thinking I'd need a separate charger and though I have inverter (small for my computer network) I'd rather not spend more electrons than I have to, specially converting voltage up and down....