Trolling Motor and LiFePO4 Battery Connection

[BrianMDTX]

I actually received my battery much earlier than expected (while I was out fishing lol). It is very lightweight and I can’t wait to charge it and start using it (still waiting on my registration decals for the hull). 
 

This battery has small stainless steel bolts that thread into the battery for the positive and negative terminals. The instructions state NOT to hook alligator clamps directly to the bolts. It says to install copper terminals under the bolts and connect the clamps to those. 
 

Yeah, my motor is old. Do new transom mount trolling motors still use alligator clips or do they have copper terminals that one installs/removes via those bolts? I have no issue with buying two copper terminals per their instructions and clamping to those, but I’m wondering if would be a better connection by removing the alligator clips and crimping on copper terminals. I’d think it would be another step to take each trip to bolt/unbolt the cables from the motor. 
 

Is it perfectly acceptable to just install copper terminals and clip to them? Battery photo and type of terminal (cable lug) photo included. 
 

[Scott F]

With the amount of current going through the connection, alligator clips are the least preferred way to hook up a motor. 

[MN Fisher]

Cut off the alligator clips, crimp copper or even aluminum terminals onto the bare wire, bolt to battery.

 

If you want to be able to disconnect easily - put a set of these between the battery and the TM...make sure the wire gauge is correct for the amount of Amps you can pull at max....usually 6AWG or 8AWG. (Pictured is 6AWG)

 

[Junger]

Also don’t run your TM at max speed for long periods of time. The Li battery will provide full voltage for a long period without dropping. You’ll wear out your brushes, potentially melt wiring, and burn out the armature. Happened to me with my Ultrex.

[padlin]

I did as MN Fisher shows. Leave a pig tail permanently attached with 50A Power Poles.

I soldered mine on and added a fuse/breaker on the battery side. You can get off brand a bit cheaper off Amazon, not that they are big $.

 

 

 

 

[WRB]

You plan to take the battery out to charge it. The terminals need to be compatible with the charger and the TM wire size when you remove the alligator clips.

The connectors shown by MN Fisher look good! 
Tom

[BrianMDTX]

1 hour ago, MN Fisher said:

Cut off the alligator clips, crimp copper or even aluminum terminals onto the bare wire, bolt to battery.

 

If you want to be able to disconnect easily - put a set of these between the battery and the TM...make sure the wire gauge is correct for the amount of Amps you can pull at max....usually 6AWG or 8AWG. (Pictured is 6AWG)

 

Do you recall make/model and where you purchased them? 

[MN Fisher]

15 minutes ago, BrianMDTX said:

Do you recall make/model and where you purchased them? 

The connector pair is HERE

[BrianMDTX]

All this goes to show how long it’s been since I operated a trolling motor lol. 

[VolFan]

I have to the same connectors as MN Fisher. At the end of the day, I clip to trolling motor, clip in the charger and BOOM… you’re charging.

[Way2slow]

The actual name of the connectors shown is the Anderson SB50 connector.  At the most, your TM probably has no larger than AWG-10 wire, so I don't think I would order the #6 connectors.  For the short length or wire you are going to be using I would go with the SB50 -10 and no larger than SB50-8.  Even with the #8 you will have to fold the copper wire in the TM lead at least once or twice to make it fill the connector enough to get a good crimp.  I crimp then solder my connectors, but I also have a very large set of special crimpers to crimp mine but doubt you want a $800 set of crimpers so I would recommend one of these (regular hand crimpers won't work on those heavy lugs) Amazon.com: Battery Cable Lug Crimper - Hammer Crimping Tool with Storage Pouch : Automotive.  If you are skilled with soldering, you can just solder without crimping, just be sure to use Rosin Core solder, just remember it's going to take a Benz-O-Matic (propane torch) unless you have one huge soldering iron.

A little gee wiz about the connectors.  They are color coded, and it does not matter what color you use, but they both have to be the same color to plug the together.  Each color has a different security tab on them, other than black, black is universal and will plug into any of them.  Also, the number 50, 75, 125. 175, 350 are the amp rating.  That's not the max they can handle, they can handle a lot more, but that's the max they can have going through them when disconnect and not cause it to arc and melt the terminal.   

Also be sure to order the copper lugs for the same size as the connectors and with the bolt the size of the bolt that connects it to the battery.  I would use the heavy copper and not aluminum.   You can find tinned copper lugs that are silver colored (they are silver plated) and those are fine.  

One other thing I should mention, if your charger comes with small alligator clips, and they will fit into the connector good enough to clamp onto the terminal in the connector, you can do that and not have to order a third connector for the charger.  At five amps from the charger, you are not dealing with enough current for the alligator clips be a problem.   If you want to make a cable for the charger to plug in, you will need three connectors.  If needing to order a third for it, I would order a black, since it would plug into any of the SB50 connectors.  Never know when you might want to have something else to charge with it. 

[BrianMDTX]

How are new transom mount trolling motors set up? Do they all have lugs on the end of the wiring, in other words, no more battery clips? 
 

All I can remember is every transom mount trolling motor I ever used had clips to attach to the + and - terminals. But they were all lead-acid batteries and that was a long time ago. LiFePO4 batteries were a pipe dream. 

[VolFan]

That depends on the motor- of the three I purchased new, they all had different terminal ends. I just swapped greased and shrink tubed what I needed on. 

[Way2slow]

Don't know, I haven't looked at a Transom mounted TM in many years.  I do know a little about current loads and heat caused by them, since I have a degree in electronics, and 25 amps is asking a lot out of alligator clips.  If you run on max a few minutes and feel the clamps, you will probably feel they are pretty warm.  That's wasted energy.  You also have to look at they are usually clamped onto a large lead terminal that give them a lot more surface area that you don't have on your battery.   If you just put steel bolts in the battery for terminals, that's a very small surface area and believe it or not, steel and especially stainless is a poor conductor of electricity.   Table of Electrical Resistivity and Conductivity (thoughtco.com)

Now, I will say it like this, it's your situation and how you handle it is totally up to you.  I know no one is going to tell me how to do something with something of mine.  They can suggest but the decision how is mine.

[BrianMDTX]

@Way2slow  My usage of “alligator clips” was poor. To me, alligator clips are small and used for checking voltage and current with multimeters making jumpers, etc. The battery manufacturer’s use of the term “alligator clip” made me say alligator clip vs. battery clip or clamp. 

The diagram below was included with the battery, which is what prompted my original question. Just an FYI. 

 

[WRB]

Crocodile battery clamp but a crimped on terminal lug is your best choice.

Tom

[Junger]

17 hours ago, WRB said:

Crocodile battery clamp but a crimped on terminal lug is your best choice.

Tom

That’s what I did with my Lithiums. The M8 bolts are pretty short so you can’t fit more than maybe 2, 3 lugs max. I ended up terminating them from the batteries to a bus bar. 

[Bankc]

On 7/6/2024 at 3:19 PM, MN Fisher said:

Cut off the alligator clips, crimp copper or even aluminum terminals onto the bare wire, bolt to battery.

 

If you want to be able to disconnect easily - put a set of these between the battery and the TM...make sure the wire gauge is correct for the amount of Amps you can pull at max....usually 6AWG or 8AWG. (Pictured is 6AWG)

 

That's what I use to connect my speed controller for my trolling motor on my kayak.  Those are great connectors!  They easily handle the load of the trolling motor and are easy to connect and disconnect.  The only issue I had was I didn't have a crimper big enough to fit them, with the 8 gauge wire.  But I did the old school, hammer a flathead screwdriver into them to crimp the wires on, and they've held up for years without issue. 

 

Now, what I use on my actual battery is just the regular eye clips with no connector, and I bolt them to my battery using stainless wingnut bolts that I bought to replace the original bolts that came with the battery.  I had to get them online, as they're metric in size and the length of the bolt matters greatly.  That way I can tighten and loosen them without tools.  I might one day switch to some connectors like those above to make things a little easier, but I'm in no rush.  

[TnRiver46]

On 7/7/2024 at 12:44 PM, BrianMDTX said:

How are new transom mount trolling motors set up? Do they all have lugs on the end of the wiring, in other words, no more battery clips? 
 

All I can remember is every transom mount trolling motor I ever used had clips to attach to the + and - terminals. But they were all lead-acid batteries and that was a long time ago. LiFePO4 batteries were a pipe dream. 

They use Ring terminals on the newer transom trollers, some not a complete ring but more of a U shape 

[txchaser]

5 hours ago, TnRiver46 said:

They use Ring terminals on the newer transom trollers, some not a complete ring but more of a U shape 

The U or C shaped terminals are nice because it is a great connection but easy to get off the battery with a few turns of the screw/wingnut/etc. 

[Way2slow]

Actually, if you use wing nuts, you should use some kind of tool, plyers, adjustable wrench etc.  There is no way you can properly tighten them with just your hand.    Using the picture he posted about his charger, you see how they say fully compress that lock washer they use, you will not do that with just your hand.  Many years ago, I used to think just by hand was good enough, until I burnt my fingers taking one off.  I was fishing a 600-acre lake and after running on max a good way back to the truck trying to beat a thunderstorm.  I quit using wingnuts after that.   

[BrianMDTX]

I decided to purchase SC10-6 copper cable lugs and red and black heat shrink tubing. I will cut the clips off and crimp the lugs on. I have access to aviation crimpers and a heat gun so I won’t have any issues with accomplishing that. Doing so will ensure good wire with zero corrosion and ensure good continuity. 

[TnRiver46]

Zero corrosion is a pipe dream here in the jungle 

[Bankc]

11 hours ago, Way2slow said:

Actually, if you use wing nuts, you should use some kind of tool, plyers, adjustable wrench etc.  There is no way you can properly tighten them with just your hand.    Using the picture he posted about his charger, you see how they say fully compress that lock washer they use, you will not do that with just your hand.  Many years ago, I used to think just by hand was good enough, until I burnt my fingers taking one off.  I was fishing a 600-acre lake and after running on max a good way back to the truck trying to beat a thunderstorm.  I quit using wingnuts after that.   

We must have different size bolts or thickness of split ring washers on our batteries or something.  I think mine are M6, if I remember correctly.  And the split ring washers it came with are pretty thin.  You say "There is no way you can properly tighten them with just your hand".  But from my experience, it's not even remotely hard to fully compress those washers by hand.  And I'm about 6'2" and 175lbs of bone and fat.  So I'm not exactly what you would call a physical specimen. 

 

Though, if you're using wing bolts, then you're probably installing and uninstalling the battery every trip.  So you probably don't even need the split ring washers.  Especially if there's no gasoline engine to create higher frequency vibrations.  The split ring washers are just there to keep the bolts from backing out under vibrations and temperature swings, and if they're only ever being hooked up for a few hours at a time and not exposed to those conditions, then they're not really going to be serving a purpose.  And then their drawbacks might outweigh their benefits. 

[Way2slow]

I'm just posting what is normally recommended.  I worked as an industrial lift truck road service tech for 20 years after retiring from the AF.  Mostly on electric equipment and some of this equipment runs two-ton batteries and can draw over 600 amps.  I've seen many times what someone thought was a good connection would do.  Actually, with that stuff, you don't even use steel washers because of the resistance they create.

Like everything, there is always more than one thought on how things should be done.

Things like some people see no harm in running a motor before launching the boat to make sure it starts.  I even watched a DNR person crank three 200hp Mercs long before the boat got to the water.  You won't see me doing that.  

You see people connecting jumper cables to these modern motors with ECU's, not me!

Then they use their boats charging system to charge the probably bad battery, not me!

You see and read about people having no issues with running gas that has sat in the tank for months and months, not me!

My daddy did it and I've never had a problem with it, that still doesn't make it the proper way of doing something.  If and when the day you do have a problem, it's going to be at the most inopportune time it can possibly be.  I try to avoid those times.