# Trolling motor power troubleshooting



## Creekchub (Nov 23, 2020)

I’m not a good troubleshooting kind of guy. Just bought a used boat with a 24v trolling motor that will not power up.
The batteries are charged and there is a breaker. There are also what appears to be inline fuses coming off both terminals on each battery. I tried to check the inline fuses but couldn’t open the storage device they are in and didn’t try to muscle it apart.
Any suggestions on how to open these? And if the fuses are fine, what to check next?


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## Golden Channels (11 mo ago)

I'll try to help. Do you have a voltmeter?


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## Creekchub (Nov 23, 2020)

Golden Channels said:


> I'll try to help. Do you have a voltmeter?


I didn’t think I did but found an old one. I tested the batteries and got 1.2 volts on on battery and 2.2 volts on the other battery


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## Creekchub (Nov 23, 2020)

Golden Channels said:


> I'll try to help. Do you have a voltmeter?


I hooked up my old two bank charger and it showed both batteries as bad, it had a red light on each bank in the charger control module.
I plugged one battery over night in a batter minder and had 12 v. I am going to charge the other battery today and see what volt it charges to and see if the trolling motor has power.

sounds like I might be replacing batteries and an onboard charger sooner than expected


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## Golden Channels (11 mo ago)

Any time a battery goes below 10V, it's completely toast. Even if you can bring them back up to 12V, they have lost their capacity to hold any reasonable amount of charge.

Yes, it's new battery time.


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## Creekchub (Nov 23, 2020)

Golden Channels said:


> Any time a battery goes below 10V, it's completely toast. Even if you can bring them back up to 12V, they have lost their capacity to hold any reasonable amount of charge.
> 
> Yes, it's new battery time.


Thanks man, I didn’t know that about the batteries. Guess I need to consider biting the bullet and get the 24v lithium now.


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## finbully (Jan 26, 2013)

BTW those fuse holders should just pull apart. Maybe give them a little twist when you pull.


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## Salmonidae (6 mo ago)

Creekchub said:


> Thanks man, I didn’t know that about the batteries. Guess I need to consider biting the bullet and get the 24v lithium now.



Just FYI, bought two of these:

SOK 100Ah 12V LiFePO4 Deep Cycle Battery 

to power the MinnKota Ulterra shown here: 









1966 Starcraft Explorer Rebuld


Thought folks might like to see my latest project, a near-total rebuild of a 1966 Explorer Deluxe. A few years ago I rebuilt a 1968 Starcraft TR-12 and am pretty happy with it but it is/was a bit small for taking out in southern Puget Sound. (got more than a little nervous a few times) So I...




www.microskiff.com





Based my purchase on a video review where the same battery was disassembled/analyzed and was impressed with the quality of the components as well as the fact that the battery was rebuild-able. 

I've been using them hard for the last several months and have been quite pleased with them. I installed a two leg 3 amp on-board charger so I can just plug the boat in when I get home which is pretty sweet. Note they HAVE gone up in price since then, but they're still very, very competitive and a far better deal then a lot of them you see out there. There were cheaper batteries out there, but I was afraid of them.

HTH,

Steve


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## Creekchub (Nov 23, 2020)

Salmonidae said:


> Just FYI, bought two of these:
> 
> SOK 100Ah 12V LiFePO4 Deep Cycle Battery
> 
> ...


I appreciate the info. I started researching different brands and it’s overwhelming with many choices. Searches turn up a couple specific brands each time so I’m skeptical about online marketing in general so it’s good to hear feedback from real users


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## permitchaser (Aug 26, 2013)

@Creekchub go to Walmart get 2, 1,000 crank batteries for less than those $500 ones and they will last for more than 2 years


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## Salmonidae (6 mo ago)

permitchaser said:


> @Creekchub go to Walmart get 2, 1,000 crank batteries for less than those $500 ones and they will last for more than 2 years


Well depends on what your goals are. If you only plan to have the boat for a short time, don't fish a lot, and/or you don't troll all day in the wind, then maybe you don't need high end batteries. 

Keep in mind that Walmart (as far as I know) does not sell deep cycle batteries. The sell automotive and 'marine/rv' batteries which are most definitely not the same thing. They are not built the same and will not perform the same. Keep in mind also, that cranking power ratings are mostly useless when shopping for trolling motor batteries. A 15 AH battery the size of your hand can put out 1000 amps, just not for very long.

As a point of interest, good SLA 100 AH deep cycle batteries run in the $200 to $300 range or about 40% to 60% of what the referenced SOK LiFePO4 batteries run. 

LiFePO4 batteries have many advantages:

*Battery Protection*
Good LiFePO4 batteries with a decent BMS (battery management system) will not allow the voltage to go too low, protect against shorts, regulate charging balance(s) and so on. 
SLA batteries don't have such things. Instead of Sealed Lead Acid, perhaps SLA stands for Stupid Lead Acid? (Sorry, couldn't resist)

*Longevity*
A generic SLA battery will typically last between 50 and 500 cycles, depending on care. (a cycle being a full discharge and recharge)
A good LiFePO4 battery will typically last 3,000 or more depending on care.
Careful treatment (mostly charging at reasonable rates and temperatures) can extend that 3000 cycles to 8000+ cycles. 

*Size* 
LiFePO4 batteries CAN be dimensionally smaller than SLA. Not all are, as many are built to standard battery form factors.
My SOK batteries are smaller than my Duramax 100 AH deep cycles (another boat) which allowed save a few inches designing the side console for the newest boat.

*Weight *
100 AH SLA batteries typically weigh from 65 to 75 lbs each. 
100 AH LiFePO4 batteries typically weigh 24-30 lbs. The SOKs weigh 24 lbs each, saving me 80+ pounds on battery weight over the Duramax units. That 80 lbs is a BIG deal when designing a boat, and a big factor in choosing to go LiFePO4. 

*Available Power*
A 100 AH SLA can only (typically) provide 50 AH without damaging the battery and can NOT provide you with the full 100 AH rating. If pushed too far, the battery can/will be ruined.
A 100AH LiFePO4 _can_ provide a full 100 AH of power. Drawing it that low may affect the remaining cycle count, but it won't kill the battery. A good BMS won't let you do it.

My Ulterra bow mount (80 lb thrust) pulls an indicated 45 amps at full draw. With 200 AH available it can theoretically run full power (4+ mph) for over 4 hours if absolutely needed. At trolling speeds, depending on conditions and what I'm dragging in the water it draws from 6 amps to 14 amps. So figuring a 15 amp draw to be conservative I could troll for 16 hours. That's enough for me and probably you. 

With two 100 AH SLA deep cycles, I'd realistically only have 100 AH available and 8 hours of trolling time. That's adequate I guess..... except for when the main motor decides to go on strike at the end of the day and you're 4 miles from dock....

*Vibration Resistance*
SLA batteries are very susceptible to vibration damage shortening their life, especially when they are not fully charged. 
LiFePO4 are virtually immune to vibration.

Think about the lifestyle of a boat trolling motor battery. Bouncing along a road being towed to the nearest fishing hole, discharged deeply on the lake/river/bay and in that vulnerable state, bounced back home. Is it any wonder SLA batteries don't last for years and years and years in boats?

*Cost/Benefit*
When I bought my SOK batteries I got the pair for under $900. Yes, they're more expensive now, but they're still a relatively good deal.
At the time, two new Duramax SLA deep cycle batteries would have been around $430. 
So the SOKs were a little more than twice the cost but they should last _at least_ 6 times longer, provide twice the power, weigh less, take up less space, and (should be) safer.
It was a no-brainer.

Oh.
A safety note: damaged LiFePO batteries do not go into thermal runaway (at least according to my research and experiences) and are very unlikely to set your boat/house on fire. You should check that out for your own peace of mind and there are numerous articles out there comparing LiFePO to LiPo batteries and other Lithium batteries. There are a number of different types with their own advantages and disadvantages.

my $.02

Steve


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## permitchaser (Aug 26, 2013)

I’ve had Walmart batteries on my boat for years group 24 is all that fits in my space. This summer we used the 24/80lb. All day with no run down


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## SkimmerSkiffer (3 mo ago)

Pretty sure those are just fusible-links. If you give them a tug and pull apart then it’s a fuse holder but it looks molded together to me making them fusible-links. Can’t troubleshoot anything unless you have a meter handy that reads DC voltage.

Need to see what you’ve got at each battery and at the motor connection.

if a batteries voltage drops below 10v they aren’t “toast” lol it definitely doesn’t help the life of them by any means. but there’s a chance these died on there own from not being charged there’s but no telling. Charge them up and get to testing!


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## Creekchub (Nov 23, 2020)

SkimmerSkiffer said:


> Pretty sure those are just fusible-links. If you give them a tug and pull apart then it’s a fuse holder but it looks molded together to me making them fusible-links. Can’t troubleshoot anything unless you have a meter handy that reads DC voltage.
> 
> Need to see what you’ve got at each battery and at the motor connection.
> 
> if a batteries voltage drops below 10v they aren’t “toast” lol it definitely doesn’t help the life of them by any means. but there’s a chance these died on there own from not being charged there’s but no telling. Charge them up and get to testing!


After multiple charges, the highest voltage I can them up to is 12.5.


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## Salmonidae (6 mo ago)

permitchaser said:


> I’ve had Walmart batteries on my boat for years group 24 is all that fits in my space. This summer we used the 24/80lb. All day with no run down


Sure, they make you happy go for it. Comparing standard SLA batteries to LiFePO4 is kind of apples and oranges anyway.


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## Salmonidae (6 mo ago)

Creekchub said:


> After multiple charges, the highest voltage I can them up to is 12.5.


As I recall, a fully charged lead acid battery should be 12.6 volts or above and typically 12.8. Sounds like probably bad, or at least marginal, unit(s).


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## Creekchub (Nov 23, 2020)

Salmonidae said:


> As I recall, a fully charged lead acid battery should be 12.6 volts or above and typically 12.8. Sounds like probably bad, or at least marginal, unit(s).


I get a rear light on my charger that I think indicates that one battery is bad. I’ll likely do a test run with the trolling motor this week while I explore battery replacement options. Currently the way the way previous owner has them I can’t access the bilge pump or put the plug on the inside of the hull.


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## SkimmerSkiffer (3 mo ago)

Creekchub said:


> After multiple charges, the highest voltage I can them up to is 12.5.


Each battery should be at 12.5 that’s perfectly fine


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## permitchaser (Aug 26, 2013)

I have an onboard MinKota charger. When both lights are green. I unplug it


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## SkimmerSkiffer (3 mo ago)

permitchaser said:


> I have an onboard MinKota charger. When both lights are green. I unplug it


Need to leave it 24/7 to keep them charged fully.


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