12v trolling motor battery recommendations

Deutch420 · May 8, 2015

I'm looking at getting a 30lb trolling motor. It runs at 12v and 20-30amps. I'm looking for suggestions on a battery setup. It seems everyone uses marine deep cycle batteries. But they weigh 40-60~ pounds and cost 80-200$. All the reviews on the cheaper ones are either 1 star or 5 star reviews.... Ide love to be able to get 4 hours of use out of the battery. Any ssuggestions / recommendations?

wesnewell · May 9, 2015

If you want to stay cheap, 4s 5000mah rc lipo packs are about as cheap as you can get and should work fine. I don't know how many you'd need to parallel for 4 hours use, but I'd think 12 would be plenty. About $300 and 14 lbs. Or you could go with a 60ah 12V lifepo4 pack at probably twice as much weight and price.

John in CR · May 9, 2015

Use a pair of Nissan Leaf modules in series. That will give you a bit more than 12V, and the 66ah at 14.6V nominal will only weigh 16.5lbs.

jaunty · May 10, 2015

post an updat if you figure something out. i also have an electric trolling motor, but i used standard duralast 100 AH lead acid.

Deutch420 · May 10, 2015

John in CR said:
Use a pair of Nissan Leaf modules in series. That will give you a bit more than 12V, and the 66ah at 14.6V nominal will only weigh 16.5lbs.

From what i can gather, they are 7.6v 60ah @ 129 USD. So 2x in series would give me a 15.2v 60ah pack. and would cost me 260$. Aagain, im not sure if spending triple to save 20-30lbs is worth it in this scenario. but an interesting suggestion!!

wesnewell said:
If you want to stay cheap, 4s 5000mah rc lipo packs are about as cheap as you can get and should work fine. I don't know how many you'd need to parallel for 4 hours use, but I'd think 12 would be plenty. About $300 and 14 lbs. Or you could go with a 60ah 12V lifepo4 pack at probably twice as much weight and price.

but a acid battery from walmart costs 1/4th that and will give me the 5 hours of use im looking for. But heavy!

jaunty said:
post an updat if you figure something out. i also have an electric trolling motor, but i used standard duralast 100 AH lead acid.

i have so much lipo in the house ide love to use. but it doesnt seem like its worth it when i can spend 80$ at walmart and get a deep cycle marine battery that everyone claims they use for 5 hours of continuous trolling. yea it weighs 40lbs, but thats not a big deal when you have 350lbs of human on board, 70lbs canoe etc... In reality, a 40lb battery isnt even 1/10th of the weight load i go out with.

So im prob gonna get a lead battery

. i feel so silly saying that, but its prooven, easy and cheap.

Hillhater · May 10, 2015

Deutch420 said:
.
So im prob gonna get a lead battery . i feel so silly saying that, but its prooven, easy and cheap.

Easy maybe, but the only thing proven about lead is you won't run continuously for 4-5 hours on a 100Ahr lead battery.
And only cheap if you don't use it frequently....because you know it will need replacing long before the LiPo does. :wink:

...... I have so much lipo in the house ide love to use. but it doesnt seem like its worth it when i can spend 80$ at walmart

Why wouldn't you use the LiPo if you already have it ??

Deutch420 · May 10, 2015

Hillhater said:
Why wouldn't you use the LiPo if you already have it ??

i have 9x 4S hardcase packs, all with 1 bad cell. im yet to figure out a way to remove the bad cell from each pack. So while i have 27 good lipo cells out of 36, i need to figure out how to remove the 9 bad ones (1 from each pack) before i can use the good 27.

I recently made a thread, maybe someone can help. But all the cells are glued together, so how i would remove one from the group, i have no idea. And they're soldered to circiut boards (2 cells per board. 4 cells per pack). I can determine what cell # is bad, and then follow the color wire from the balance tab to the individual cell, so i know which one is bad. i just dont know how to remove it from the group physically.

amberwolf · May 10, 2015

There are a number of threads about repairing such packs, if you look around.

999zip999 · May 11, 2015

You should do a capacity test on each cell so as to make a matched battery that can keep in balance. Lowering the fire risk. Using 70% or less. Plus how old are these packs ?

Deutch420 · May 11, 2015

999zip999 said:
You should do a capacity test on each cell so as to make a matched battery that can keep in balance. Lowering the fire risk. Using 70% or less. Plus how old are these packs ?

One year maybe. I'm not too sure why the 1 cell went bad in all of them. I assume something went bad in the harness or something. But these were for a 3rd bike for when people came over. Wasn't used much at all. Tried to store them @ 3.83 when I knew it wasn't going to be used for a while. It was a 50v15ah pack.

Deutch420 · May 13, 2015

Not to hijack my own thread, but is anyone familiar with charging a basic deep cycle marine Acid battery? I have a few questions regarding the charging. I called the battery manufacture and they say max charge is 12.7-12.9v and max amps during charge is 10amps. But then they say to charge at 2.4v per cell which is 14.4v!! So I read these acid batteries need higher voltage to reach the desired voltage. But 14.4v???? I stopped my I charger when it read 12.92v. Took a reading from the terminals, it was 12.73v. 1 hour later it was 12.63 and stayed there. If I let it go to 14.4v wouldn't that be a severe overcharge??? I called the battery manufacturer and they said charging at 14.4v is normal, but I'm personally totally confused on how 14.4v charge will get me 12.7v??

PS: I'm referring to the 29DC Walmart battery. I went out in 10mph winds today for about 5 hours. Trolling for about 2.5 -3 of those hours. Battery went from 12.7-12.55v. So this battery definitely has some serious longevity.

Punx0r · May 14, 2015

A lead acid battery is normally stated as at full charge when the resting voltage is 12.65V (discharged at 11.8V). This is unloaded and with any "surface charge" dissipated. Surface charge is the higher you see when measuring the voltage soon after disconnecting the charger - the battery reads a higher voltage but this doesn't indicate any extra capacity over the 12.65V figure. The surface charge will dissipate with application of a small load or leaving the battery to stand for a day.7

Anyway, onto charging. The battery has a float/standby charge and a fast/full charge voltage. 14.4V is the fast charge and will theoretically get you to 100% of rated capacity, however it causes gassing in the battery and cannot be left in this state for long periods, or the battery will eventually lose its electrolyte.

The float charge voltage is normally given as 13.8V, but for serious applications is derated for higher environmental temperature and might be as low as 13.2V. This will get the battery to within a few percent of full rated capacity but can be left on the charger indefinitely (and indeed this is the best way to store a lead-acid battery).

In summary, charge at 14.4V and disconnect when the charge is complete. Or charge at 13.8V and don't worry about how long the charger is left on the battery. My preference is for the latter unless in a hurry, but fast charging isn't good for lead-acid batteries. I suspect it will come down to what your battery charger happens to do - which I suspect will be 14.4V Best to check because I've seen some cheap-and-nasty automotive chargers go as high as 17V!

It sounds like you used approximately 15% of your battery's capacity on your trip.

Deutch420 · May 14, 2015

Punx0r said:
A lead acid battery is normally stated as at full charge when the resting voltage is 12.65V (discharged at 11.8V). This is unloaded and with any "surface charge" dissipated. Surface charge is the higher you see when measuring the voltage soon after disconnecting the charger - the battery reads a higher voltage but this doesn't indicate any extra capacity over the 12.65V figure. The surface charge will dissipate with application of a small load or leaving the battery to stand for a day.7

Anyway, onto charging. The battery has a float/standby charge and a fast/full charge voltage. 14.4V is the fast charge and will theoretically get you to 100% of rated capacity, however it causes gassing in the battery and cannot be left in this state for long periods, or the battery will eventually lose its electrolyte.

The float charge voltage is normally given as 13.8V, but for serious applications is derated for higher environmental temperature and might be as low as 13.2V. This will get the battery to within a few percent of full rated capacity but can be left on the charger indefinitely (and indeed this is the best way to store a lead-acid battery).

In summary, charge at 14.4V and disconnect when the charge is complete. Or charge at 13.8V and don't worry about how long the charger is left on the battery. My preference is for the latter unless in a hurry, but fast charging isn't good for lead-acid batteries. I suspect it will come down to what your battery charger happens to do - which I suspect will be 14.4V Best to check because I've seen some cheap-and-nasty automotive chargers go as high as 17V!

It sounds like you used approximately 15% of your battery's capacity on your trip.

While I understand and comprehend what you said, I'm still confused.
For example, I left my icharger on the 2.4v per cell option like the charger manufacture, battery manufacture and you suggested. However, I got concerned when it got near 13v (charger readout), so I stopped the charge early. Let it sit overnight, and its resting at 12.64v. So your telling me if I let it go to 14.4v its only going to charge my battery .05v more? This totally makes no sense to me and the voltage I'm.seeing from my b ttery terminals (after 20 hours of rest) corrilates with my confusion. BC it appears 13v puts me at 12.65v rested after only a 30 min charge at 2amps (only discharged to 12.55v) Why on earth would I go to 14.4v

Deutch420 · May 14, 2015

dnmun · May 14, 2015

what is a surface charge?

Deutch420 · May 14, 2015

dnmun said:
what is a surface charge?

according to the replies ive recieved above, surface charge is the artificial volts shown at the battery terminals after charging. The volts will dissipate down after charge, eventually hitting the real, "rested" volts. You see higher volts at the terminals after charge b/c "In order to recharge a 12-volt lead acid battery with a fully charged terminal voltage of 12.6-volts, the charger voltage must be set at a higher voltage.During the battery recharge cycle lead sulphate begins to reconvert to lead and sulphuric acid." So surface charge address's the extra volts you will see at the terminals after a charge, before the extra volts needed to charge the battery have a chance to dissipate. the extra volts seen at the terminal after charge are superficial, and will drastically drop over the next 15 +- hours or if you apply load. again im new to all this, but this is what i gather from what im reading and seeing when applied in life.

Punx0r said:
A lead acid battery is normally stated as at full charge when the resting voltage is 12.65V (discharged at 11.8V). This is unloaded and with any "surface charge" dissipated. Surface charge is the higher you see when measuring the voltage soon after disconnecting the charger - the battery reads a higher voltage but this doesn't indicate any extra capacity over the 12.65V figure. The surface charge will dissipate with application of a small load or leaving the battery to stand for a day..

bigmoose · May 14, 2015

If you want lead, get two 6 Volt golf cart batteries at Costco. It was the best $/kwh with good cyclic life that I found. I use them on a 12 volt sump pump in the basement. They are not light.

Deutch420 · May 14, 2015

bigmoose said:
If you want lead, get two 6 Volt golf cart batteries at Costco. It was the best $/kwh with good cyclic life that I found. I use them on a 12 volt sump pump in the basement. They are not light.

better than 120ah for 95$?

bigmoose · May 14, 2015

I paid about $60 apiece. We all think they are very close to Trojan T-105s ... though we can't prove it. Trojan data sheet below. Amp hours will require the definition of discharge rate for comparison.

Hillhater · May 14, 2015

As previously stated, the 14.4 v (some even higher) charge setting is for a faster charge.... More volts means also more amps,. It can reduce the charge time significantly.
It won't " boil" the battery, but it will cause a lot more gassing and if left on for extended periods will cause the battery to heat up...maybe 30-40deg C.
Generally , you can recharge most (75 % ) of the capacity before any gassing will occurr.
What amperage are you seeing at these charge voltages, ?
Charger rating..amps... Should be proportional to battery capacity.

In a previous life, I have bought many genuine Trojan 105's for industrial floor cleaners.
Even with relatively light daily use, < hour per day,..after less than a year, the capacity is dramatically reduced to near half, such that they become unusable for reliable operation.
At $1200+ per set! they were a painful lesson in selecting floor cleaning equipment !

kje · May 14, 2015

I made my own lithium battery for my 12v trolling motor.

I used old laptop-batteries and got some good advice from DrkAngel's tread.

Punx0r · May 15, 2015

If ~13.2V gets it charged in the time you need then go for it

2A charge on a 100Ah battery is a very low charge rate (0.02C)

Deutch420 · May 17, 2015

Punx0r said:
If ~13.2V gets it charged in the time you need then go for it 2A charge on a 100Ah battery is a very low charge rate (0.02C)

i think i have it figured out now. I charge at 10amps. charger drops from 10 amps to 1 amp once it hits 14v. after surface charge is removed, im left with a 12.75v charge. works great. last discharge was to 12.51. icharger at 10amps got it to 14v in 1 hour 29 minutes.

Hillhater · May 17, 2015

.......last discharge was to 12.51. icharger at 10amps got it to 14v in 1 hour 29 minutes.

So allowing for charger/charging efficiency, you are probably only putting 12-14 Ahrs back into that battery.
If that is a typical use and charge cycle, your trolling motor is not using much juice !

?..... I went out in 10mph winds today for about 5 hours. Trolling for about 2.5 -3 of those hours. Battery went from 12.7-12.55v. .......

...you might have been able to do the same with 3 of those 3 S. LiPo packs ! :shock:

Deutch420 · May 17, 2015

Hillhater said:
.......last discharge was to 12.51. icharger at 10amps got it to 14v in 1 hour 29 minutes.

Click to expand...

So allowing for charger/charging efficiency, you are probably only putting 12-14 Ahrs back into that battery.
If that is a typical use and charge cycle, your trolling motor is not using much juice !

?..... I went out in 10mph winds today for about 5 hours. Trolling for about 2.5 -3 of those hours. Battery went from 12.7-12.55v. .......

Click to expand...

...you might have been able to do the same with 3 of those 3 S. LiPo packs !

You can say that again!!! The motor only pulls 30 amps max speed. 15amps middle speed. And I went a few miles with it. Still yet to have a discharge under 12.5v Lol. But I did go with the massive 60lb 125ah battery. Once I go into the bay I know I'll be consuming more, but these fresh water trips aren't eating up much juice at all!!

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