On Board Chargers

[Quarry Man]

looking at a new boat. if i end up purchasing the boat, I will want a very nice trolling motor. likely a 36v but maybe a 24v. In a 16' boat with this tm, is an onboard charger worth it? Which minnkota charger should i get?

[J Francho]

A 24v system will be more than enough in a 16' boat.  I've only ever used Dual Pro chargers.  They are worth it. 

[Tennessee Boy]

You're the only person who can answer the question,  is it worth it?  An onboard charger is nice.  It will make your life a tiny bit easier.  It will not help you catch more fish.

[Quarry Man]

36 minutes ago, Tennessee Boy said:

You're the only person who can answer the question,  is it worth it?  An onboard charger is nice.  It will make your life a tiny bit easier.  It will not help you catch more fish.

I realize that they make life easier, but do people use them on 16' boats?

37 minutes ago, J Francho said:

A 24v system will be more than enough in a 16' boat.  I've only ever used Dual Pro chargers.  They are worth it. 

Even if i fish electric only lakes and use it as my main method of getting around the lake?

[Tennessee Boy]

10 minutes ago, Quarry Man said:

I realize that they make life easier, but do people use them on 16' boats?

I don't know how much they are used on smaller boats.  I think if you have room to mount it and want it then go for it.  

 

10 minutes ago, Quarry Man said:

Even if i fish electric only lakes and use it as my main method of getting around the lake?

I've been fishing for 30 years out of aluminum bass boats with 24 volt TMs.  I have never run out of juice or had my batteries get so low that it affected my fishing in any way.  I've never fished an electric only lake but I'm confident I could without a problem.  On my worst 12 hour day of heavy use, I see my top trolling speed drop from 3 MPH down to 2.5 MPH in my 18ft Aluminum Bassboat.  That's with a 24 volt 80lb thrust TM.

[J Francho]

1 hour ago, Quarry Man said:

I realize that they make life easier, but do people use them on 16' boats?

Even if i fish electric only lakes and use it as my main method of getting around the lake?

A 36v will not get you any more run time.  Bigger capacity batteries do that.

[Tennessee Boy]

20 minutes ago, J Francho said:

A 36v will not get you any more run time.  Bigger capacity batteries do that.

Are you saying three batteries of a given size do not have more capacity than two batteries of the same size?

[J Francho]

2 minutes ago, Tennessee Boy said:

Are you saying three batteries of a given size do not have more capacity than two batteries of the same size?

Three batteries, at 36v, yes that's correct.

[Tennessee Boy]

2 minutes ago, J Francho said:

Three batteries, at 36v, yes that's correct.

I'm gonna have to disagree with you on that one.

[SloppyJ]

I put an onboard charger on my 18' tracker. It was worth every penny. I leave an extension cord in my garage where I store my boat and I flip the hatch and plug it in when I get home. I got a cheap Genius 2 bank off of amazon and I wouldn't hesitate to get another one. It doesn't do anything but make charging batteries easier. 

 

As far as trolling motor goes, I still run a 12v 55# motorguide. It's perfect for my boat. If I got a new one, I'd opt for a 24v system and a 3 bank charger. That's probably the sweet spot for an aluminium boat. 

[J Francho]

14 minutes ago, Tennessee Boy said:

I'm gonna have to disagree with you on that one.

You'd be wrong, still.  Google "difference between series and parallel'

 

[Tennessee Boy]

Let say you are powering a 100W light.  At 36 volts you will be pulling 100/36 = 2.78 amps.  At 24 volts you will be pulling 100/24 = 4.16 amps.  So each battery in the 36 volts system will be doing less work than the batteries in a 24 volts system so they will last longer under identical power requirements.  Higher voltage provides the same wattage at lower amperage.  If you had the batteries in parallel you would have 100 watts / 12 volts = 8.3 amps but that 8.3 would be divided by the number of batteries in parallel. 

 

https://en.wikipedia.org/wiki/Electric_power

[PECo]

I have a three-bank Minn Kota Precision Charger (MK345PC). It works, but is a little finicky about the line voltage from the wall. If I use an extension cord that’s too long or is made with too high of a gauge (i.e., smaller diameter) wire, it sometimes fails to properly detect the batteries and begin the charge cycle.

 

I’d try another brand of intelligent charger, first. Newer Dual Pro and Noco chargers have gotten good reviews.

 

Regarding 24 volts versus 36 volts, Minn Kota says the higher the voltage, the more efficient the motor. If the longest possible runtime is important to you, go with 36 volts. However, a 24 volt system should be more than enough for a 16 foot boat.

 

And I think that the convenience of an onboard charger is worth the expense and effort of wiring it up.

[Further North]

11 hours ago, J Francho said:

A 24v system will be more than enough in a 16' boat.  I've only ever used Dual Pro chargers.  They are worth it. 

Agree on 24 volt on a boat that size.

 

I will never own another boat without an onboard charger for longer than it takes me to buy one, have it delivered and get it installed.

 

Why anyone would want to mess around with any other system is beyond me, unless they cannot afford it...and that is what it is.

 

All the major manufacture's chargers will be fine.  Buy what fits your budget.

9 hours ago, J Francho said:

A 36v will not get you any more run time.  Bigger capacity batteries do that.

That's true...if that's all the further you take it.

 

a 36 volt system will, just by default, last longer than a 24 volt system.

1. You won't run it as hard.
2. You won't run it as long.
3. You will have more capacity when you want/need it.

I still think 24 volt is plenty for a 16 ft. boat, but that's a different subject...

 

 

[WRB]

What outboard engine do you plan to run on your 16' boat?

Tom

[J Francho]

8 hours ago, Further North said:

a 36 volt system will, just by default, last longer than a 24 volt system.

1. You won't run it as hard.
2. You won't run it as long.
3. You will have more capacity when you want/need it.

You will not have more capacity.  The first two items *may* be true, but that does not mean increased capacity.  If you have three batteries or four or ten in series, the amp hours are the amp hours.  Period.  A 36v system is a series circuit.  If several batteries are rigged in parallel, then you increase capacity, but you do not increase voltage.  This is science folks.

[Arcs&sparks]

Just now, J Francho said:

You will not have more capacity.  If you have three batteries or four or ten, the amp hours are the amp hours.  Period.  A 36v system is a series circuit.  If several batteries are rigged in parallel, then you increase capacity, but you do not increase voltage.  This is science folks.

Yes and no.  What you’re saying is misleading.  Using a 36v motor vs a 24v motor under the same conditions,  (watt output) you will ABSOLUTELY get longer runtime out of the 36v.  What you’re thinking of, is running both motors at the same amps.  In that case you are correct,  but that shouldn’t be the case in real world situations.

 

Hypothetically, if both motors draw 300watts to go 1mph,  36v wins.

 

Since the watt hours of a 24v system with two 100AH batteries is 2400WH

 

36v with same batteries is 3600WH

 

same task=MORE CAPACITY

 

science

 

-Taylor

Master Electrician

[J Francho]

I totally get what you're saying, and it's arguing semantics. 

[fissure_man]

@J Francho with a higher voltage TM you are drawing fewer amps to deliver the same power.  So even if the amp-hours rating on the batteries is the same, you will go further on a charge with the 36V. 

 

The efficiency of the battery also depends on amp draw - in practice you’ll get fewer amp hours out of your battery when draining it quickly (high amps) than you will at a slower drain.  The lower current draw from the higher voltage TM (for equivalent thrust) is better in this sense as well

 

But in terms of space, weight, and thrust needed to pull around a 16’ boat, I agree that 36V is overkill.

[J Francho]

You're all talking about batteries that operate in a vacuum.  You added weight to the system in not only the batteries, but in wiring, and the unit itself.  The gains are not significant.  I get the feeling some readers may be under the impression that three times the batteries = three times the run time.  Nope.  You are not increasing amp hour capacity.

 

http://www.batteriesnorthwest.com/batteryschool.cfm?TID=17#ANC17

[Arcs&sparks]

7 minutes ago, J Francho said:

You're all talking about batteries that operate in a vacuum.  You added weight to the system in not only the batteries, but in wiring, and the unit itself.  The gains are not significant.  I get the feeling some readers may be under the impression that three times the batteries = three times the run time.  Nope.  You are not increasing amp hour capacity.

You are increasing watthour capacity.  For the same load, yes,  you tripled the capacity.  Watts are the importance here, not amps

[Way2slow]

What JFrancho is saying about Ah capacity is correct one 120Ah battery is going to have the same Ah capacity as three 120Ah batteries in series but the available power in the terms of watts is going to be more than three times that of one battery.

It takes a given amount of power to move a boat at any given speed.  The more hull drag from weight, design or speed is going to increase the amount of power (WATTS) needed. It takes volts X amps to make power (WATTS).

Because 36 volts can deliver three times the voltage, it takes 1/3 the amperage of 12 volts.  That's mean three times longer run time.

However, there are several other factors that make 36 volts run much longer than a 12 volt system.

First, a 24V TM is about 25% more efficient than a 12V, and a 36V is more efficient than a 24V, so there is less battery drain just from the internal characteristics of the different motors.

Second, as the load increases on a battery, it's efficiency and Ah rating goes down considerably.  Since a 36V systems pulls 1/3 the amps of a 12V system for the same power, battery load is greatly decreased and run time increases. 

[McBass_Arkansas]

I am not a fan of onboard chargers. I have had several different brands and they have all failed and caused me battery problems. I got away from them all together. I use three Schumacher ShipNshore chargers and they always work and I do not have any battery problems. It may take maybe two more minutes to hook up, but not having problems is definitely worth it.  And it will save you some weight.  Just my opinion.

 

God bless and good fishing  

[Further North]

2 hours ago, J Francho said:

You will not have more capacity.  The first two items *may* be true, but that does not mean increased capacity.  If you have three batteries or four or ten in series, the amp hours are the amp hours.  Period.  A 36v system is a series circuit.  If several batteries are rigged in parallel, then you increase capacity, but you do not increase voltage.  This is science folks.

OK...I've not been saying this right...

 

What I'm getting it is that I run my 36 volt trolling motor at lower speeds than I ran my 24 volt trolling motor...so I wind up using less stored power.

 

I'm trying to equate it to getting better "gas mileage" because the motor is turning at much lower RPMs and doing a bad job of it.

[Log Catcher]

Several years ago I fished with a fellow on Lake Norman in a Ranger boat. When we got the boat put away he got out some portable chargers. When I asked him about it he said he would not have an on board charger. He said he had seen too many boat fires caused by them.