Anyone use an onboard DC alternator charger?

[Rockin Rod]

Looking at a Stealth or the Minnkota DC alternator charger for my trolling motor batteries for when I go on long excursions up to LOW with no power. Does anyone have any experience with either?

[h8go4s]

I did some research on this last fall. I have a single main battery and a single TM battery, so I was looking into the Minn Kota MK1 (1-bank).

The manual says this: "In order to achieve full output from the DC Alternator Charger, the minimum input from the engine alternator must be as follows:MK-1-DC: 12 amp minimum " My outboard manual (F50 Yamaha) says this: "Maximum generator output 16A."

I talked to a customer service rep at Yamaha and he said at 2-4000 rpm the generator output is 3-4 amps (vague, in my opinion), at 4500 rpm 4 amps and full output at 6000 rpm. That is what we used to call a hockey stick curve, and I'm not confident that I was getting good information. I asked if he could talk to his engineering department and get a chart or graph showing the full rpm vs. amp output for me. He said that he'd have to contact Japan for that and was unwilling to do so.

I then emailed Minn Kota customer service and got this response: "The 12 amp minimum from the alternator is required for the charger to switch over and charge to the trolling motor batteries. I am not sure what the full output of the outboard is however if it at full output at 6000rpms that is what would be needed to apply a charge to the batteries using the alternator charger. If output at 4 amps at 4500 rpm that would not meet the requirement of the charger and would not charge the batteries."

I didn't think any of that was very helpful, so I gave up. I also looked at the Yaninda battery combiner, which sounds like it would work for me, but haven't found a retailer who handles them, so I'm a little gun-shy.

http://www.yandina.com/c100InfoR3.htm

[Loon]

I know that my Mercury has a 50 amp alternator and I have the 2 - bank DC charger and the charging light is on even at idle and I rarely have to charge my trolling batteries.

I have huge AGMs and don't run the trolling motor super hard but I fish 5 times a week and figure it can't hurt to harness the otherwise wasted amperage being produced by my outboard.

My week-long trip to an island on Rainy was the original reason for the purchase but we have a nice Honda generator now so it is no longer necessary.

As satisfied as I have been with the purchase I am not 100% positive that I will put one in my next boat but that is simply because I have a nice generator now...not because the product doesn't perform as advertised.

[CaptainMusky]

Good info Loon. I am assuming you have the minnkota model correct?

[CAMAN]

Pssst....

Quote:

Always allow batteries to "cool off" after charging. The cooling time is very important because heat is generated during the recharge and discharge cycles. Without the cooling time the heat grows, accelerating grid corrosion, which is one of the major causes of battery failure.

Opportunity charging (quick charging between uses) is detrimental to battery life. While it is true that the shallower the cycle, the more cycles the battery can deliver, opportunity charging is not good because the cooling time is eliminated, shortening life. (I.e. One charge cycle per day is preferable.)

[CaptainMusky]

Cite your source.

Again, I trust someone who has actually used these systems and their experience with them then some random quote.

You obviously haven't read or comprehended the information I provided at your request.

Why don't you move on Caman since you "don't want or need one"?

[CAMAN]

You're defending these things like you own part of the company...

And you know dang well if I cited my source properly I would get a "timeout"

It came from a website called "northwest battery" and a few other sites say the same thing...

[CaptainMusky]

Whatever dude. Just move on. You cannot stand to be wrong or realize you don't know something.

Why do you care again I ask since you don't "want or need one"?

I on the other hand WILL be buying one based on feedback from others and research because I see a tremendous benefit.

You go an putt around on your ponds and plug into your 120 outlet at the end of the day. Those of us who fish in places who don't have that option look for solutions to meet a need.

[fishwater]

I'm interested in installing one on my boat, I do a lot of camping out of it. I searched through a pile of reviews of the Stealth1 dc charger and did not find one incidence of anyone having a single complaint of any kind. In all honesty, I only found one complaint for any brand, and that one is no longer available. A number of long time users of the stealth1 claim they got longer battery life, even suggesting they could use off-brand batteries with improved performance.

I think the suggestion to not "opportunity charge" is for instances where the duty cycle between discharge and charge is too continuous. Discharging, then re-charging (at a fast rate) with little downtime. I don't think any of the marine dc chargers will overheat your batteries, reducing battery life.

[CaptainMusky]

Ssshhh fish water! Don't tell caman this he won't understand and it can be our secret.

I'm impressed by the stealth1 as well but not as much on the price. Its basically double the price but maybe its worth it.

I did talk with the guy in charge at stayncharge earlier this week. Great guy and really helpful. Still not sure which way to go but I have to do something along with replacing ALL my batteries after only 3 years because they are shot. One won't take a charge and the others are acting up as well.this is the result of religiously using an AC charger after every use and monitoring levels etc.

There is no way my battery life decreases when I get one.

[Rockin Rod]

Of the available options out there, I've narrowed it down to the minnkota or the Stealth. Leaning towards the stealth, but I'm a little intimidated about installing it versus if I go with the MK my dealer will put it in for me when my boat comes in from the factory.

Also, as part of the boat deal I worked, a minnkota precision 2-bank charger was part of the deal. Can't decide if I should leave that in or have them credit me and go with an AC/DC Stealth system.

Decisions, decisions.

[CaptainMusky]

Oh the quandary! The minnkotas precision is as good as anything out there for an AC charger. I say keep that since its included and they probably wouldn't credit you the real value of it to replace with something else.

After that get whichever DC system you like. The one thing about stealth as opposed to minn kota is you don't have to wire into factory harness with the stealth with the "purple wire". Not a major deal but if you have to do yourself it may make you uneasy.

[CAMAN]

Whatever dude. Just move on. You cannot stand to be wrong or realize you don't know something.

Why do you care again I ask since you don't "want or need one"?

I on the other hand WILL be buying one based on feedback from others and research because I see a tremendous benefit.

You go an putt around on your ponds and plug into your 120 outlet at the end of the day. Those of us who fish in places who don't have that option look for solutions to meet a need.

LOL!

And I see you aren't denying you own any stock in the company...

Opportunity charging is exactly what these things do, how long is it between you pulling the motor up and cranking up the motor? 10 seconds? It takes a heck of a lot longer than 10 seconds to cool down the internals of an 80 pound battery. Then turning off the motor and starting the trolling motor another 10 seconds maybe 30 if your slow?

[CaptainMusky]

Which company do I own stock in? Since I have mentioned at least 3 of the main players.

I get it, you cannot comprehend how these things work.I don't know how many times I can tell you that NONE of these solutions force ALL of the amperage from the outboard for you to understand OR the fact that some of these systems charge for mere minutes at a time on a single battery to eliminate any concern of heat buildup OR the fact that thousands of people use these including law enforcement, us military, coast guard etc. But I understand its "opportunity charging".

What if you pulled your motor out and then immediately plugged the ac charger in? SMH

[CAMAN]

Calm down Mr Musky...

Some people can get riled up over the most insignificant things.

Oh, and please tell me how charging a battery in 10 minutes immediately after it has been used for an hour is good for it...

Quote:

One of the systems will recharge your trolling batteries in 10 minutes for every hr you used your trolling motor on high.

And don't say "it switches back and forth" because you would need probably 40-50(maybe even more) amps to fully charge a partial battery in 5 minutes. Read between the lines of what these manufactures are saying they sound all great but when you look into it they aren't all that great for your batteries lifespan.

At this point if you REALLY needed one the Minnkota charger is probably the best as it limits the amperage. But i would still let the battery cool down before and after charging.

[CaptainMusky]

At this point I could honestly care less about what "you" would do since you have never used ANY of them to provide any factual evidence which is what was asked for by the OP.

You do understand that in a 24 volt system the amperage draw is split evenly amongst the two batteries (provided they are in equal condition)?

24 amp draw may require as few as 5 minutes to restore each battery (depending on output). I know its hard to understand for the obtuse.

[CAMAN]

Oh booohooo, someone disagrees with you. That gives you right to call them names. You know I would have given up on this thread 3 pages ago if you didn't keep calling me out. I like jabbing the bear when they start calling me names. See ya bozo!

[delcecchi]

Caman, why would a battery get hot as it is discharged? The internal resistance is quite low, much less than an ohm, as can be seen by the fact that the battery voltage doesn't drop very much as load is increased.

And likewise the overvoltage to charge a battery is only a couple volts over the 12.6 volt electrochemical voltage. So charging at 20 amps puts maybe 60 watts into that 80 pound battery. Take a long time to heat it up at that rate, and most of the heat would conduct away into the air.

So for typical trolling motor and charging currents I am skeptical of claims that heat is an issue.

[CaptainMusky]

Del don't start applying more logic with this guy. You cannot provide enough info for him to "get it" even though he "doesn't want or need one".

[CaptainMusky]

Oh booohooo

boohooo that's the best you can come up with? At least know what you are talking about if you are going to interject your opinion on something. Then and only then does your opinion matter.

[CAMAN]

Caman, why would a battery get hot as it is discharged? The internal resistance is quite low, much less than an ohm, as can be seen by the fact that the battery voltage doesn't drop very much as load is increased.

And likewise the overvoltage to charge a battery is only a couple volts over the 12.6 volt electrochemical voltage. So charging at 20 amps puts maybe 60 watts into that 80 pound battery. Take a long time to heat it up at that rate, and most of the heat would conduct away into the air.

So for typical trolling motor and charging currents I am skeptical of claims that heat is an issue.

[CAMAN]

boohooo that's the best you can come up with? At least know what you are talking about if you are going to interject your opinion on something. Then and only then does your opinion matter.

Yup and my opinion matters just as much as yours.

So glad I just found the "ignore this user" button!

[Rockin Rod]

And then you can find plenty of info online that says the opposite.

From Interstate batteries:

Should I allow my battery to become highly discharged before recharging?

Short Answer: No.

A lead-acid battery doesn’t require to be discharged to a specific level prior to being recharged. However, the more times it is discharged to a low state-of-charge the less cycle life. As a point, “opportunity charging” is a term that refers to battery charging when the opportunity presents itself rather than waiting until the battery reaches a specific discharge level. If it is a convenient opportunity to recharge daily and the battery is showing 75% charged, don’t wait; charge it.

from mpoweruk

Opportunity Charging

Opportunity charging is charging the battery whenever power is available or between partial discharges rather than waiting for the battery to be completely discharged. It is used with batteries in cycle service, and in applications when energy is available only intermittently.

It can be subject to wide variations in energy availability and wide variations in power levels. Special control electronics are needed to protect the battery from overvoltage. By avoiding complete discharge of the battery, cycle life can be increased.

Availability affects the battery specification as well as the charger.

Typical applications are:-

Onboard vehicle chargers (Alternators, Regenerative braking)

Inductive chargers (on vehicle route stopping points)

Solar power

Wind power

[CaptainMusky]

You haven't said what being "charged or discharged" at a high rate is? 10 amps? 15? 20? Just so you know most AC chargers will put 10 to 15 amps back into a battery then float charge the rest of the way to reach capacity. Are these doing so at a "rapid rate"?

I have no idea why you are interested in any discussion since you "don't want or need one". Sounds like someone just came to troll.

[Surface Tension]

There are some good points but bad delivery.

There isn't any need to get after each other so lets try and get along.

A high rate is a rate that boils the battery.

I have a 3 phase bulk, absorption, float 15 amp charger and rarely will the battery take more then 10 amps and that is for a short time.

There are pros and cons with the DC charger hooked up to a deep cycle in use.

There are 3 common causes for early battery failure.

Sulfate and more then one way for that to happen:

If your going to charge your battery Its Best to charge it to full. Interrupting the charge before its charged fully is not good for the battery.

Charge the battery soon after use. Best would be when you get home after a days fishing.

Keep the level up in the battery. If the plates are exposed even once you've built up sulfate.

If you have a DC charger and are out for only the day, turn it off and charge the battery when you get home. If your out for the weekend or longer use your DC charger. Really thats where these shine. With a little management, use the charger so that your relatively sure that you'll complete the charge to full when in use.

Heat:

Batteries overheat when not subject to the charge and discharge repeat cycles so believe it that your going to build up more heat when you do.

Being in a battery box and usually a confined closed space, this heat isn't going to dissipate.

If you troll for a few hours then run for 20 minutes and repeat I can see heat building up.

If you troll a few hours and run for a few minutes, that incomplete charge isn't any good either.

BEST.

A battery charged after each use to full.

Levels kept up.

One that hasn't been overheated.(I charge my in the evening)

Getting pounded in the bow of the boat isn't helping either but what can you do there.

DC Charger

Convenient and extends run time on long weekends or extended weekends.

But not the best in charging management and heat although the intermittent pulse addresses some of that heat. Having to buy a new battery more often for the benefits of the charger

is probably a small trade off for those that need it.

[CaptainMusky]

BEST.

A battery charged after each use to full.

Levels kept up.

One that hasn't been overheated.(I charge my in the evening)

Getting pounded in the bow of the boat isn't helping either but what can you do there.

DC Charger

Convenient and extends run time on long weekends or extended weekends.

But not the best in charging management and heat although the intermittent pulse addresses some of that heat. Having to buy a new battery more often for the benefits of the charger

is probably a small trade off for those that need it.

Very good points Surface!

It was never my intent to use a DC charger as a replacement for an AC charger. Merely looking for a way to charge my batteries when AC is not an option like on week long trips to LOW camping.

My plan has been that I would disconnect the DC charger from the system when doing short runs. My install was going to actually use the Marinco plug (same as used for trolling motor) and plug the unit directly into the receptical in the back when I wanted to use it. I would still rely on my AC charger for normal use when I have the ability to plug it in.

[CAMAN]

Thank you Frank, you are obviously more fluent with your fingers than I am.

[delcecchi]

Surface, why do you think that partially recharging the battery during the day is a bad thing?

[CaptainMusky]

I wanted to bring this back up after I completed my purchase and install.

I ended up going with the Stealth1 DC. I am using it in conjunction with the 2 bank Minn Kota AC charger I had already.

I will admit I was a bit intimidated by the install before I got started and with my LOW trip looming (leave on June 17th) I was nervous about getting it installed and functioning properly before I left.

Why did I decide on Stealth? Well, #1 it was Danny at Stealth. The guy is very willing to help and explains things in great detail to make sure 1) he understands what you are trying to accomplish 2) knows how your boat is wired (mine is 24 volt, but its "jumpered" in the plug not 2 batteries in series) 3) comes up with a plan to address your needs. #2 it seems very well built. It is made out of steel which most things are plastic these days and completely potted on the inside so it should be waterproof.

I thought long and hard about going with the Minn Kota option. I finally went with Stealth because I felt it was a more quality piece though I am sure the Minn Kota would work fine because I have had great luck with their other chargers over the years.

I received the unit Monday and began the install then and finally wrapped it up last night getting everything hooked up, but not fully knowing whether it was actually working or not.

The one good thing I have come to realize off the bat, not only will I have the capability of charging my trolling motor batteries while on the water, but now I can charge my cranking battery by just plugging in my AC unit whereas before I had to plug in a separate charger since I didnt have a 3 bank charger.

Basically my AC unit connects to the Stealth1 DC which is feeding off my cranking battery. When my charging needs to the cranking battery have been met whether it is my motor's alternator OR the AC charger THEN and ONLY then will my trolling motor batteries be charged.

Over lunch today I confirmed this. I was using my digital meter to measure voltage at the crank, trolling batteries, etc. At rest my crank battery was 12.8 volts, while my trolling motor batteries were 26.1. If I plug in the AC unit my crank voltage would climb to 13.1 while my Stealth Gauge would start at 26.1, but when the crank hit 13.1 the stealth gauge then climbed from 26.1 to 27.9. This was proof that my AC unit was essentially charging my trolling motor batteries being driven by the Stealth1 DC.

I havent had it on the water yet to test the effectiveness while the big motor is running, but since it worked with the AC on and switched over I am confident it will there as well.

Is this someone for everyone? Absolutely not. Many folks may spend the vast majority of their time on small bodies of water or not really work their trolling motor much. This isnt something you would benefit from. If you always have access to electricity but use your trolling motor heavy and spend multiple days on the water you may not need it either but in an individual day your time on the water could be lengthened because of having it. But if you spend time in areas where you use your motor heavily, have little or no access to electricity for days, this is something that could really help you out.

When I get back from Canada next week I will be sure to share my experience with the unit because I will have no electricity for 5 days. We do have a Yamaha inverter generator that I could use, but I want to see at the end of each day what my battery life is like.

I know at the end of each day last year I had 50% or less. Interested to see how it pans out now.

[Rockin Rod]

And I went with the Minnkota on my new Lund, mainly because I could get it installed by my dealer when I got the boat.

I haven't put it through the paces yet, but will next month up at LOW.

[CaptainMusky]

Cool!