Charging System - 50hp Merc 4 Stroke

[sacman11]

I have been reading the large amount of posts relating to dual battery charging, onboard charges, isolators, etc. but I cant seem to figure out the best solution for my situation.

So here is my layout:

99 - 16.5 ft Alumacraft fishing boat
99 - 50hp Merc Marine 4 Stroke (electric start)
30lb Minkota Trolling motor
Stereo
Lights
Bilge pump, and livewell pump.

I currently have two batteries (27) for this setup.

#1 battery is connected to 50hp Merc for starting and running of all my accessories except for the trolling motor.

#2 battery is on its own and only runs the trolling motor.

Right now I charge the batteries individually at home with a standard marine battery charger. This requires unhooking each battery, pulling them out of the boat and charging them.


I would like to hook up the batteries to a charging system which would allow me to charge both batteries from the 50hp Merc (if even possible) when it is running, as well an onboard battery system like promarine which I can just plug into when I get home and it will automatically recharge both batteries without having to remove them.

I have also read about the stay-n-charge system which would allow the charging of the batteries while pulling the boat home.

What is the simplest, move cost effective solution for me.

I do alot of back country fishing/camping where I dont have access to 120v DC plugins for 2-3 days. I would like an onboard motor/charge system to help me keep the trolling motor charged during trips like this.

Thanks

 

[lncoop]

Re: Charging System - 50hp Merc 4 Stroke

The bad news: Unless someone makes a really high dollar one I'm not aware of there is no effective charger available that doesn't require 120VAC. There are solar models, but they're just maintainers and won't really charge your batteries. Excellent dual bank on board chargers can be had for less than $200 and are worth every penny for reasons I won't get into unless you ask, but they require a nearby receptacle.
The good news: Two good batteries provide your rig with lots of power that your setup won't rapidly drain assuming everything is hooked up properly. You should be able to get a couple of days' fishing in on your TM battery if you don't run it on the highest setting.

If you know you're going to be away from AC power for several days you might just need to have a third battery on hand in case. Your motor will charge batteries, but not very quickly. If you want it to charge the second battery you just need to install a battery selector switch, which you can find here on iboats. They're not difficult to install. You'll find all the help you need by performing a key word search in this section. Welcome to iboats.

 

[Silvertip]

Re: Charging System - 50hp Merc 4 Stroke

Why do you pull the batteries out to charge them. They can remain in the boat and charged there -- unless of course the boat is stored in a lot somewhere. If finances are an issue, then all you need is a single output on-board charger such as a 6 amp Guest which is available for about $75 give or take a little depending on how you shop. Attach that to the troller battery and plug in at home. It can be left on indefinitely without harming the battery. Your 50 Merc does not have enough alternator output to keep a troller battery topped off. Even if it did, you would need to make very long wide open throttle runs to accomplish that. For your back woods outings I suggest you buy a small generator that has a 12 volt charging output. These units can be found brand new for about $100. Our local farm store and Cabelas had them. Keep in mind these are not power houses and are not intended for continuous duty. They are temporary power sources and for you they would be ideal. Solar panels are not practical for your application.

Adding an ACR (automatic charge relay) to your boat would probably allow slightly longer run times for the troller but it is not a replacement for the on-board charger.

 

[sacman11]

Re: Charging System - 50hp Merc 4 Stroke

Thanks for the replys.

Budget is not an issue. I am really looking for a solution that makes the most sense. I dont want to add another battery because of room contrainsts. I am not sure why a ACR or charge-n-save system wouldnt work? IT appears that for $300 I can get a system that will charge batteries while trailering, and while on the water.

Silver mentioned my 1999 50hp merc would not have enough alternator to charge my battery. Can anyone confirm this. I was under the assumption that this motor would provide 10-15amps depending on speed, idle, etc.

Thanks

 

[lncoop]

Re: Charging System - 50hp Merc 4 Stroke

It wasn't my intention to dissuade you from buying an ACR. That will definitely help some, but I don't think you'll find anything other than a generator that will give you the charging capacity you're looking for. If you have the money to spend go ahead and get whatever you think will work best for you. It's clear you know what your needs are and you seem to be plenty handy. My thought with the third battery was not to install it in the boat, but to always insure that it's fully charged then leave it in the truck until you need it. That way on day three of the back country trips you'll have a fresh battery for the TM. That's always worked well for me. By the way, the thought of those back country trips makes me jealous.

 

[Silvertip]

Re: Charging System - 50hp Merc 4 Stroke

Here's the deal on alternator output but lets start with the troller. A 50# trolling motor will draw about 45 amps of current so if the motor ran for one hour that amounts to 45 amp/hrs. If you look at the label on the troller battery it probably has a number stated as "Reserve Minutes: xxx @ 23 amps. The XXX in this case will likely be in the 150 range which is about 2.5 hours. In a nutshell that set of numbers means the battery will be able deliver a minimum of 23 amps for 2.5 hours and remain in spec. So, run your troller wide open and you are drawing nearly twice the test rating and in a couple hours would have what is essentially a dead battery. Obviously running at slower speed will lengthen that time to some degree. Now to the motor. The 16 amp alternator on your motor delivers 16 amps PER HOUR at WOT. So to replace the current in that battery you would need to run wide open for about 4 hours or looking at it another way, it would take three times as long to recharge as it did to discharge the battery. Sound practical to you?

 

[sacman11]

Re: Charging System - 50hp Merc 4 Stroke

Well, its been awhile since my original post and I am still without a solution to my original post. Incoop and Silvertip have provided some excellent advice, and I may be simply leaning toward adding a third battery.

What I am wondering is if anyone has any expirence with a VSR system like this from BEP Marince
http://www.bepmarine.com/home-mainmenu-8/product-272/trolling-bank-vsr-module

I am wondering if this on board charging system would allow me to manage all three batteries and maintain a charge with my 99 50hp Merc 4 stroke.

Does anyone have any expierence with this type of charging system and my type of motor.

Thanks

 

[Silvertip]

Re: Charging System - 50hp Merc 4 Stroke

Gosh, we just explained that you can't keep two batteries charged from the engine -- much less three. Forget charging from the engine as it of little to no advantage unless you run very long distances between fishing holes. And I'm not talking a mile or two but rather an hour or more. It doesn't matter what device you use to manage charging. It is the engine that supplies the power and the switch or ACR/VSR simply sends it to a specific battery. However, if you are intent on adding an ACR/VSR or dual battery switch go ahead and do it. In your case an ACR/VSR is probably best but those do not have the versatility of a switch. A dual bank charger with 10 amps per bank will do nicely for an on-board charger. Since you are also considering a three battery setup, be aware that a dual battery switch and ACRVSR are basically two battery devices so that still leaves the third needing to be paralleled with one of the others. As a final "numbers" reminder, for every 16 amps you suck out of the battery you need to run the outboard wide open for a minimum of one hour to replace that energy. Remember also, 16 amps is not much power and represents a little less than 1/3 of the maximum current draw of the troller.

 

[Boatist]

Re: Charging System - 50hp Merc 4 Stroke

Slivertip is right your 50 HP Merc can not recharge your Trolling motor battery. If on a windy day you ran trolling motor on high and used 45 amp hours in one hour.

Now you try to recharge with your 15 amp alternator on your motor. You might think you could run your motor for 3 hours fast enough to put out 15 amps and the battery would be fully recharged. Well it will not be fully recharged in 3 hours. The motor will put out a voltage around 14 volts and the battery will start recharging. At first it may take 15 amps but as it charges at 14 volts the amperage will drop off. After an hour of recharging at 14 volts the battery will lileky only take 7 amps and after 2 hours only 5 amps. So to fully recharge will take 5 or 6 hours at least.
Another factors is outboard alternators are designed to recharge your starting battery. This would normally take 5 minute to replace the current need to start your motor. Most are not designed to run at full output for hours and many will over heat at max charging for any length of time.
The bass boat we fish tournaments in we use a group 27 battery and on the prefish day we usually fish from 5 am till noon then head home. About 1300 we will hook up a 15 amp automatic charger. Then the next day will leave at 330 to 400 am to get to the blast off. So the battery has been charging for 14 hours with a 15 amp charger and it is still not fully charged. It will still be taking 1 to 2 amps. In the tournament we use two group 27 batteries. First sign of any power loss we switch to the second battery. We do not try to charge with the 200HP outboard.

On my larger boat I have 65 amp alternator with a battery isolator and 2 group 24 batteries. It has no problem charging both batteries but I do not have an electric trolling motor so do not have deep discharges. If I did have big trolling motor then it would still take many hours to fully recharge. The Reason is the alternator will put out a safe voltage. This voltage is about 13.8 volts to 15 volts. You could charge the battery faster at a higher voltage but you would burn up your GPS, Fish Finder, Marine Radio and navigation lights. I just have small group 24 batteries because I do not have things that draw large amps like a eletric trolling moter or high watt Stereo.

On my boat I can also charge from my Truck's 100 amp alternator while going down the Road. All I have to so is to hook up a connection from the trailer to the Boat. It will charge both batteries through the same battery isolator that my boats alternator uses. On the truck I have a 8 guage wire from trucks battery though a circuit breaker to the trailer plug. Then the Trailer has a 10 guage wire to another plug on the trailer. Then run to a plug on the Bow of the boat. I have only used this a few times. On the truck I use often when go camping with our camp trailer to recharge its battery.

I also think your best option is a small power gererator. Then charge from the dc output or the 120 volt output with a battery charger.

 

[sacman11]

Re: Charging System - 50hp Merc 4 Stroke

Thanks for the advice fellas. I might have been a little misunderstood from my post. When I suggested I would add a third battery, I was suggesting that would be the answer to my issues of running my Trolling motor for most of the day. Instead of trying some type of on board - motore charging system. Adding a third battery instead of a charging system for the two. My 50hp keeps my starting battery fairly well charged as it is right now, and I am running my stereo and finder/GPS off that battery as well.

Thanks for the great information.

Any recommendation for an onboard charing 110v system - Quest/ Pro Mariner / etc.

Thanks

 

[Silvertip]

Re: Charging System - 50hp Merc 4 Stroke

I'm partial to Guest (not Quest).

 

[Luca7816]

Hello all question i have a 1999 Merc. 4 stroke with two new batteries this year and on my Voltage gage movies like up and down never stays on one spot please help

 

[GA_Boater]

Hello all question i have a 1999 Merc. 4 stroke with two new batteries this year and on my Voltage gage movies like up and down never stays on one spot please help

This is a 10 year old thread ans inactive. Please start a new thread of your own.

Closed.