2008 Merc 50 hp 2 stroke charing two batteries??

[darklcd]

hey all

I am thinking of setting up my outboard to charge two batteries due to the fact that I have no way to run solar chargers as they will get broken and I have no way to run an on board charging system.

My plan is to set up a line to the front battery and have a switch to only charge it when I am running full out. I am going to set up a relay that will allow the boat to start off the back battery only and use a switch on my panel that is not being used at the moment so I can chose when I want to charge them both.

I know that from the electronic and set up stand point it will work my big question is will the stator in my outboard handle it or not. If it was an alternator then I would not have an issue but with the stator I am not sure. I have herd some people say that it will work and others say it will not so I wanted to get a better idea from people on here.

Please let me know what you all think

Thanks

 

[Silvertip]

Re: 2008 Merc 50 hp 2 stroke charing two batteries??

Install an acr and you won't have to worry about it. The aux battery will charge when the primary battery is topped off. And just so you know, your charging system is an alternator. It produces AC which is converted to DC by the rectifier.

 

[Texasmark]

Re: 2008 Merc 50 hp 2 stroke charing two batteries??

The next time you are in an auto parts store and purchase a replacement alternator, look at the caution note inside the box. It says that prior to installing the rebuilt alternator the battery should be fully charged. Reason being, as current flows through wire there is heat developed. To charge a battery(ies) that are discharged, it takes a lot of current as compared to the current to keep one topped off.

The problem is that the heat is detrimental to the winding insulation, terminations, and core material of the alternator and you are just asking for a failure.

For this reason, most folks have their engine connected to the starting battery, used for starting only, or light discharges, and the TM gets run off separate batteries which get charged when you get home from your household power.

HTH,
Mark

 

[Silvertip]

Re: 2008 Merc 50 hp 2 stroke charing two batteries??

If you are indeed trying to charge a trolling motor battery then your idea is a bad one. While it may prolong fishing time, there is no way the charging output of a 50 HP engine will keep a troller battery charged. You'd need to run wide open for hours to do that. Here's why! A 50# thrust troller draws about 45 amps worst case. If you ran the troller just one hour at that current draw, you would need to run the engine wide open for three hours to replace that current. Your alternator has about a 15 amp output. 45/15 = 3. If the second battery is NOT used for a troller then you can safely keep it topped off. Again -- an ACR is your friend in that application -- and it is autoamatic.

 

[Don S]

Re: 2008 Merc 50 hp 2 stroke charing two batteries??

I looked it up, the charging system on that engine is 18 Amps. It should put out 18 A at 2000 rpm or more, 8.3 at 1000 rpm.

If your trolling motor pulls 30A, that means it will pull 30 amps out of your battery in one hour.
It will then take your motor running over 2000 rpm almost 1-3/4 hours to charge back up.

 

[Maxz695]

Re: 2008 Merc 50 hp 2 stroke charing two batteries??

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[Faztbullet]

Re: 2008 Merc 50 hp 2 stroke charing two batteries??

This is what I install on my customers with aux battery's. I also install these on the fellows with 24 volt systems and use one rectifier for input on the Merc motors, takes a tad longer to install but throws 20 amps at batterys!!!!
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