Silly Questions

Turning Point

Recruit
Joined
Nov 17, 2009
Messages
3
Hi Guys & Gals,
Have a (silly) question for you experienced motorheads. I have a "86 60 HP Mariner with trim & tilt. 19' Starcraft Superfisherman boat. I fish on the Great Lakes a lot. I run a lot of extra equipment (downriggers, power planer board reels, autopilot). I have the chartplotter/fish finder and radio on a separate stand alone deep cycle battery to eliminate interference. I constantly charge both batteries (the deep cycle and the starting battery) upon returning from fishing. The 60 hp engine can't possibly keep up with the load requirements I run on the starting battery. When I put the charger on the battery it usually reads that the battery is 50% discharged. It is an Optima gel starting battery, 4 years old.

The question is this- can I put another dual purpose (starting & deep cycle) battery in series on this battery, retain 12 volt current for the absolutely necessary fishing goodies, and expect the motor to somewhat charge the system? I am beginning to believe that no matter what, my demands for electrical power are too much for the motor and I am destined to live a life of constant recharging the batteries.

Thanks for your input in advance,
Chuck
 

Fuzzytbay

Chief Petty Officer
Joined
Jun 6, 2008
Messages
557
Re: Silly Questions

With a four year old battery, you should start fresh. If you put another battery, (in parallel not series, unless you want 24 volts to really crank your starter, at least for a moment :rolleyes:) the weaker battery will lower the fresh battery, to its level, and you will still not get the cranking amps you need. I would set the system up with fresh new batteries, and yes two in parallel would be better for yours I think. As for charging, I am not sure what your motor's DC chargeing output is, or if there is an optional larger one for it. Perhaps others here can tell you that information.
 

emckelvy

Commander
Joined
Jan 16, 2004
Messages
2,506
Re: Silly Questions

You're pretty much stuck with the stock charging system which is approx 10 amps max.

If you're gonna install dual-batteries, as the poster suggested, for best results they should both be new, also the same brand, same size.

BTW if you have a voltmeter in your system, check charging voltage while you're underway with a light electrical load, if your rectifier was marginal, voltage would be somewhat low. Or throw a digital V.O.M. on the battery terminals to see what you've got.

It's an unregulated system, so it's possible to run batt voltage up to 18V or so, lightly-loaded. But I don't expect you'll ever have that problem, with all the electrical loads you have on at any given time!

HTH...........ed
 

Turning Point

Recruit
Joined
Nov 17, 2009
Messages
3
Re: Silly Questions

Thank you for your replies, FuzztTBay & Emckelvy! I will put a volt meter on the batt next time I am out. I have the cranking amps for the starter all the time with no problem there. So, I believe the stator and rectifier are ok. I have a dual purpose Blue Top Optima (new) D3M CCa 900,MCA 1125, AH 75. I am thinking to get another and hook them up. I will still have to charge these batteries every time I take the boat fishing, but with the size of the 2 batts, they should last quite a while as I will not be drawing them down past 30% charge. Do you think this is a good solution, or should I get that 29' Hydrasports Vector I've been drooling over?

Thanks again,
Chuck
 

trendsetter240

Lieutenant
Joined
Jun 22, 2009
Messages
1,458
Re: Silly Questions

Thank you for your replies, FuzztTBay & Emckelvy! I will put a volt meter on the batt next time I am out. I have the cranking amps for the starter all the time with no problem there. So, I believe the stator and rectifier are ok. I have a dual purpose Blue Top Optima (new) D3M CCa 900,MCA 1125, AH 75. I am thinking to get another and hook them up. I will still have to charge these batteries every time I take the boat fishing, but with the size of the 2 batts, they should last quite a while as I will not be drawing them down past 30% charge. Do you think this is a good solution, or should I get that 29' Hydrasports Vector I've been drooling over?

Thanks again,
Chuck

Hi Turning Point,

I think, as mentioned, you need to replace your 4 year old starting battery. Starting batteries don't last long if they get discharged down to 50% and after 4 years that one is likely on it's last legs.

The Optima that you described sounds like a sufficient size. If you are going to be adding another battery in parallel then do it with two new batteries, don't mix old and new. Also, don't buy a battery now if you are just going to store it until spring. Batteries have a limited lifespan & warrenty so no point in wasting 6 months of both.

The greatest benefit you will get from dual starting batteries is the longer life. The less you discharge your starting batteries each trip the longer they will both last.

Cheers!
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Re: Silly Questions

Great information so far but the major problem is your charging system. That charging system puts out 10 amps at WOT and at trolling speeds only 2-3-amps so your using more power than you can replace. Before I replaced any batterys I would have them tested to see if they are still within 90% of rating and if ok they dont need replacing yet. Do not hook the batterys together as both will discharge at same rate and then the engine will not have enough amps to recharge them.:(
Quote from Mercury marine:
"Using an outboard to charge two batteries is only effective if the outboard charging system is capable of delivering more than 15 to 20 amps. One point to remember: most systems are rated at wide-open throttle and charge substantially lower amounts at slower engine speeds"
(http://www.mercurymarine.com/serviceandwarranty/outboardfaqs/electrical.php)
One option is the Procharge "Charge on the run system" or the Stay n Charge. Both systems keeps batterys "stand alone" and charges them when ever motor is running and only charging battery that is the lowest 1st. This way when starting battery reaches 100% engine will only charge your "extras" battery!:D The Stayncharge does the same but allows you to recharge from your towing vehicle to and from lake!
 

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: Silly Questions

I think your best bet would be 2 batteries for the engine, with a switch. That way if you kill the main one fishing, you'll have the backup with a flick of the wrist to get you back home.

You can alternate the battery in use to even out the wear.

hope it helps
John
 

sschefer

Rear Admiral
Joined
Nov 13, 2008
Messages
4,530
Re: Silly Questions

I run two Group 27 deep cycles for my accessories and a group 24 starting battery. I have an onboard ProMariner 20 amp charger and it takes it a good 8 hours to charge all three batteries after a day on the lake. Now, I'll mention this as a possibility but you'll need to work through the details. I have a V-6 and I don't know if you have enough room under your cowling to do this or not but I got a hold of a 50 amp alternator off a 98 Optimax DFI engine and used the pulley and mounts with a little fabrication to bolt it on my engine. The DFI engine uses a V pulley belt rather than a serpentine belt so it's really easy to set it up and it fits nicely under my 98 DFI cowling on my 91 engine.

I'm not quite finished with the install yet but my intentions are to run a battery isolator and charge the two Group 27's that are setup for 24v at 12v each. Alternatively, I'll hook up an inveter to it and run the onboard charger (110v) but that is my last resort because that's not very efficient.

Just for info, the two group 27's are setup to provide both 24 and 12 volt power and I can run my 60lb Minkota trolling motor all day and not go below 60%. That's the magic number for deep cycles by the way.
 

joed

Lieutenant Junior Grade
Joined
Sep 28, 2002
Messages
1,132
Re: Silly Questions

If you are going to replace the batteries anyway why not buy one large one instead of two smaller ones and putting them in parallel?
 
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