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Author Topic:   Battery Recommendation
1985supersport15 posted 08-13-2012 09:37 AM ET (US)   Profile for 1985supersport15   Send Email to 1985supersport15  
I have a 1985 supersport with an original 1985 evinrude 40hp.I need to replace my battery and was wondering if anyone could give me some advice in terms of deep cycle vs. dual purpose vs. cranking batteries. I am running a deep cycle now and it seemed to work ok but it is old and I am due for a new battery. All I am using the battery for is to start the engine and to run a 5 inch color screen GPS and running lights. Recently my engine has struggled to turn over after shutting it off. I am not sure if the mechanism in the motor is charging the battery but in either case I am due for a new battery. Recently I also have noticed that if I start my engine with my GPS on the unit display often freezes. Last time it did that it left a permanent burnt line in the display (not very visible though thankfully). This just started happening and I am wondering if the weak battery is causing the unit to have a big voltage drop when I start the engine. I have an inline fuse connected to the positive lead and it has been fine in the past.

Any advice on a battery would be appreciated as well as any ideas as to why my GPS is freezing when I start my motor.



Jefecinco posted 08-13-2012 10:19 AM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     

I've had exceptionally good results using AGM batteries for my boats over the years. The Sears Diehard Platinum AGM batteries are highly regarded by many and would be my choice for a replacement battery. They are pricey but I believe they are a good value given their reputation.

When a battery gets old it's not uncommon that cranking an engine will reduce the voltage throughout the electrical system. Depending upon the low voltage tolerance of your GPS low voltage could be the reason the display freezes. Another possibility is that you may have some high resistance connections in your system. I suggest you check and clean your battery connections at both ends and see if that helps your GPS problem.


nats posted 08-13-2012 10:28 AM ET (US)     Profile for nats  Send Email to nats     
I got my battery a Costco. I was told that they are made by Interstate. Plus the price was right.
Tom W Clark posted 08-13-2012 10:50 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
I'm not sure a 1985 Evinrude 40 has a voltage regulator. The battery acts as the regulator to absorb excess output. Because if this, you should use a conventional wet cell battery, dual purpose or deep cycle.
jimh posted 08-14-2012 12:20 AM ET (US)     Profile for jimh  Send Email to jimh     
..why [is] my GPS...freezing when I start my motor[?]

You probably don't have your own global positioning system. I think you mean your chart plotter is freezing when you start your motor. The reason for this is probably because the input voltage to the chart plotter is too low during engine cranking.

1985supersport15 posted 08-14-2012 09:44 AM ET (US)     Profile for 1985supersport15  Send Email to 1985supersport15     
Thanks to all who replied. As a follow-up could anyone point out the major difference between a dual purpose and a deep cycle battery. What would be best for just starting an engine, running a color screen chart plotter and running lights? I would like to be able to shut off my motor and run the color screen chart plotter for a decent amount of time without worrying about draining the battery.

fishgutz posted 08-14-2012 10:24 AM ET (US)     Profile for fishgutz  Send Email to fishgutz     
Here are some pretty good articles explaining batteries: catalogId=10001&langId=-1&mode=article&objectID=32826
I have 5 years of excellent service with dual purpose batteries. I have a 75 Merc 2 stroke. I rarely turn off any electronics when I'm fishing and the big motor's off.
I bought maintenance-free batteries as they are in the console and very hard to get at. Plus they weren't very expensive. My "Battery guy" explained it as starting batteries give you that burst of amps to start you motor. Deep cycle batteries give you constant amps for a long time for running lights and electronics. Dual purpose batteries have a good amount of both. You can compare them all side by side at a good battery store. Compare CCA Cold Cranking Amps for starting and AH Amp hours for running electronics and lights.
goldstem posted 08-14-2012 12:17 PM ET (US)     Profile for goldstem  Send Email to goldstem     
I would go deep cycle or dual purpose. the 40 takes very few amps to crank it over. starting batteries are needed for big V8's. the more robust construction of a deep cycle, and especially the ability to survive a full discharge, is worth the money. as a reference, with our old 140 evinrude, we used to go through a starting battery every other season. then, we switched to a dual purpose, and the battery went 8 seasons and was still fine when we sold the boat with it.
1985supersport15 posted 08-15-2012 09:44 PM ET (US)     Profile for 1985supersport15  Send Email to 1985supersport15     
Great. I think I am going to go with a dual purpose battery. What size would be best for a 40hp motor and to run my chart plotter and running lights?

West Marine has a dual purpose SeaVolt battery, group 24, 680 cranking amps for $132. Another marine retailer has an Interstate dual purpose battery that has 500 cranking amps and is $105. I do not know much about SeaVolt except that the brand belongs to West Marine. I have heard that Interstate has a good reputation.

swist posted 08-19-2012 09:17 AM ET (US)     Profile for swist  Send Email to swist     
I use a dual-purpose, but would not hesitate to use a pure deep-cycle battery on any engine under 100 hp in good condition - the cranking demands are so low.

And having a battery that survives discharge is so much better insurance for the inevitable times things don't get turned off or a humongous storm causes the bilge pump to run all the time, etc. With a starting battery, it's something like three strikes and you're out.

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