Which Battery is best?
 

I have a 1977 20'MA, with a 200 HP Mariner. Time to purchase my first set of batteries. I have a perko switch, 2 batteries, 1 deep cycle, 1 starting. Can anyone recommend a starting battery that would be appropriate? A good deep cycle battery? My only electronics at the moment are the standard lighting, an illuminated compass, a GPS and a fish finder. Any recommendations would be greatly appreciated.....

I've had very good luck with Optima blue tops and being gel I believe they're safer

I'd look in to the AGMs. Sam's Club has them at a good price and everyone I know that has them has had good luck.

If you have a batteries plus in your neighbor hood check them out...good price, service, and warranty. go with the agms.

Some Gel and/or AGM batteries require a different charging voltage for optimum life, so you might want to research that requirement to see if it's compatible with what your motor puts out. The reason I mention this is that on some new cars, the engine computer software that controls the alternator output must be tweaked if you change the battery! I personally think a good quality lead acid battery like a Deka is still the best bang for the buck!

Thank you guys. Any recommendations on the number of cranking amps for the 200 hp? I'm almost done and ready to reassemble her. New paint, new gel coat inside, completely redone console, new windshield. I love this boat !

Do not mix batteries on the same charging system !!
The charging system will fail trying to charge a deep cycle and
a starting battery...

The outboard does not produce enough amperage to compensate
for the deep cycle.

Two standard starting batteries will surfice just fine..

The two major battery manufactures are Johnson Control and Globe.
They all come from these two and are labeled with whoever markets them.

Just my 2¢ worth..

BTW: Welcome to CSC

The biggest things to limit starting motor performance are the starter, cable connections, cable diameter, cable length, and the battery. If the battery is new, and fully charged regularly, then I think the type is mostly irrelevant. Certainly the outboard wasn't engineered to work with an AGM but not a flooded battery. And for recreational use, I think overcharging is far less likely than undercharging. And letting an undercharged battery sit is bad for life. There are only a few manufacturers but lots of brands. And generally capacity is related to the amount of lead and not a lot else. Starting power is related to plate surface area. Get the newest flooded battery you can- check the date code. And verify the cables and starter are in good shape. I have had more expensive batteries quit than Wal-Mart ones.

Do yourself a favor and install an automatic charging relay. It will guarantee a topped off charging battery. Its worth the peace of mind alone for me, but Im pretty sure it pays for itself every time in extended battery life

Doh!

I've used Interstate batteries for more than twenty years with no problems.Currently,on my Tsunami,I'm running two batteries,one is a grp 24 marine cranking battery and the other is a grp 27 deep cycle.These are in conjunction with a perko switch.

God, I'm terrible with my batteries,I rarely check them,and I keep saying that I'll switch back and forth from day to day,or that I'll always run the deep cycle when I'm trolling with the elec.downriggers,vhf.radar, etc all on.The truth of the matter is I forget,so god only knows how many hours are on each one.
Been 6 years now,they still test good,but maybe one of these days it's going to be time for a couple new ones.
I think I'll have to put a big sticker next to the ignition switch that reads,

" HEY! STUPID, CHECK THE BATTERIES"

Deka and Universal Power make excellent AGMs. Get em anywhere you'd find RV, marine or construction machinery.

Group 27s and 31s about 150-175 clams, sometimes get blems for 120. Deka/East Penn is the best bang for the buck I've ever experienced in a battery. Well over 220 at west marine so dont go there unless you have a supply deal. Concorde, Rolls, Trojan also great but super pricey and rarely find bargain price. AGMs are great for northern boaters or anyone forced to neglect their boat a while. But but like No Bones said, dont mix the charging systems.

What he said.



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For this dummy, what does an automatic charging relay do? And where in the system is it installed?

It's in here......

https://www.bluesea.com/products/761...4V_DC_120A/FAQ

Basically the Automatic Charging Relay allows you to have two batteries, one for the engine and one for the house, and keep them isolated from each other (that way you cant accidentally kill the engine start) but also allow them to each charge independently from one charging source.
Throw away the 1-2-All battery switch and get an on-off-combine switch and the relay.

https://dh778tpvmt77t.cloudfront.net...0_diagram2.png

This kit will do that for you.

https://www.bluesea.com/products/764...tery_Kit_-_65A

Another advocate of Blue Seas add a battery switch, and acr, w battery isolator. Very first thing I bought for my seafari.
Great product of real value, safety, and reliability.

Ditto that!

Attachment 10728

So, I am still confused. What battery group, and how many marine or regular cranking amps do I need for a 200 hp, if I have 2 batteries?

?????

You go to the battery store and you buy the highest CCA rated battery they have that fits in your battery tray, normally size 24 or 27 series, you install it and waala you're done. That battery will also crank 300 - 350 hp motors so you are good with your 200 hp.

Here's a link that should answer many of your questions. Here's another link with a lot of good info. Battery group really only refers to dimensions, important for automotive applications, but not so much on marine stuff. Deka also had a marine applications link where you just look up the cranking amps for brand, and size of motor, but can't find it today for some reason. I think the requirements for a carb'd V-6 are generally about 800 CCA, but I'm sure you can get by with less. Separate starting and deep cycle batteries with a selector switch and/or and ACR is the optimum setup.

So can you mix batteries if an ACR is installed or will the charging system fail trying to charge a starting battery and a deep cycle battery as No Bones stated in an earlier post?

Maybe Ken knows something I don't, as he's an electrical engineer and I'm mechanical, but I don't know of any reason the alternator would actually fail if it had relatively low output compared to battery capacity. More likely you'll just end up with an undercharged battery IF you have a large deep cycle battery and you pull a lot of amps out of it running accessories and either run time and/or alternator output is too low to replace the amps used.

This may be why a lot of bass boat guys who run big live wells AND trolling motors also have permanently installed 110V battery chargers on their boats. I think it's basically just a conservation of energy deal. You could have a huge battery and a little dinky alternator, but if accessory loads were small, you'd never have a problem. The alternator on my old 1975 115 only put out 6 amps, max! (With NO voltage regulator! If battery was fully charged, it just boiled water!) My only accessories were the VHF, running lights and a depth sounder. (This was BEFORE GPS existed!) Yet I ran both starting and dual purpose (think HD starting or light duty deep cycle) batteries with a selector switch for 31 years and never had a problem with that dinky little alternator!

sears AMG
no issues for 3 years now

Been a long time since you have been on the forum, good to see you are still kicking!! :)

yeah, still lurking. LOL
Boat is still in Apollo doing well. How about you?