I need a starting battery, here are specs. Been starting w/ a 'deep cycle' batt !!!

[Philster]

Howdy again. I pop in from time to time to explain that electric is not my thing. Yep... right down to batteries.

You folks helped me relax and install my Livorsi gauges, right down to a GPS speedo wired to my Garmen GPS unit. (So I've attached a pic of completed work below. Thanks for the help!!!).

I have an 8.2L, 502 CI Merc. The previous owner has installed a "deep cycle" battery as the only battery! She cranks... not fast, but barely effectively, and I am going to move that to a secondary battery, not for starting.

Merc recommends this to start an 8.2L Big Block:

Minimum 650 cca/825 mca/150 Ah

I found this at my local dealer:

Cold Cranking Amps at 0?F : 700amps
Marine Cranking Amps at 32?F : 875amps
Reserve Minutes at 25 Amp: 182min.

Now, I can see that the battery I've found at my local dealer is above minimum, but are there any rules of thumb that I should know (such as, "hey, you have to go way beyond the recommended minimum when it comes to batteries), or am I on the right track?


Link to battery at my local Eastern Marine dealer:

http://www.easternmarineoutlet.com/DEKA-12V-Marine-Master-DP31DT-Dual-Purpose-Battery/

Thanks for helping me dive into marine wiring, understanding the colors AND wiring a speedo to me GPS. Sweet!

 

[ajgraz]

Re: I need a starting battery, here are specs. Been starting w/ a 'deep cycle' batt !

My 2 cents...

Always a good idea to have 2 batteries on board if you're going to be going further from the dock than you'd want to row.

As to battery types: you can use a deep cycle for starting, but not a starting as a deep cycle. It's good to know that your deep cycle will start the motor, if needed as an emergency backup cranking battery.

As to stats on the new cranking battery; you can never have too many cranking amps, IMO...especially if it gets cold where you live. Personally, I would want more than the 5%-7% or so cushion on the battery you spec'd. As for the reserve capacity on the cranking battery, much will depend on how you intend to use it...will all your other stuff (lights, stereo, sonar, etc.) run off it, or off the (now) "house" battery?

 

[Philster]

Re: I need a starting battery, here are specs. Been starting w/ a 'deep cycle' batt !

Ok. What's the last number posted by Merc mean?

Minimum 650 cca/825 mca/150 Ah

I don't see the number listed in many battery specs, and when I do see it listed it is often a lower number.

 

[ezmobee]

Re: I need a starting battery, here are specs. Been starting w/ a 'deep cycle' batt !

Phil I got a BassPro ad in the mail yesterday and they had a sale going on a big honkin' 1000cca battery for $89. Would be perfect for your boat. I'm thinking about getting one even though it would be overkill for me. Not that you can have too much battery! (crap I now see they have no BassPro anywhere near you)

 

[Philster]

Re: I need a starting battery, here are specs. Been starting w/ a 'deep cycle' batt !

I am worried that the last number, the 150 Ah, refers to the total capacity of the battery. I am not with the boat right now, but the battery is much longer than a standard battery.

Getting above the cranking amps seems easy. But wow.... the Ah ratings are like 60, 70, 80.

Anything over 150 Ah is over 350 bucks. To actually see one in a local store, I am pushing 350-500 bucks.

So, I can nail down the CCA and MCA for less than 200 bucks. but I need to refinance my house to get at least 150 Ah.

 

[John_S]

Re: I need a starting battery, here are specs. Been starting w/ a 'deep cycle' batt !

My 2 cents...
As to stats on the new cranking battery; you can never have too many cranking amps, IMO...

That's about what I did for my starting battery for my 5.7L. A 1000MCA was the largest that fit in the existing battery box. I have no 2nd battery, but don't boat big or dangerous water. It has never come close to be slow cranking, and is on its 3rd season.

 

[Philster]

Re: I need a starting battery, here are specs. Been starting w/ a 'deep cycle' batt !

I am looking at 27 series batteries. That's about 12.5" long. These just have more total capacity.

 

[ezmobee]

Re: I need a starting battery, here are specs. Been starting w/ a 'deep cycle' batt !

This seems pretty close http://www.sears.com/shc/s/p_10153_12605_02827415000P?mv=rr

 

[ajgraz]

Re: I need a starting battery, here are specs. Been starting w/ a 'deep cycle' batt !

I am worried that the last number, the 150 Ah, refers to the total capacity of the battery. I am not with the boat right now, but the battery is much longer than a standard battery.

Getting above the cranking amps seems easy. But wow.... the Ah ratings are like 60, 70, 80.

Anything over 150 Ah is over 350 bucks. To actually see one in a local store, I am pushing 350-500 bucks.

So, I can nail down the CCA and MCA for less than 200 bucks. but I need to refinance my house to get at least 150 Ah.

Well that's why I'm wondering:
a) Are you going to be running your other circuits (lights, electronics, etc.) off the cranking battery or the secondary deep cycle?
b) What all other circuits (and what amp draws) do you have, anyway?

If you're planning on putting basically everything but the starter and the bilge pump onto the house/deep cycle, then the RC on the starter battery won't be so important.

BTW, is this moored or a trailer boat?

 

[Philster]

Re: I need a starting battery, here are specs. Been starting w/ a 'deep cycle' batt !

The boat: It's rack stored... indoors.

Currently has a one-battery setup. I will eventually move to a two-battery setup, but not immediately (the deep cycle that is being replaced with a true starting battery will be the house battery). For now, I want a good starting battery, and when not under power (tanning, drifting, waiting for kids to set up tube) I will have the radio playing and my depth gauge running). The bilge pump will be running off the solo/new battery, but I don't need it to save my boat while moored.

I guess I am hung up on the bigger series batteries because I currently have a bigger battery and Merc specs 150 Ah.

Geeze, Louise, that Sears site gives me a headache.

 

[TerryMSU]

Re: I need a starting battery, here are specs. Been starting w/ a 'deep cycle' batt !

150AH means 150 amp-hours. As an example, you could draw 1 amp for 150 hours, 10 amps for 15 hours, or 30 amps for 5 hours. These are approximations, so as you go toward either extreme, the numbers ate going to be a little lower. Also, it means that fully dead a 15 amp charger will take about 10 hours to charge the battery. Don't ever let your battery get fully dead, as it is VERY hard on a battery, especially a non-deep cycle battery.

Basicly, it means that the product of current draw times usage time must be less than 150 hours. Is 150 amp-hours enough for you? That depends on how you use the battery. Add up the current draw for all the loads that you might expect to run. Take 150 and divide it by that number. The result is how long you can expect the battery (when brand new) to support that load for. As the battery ages, the available amp-hours will become much less. (Sorry, but I do not know how much less it becomes.)

TerryMSU

 

[bruceb58]

Re: I need a starting battery, here are specs. Been starting w/ a 'deep cycle' batt !

Hard to imagine that you would need 150AH for a starting battery. You don't need much capacity for a starting battery.