Deep Cycle vs Starter Battery

[Don Macleod]

Just purchased 2 interstate deep cycle batteries with a CCA of 550 and a MCA of 690. On my first time out it was a bit hard to start on battery #1, but I did get it going after numerous times. I thought once i got it out running it would be fine, but it was only just satisfactory on a couple of test start-ups. I put the battery switch to ALL and no problems starting. I have a 19 foot cuddy with a 4.3 merccruiser. My question is: is this the best way to start the boat in the All posistion, do I leave it in the All posistion when running? And then when stopped rotate it between #1 and #2 for accessories. Or should I have a regular automotive starting battery as the number #1 battery and the deep cycle battery as the #2

Thanks for your help
Don

 

[Silly Seville]

Re: Deep Cycle vs Starter Battery

Hmm, sounds like your batteries were not completely charged, OR you have a defective one. There is no reason why 1 battery would not crank a V-6! You said it took "numerous times" to start. That isn't the battery's fault...sounds like engine issues to me. Maybe more details would help us identify engine starting problems.

Yes, you can use ALL to start engine.
Yes, you leave it on ALL when running (that charges the batteries)
Yes, switch to 1 or 2 when on the hook to protect the start battery.

I have three batteries. One big arse automotive battery (1000 CCA) for the starter, and two deep cycles wired in parallel together for on-the-hook. You may not need that much back up amperage (we overnight with fridge and fans running) but I love the three battery, two switch position. YMMV!

Oh, and welcome to iboats!

 

[Don Macleod]

Re: Deep Cycle vs Starter Battery

Thanks for your reply.

Never have had a problem with starting the boat, prior to getting the new batteries, other than the typical first start of an outing. Before i got the two new batteries from the supplier I always started it in the All position, and had no probs. The dealer told me that starting it in One was good enough, but Im starting to think the engine needs more cranking power than what it actually is getting from just the one battery. Maybe I should get a larger deep cycle battery as my "starter?"

Don

 

[Don Macleod]

Re: Deep Cycle vs Starter Battery

Thank you I have been wanting to join for some time now!!

 

[Silly Seville]

Re: Deep Cycle vs Starter Battery

Don, this is a great place. I hope you enjoy your time here and learn much!

I have a mild performance build Vortec 350 that doesn't mind a bit having a 550 MCA battery spin her flywheel. You might consider looking at the date code on your batteries, and having them load tested at your nearest auto parts retailer. Preferably, where you bought them from...for warranty reasons.

 

[truckermatt]

Re: Deep Cycle vs Starter Battery

I have the same engine as you and I have a 1000ca starting battery and a 650 ca deep cycle battery, I changed the switch each time the boat is out so they are both charged,

Never had the need to use the ALL selection.

 

[H20Rat]

Re: Deep Cycle vs Starter Battery

Never have had a problem with starting the boat, prior to getting the new batteries, other than the typical first start of an outing. ...
but Im starting to think the engine needs more cranking power than what it actually is getting from just the one battery.

If a stock v6 is taking more than a standard battery can put out, you have other issues! (in other words, that isn't a problem) So it wasn't a problem before, and is now. Were your batteries fully charged? You never want to put new batteries into a vehicle of any kind without charging them. If they have enough charge to start it, they can destroy alternators by pulling excessive current. Especially with two of them trying to charge themselves...

The other alternative is that something was screwed up during the install. Did you tighten down the terminals? If you used the marine wingnut terminals on the battery, did you tighten them with a wrench? Hand tight won't cut it.

 

[jcornell26]

Re: Deep Cycle vs Starter Battery

Hey Don,
I had what sounded like similar issues to your a few weeks ago. Brand new battery, would start sporadically and then only when I had it on a jump box or jumped it. Turned out my starter was shot. What does it sound like when it won't start? I have a video towards the end of the thread on how mine sounded.

Here is my thread on it:
http://forums.iboats.com/showthread.php?t=558527

 

[captain zac]

Re: Deep Cycle vs Starter Battery

You should have a starting bat in the Number 1 position
Deep cyc bats in most cases will not have the CCA's for starting
they do make a dual purpose deep cyc. (but since you have 2 bat's I would go with one starter)
exchange the # 1 for a starter and you will be fine
start with # 1 run on # 1 and switch to # 2 when engine is off on the hook
bat's off when not using the boat
both only when you have an emergency start

Harry

 

[Don Macleod]

Re: Deep Cycle vs Starter Battery

Thanks everyone for your comments it has been very usefull, and I'm on it today! To the American posters happy July 4th here in Canada we celebrated ours, and it was great..., cheers to all. Don

 

[Don Macleod]

Re: Deep Cycle vs Starter Battery

Smokingcrater: When I bought the deep cycle batteries from the marine dealership they installed them using nuts they provided. I do not believe they were "charged" and were just taken off the shelf. They were tightened by a wrench though.
It wasnt like I couldn't start the boat on the number One battery it just didnt "Kick in" as agressively as the batteries I had that came with the boat when I purchased the boat a few months ago ( I had those batteries tested at the marine dealership and they told me they were running low and should be replaced). When I put it in the All position It certainly seemed to have plenty of "kick" therefore, I was thinking that for my number One battery a starter battery with more crank would be more suitable

Don

 

[captain zac]

Re: Deep Cycle vs Starter Battery

Sir

You might want to check but I think that the 4.3 requires 550 CCA and 700 mca
if those numbers are right then your bat would have to be in perfect shape at all times to
ensure a start
but check your manual it should give you exact numbers (based on a starting bat)
It also appears that you have dual purpose bats and someone on the sight has writen before that you need
10% more CCA's if you use a dual purpose

Harry

 

[H20Rat]

Re: Deep Cycle vs Starter Battery

Sir

You might want to check but I think that the 4.3 requires 550 CCA and 700 mca
if those numbers are right then your bat would have to be in perfect shape at all times to
ensure a start

A starter on a gas engine doesn't require 550 amps... You would be melting the starter into a puddle of molten metal at 550 amps. Realistically, that engine will require 100 to 150 amps for about 1 second to start. 550 CCA is to provide lots of headroom for a engine that doesn't feel like starting.

 

[captain zac]

Re: Deep Cycle vs Starter Battery

Just stating what the manufacture suggests for that size engine
As a matter or fact Merc requires that you use a starting bat
use what ever you want I just like to follow the manufacture just figure that the
engineers know more than I

 

[Greg Mrozinski]

Re: Deep Cycle vs Starter Battery

Don,

Zac is correct. Deep Cycle bateries are not designed to start engines because they are not designed to discharge current (amps) at the rate needed by a starter. You have one of two options: 1. Keep both batteries you have and set the battery switch to all when starting; 2. Replace #1 battery with a marine starting battery and use it to start the engine and the the deep cycle battery when on the hook. Option #2 is the best based upon the fact that your stock OEM alternator is designed to charge starting batteries best. If you have a drained deep cycle battery and you want to charge it using your engine, you will have to run your engine at high speed for a very long time to charge it up again. Point being is it is impracticle to do this and I highly recommend that you use a marine battery charger properly sized to charge your batteries fully between outings.

 

[Don Macleod]

Re: Deep Cycle vs Starter Battery

Awesome guys, thanks for all your help, im heading down to exchange one of my deep cycle batts for a starter batt

Love this site