Default Battery Help Needed: Replacing 24M with 29HM?

[enginesilo]

My battery is finally going bad after many many years past its warranty period. I'm looking to replace it with a larger battery and my question is, If this battery fits into my battery tray, would it be ideal to use with a Mercruiser 3.0L engine? Would it be too big for my alternator or will it charge and power just fine?

The current battery I have is:
Interstate Marine
24M-HD
500 Cold Crank Amps
625 Crank Amps
95 Reserve Capacity
Link to Battery

The battery I am looking at is:
Advance Auto Marine
29HM
625 Cold Crank Amps
Crank Amps
210 (Calculated amp hour rating at 25 amps of 106) Reserve Capacity
Link to Battery

 

[alldodge]

My battery is finally going bad after many many years past its warranty period. I'm looking to replace it with a larger battery and my question is, If this battery fits into my battery tray, would it be ideal to use with a Mercruiser 3.0L engine? Would it be too big for my alternator or will it charge and power just fine?

The current battery I have is:
Interstate Marine
24M-HD
500 Cold Crank Amps
625 Crank Amps
95 Reserve Capacity
Link to Battery

The battery I am looking at is:
Advance Auto Marine
29HM
625 Cold Crank Amps
Crank Amps
210 (Calculated amp hour rating at 25 amps of 106) Reserve Capacity
Link to Battery

Will not hurt a thing, your alternator will charge it just fine. You could put in an 8D (would not recommend due to weight) and it would also charge it without issue. Put two in parallel and it would also be ok

 

[enginesilo]

Will not hurt a thing, your alternator will charge it just fine. You could put in an 8D (would not recommend due to weight) and it would also charge it without issue. Put two in parallel and it would also be ok

Thanks for the knowledge. My boat battery tray is 1/8" too small, I might try to cram it in anyways.

Are the specs on that battery good for what it is?

 

[alldodge]

Thanks for the knowledge. My boat battery tray is 1/8" too small, I might try to cram it in anyways.

Are the specs on that battery good for what it is?

It's better then what you have and will do fine. You can get a group 27 would be even better but then again your going to need another battery rack. More amps is always better, but we do need to decide just how many

 

[enginesilo]

It's better then what you have and will do fine. You can get a group 27 would be even better but then again your going to need another battery rack. More amps is always better, but we do need to decide just how many

Do you say a group 27 would be better because it is just slightly smaller and would fit? I see they also have this battery:
http://shop.advanceautoparts.com/p/...-27dc-2/2080036-P?searchTerm=marine+group+27#

I definitely want to be able to listen to the radio while i'm out, something I used to do when my battery was a youngin', but now never do in fear of using too much juice.

 

[alldodge]

The group 27 will not fit in a 24 rack. Don't get the deep cycle battery mixed up with a starting battery. You need a starting marine battery, this one is a group 24 at 800CCA's. http://shop.advanceautoparts.com/p/...ttery-group-size-24m-800-cca-m24-3/16940017-P

My point is you can get more amps with a larger group battery, but you do only have a 3.0 which recommends 500CCA as minimum. So if you get the 800 your better off. It should have no issue with running a radio provided you don't have a power amp

 

[H20Rat]

A marine deep cycle is generally fine as a starting battery, I've used them for many, many years on different engines. Marine deep cycles aren't true deep cycles anyway, they are more or less a hybrid battery. True deep cycles are the ones used in golf carts and some RV's, made by trojan and crown.

(both my current boats have a single deep cycle to support starting and a large stereo. V6 2.5l merc outboard and v6 4.3l mercruiser. Starts them great!)

 

[enginesilo]

Do you say a group 27 would be better because it is just slightly smaller and would fit? I see they also have this battery:
http://shop.advanceautoparts.com/p/a...rine+group+27#

I definitely want to be able to listen to the radio while i'm out, something I used to do when my battery was a youngin', but now never do in fear of using too much juice.

So I went and picked up this Group 27 Deep cycle battery because they had it in stock, and the Group 29 was just a little too big. The Group 27 fits into my battery holder just fine:
http://shop.advanceautoparts.com/p/a...dc-2/2080036-P

Now i'm debating if I should have gone with the Group 24 Starting battery you listed instead. I mostly start the boat, no wake cruise for about 20 minutes, speed for about 5 minutes, shut it down and listen to the radio for say 2 hours, no amplifier. Then head back in. I read that Deep cycle batteries need a longer charge time.

Think i'll be fine with the Group 27 Deep cycle, or should I return for that Group 24 Starting battery? Or bite the bullet and go with a dual purpose Optima Blue Top at way more cost?

A marine deep cycle is generally fine as a starting battery, I've used them for many, many years on different engines. Marine deep cycles aren't true deep cycles anyway, they are more or less a hybrid battery. True deep cycles are the ones used in golf carts and some RV's, made by trojan and crown.

(both my current boats have a single deep cycle to support starting and a large stereo. V6 2.5l merc outboard and v6 4.3l mercruiser. Starts them great!)

I read this after my response to AllDodge. So the other side of the fence. Sounds like you think I'd be just fine with the Deep Cycle. Do you ever find the battery low or slow to charge or anything like that?

 

[achris]

I know I'm a bit late to this party and your questions have been answered, but I would like to add a comment.

Alternators (unlike the old generators) have a maximum output current. On most modern pleasure craft marine engines that's in the order of 55A. It matters little of the size or number of batteries hooked up to that alternator. It will only output a maximum of 55A. If it needs 20 minutes to charge one battery, and you put 3 batteries on, the only difference is it will now take an hours to charge. Think of it like filling buckets from a hose with a maximum flow (that's what amps are, electrical flow), and instead of one bucket, you have 3. It doesn't matter how many, or how big, the bucket is, it will just take longer to fill. That does not mean a bigger battery will take longer than normal to recharge if you are just starting the engine. Again, think of the bucket. If the engine requires only one gallon to start, it doesn't matter if that 1 gallon comes from a 2 gallon bucket or a 5 gallon bucket, it's still only 1 gallon, and the hose (alternator) is delivering 1/2 per hour, then it will take 2 hours to refill, again regardless of the buckets' original size.... I hope that makes sense...... The point being that the only way you can 'overload' an alternator is by having accessories that draw more than the alternator can deliver, and the only consequence of that is the battery will 'pick up the shortfall' and eventually go flat.

Chris......