Dual batteries or will a booster pack suffice?
 

My latest ride has a single 496HO and I am surprised it only has a single battery but the engine bay looks super clean and simple, which I really like. One battery, one set of cables and one on/off switch. It will probably be used once a month and we don't have back up like SeaTow so one battery on its own is not wise. The boat only has a modest stereo and no fridge or other things to drain the power.

Obvious answer is to install another battery but rather than complicate everything and have another battery to keep an eye on, would you feel secure with just a good quality booster pack? Carry it onboard at the start of the day and take it home afterwards. Cost isn't the issue, I'm thinking about simplicity in a boat that won't be used a lot. I'm only wanting to cover an emergency start then I'd cut the day short and head home.

Tell me I'm off my nut if you think so, any input is appreciated.

RR

I can tell you that the 496's like a full charged battery, I'd see how it rides and if it needs weight moved around just mount a second battery. What did you get??

Thanks for your input, I bough a 27ZR. (I hope it does what I want!)
Battery is on the starboard side, way back almost against the transom. With the dual battery option, the second one is opposite on the port side. Don't think weight distribution would be significant. if I go for dual batteries, I'm sure the port side is the right place.

The boat is still 6 weeks away, it's a long wait..............

RR

I don't see any need for a 2nd battery. The jump pack idea seems like a sufficient back-up.

I have dual batteries in my 27 ZR. Both are on the starboard side. I also ALWAYS carry a jump box, it has saved myself and others many times.

https://www.amazon.com/STANLEY-J5C09...anley+jump+box

This is the one I have, motor will start without hesitation.

It's up to the boat owner......your decision.

A dead/shorted battery that won't accept a charge can be very interesting to try to drive home once started - even with a jump pack attached. Tough with a carbureted engine, brutal with a FI engine.

Thank you "Torch".
I've seen pics of others with the second battery on the port side. They're always changing things in production so I guess the boat isn't that finely balanced to make a difference.
Im leaning towards the jumper pack at the moment.
Thanks.

RR

Do you plan to use the stereo while you are out during the day, docked, rafted, whatever? I'd go with the second battery.

I'm glad to know the cats out of the bag on what Donzi model you bought, my .02, good choice. With the battery debate it's goes both ways. If I have only one battery I buy the biggest deep cycle j can. I have listened to my sterio at almost max all day on one and it fired up my 440 that had an old starter that wasn't the best. The boat had a second battery I just didn't use it that day because I wanted to see if it would do it. Now my 22 donzi only has 1 battery and I haven't had any issues with it either. As long as your charging system works you should be fine. I would only be worried if I was over nighting on the boat and had something running the whole night. The jump pack should get you started and the alternator should do the rest once running. Just my opinion.

My Velocity 280 only had one battery, the VR 1 has two. Never had an on the Water problem with either but i really like that I now have a back up battery. Was always going to add a second to the 280 but never did.

padraig

I'd go with the second battery. Especially since you said it was an option, already a place for it. Play the stereo during the day and be able to flip it. Not to mention if you happen to break a cell in the battery, may be a chance even with a jump box that the EFI will not fire. You can get a great second battery for about a 100 bucks. That's cheap for piece of mind. Just my thoughts.

I'd like this post, but ya know... Yes, the 496 needs lots of juice to start. I got stranded one time last year and couldn't even get it to fire off good quality jumper cables from a running boat next to me. It turned over fast enough to start, but not enough juice to fire. I understand liking the clean look, but a 2nd battery is the way to go.

I'd give a thumbs up but its no longer an option...lol:poopoo:

I'd go with a second battery. I probably would install it on the starboard side also to counteract any prop torque.

OK , my .02c
Magnum 25 , single 502 , 2 x 27 series batteries . One port , one stbd , like they SHOULD be .
If , by chance , you're in the water permanently the Mercathode constantly drains the battery it's hard wired to .
Solution , a mini solar panel charger wired to that battery that quickly disconnects for when you want to head out . If you trailer pull the fuse for the Mercathode when you're on land .
IMO hauling a booster pack in and out all the time is more inconvenient than permanently hooking up a 2nd battery and the suitable battery switch once and for all .

Tesla now makes solar shingles, see if they can make a solar Faring

Good responses, thank you all. I was hoping for a one-sided argument but the opinions are mixed. :rolleyes:
I'll never overnight on the boat, it's only a basic stereo to power when at anchor for a couple of hours, think I might just keep track of the for v against posts and go with the numbers.

@DBleil, avatar updated. ::D

RR

I vote for the second battery option, I just had to be towed back because 45 minutes from home my only battery decided not to hold a charge. The motor would turn over fine and idle fine but once I tried to get on plane it would fall on its face.

You dual battery folks are nuts. They weigh the boat down and lose both handling and speed all for what? Batteries such as glass mat are totally faithful for years and years. Carry a set of jumper cables and call it a day.

Should have done it to start, I've added an anonymous poll, please vote, there's more relevant knowledge on here than in the whole of Thailand.
BTW, I ain't voting!

I voted dual batteries. However, I think dual batteries AND a jump pack.

I have a single, 496 boat with dual batteries. Wouldn't have it any other way. Has come in handy on more than one occasion over the years.

Getting a few things ready before putting her in the water.
To my surprise, the battery switch panel already has 3 switches for Stbd, Port and Parallel plus the posts for jumping a battery. Dual batteries were an option so I guess they just used the same panel. It's a no-brainer.

Current battery is cactus so I'm ditching it. What do I need for a single 496? Will 2 x 70 amp batteries suffice or do I need 76 amp AGM batteries? Easy answer is go the bigger batteries but the smaller ones are local manufacturer and 100 bucks each whereas the bigger ones are imported and nearly 500 each! Are the bigger batteries overkill? Am I just spending money needlessly?

RR

AGM's not needed. What's the CCA of the smaller batteries ?

Any chance you can post some pictures of the engine bay, and the whole boat on the trailer, or in the water ?
I would get 2 of the local AGM marine batteries with the highest CCA rating, and call it a day.
The reason I would get the AGM batteries is that they are maintenance free.
I trailer my boat, and have a battery tender that stays plugged 24/7 when my boat is on the trailer.

I have 2 of the Optima Blue Top D31M in my 27 ZR, mounted in Eddie Marine billet battery boxes. I have been very happy with these so far.

Needed more coffee for me to finally get it. Your statement above in AMPS didn't get thru to me. Now it has. Overseas uses amp/hrs for a rating vs our (US) CCA/MCA .

Not sure on the 8.1's - BUP would know, but I have a Merc Bulletin that states Minimum 150amp/hr for the 454/502EFI engines.
V8 EFI 454 (7.4) V8 EFI 502 (8.2) Min 650 cca or 825 mca or 150 Ah.

For a comparison The 5.7L EFI's require min 120 Ah.
Min 550 cca or 700 mca or 120 Ah.

Fôund that bulletin you referred to and if amps are the same as amp hours, even the little 4 cyl 2.5 and 3.0 liter engines require 90 amp hours so there's no way a 496 would turn over! The electronics guy I'm dealing with supplied new batteries for my last boat and he checked his records, they were 76 amp AGM batteries. That was for Verados and I was told they needed pretty substantial power to start them. Never had a problem.

There must be a different measuring scale. This guy supplies batteries to most of the boats in the marina and he couldn't be that far off. Back in Australia we used CCA as the measure.

Google, hello! Are you there?

RR

@350scarab, haven't put her in the water yet, here's the engine bay and a pic on trailer (probably upside down) taken yesterday.

Could the amps he told me be related to the alternator and a corresponding battery? I notice the alternator output is 65 amps hot and 72 amps cold.

you know as a kid i always thought everything on the other side of the world was upside down . . . now i guess we have proof :D . . . . . go with the big AGM's . . . you can mount them on their side . . . or upside down as it where lol :D


Super sweet ride by the way . . . you gotta be excited to get that thing out on the water :cool:

Thats an understatement.

This one is not the biggest, fastest or newest boat I've owned but I think im gonna really enjoy it. Just a boat to go and enjoy without trying to entertain a crowd. Simple and manageable with no stress. :party-smiley-048:

RR

A decent jumper battery pack is not light and would need to be secured, I do always carry a set of extra long cables in case I can help out.

More homework. The Merc bulletin SB mentioned states 150 amp hours or 650 cca. We've now established that the 76 amp AGM battery is 600 cca. I can't remember my physics equations from school so amps, ohms, coulombs, watts and volts are a bit of mystery now. I figure a pair of the 600 cca's will do the job. They'll be fitted tomorrow morning.

Reading the label on the battery, I'd say they come from your West Coast. Tell me they're a pos battery if they are but it's the best I can readily get hold of here!

Thanks for all the helpful input, greatly appreciated.

Cheers,
Jon.

Damn, you made me Google and I cam across this: Battery University: Battery Information Table of Contents, Basic to Advanced
Damn it. :)