Battery issue

[jorgeoliva]

I have a 5.0 - 8 cylinder year 2000 what should my battery cold crank be and should I install a dual battery will this help

 

[spoilsofwar]

Are you having starting/battery issues as it is?

A single, healthy battery should have no problem starting your engine. Dual battery setups are excellent for redundancy and for separating into starting and house banks, so you can run accessories with the engine off without danger of killing your start battery. The "house" battery should be a deep discharge or dual purpose battery, probably an AGM. Using two batteries to start an engine the size of what you have is not needed unless something is wrong (say, you have two weak batteries, but linked together in the switch's "both" position, they get the job done.)

 

[thumpar]

I ran dual batteries on my old boat. I used an isolator to separate the starting battery and the accessories. On my current boat I replaced the battery at the beginning of the season and went for the biggest marine battery that Costco had. The single battery works fine for me and that is with a decent sound system I use when the engine is not running. If you are worried you could get a jumper pack but make sure you keep it charged.

 

[bruceb58]

A rule of thumb for a carb'd engine is CCA > Number of cubic inches of your engine. So almost any battery will work. If you have EFI, that number must be greater and will be specified in your owners manual.

 

[Fun Times]

BATTERY

IMPORTANT: Boating industry standards (BIA, ABYC, etc.), federal standards and Coast Guard regulations must be adhered to when installing battery. Be sure battery cable installation meets the pull test requirements and that positive battery terminal is properly insulated in accordance with regulations.

IMPORTANT: It is recommended (required in some states) that battery be installed in an enclosed case. Refer to regulations for your area.

IMPORTANT: Engine electrical system is negative (?) ground.

Select a battery that meets all of the following specifications:
?12 Volt Marine Type
?Tapered post connectors or side terminal connectors.

IMPORTANT: Do NOT use a battery with wing nut connectors.

• Battery capacity rating of at least:Gasoline Engines:

Engine(Cyl./Type)​	cid (l)​	Minimum Required Cranking Battery Size​
V6 EFI​	262 (4.3L)​	550 cca/700 mca/120 Ah​
V6 Carb​	262 (4.3L)​	375 cca/475 mca/90 Ah​
V8 Carb​	305 (5.0L)​	375 cca/475 mca/90 Ah​
V8 Carb​	350 (5.7L)​	375 cca/475 mca/90 Ah​

Mercruiser Service Bulletin No. 2002-12
New EFI/MPI Battery And Battery Cable Gauge Recommendation Information:
This new battery cable recommendation will be going into the service manuals and installation manuals.
NOTE:
Battery should be located as close to engine as possible.
Step 1. Select proper size positive (+) and negative (-) battery cables using the chart. Step 2. Add the positive and negative cable lengths together. Step 3. Divide by 2 to obtain the average cable length.
IMPORTANT: Terminals must be soldered to cable ends to ensure goodelectrical contact. Use electrical grade (resin flux) solder only. Do NOT useacid flux solder, as it may cause corrosion and a subsequent failure.

Cable Length, Cable Gauge
Up to 1.1 m (3?1/2 ft.) 25 mm2 (4)
1.1?1.8 m (3?1/2 ? 6 ft.) 35 mm2 (2)
1.8?2.3 m (6 ? 7?1/2 ft.) 50 mm2 (1)
2.3?2.9 m (7?1/2 ? 9?1/2 ft.) 50 mm2 (0)
2.9?3.7 m (9?1/2 ? 12 ft.) 70 mm2 (00)
3.7?4.6 m (12 ? 15 ft.) 95 mm2 (000)
4.6?5.8 m (15 ? 19 ft.) 120 mm2 (0000)

With the old battery cable recommendation, the negative (-) and the positive (+) battery cables were measured separately. Then you selected the correct cable gauge to fit the length measured for each. This was OK if they were both the same length. It did not work well if there was a battery switch installed in the positive (+) battery cable, between the engine and battery. Then, the positive (+) cable had to use a much larger gauge than the negative (-) did.

In the example below, this would have meant the shorter 91.4 cm (36 in.) length negative (-) cable would have used a 25 mm2 (4) gauge cable. The longer 579.1 cm (228 in.) positive (+) cable would have used 120 mm2 (0000) gauge.

Example:

A person measures 91.4 cm (36 in.) length of negative (-) cable between engine and battery. They measure 274.3 cm (108 in.) of positive (+) cable between the engine and the battery switch and 304.8 cm (120 in.) between the battery switch and battery. Add 91.4 cm (36 in.) + 274.3 cm (108 in.) + 304.8 cm (120 in.) = 670.5 cm (264 in.) divide by 2 = 335.3 cm (132 in.) or 3.4 m (11 ft.). So BOTH the negative (-) AND positive (+) battery cable use the 70 mm2 (00) gauge cable.By using the same gauge battery cable, 70 mm2 (00) gauge in the example above, for BOTH the negative (-) and positive (+) cable, the longer length positive (+) cable can use a smaller gauge cable than it would have if the negative (-) and positive (+) gauges were sized to their respective lengths.


New Minimum EFI and MPI Cranking Battery Requirements

Models Affected: All EFI (TBI) and MPI models, including all product produced prior to this service bulletin.

NOTE: All EFI and MPI products produced prior to this bulletin have to meet this newrequirement when the current battery in the boat has to be replaced.

NOTE: Carbureted engine minimum battery requirements remain the same as before.

Situation: Due to increasing current requirements with MerCruiser gasoline EFI or MPI engines, MerCruiser has changed the minimum battery requirement for all of these engines.

New minimum: 750 cca, 950 mca, OR 180 Ah.

NOTE: When selecting a battery, any one of the ratings must be met. It is not necessary
to select a battery that meets all three ratings.

 

[jorgeoliva]

just saw "fun Time post: it said IMPORTANT: Do NOT use a battery with wing nut connectors. why is wing nut bad, all the marine batteries at Advance auto part have booth regular post and wing nuts together, my current battery is from 2013 which I think its old even though it was not use much because been nursing this engine back to heath

 

[thumpar]

The wing nut connections don't provide a good connection for high amps like the starter needs. Mine has both. I use the wing nut connections for the stereo the main connection is on the posts.

 

[jorgeoliva]

oh ok that what am going to do place a regular post and connect the electronics to the wing nut. and buy a new battery mine is from april of 2013

 

[jorgeoliva]

oh one other question I have a Magellan plotter on the screen it says boat speed etc. next to that it says 13.5 volts is that the alternator volt reading the charge that is sending to the batteries

 

[bruceb58]

oh one other question I have a Magellan plotter on the screen it says boat speed etc. next to that it says 13.5 volts is that the alternator volt reading the charge that is sending to the batteries

It's measuring the voltage where the plotter is connected so if there are any voltage drops between the battery and where the plotter is connected, it will be reading slightly lower.

 

[bruceb58]

oh ok that what am going to do place a regular post and connect the electronics to the wing nut. and buy a new battery mine is from april of 2013

Ditch the wing nut and use a stainless nyloc nut. I know its not the post for the starter but I still hate wingnuts. Rookies use wingnuts!

 

[jorgeoliva]

trying to wrap my head around this dual battery switch if I have 2 batteries and my dual switch is on #1 is battery # 2 getting charge from the alternator

 

[thumpar]

trying to wrap my head around this dual battery switch if I have 2 batteries and my dual switch is on #1 is battery # 2 getting charge from the alternator

No. That is why I used an isolator.

 

[jorgeoliva]

mmmmmmmmm interesting but I don't have an isolator but can I do this have 2 batteries Battery 1 is to start the boat, battery 2 is for my electronics. when I start the boat I put the dual switch to #1 boat starts while the engine is on I switch to ALL now both batteries are getting charge when I hit the sand bar for a day of fun I put the switch to #2 which plays my stereo and electronics after a long day I switch back to #1 to start the boat then switch back to booth to recharge battery #2 so basically can I switch my dual to ALL while the engine is running. I know this sound dumb but I have no idea on boat electricity

 

[thumpar]

Yes, you can have it on all while running. The reason I used an isolator is to keep battery 1(start) and battery 2(electronics) separate. I could run the stereo all day long and even if I drained battery 2 I would not drain battery 1 so I never had to worry about getting the motor started. It is kind of like an automatic switch. They now have a thing call an ACR. If I ever go to dual battery again it will be with an ACR. It is kind of like an isolator but more efficient.

 

[airshot]

I agree with using the posts of a battery for starting purposes but the use of wing nuts for accessories is not a problem if you use a pair of pliers to tighten them. The real problem with wingnuts is people only finger tighten them and then they either come loose or corrosion gets under the loose connection, so use a pair of pliers or other tool to be sure they are tight and you will be fine for accessory use only.

 

[jorgeoliva]

ok 1 more question and I think I'm done when I had a motorcycle my battery was hook up to a float little device that plugs into the battery and you plug it into the outlet to keep the battery charge up I still have one in my shed can I hook this to a boat battery without damaging it it claims that you can use it in 12v batteries.

 

[jorgeoliva]

oh so it safe to switch to ALL while the engine is running

 

[thumpar]

Yes, you can use a float charger. I have one I use. It is really important to use one over winter.

 

[bruceb58]

oh so it safe to switch to ALL while the engine is running

Yes...just never switch to off while engine is running.

Get an ACR and you never have to do the battery switching game. One mistake when you leave it in the ALL position and have 2 dead batteries will make you wish you had an ACR.

https://www.bluesea.com/products/cat...harging_Relays

I have dual batteries in both of my boats. Would never have a boat with just one.