whats the best battery size and brand

agaldamez

Seaman
Joined
Mar 31, 2013
Messages
55
Looking for advice on the best battery size and brand for a mercruiser 4.3. bow rider, radio with 2 amps is really all I run on my boat.
 

enginesilo

Petty Officer 1st Class
Joined
Jun 9, 2008
Messages
355
Interstate Marine Battery has done me well for many years. I'll need to check the model, but it is the original battery from 2005 that is still going strong. I thought it would have been toast by now but I guess we will see who it is after the winter. Either way I've always had good luck with Interstate batteries in my boat and cars.
 

Fun Times

Moderator
Staff member
Joined
May 16, 2009
Messages
8,776
Is your engine carbureted or fuel injected? Below are the minimums you should have for the engine.
https://www.perfprotech.com/blog/articles/mercruiser-battery-cable-requirements
http://www.marinemechanic.com/site/page103.html

If it's fuel injected the size has recently changed a little both in battery CCA's and cable sizes compared to the old info in the two links above.
Mercruiser Service Bulletin No. 2002-12
New 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.
 

airshot

Rear Admiral
Joined
Jul 22, 2008
Messages
4,216
"best" battery is the one you have good luck with. I have owned many different brands over the years and most were quite good but as with anything you can always get a bad one no matter whose name is on it. Keep in mind there are only a few actual battery manufacturers out there, they just make batteries and different names on them. For the past few years I have used Walmart batteries with good success and will continue to use them as they do cost less than most others. So if I do get a bad one on occasion it will still be well worth it in the long run. Sort of like which "oil" is best?
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Howdy,

The parameters above are quite important to get good service from a battery.

I would add one more if you use your boat mostly seasonally,

Get yourself a sealed gelled battery and an automatic electronic controlled trickle charger for the off months.

They seem to last the longest. I have a wheel chair battery in my John Deere lawn tractor and it goes 6-8months without even being charged and always works.

I have a Concorde RG-35 in my airplane and it also sometimes sits for 6 months or more and will still crank the engine
http://www.chiefaircraft.com/aircraft/batteries/concorde/cb-rg-35a.html

You don't need to get an aircraft battery but I have used wheel chair batteries in the airplane and they work just fine.

I put an Optima in our community water-well auto start generator in 2009 and it's still in there. It starts every wed.

I would use an Optima or equivalent in my boat........and will when the current battery is replaced .............. Brand is more less irrelevant. There's FAR MORE "brands" than there are actual battery manufacturers

Cheers,


Rick
 
Top