..:: Cranking Battery Size Advice on RT188 ::..

[VA_Bassn_64]

I have a 2015 RT188 with Mercury 115 4s. I run a HDS 12 and 7 inch TI at console and a HDS7 at the bow. I like to run recirculation all day but doing so is running my cranking battery dead and having to jump more than I prefer. What size and name brand would you recommend for my setup?

[krr6581]

Group size 27 AGM battery. A little more expensive than a standard lead acid battery but it will run your motor and electronics all day. Mine does.

[VA_Bassn_64]

Thank you!

[Transom]

I would get a group 29 or 31 for cranking these days. Your motor does not need it. If running your electronics all day the extra capacity is worth the few extra bucks. Wet cells perform just fine but I have the same opinion as a lot of folks about getting them out of a tin boat. I just replaced a group 24 wet cell with a group 31 agm for the starting battery in my tracker and will replace the two group 27 wet cell TM batteries with group 27 AGM when the time comes.

[tobyfrommo]

I run an East Penn/Deka Intimidator group 31 AGM...haven't killed it yet. My motor is a 150 Etec. I think I paid $240 for the battery.

Accessories I run all day...
- (2) Garmin 93sv's
- (1) Garmin 73cv
- Garmin Network port expander
- Garmin Live Scope
- Livewell aerator pump
- Stereo
- Phone charger

[Team Colibri]

Keep in mindt that "group" refers to the physical size of the battery, but what is important are CCA, and if used to run anything else than your outboard, available amps for deep discharging. Group or brand does not tell you anything about that. Kinda like looking at a car and trying to tell how fast it is, or how well it corners, based on physical size. Sure, size matters, but depending on the engine and suspension etc, two cars of equal size can give very different rides.

Your engine gives lots of amps when running, but like all outboards the regulator is a bit spooky so you should run at least a 100Ah battery on it to avoid cooking the battery. Lead-based batteries like AGM do a good job in that regard as long as it is ment for that kind of use.

Ideally you would like to use (at least) two batteries in a modern boat for sportfishing. One for the outboard, where you would also connect equipment normally used when the outboard is running, and one for your electronics (a third for your TM). This enables you to use purpuose buildt batteries that will both perform better and last longer than a "do it all"-battery will. As long as we are talking about lead based batteries, there is simply no way to build that battery so that it both gives a high starting-power (CCA) for numerous starts, and can take a deep discharge. It will always be a compromize. Ideally you use a AGM buildt as a crancking-battery for your outboard, and a lithium-based battery for your electronics. The only exeption is if you use your boat in cold/freezing conditions, if so I would use AGM- or Gel-type battery also for the electronics as lithium-based batteries (in a pricerange most would consider) looses Ahs in cold conditions.

In order to give good advice on the battery for deep-discharges, you need to provide more information on the consumers. Calculate the Ah needed, you find the information you need to calculate that in the manual(s) for your electronics. Without that info we are all just guessing, and you will (most likely) keep on wrecking batteries. Right now you are asking how far a car can go without refueling, without telling us the size of the tank or the mileage per gallon.

[fishon396]

Would a 50AH lithium battery be enough run a solix 12 onix 10 and a livescope set up all day.

[VA_Bassn_64]

Lots of great information given, really appreciate everyone taking the time.

[Team Colibri]

Would a 50AH lithium battery be enough run a solix 12 onix 10 and a livescope set up all day.

Probably not, but if you check the manual for that equipment so you know the Ah we can do the math and find out.

[n2ratfishin]

The group 27 Duracell AGM I put in mine today while I had the batteries out says 27ah for 20 hours and 900cca. The 27 lead acid was just taking longer than my group 31 AGM'S to recharge after a day of fishing. I'm running a 115 4S and two HDS 7's.

The 27 series marine Duracell AGM was 158.00 at Sams. I think the 31's are about 20.00 more?

[T-Mac]

Some good info here

[Team Colibri]

The group 27 Duracell AGM I put in mine today while I had the batteries out says 27ah for 20 hours and 900cca.

Here is a good example of my point in #6.
The Ah on this battery is 92 for 20 hours. How often are you fishing for 20 hours?

There are several ways to measure maximum Ah. The two most used methods is by using a consumer (usually a lightbulb) that consumes 1Ah (one amp per hour). You connect the bulb to the battery and clock it to see how long the battery lasts. This test is then reversed, where one tests how mane amps one can draw from the battery within a certain time, usally with 10, 20 and 100 hours. This telles us the maximum Ah, but we still need to find the Ah we can draw from the battery without starting a strong sulfatation-process. And that is where one needs good speccs on the battery one is buying.

Here comes to part that gives us problems....
We dont fish for 20 or 100 hours. We fish for (maybe) 10. Due to the resistance in a lead-based battery, it will not be able to deliver the same amount of amps in 10 hours as it can in 20 or 100. Kinda like us, it looses its breath and has to take a rest, after the rest it can deliver som more. :) Unfortunately I can not find any info on A over 10 hours for this battery but it is probably close to 65 based on the weight. In other words - this battery is not suited for modern outboards with a high amp-output and one should keep a close eye on the power-consumption since the battery is so small so the available amps for cosumption is low. Again no real information on that is given but a guess is that it is around 20 amps over 10 hours. The two HDS 7s mentioned here draw an average of 2-2,5Ah so in 10 hours you have used 20-25 amps and are on the brink of what your battery can handle without starting the sulfatation-process which in the long run kills the battery.

In short, a lot of the companies selling and making batteries give really piss poor info on their products, and that leads to a lot of the issues we see.

[GeauxTide]

I ran 27 Interstate that came with the boat. I replaced with Duracell AGM 31 for the starter/elecs and 27s for the TM.