Cranking Battery

I have a Mercury 250 Optimax on my boat with (2) power poles, an HDS12 and an HDS9 and these are all connected to my 12V cranking battery. How much of a load does this normally put on a battery? I was fishing yesterday and had the motor on for about 5 minutes total and then was on the trolling motor the rest of the time - about 6 hours of fishing. My cranking battery died and I had to get a jump start. Should I be running my outboard on the cranking motor more frequently to recharge the cranking battery and if so, is there a rule of thumb to follow as to how much time you should run your motor to keep the cranking battery fully charged?

You need a battery with more RC... NAPA 7234 is a good choice.

Those units use alot of battery. If one is at the console put it on standby or power off while you're fishing and vice versa for the bow unit when you're driving

make the entry into Lithium and get only one separate battery for your electronics and isolate some or all of your electronics like your poles away from your crank battery.

u won't be sorry.

A good agm will handle that load easily. It’s when you get into 3-4 12” units when they suffer big time. Sounds like you are consuming around 5 amps of current per hour based on that setup. A good group 31 agm should provide you with atleast 12 hours of run time with your setup. There is a way to calculate but it’s not exact. Take 100ah which is about the size of a group 31 agm. It will display the ah rating on the label. Agm can’t supply the full 100ah like lithium does and on average it might only be good for say 70% of that rating. Also remember agm gets weaker each time it is discharged below 12.0v Take your 70% of 100ah = 70ah. Divide 70ah by the current draw on your boat. Guessing 5 amps. 70/5 = 14 hours of run time.

Depends on what battery you have an what condition it is in. I new battery with good specs will handle it but I battery at or near the end of its useful life will not.

What battery do you have an how old is it?

Either jump to a big lithium or buy new starting battery every 2 years.
Also keep a jump pack on board like the Noco GB40.

It’s a Sea Ark made by Deka. I’m hearing that an X2 Group 31 AGM is a good choice based on feedback I received today. They are heavy - 75 lbs and expensive, but they also have a 4-year warranty.

Yes - considering X2 Group 31 AGM.

Yes - had a jump start on board and it only had 60% charge so it didn’t do the job. Been on charge for 2 days and can’t get passed 60% so I need to replace that as well.

Quote:

---

Originally Posted by Hicangler

Yes - considering X2 Group 31 AGM.

---

Very good choice, as is the Odyssey 2150. Make sure that you have a high quality AGM charger to get proper charging and maximum battery life.

Quote:

---

Originally Posted by 21XDC

You need a battery with more RC... NAPA 7234 is a good choice.

---

thats what i have,no problems and $150.00 at napa

I sincerely appreciate the feedback from all you guys -it’s been very helpful!

This is the same battery as the NorthStar 31 AGM marine, or the Cabelas 900 AGM. All are big, heavy, and expensive, but they get the job done, and properly charged, will last for years. There is no substitute for CCA's and Reserve minutes in a cranking battery, and these have it. Carrying a portable jump starter is a great idea, IF YOU KNOW HOW TO CONNECT AND USE IT!

I personally use, and have recommended for over 15 years now, a Stealth 1 charging system. This is a unique battery maintenance system that uses the power from the outboard to keep all your batteries fully charged when the outboard is running. Tops off cranking battery first, then the trolling motor batteries. By using the Stealth, I've run a 3 battery, 36 volt system for over a decade now, with NO issues of running down the cranking battery. I'm currently running this system on a Lynx, with a 300 4s Merc, and two Solix graphs.

What kind of charger would you recommend for an SLI 31 AGM battery? I need one charger/ already have a 3-bank for my 3 trolling batteries. Is using a battery tender on an AGM battery a wise choice or go with a charger?

This battery is going to be used for starting and electronics.

The NAPA battery is a beast and leaves you heavier in the wallet area at the same time. LOL

If you go to the link in thread 6, the battery I bought is listed there as a recommended battery.

The AGM battery that you bought is a relabelled Northstar. In a contact with Northstar, they recommended either a Dual Pro (Pro series) or a Powermania charger to me. That is a beast of a battery with a great warranty as well.

NAPA

Group 31 AGM and call it a day. My big Interstate AGM is nearly 4 years old and still going strong. Nearly choked when I paid for it and hurt myself lifting it into the boat but well worth it.

Quote:

---

Originally Posted by 21XDC

You need a battery with more RC... NAPA 7234 is a good choice.

---

What do you think about the Grp 31 AGM from Napa?
https://www.napaonline.com/en/p/NBP9...ercial+battery

Quote:

---

Originally Posted by PlanoKeith

What do you think about the Grp 31 AGM from Napa?
https://www.napaonline.com/en/p/NBP9...ercial+battery

---

I am very familiar with both of those batteries and there are trade offs but I give edge to the BAT 7234 because it is 100.00 less expensive and its useful life is almost as good as long as you are not consistently pulling it down to less than a 50% state of charge, if so go with the AGM, or spend another 130.00 and get the X2
I run similar setup as you and just replaced my 7234 at four years old, I consider that a very good value for 170.00 dollars
The 7234 has a lot more cold cranking amps at about the same reserve and that is a big plus for optimax motors

Quote:

---

Originally Posted by 21XDC

You need a battery with more RC... NAPA 7234 is a good choice.

---

I took 21XDC advice three years ago and bought the NAPA 7234. My conclusion, GREAT BATTERY plenty of cranks and RC !!! Absolutely a solid battery.

I have the same setup. 3 bank on board for the trolling motor batteries. I use this charger for my X-2.
Works great and can be used around the shop.

https://www.amazon.com/NOCO-GENIUS10...2257828&sr=8-1

I think it matters some why the original died. If old is different then if you ran it down. I proactively replaced a smaller lead acid that had never failed with larger X2. I get to Florida in March to find I left an assec switch on with nothing running. X2 was fried. I could not jump it nor could Batteries plus. Maybe some true expert could or maybe not.

I am not anti AGM just sometimes simple and cheap works. carry the NOCO for insurance. I have one in my boat at all times now.