2 Starting Batteries Parallel?

I’m getting carried away with my electronics. I recently added 360 and now have 5 units. After 6/7 hours on the boat my Optima Bluetop is dead. I’m considering 2 batteries hooked in parallel. Should I use Dual purpose or starting batteries? Does anyone have experience with this setup?

I would get a large battery just for your electronics. Then you don’t have the chance of not being able to start your motor later in the day. Add a combiner and your alternator will charge the second battery also. With that added you wouldn’t have to change your battery charger either. When one is full it moves the power to the other battery. I have 3 12’s, livescope, and panoptics running off a 100 ah lithium. My battery has Bluetooth so I can check the level and see how many amps are being drawn. It’s quite a bit. Until you actually change them out you can turn your brightness down from 10 to 8. That will reduce the power consumption a lot

When the group 24 starting battery that came with my boat couldn’t power my increasing number of screens, I added a second identical battery hooked in parallel. That worked fine for 5 years until the batteries started to fade. I replaced them with 1 group 31 Duracell deep cycle battery that has worked well both starting my motor and powering 4 graphs for about 10 hours.
When I retired, I delivered parts for an auto parts store. After seeing Optima’s terrible customer service up close, I have a sincere and monumental dislike for anything with an Optima label on it.

If you decide to run 2 batteries in parallel make sure they are indentical batteries or the internal resistance will drain the batteries.

FYI: I run two group 31 agm batteries for starting and all electronics. I have an A-B switch. I just bought new batteries after 5 years, and I always just run everything on one battery so in case one would drop so low it won’t start the main motor I can switch it over to the other and it won’t be an issue. Earlier this year before I bought new. I could go about 8 hours running live well, 3 graphs 2-10″ and a 12″, a vhf radio and a stereo. At about 6-7 hours I started getting low voltage warnings. With the new I fished 12 hours before I got a low voltage warning but it started the main with no issue at 12.5 hours.

Thanks, this might be the ticket. Any certain brand that might work best?

Onthewater wrote:

I would get a large battery just for your electronics. Then you don’t have the chance of not being able to start your motor later in the day. Add a combiner and your alternator will charge the second battery also. With that added you wouldn’t have to change your battery charger either. When one is full it moves the power to the other battery. I have 3 12’s, livescope, and panoptics running off a 100 ah lithium. My battery has Bluetooth so I can check the level and see how many amps are being drawn. It’s quite a bit. Until you actually change them out you can turn your brightness down from 10 to 8. That will reduce the power consumption a lot

Thanks, this might be the ticket. Any certain brand that might work best?

I run 2 dual purpose in parallel to run everything. No issues yet fishing 10 hours. I keep a jump box in the boat also just as cheap insurance.

Here is what I did. I have been running a single NorthStar gp31 AGM deep cycle to run everything. 3 Helix units, pumps, radio and lights. Never had a problem starting the big motor or have my units shut down when I did.
This year I added Mega live, Mega 360, and another Helix 12. I started to worry a bit more about my capacity. I added a house battery just for the electronics. I got a Renogy 100 amp hr lithium battery, with self heating option, on Amazon for $679. I also got a Renogy 20 amp DC to DC charger to charge the lithium from the big motor. The DC to DC charger has a alternator “on” trigger wire.
So far I’m really impressed. Every time I get home and hook up the NOCO 10amp lithium charger it goes very quickly to the flashing green light. The green light goes solid in a short time. I believe I could fish for a week and not run out of power to my electronics. And the Humminbirds really like that the voltage never goes below 13 volts.

gizmoguy wrote:

I also got a Renogy 20 amp DC to DC charger to charge the lithium from the big motor. The DC to DC charger has a alternator “on” trigger wire.
So far I’m really impressed.

I have had a Stealth DC ALternator charger for several years and it is by far the best investment besides good electronics I have made for my boat. Just spent a week on LOTW in Canada and while the other two boats charged their batteries using a generator every night, I never did. I could fish for several house using the trolling motor, go to new spot and batteries would be charged back up to full.
Now if I could figure out how to run both my GPS units at the console without draining down the cranking batteries I will be in business. I am thinking about switching them from being powered by the Master switch to the Accessory switch. There is only one thing hooked up to it I believe which is the front GPS unit. That unit will read 12 volts pretty much the whole time, but the console units rarely do and drop down below 10 then I have issues with the GPS shutting down. I think I am going to install a larger bus bar too. The one from the factory is pretty tiny.

Tom Berry wrote:

Thanks, this might be the ticket. Any certain brand that might work best?

I’ve had good luck with Duracell batteries. They are made by East Penn and sold at Sam’s and Batteries Plus. Both stores stand behind them.

Hi, How is your renogy 100ah battery lipo4 performing? Are you happy with it, I just ordered 2 and have some concerns even before I receive them as customer service is well challenging just to get a tracking number. But are batteries are good? does the Bluetooth work?

Thanks,
Dan

I would run one group 24 battery just for starting the motor, and the bilge/ livewell pumps, and the biggest battery I could afford for the electronics, and hopefully a lithium.