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Using cranking battery for electronics.....

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18K views 27 replies 17 participants last post by  dunedawg  
#1 ·
I've just upgraded to the new technology with Garmin livescope. ........is it generally accepted to use the cranking battery for power? I have 3 batteries under my console right now in my shallowsport 21 bahia ........and it won't take another battery. That shelf is maxed out. I hope they have upgraded the strength there in the new boats. My boat is 2011. Or should i use a dedicated power source for my electronics. Although i have no idea where i would put a 4th battery. I think in the bow would destroy it. Also, i hope shallowsport has increased the size of the bow rigging tube from my model. It's very small. Thoughts? Ideas?

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#3 ·
The electronics (and trolling motor if you have one) should be deep cycle battery(s), not a cranking style battery. The electronics in most modern engines needs 800 cranking amps to keep from low voltage to them. Not only will the boat not crank, but it could damage the electronics in your engine.

A lot depends on how you use the boat. Lots of trolling motor (/electronics) use, IMO, two deep cycle batteries are needed and one cranking battery, all on a Perko switch so you can throw them all into cranking the engine as required.

If no TM, then a single deep cycle for the electronics and two cranking batteries. Again all on a Perko to vary usage.

In any case, NEVER, use the cranking batteries for anything other than dedicated for cranking your engine. When it gets dark on the bay, the mosquitos get FIERCE, and you want to be in the truck headed home, not wishing you had mosquito spray.
 
#6 ·
RB II said:
The electronics (and trolling motor if you have one) should be deep cycle battery(s), not a cranking style battery. The electronics in most modern engines needs 800 cranking amps to keep from low voltage to them. Not only will the boat not crank, but it could damage the electronics in your engine.

A lot depends on how you use the boat. Lots of trolling motor (/electronics) use, IMO, two deep cycle batteries are needed and one cranking battery, all on a Perko switch so you can throw them all into cranking the engine as required.

If no TM, then a single deep cycle for the electronics and two cranking batteries. Again all on a Perko to vary usage.

In any case, NEVER, use the cranking batteries for anything other than dedicated for cranking your engine. When it gets dark on the bay, the mosquitos get FIERCE, and you want to be in the truck headed home, not wishing you had mosquito spray.
Click to expand...
Lol!! Been there but it wasn't engine issues. I was grounded. Worse!

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H
#4 ·
id always have a dedicated cranking battery. i assume you have trolling motor and thats why there are 3. do you know if trolling motor is 12 or 24 volt? we just rewired our boat to have 2 dedicated cranking (2 engines), 2 dedicated house which run everything else, and 1 generator battery all on a perko switch to regulate usage (much bigger boat of course). we also have a parallel switch which will pull from all the batteries as a last resort.

if your trolling motor is 24 volt might have to find another option such as running of the cranking battery if its your only 12 loop, although i imagine you are running 12v somewhere (lights, horn, radio, etc.) you can probably tap into that power bus.
 
#5 ·
Ok. I need to clarify. I do have a 24v TM.
Blue top ultima. Cranking is also an ultima grey body. All going into a perko. Everything i have which isn't much runs off crank battery.
Nav lights, baitwell, anchor stick, old sonar. Not once in 7 yrs has the engine failed to start. I bought the rig new and still have the original crank battery. Just replaced the two TM batteries. I think my perko is ....off 1 2 all.
I have never used the perko past...1.
Quite frankly i don't remember what 2 ........and all are for. I do remember the guy telling me if the engine wouldn't start i think to put it on all. I could use a refresher course on that perko. For 7 years i just put it on 1 ........and go fish. That 2011 etec has not failed one single time ever. I need to get this sorted out. If i need to dedicate another battery i need to get on it. I'm ready to install the electronics.

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S
#10 ·
Boat Batteries

I f you really want to know about boat batteries I encourage you to google "dual purpose" marine batteries. One example is the Excide battery at Academy. 31 series. They are designed for vibration etc. of marine usage. There are several manufactures that make several boat batteries. There is a big difference between a "Cranking" battery and a "deep" cycle battery. One of the areas that many people miss is the charging procedure for both. If you want your battery to last it's longest, "read" about type on google. Then there is the issue of "wet" cell, agm, or gel batteries. Just things to think about. It's almost too much information but knowledge is great. One last thing. I have found that most manufactures of outboard motors have a cca rating for each size of motor.
Smaller cca batteries will work but you don't always get the amperage the starter is rated for. Thanks for reading.
 
B
#11 ·
You could pull the power for your electronics from your two trolling motor batteries, using a voltage reducer to lower the voltage from 24V to 12V. Here's such a device:

https://www.amazon.com/Converter-Regulator-Reducer-Waterproof-SupplyTransformer/dp/B0756W6V4F

The above wouldn't work so great if you run your trolling motor batteries low often.

My boat used to have the electronics pulling from the cranking battery, and every time I started the motor, the GPS would flake out briefly.
 
T
#12 ·
I agree that you can use trolling batteries for electronics. I run my amps and radio off my trolling motor batteries. BTW - you do not HAVE to have a voltage regulator to do this. You can hook your electronics to the pos and neg of one battery and it will only get 12V even if you have your batteries wired in series to get 24V or 36V to your trolling motor. Some people are going to disagree with this statement, but it's true (otherwise I would have fried many a head unit and amp over the past 5 years).

The benefit of the regulator would be that your 12V electronics would draw evenly from all batteries and therefor not shorten the life of one battery relative to another.
 
B
#13 ·
I've been mulling this same thing for a while since all of my electronics also run off of my cranking battery. I was just going to pull a 12v circuit off of one of my TM batteries, but I like the voltage regulator idea. I see there are two versions. Would the 10A 120w version be enough to run a stereo and GPS and maybe some other items like lights or live well pumps, or would the 30A 360W be needed?
 
H
#15 ·
texasislandboy said:
Man Lots of not so great info being tossed around. Hook it up just like your old sonar/gps is hooked up. It's not going to pull enough power to kill that battery.

I agree, hook it up to your cranking battery. Every time you start and run your motor it's recharging. It won't draw enough to pull down a strong battery. Hook it up and go fishing....
Click to expand...
 
#19 ·
Lots of ways to do this. If you are only counting on one battery then like others have said have the best/biggest battery you can fit (group 31 agm dual purpose like a odyssey pc 2150 or similar ) and most of all keep it fully charged with a charger you plug in. Also recommend to always have one of these GB-40 or bigger on your boat. I carry a 70 in my Jeep and move it to the boat when I launch. These are amazing and academy carries them.

Image


If funds are not a big concern and you understand the advantages of lithium then you can do a single cell lithium for your trolling and the other two as cranking and house.

Customizing one sled at a time
Mobile Marine audio and electronics
832-726-5513
www.yellowskeeter.com
 
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