Battery Life And Reading Volts

[tntitans21399]

I had a battery gauge on my last boat but on my new boat I have two fish finders, front hooked to trolling motor and deep cycle battery and the other at the console hooked to the starting battery. Looking up some info it sounds like if the starting battery drops below 9.5 volts it wont be enough juice to start the 115hp I have. Is that correct or what volt should I watch out for? Mainly when I am out night fishing and losing all juice in the dark is bad. Second question is with the one up front on the trolling motor. I've never ran out of juice on a deep cycle in one day but just curious if it got low what voltage I should look at for. If it starts getting low will it cut off or just get slower with wesker power like most electric motors? Just curious.

Thanks Again

Chris

[KevO]

It will probably still start your motor at 9.5v but it will draw so much it will shut your depthfinder off.  I had a bunch of problems with my battery and depthfinders.  The cranking battery wasn't big enough to handle all the electronics and accessories so everytime I would start the motor it would shut everything else off or restart them.  I upgraded to a 31series agm battery and hard wired my electronics to the battery and it fixed all my problems.  I fished all night last weekend at dale hollow with both depthfinders on, nav lights, and black lights and never saw the volts drop below 12.5.

[tntitans21399]

I am thinking about a all night fishing and taking it out the next day is why I asked. Have you ever had a battery get to low to start?

[slonezp]

If the trolling motor batteries are low, the motor will slow down and eventually stop. A good quality starting or dual purpose battery(depending on the mca your motor requires) should last thru the night. I would recommend running all the accessories off the starting battery. I've never not been able to start the big motor and that's with running 2 side imaging graphs and livewell pumps all day. I keep a battery jump box in the boat just in case. Some guys carry jumper cables to jump off the trolling motor batteries but my starting battery is in the stern and TM batteries are in the bow.  

[KevO]

I am thinking about a all night fishing and taking it out the next day is why I asked. Have you ever had a battery get to low to start?

Not since I got a bigger battery.  Before that I carried a jump box in case the battery died.