Navigation lights wired to cranking battery or trolling battery?

[LA CrappieMaster]

My navigation lights are wired to the cranking battery, is this correct?

Shorty version of the story: went fishing yesterday, motor started fine,
fished a few hours, started engine for about 10 minutes while moving to another spot. At this time, it was getting dark so we turned on the anchor light while fishing. After fishing about thirty minutes, I attempted to start engine but there wasn't enough voltage to turn engage the starter.

When I got home I put plugged in the onboard charger. After charging for about 12 hours, I unplugged the charger and checked the voltage. The trolling battery had around 13.4, while the cranking had about 12.6

[wannabe fisherman]

sounds like it's getting time for a new battery--yes running lights are usually run off starting battery.

[M R Dux]

I never leave home without a set of jumper cables in my boat. They have saved my butt several times as well as being able to help others on the water. Cheap insurance.

My trolling motor batteries are dedicated service. Everything else is off the crank battery.

[LA CrappieMaster]

Yeah I am thinking the same thing. I am running some tests right now to check the voltage drops with the different lights on. The more I think about it, I am thinking it may have been the cooler weather last night compared to the daytime weather.

[LA CrappieMaster]

I never leave home without a set of jumper cables in my boat. They have saved my butt several times as well as being able to help others on the water. Cheap insurance.

My trolling motor batteries are dedicated service. Everything else is off the crank battery.

I don't have the cables, but my cranking leads are long enough to reach the trolling battery. however I will probably buy some jumper cables in case I need to give or receive a boost from another boat.

[CrappiePappy]

I carry a mini set in my boat. I've had them for a long time, and don't remember the brand.

These are the cheapest I've seen online : 12 Ft. Marine Battery Emergency Jumper Cables #00168

or Yamaha MAR-JUMPR-CA-BL Jumper Cables; MARJUMPRCABL

or Amazon.com: IIT 16700 Jumper Cable - 12 Feet, 8 Gauge: Automotive

... depending on where you like to shop, & what the S/H charges are.

... cp

[LA CrappieMaster]

Here are my results from the test:
Turned on Running lights only (anchor light unplugged) battery voltage 12.4
12.3 volts at 11:34
12.24 volts at 12:39
Cutoff running lights at 12:40 voltage 12.45 at 12:45

Turn on anchor light only, voltage 12.32 at 12:46
12.27 volts at 1:06
11.23 volts at 3:36

Cut lights off , tried to crank. Turned over very slow but wouldn't start. Voltage at 10.4 after attempt.

[Tracker123]

I made myself some short jumper cables after being stranded myself a few years ago. Clamps on 3 foot leads to jump off my trolling motor battery if need be from material I bought from Lowes. Fit nicely in a gallon zip lock bag put up out of the way.

From your test, seems like excessive draw from the battery. Battery may be weak. May consider lowing the wattage on the bulbs by using LEDs as well.

[LA CrappieMaster]

Yeah I'm probably going to replace with LED. I may see if autozone can test the battery. Sure seems like a lot of drawdown for a single light.

[Scrapper]

LED will do the trick. They will probably tell you it needs to be charged. Ours would want to keep your battery for few hours to charge it. You can do that at home. I would look for a short somewhere in the light. Not a dead short...but something is either causing resistance or helping to pull the battery down. But like you said the LED will be the way to go. Or just go with some bluewaters and be done with it!