When I start the big motor my graphs turn off. I can turn them back on, but it gets anouying. Any help?

When mine did that it was my starting battery getting weak. My Lowrance units will display the voltage on the screen. Pretty easy to monitor battery status while on the lake.

too much voltage drop maybe starter pulling too many amps

Sounds like your starting battery is low. May need a charge or replacement. Check the electrolyte level and add distilled water if necessary. I had to replace my battery when this happened to me.

Yup battery would be the most likley cause--if the starter was pulling to many amps you would notice a difference in starting.

the biggest voltage drop occurs at the initial turn of the key , it only takes a nano second to show up in your electronics so you may not even notice it , put a amp meter on it and check the starters specs

The trip my graph started turning off like that was the trip I got towed back to the ramp. Check your cranking battery.

when battery voltage goes below a certain amount, they will turn off. Also, when you crank your big motor, you use a LOT of juice at one time- which may push that minumum voltage threshold down, resulting in an instant OFF on your graphs.

TxBuddha has it right- check your cranking battery or whichever one is connected to your graphs. I had to go to a larger battery (group 78) for my cranking battery.

Voltage drop yes--it would happen quick but if your starter is pulling more amps than it should--it is because there is a problem with your starter and you would notice that--with that being said it is more than likely your battery. Deano--most places (I know walmart does it) will check ur battery for free

Most electronics need 10.5 volts to operate. Like already said the voltage is probably dropping due to a weak battery or starter pulling to many amps. Put a volt meter on the battery and see what it drops to while starting the motor.

If your battery is good, check the cables. I had problems with mine recently and ended up towed in from 5 miles off shore, and then after replacing the battery starter and relay I got stuck at the ramp and couldn't get the motor to turn over.

Turned out that the Negative battery cable was corroded and loose on the engine block. Cleaned the cable ends, and tightened the bolt and not only does the motor turn over better, but my voltage at the console increased as well...

little trick i used to avoid this or ANY other problem with interference with starter or trolling batteries was to take a lawn mower battery and mount somewhere and use it as the primary source for my Lowrance. this fixes all problems with battery interference. whether it be a low battery or starting battery pulling to much ampereage shutting off unit. also makes unit crystal clear due to the fact its the only thing pulling amperage. no false readings. only problem is its another battery and takes up the additional room. well worth the sacrifice tho.
just something i do. may not be practical for some. have a good day guys.
P.S. make sure its a 12v battery and not a 6v (if they even still make those)

Bone
What did you use to charge the battery back up? Did you just hook it up to a regular charger?

yes, i have a good charger i bought at walmart that i use to charge batteries. just hook it up to it and leave it on......didnt want to hook up my high dollar on-board charger to it.....was afraid it would screw it up. plus have all the lines hooked up to my 3 batteries.