Blank screen

[ROOKEV]

Hi there I was fishing with my sounder on and the engine off and I started the engine and the sounder went blank. This has happened once before and I found that the fuse was blown but this time the fuses are ok. Both times the battery was a little low and I had to crank the engine a little bit. Every other time I've started the engine with the sounder on the battery was fully charged with no problems. Any help would be appreciated. Thanks.

 

[Scott Danforth]

does it come back if you turn it back on. if so, stop running the batteries that low. thats a low voltage shut-down which is normal. When you crank the motor over, the battery voltage drops to about 9 volts which shuts off all electronics

 

[garbageguy]

does it come back if you turn it back on. if so, stop running the batteries that low. thats a low voltage shut-down which is normal. When you crank the motor over, the battery voltage drops to about 9 volts which shuts off all electronics

When you crank a motor over does the battery drop to about 9 volts always? Or only if batteries are run down?

 

[Scott Danforth]

When you crank a motor over does the battery drop to about 9 volts always? Or only if batteries are run down?

Depends on the size of the motor, the size of the starter the size of the battery cables, the cleanliness of the battery cables and connections, the size of the battery and the health of the battery.

for example, a big block will require about 200 Amps to turn the motor over with an in-rush current of about 400 amps. this instantaneously drops a healthy group 27 down to about 7 volts for about 10ms, and will stay at about 10 volts while cranking.

all storage batteries have a voltage drop when a large load is applied to them. the amount of voltage drop is based on the conditions at hand.

OP doesn't state what he has for a motor, what he has for a battery, the health of the battery or the cleanliness of the connections. he only states that the battery was a "little low". So I am going to assume a day of fishing and the battery is below 12 volts (fully discharged). then even an outboard will drop the voltage of a group 24 or a group 75 to under 9 volts when trying to start it.

add marginal battery connections and the voltage drop is even more significant.

either way, 12 volt electronics generally need more than 9 volts to function

 

[GA_Boater]

Welcome aboard.

Agreed on the low battery comments causing the shutdown.

It would be helpful to know what FF you have for better advice.

 

[ROOKEV]

does it come back if you turn it back on. if so, stop running the batteries that low. thats a low voltage shut-down which is normal. When you crank the motor over, the battery voltage drops to about 9 volts which shuts off all electronics

No it wont come back on and as I said
last time it was a fuse but the fuses are ok this time. Driving me crazy, do you think it could of blown the sounder it self

 

[ROOKEV]

Welcome aboard.

Agreed on the low battery comments causing the shutdown.

It would be helpful to know what FF you have for better advice.

Hi I have a Lowrance HDS5

 

[Bondo]

Ayuh,.... Welcome Aboard,.... Did ya test light it to see if it's gettin' Power, through it's power wire,..??

How 'bout the Ground,..??

 

[Scott Danforth]

Have you cleaned the connections to the battery?

 

[dingbat]

Hi I have a Lowrance HDS5

And there in lays the problem.....lol

They saved a couple of bucks on the transformer by limiting the low voltage input to 10.8 VDC.

Having said that, your blown fuse is indicative of on under voltage condition.

Looking at the specs, the thing is a power hog (who gives power ratings for 12v equipment at 13.8Vdc?)

The combination of poor power regulation combined with an under voltage condition at the battery and or under sized wiring going to the unit is causing the problem

 

[ROOKEV]

Ayuh,.... Welcome Aboard,.... Did ya test light it to see if it's gettin' Power, through it's power wire,..??

How 'bout the Ground,..??

I have checked all power under the cockpit with a multi meter and all is good. I'll just have to recheck again and maybe take the screen out and get it checked by professional as I really need it as I fish in shallows and over reefs a lot. I'll keep you all posted as what the problem is for future reference. Thanks for the input and the welcome.
Kevin

 

[Alumarine]

Run a new cable from the sounder directly to the battery with the correct fuse and see if that solves your problem.

 

[ROOKEV]

Run a new cable from the sounder directly to the battery with the correct fuse and see if that solves your problem.

That's a great idea before I pull it out. I'm going to ring Lowrance first to see what they make of it all.

 

[dingbat]

I have checked all power under the cockpit with a multi meter and all is good.

Useless exercise unless done under the same conditions at the time of the failure.

At a minimum you need to check the voltage while cranking the engine, preferably using the battery in the partially discharged state you noted earlier. Even then, capturing the instant the voltage bottoms out prior to normalizing would be hard without a min/max. function on the meter.

When was the last time you had the battery load tested?

 

[ROOKEV]

Useless exercise unless done under the same conditions at the time of the failure.

At a minimum you need to check the voltage while cranking the engine, preferably using the battery in the partially discharged state you noted earlier. Even then, capturing the instant the voltage bottoms out prior to normalizing would be hard without a min/max. function on the meter.

When was the last time you had the battery load tested?

My battery is fine now as I'm using the boat most weekends. It was a little low on charge as I didn't use it that much over winter when the problem occurred. I rang Lowrance they weren't much help. I'm thinking if I run power to the screen and it works then at least I know its wiring somewhere and not the actual screen.

 

[dingbat]

. I'm thinking if I run power to the screen and it works then at least I know its wiring somewhere and not the actual screen.

Lets back up a bit... I thought you where asking why it shut off when cranking the motor.

Are you now saying the unit shut off and will not power back up?

If you have 12 volts at the connector, it should power up. If not, time to do a bit of surgery in hopes of finding an internal fuse. Otherwise you have a great excuse to “upgrade” the unit

 

[Alumarine]

I as well didn't realize it wasn't coming back on.
I missed where Scot asked that and got the answer.

 

[lmuss53]

Take it and plug it in to someone else's working cables to see if you have a cable or unit issue.

Look in the plugs for corrosion, they will sometimes get green in there when unplugged for the down season. 12 volts at the plug doesn't necessarily mean the unit will run, corroded or frayed wires allowing 12 volts at milliamps to flow will not power the unit, that's why you try it on someone else's good cables, if it works there you have a cable problem, if it doesn't work there probably a unit issue.

 

[ROOKEV]

Take it and plug it in to someone else's working cables to see if you have a cable or unit issue.

Look in the plugs for corrosion, they will sometimes get green in there when unplugged for the down season. 12 volts at the plug doesn't necessarily mean the unit will run, corroded or frayed wires allowing 12 volts at milliamps to flow will not power the unit, that's why you try it on someone else's good cables, if it works there you have a cable problem, if it doesn't work there probably a unit issue.

Thanks, that is what I'll do this weekend. Hope its just a cable problem as there not cheap as you all know.

 

[Scott Danforth]

Thanks, that is what I'll do this weekend. Hope its just a cable problem as there not cheap as you all know.

as FF's go, it is on the lower half of the price scale.