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battery/smart craft issues

Old 06-04-2016, 11:08 AM
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Default battery/smart craft issues

My smart craft gauge on the port side is sounding a low battery alarm. I have checked the battery with a multimeter and it shows 12.25 to 12.5. When I place the port battery switch to 1+2 the smart craft is still showing 11.4 when on plane and it rises to 11.8 when idling. My auto pilot is wired to the port battery and it flashes low battery on occasions. Can my smart craft gauge be bad or is there another explanation of the problem?
Old 06-04-2016, 12:56 PM
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Originally Posted by Tireless View Post
My smart craft gauge on the port side is sounding a low battery alarm. I have checked the battery with a multimeter and it shows 12.25 to 12.5. When I place the port battery switch to 1+2 the smart craft is still showing 11.4 when on plane and it rises to 11.8 when idling. My auto pilot is wired to the port battery and it flashes low battery on occasions. Can my smart craft gauge be bad or is there another explanation of the problem?
11.4 is way low when running. Should be 14.2/4. Sitting it should be min 12.2 -12.8
When you combine it should be stronger. I am going assume a bad batt or alternator.
Old 06-04-2016, 07:21 PM
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if the voltage at the battery posts is less than 13 when running, it is not getting charged.

12.25v at battery and 11.4 at smartcraft = wiring problems.
Old 06-05-2016, 03:15 AM
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Agree with posts 2 and 3.
The Smart Craft gauge and Auto Pilot are both doing their job of advising low voltage.
You need to look at the charging system.
Old 06-05-2016, 03:56 AM
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Originally Posted by mickt243 View Post
if the voltage at the battery posts is less than 13 when running, it is not getting charged.

12.25v at battery and 11.4 at smartcraft = wiring problems.
That is what I was thinking. I need to check the wiring from the battery to the motor and see if I have any failed connections or bad wire.

I am not familiar with the way the smart gauge receives it's data. Is the voltage on the gauge showing the battery charge or the motor output? I assume it's from the motor since the battery is testing fine.
Old 06-05-2016, 06:56 AM
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Originally Posted by Tireless View Post
That is what I was thinking. I need to check the wiring from the battery to the motor and see if I have any failed connections or bad wire.

I am not familiar with the way the smart gauge receives it's data. Is the voltage on the gauge showing the battery charge or the motor output? I assume it's from the motor since the battery is testing fine.
It's what's at motor. There is an outside chance you have a bad alt. When the motor starts you should see the voltage jump up. Not be flat.
Check and make sure grounds are tight and all grounds at batt connected together.
Old 06-05-2016, 08:48 AM
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Originally Posted by Dockholiday74 View Post
It's what's at motor. There is an outside chance you have a bad alt. When the motor starts you should see the voltage jump up. Not be flat.
Check and make sure grounds are tight and all grounds at batt connected together.
Thanks. I will start there.
Old 06-05-2016, 03:25 PM
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Still perplexed. I home run a fresh positive wire from the battery to the motor, bypassing a post connection in the transom. That involved pulling 20 ft of 4 wire from the battery switch directly to the motor, 20 linear ft of wire. Everything is testing at 12.25 to 12.5 on the multimeter while the smart gauge shows 11.4 at rest. I checked the ground connections and everything is fine. Either the smart gauge is messed up or is there a voltage regulator on the motor that is messed up? I hate electrical stuff.
Old 06-05-2016, 07:45 PM
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Load test the batteries, one is bad. It's bad and your system is not isolated, meaning wired correctly, that is why you "think" your reading 12.5vdc. You have something wired incorrectly, im certain based on what your reporting.
Old 06-06-2016, 04:54 PM
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Originally Posted by Lordwrench View Post
" My smart craft gauge on the port side is sounding a low battery alarm. I have checked the battery with a multimeter and it shows 12.25 to 12.5. When I place the port battery switch to 1+2 the smart craft is still showing 11.4 when on plane and it rises to 11.8 when idling"

you are using meter to check BOTH the batteries individually? Then connecting both batteries for the smartcraft reading? what does smartcraft show when u select each battery separate on the batt switch?

B
I will run that test next weekend.
Old 06-06-2016, 07:01 PM
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Also, #4 is way to small for a run that length. Opti's are power hungry. I would have to look, but I believe for a run that long, you should be using either 1 or 0 AWG cable, maybe even 00.
Old 06-07-2016, 05:54 AM
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Originally Posted by lyndonc View Post
Also, #4 is way to small for a run that length. Opti's are power hungry. I would have to look, but I believe for a run that long, you should be using either 1 or 0 AWG cable, maybe even 00.
I believe the stock wire was the same size. Maybe it has always been undersized. I will have to check that next weekend as well. I rewired the starboard motor last year using the same wire and I haven't had a problem.
Old 06-07-2016, 02:26 PM
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Let me ask the THT Electronics Brain Trust this question. What size wire should be used to connect a group 27, 1000 cca battery to a 225 hp Optimax using 20 ft of wire?
Old 06-07-2016, 06:03 PM
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#4 is not large enough.
1/0 at minimum with GOOD crimps.
Old 06-08-2016, 11:13 AM
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Originally Posted by Dan Hicks 2 View Post
#4 is not large enough.
1/0 at minimum with GOOD crimps.
What are you basing that comment on?
Old 06-08-2016, 11:20 AM
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Here is chart
Attached Images  
Old 06-08-2016, 07:56 PM
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Originally Posted by Dockholiday74 View Post
Here is chart
I am definitely undersized. I love pulling wire. The battery will be replaced as well.
Old 06-08-2016, 08:17 PM
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I really don't think that's your problem. I mean wire size. 4ga will pull a lot of amps. I think you have a bad cell on one of your batts or bad alternator.
Old 06-09-2016, 05:16 AM
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Dont know how a dodgy voltmeter reading, through a 250mAmp fuse is now discussing battery cables.
The OP doesn't have a starting issue, rather a charging one.
Old 06-09-2016, 06:47 PM
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probably started with my suggestion of a wiring fault, and snowballed from there....


but, didnt you know that 20 feet of 4/0 cable is only good for 250mA

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