Voltage Worries

[Boss Hawg]

OK, I've run my boat all summer & still going strong
Problem is i just installed a Lowrance unit that reads voltage -
Today is the first time i had it on the water using the Lowrance, all day it only read 12.4 - 12.5 volts I have it running through the fuse panel & not directly to the battery-
Before after each days outting i've always just pluged into a 2 bank on board charger & both batteries only take a half hour or so to charge to full so i never worried about my cranking battery not being charged by the motor - Do i have a bad rectifier or do i need to hook the Lowrance directly to my starting battery NEVER had any indication of my cranking battery being low- Now that i THINK i can read the actual voltage in my cranking battery I'm concerned about it or am i just being parinoid or do i have a charging problem or just a hook up problem
Dang new fangled stuff, never gave it a second thought till i put in this Lowrance

 

[Barnacle_Bill]

Re: Voltage Worries

Assuming the fuse panel is fed by the starting battery, I would test the rectifier. Connecting it directly to the battery will not make any difference.

 

[trendsetter240]

Re: Voltage Worries

Get a volt meter and test the voltage at both batteries while your engine is running. If you get 12.4v then your engine charging system is not working. A fully charged battery should read 12.7v or 12.8v. With the engine running it should be higher than 13v. Some even charge at 15v.

i've always just pluged into a 2 bank on board charger & both batteries

By the sounds of it you have a starting and deep cycle setup. Is there a battery isolator between them? Have you checked for loose connections and corrosion?

 

[Boss Hawg]

Re: Voltage Worries

Assuming the fuse panel is fed by the starting battery, I would test the rectifier. Connecting it directly to the battery will not make any difference.

I was afraid of that- I'm luckly enough to have a great running 1987 110hp Johnson that seems to have a $200 rectifier

 

[Boss Hawg]

Re: Voltage Worries

Get a volt meter and test the voltage at both batteries while your engine is running. If you get 12.4v then your engine charging system is not working. A fully charged battery should read 12.7v or 12.8v. With the engine running it should be higher than 13v. Some even charge at 15v.

By the sounds of it you have a starting and deep cycle setup.  Is there a battery isolator between them?  Have you checked for loose connections and corrosion

?

Thats my setup-no isolator - My deep cycle is totaly independent mounted under my center console with TM, radio & cigar lighter hooked to it.

 

[Silvertip]

Re: Voltage Worries

If you don't have a dual battery switch, isolator, or combiner between the two batteries, the house battery will not be charged by the engine and must be charged with an on-board charger or a portable charger that can be plugged into house power at the dock. With the engine running at about 1500 rpm the voltmeter connected to the starting battery should show 13 volts or higher. Typically 13.5 - 14.6 or so. If the battery is older, if it sits for an hour or so while fishing the voltage may not rise to those levels immediately after starting the engine. It takes time to charge that battery again. But after a mile or so it should be into the above range again. The battery should measure 12.6 volts in a static test.

 

[180shabah]

Re: Voltage Worries

I was afraid of that- I'm luckly enough to have a great running 1987 110hp Johnson that seems to have a $200 rectifier

Test as mentioned above, BEFORE you spend the $200. You could have a perfectly healthy charging system, BUT a healthy amount of voltage drop due to corrosion or bad connections.