Troubleshooting battery or wiring problem

[YUT18]

The last 3 out of 5 trips out on the water has resulted in breaking out the jumper cables because the crank battery (27 Blue top)  died.  The battery was tested after the first incident and passed.  The batteries are always hooked up to a bank charger when the boat is stored and since the TM batteries are not having the same problem I have ruled out the possibility of a bad bank charger.  Here is what I know at this point (1) low voltage warning on both Humminbirds (898/Helix 9) was set on 11.5v, (2) volts fluctuated between 12.2 and 11.9v over a period of 2 hours (daylight) with electronics on, (3) every time I started the motor the low voltage warning displayed, and (4) once the auto circulate was turned on for the livewell the battery died within 10-30 minutes of use without low voltage warning going off.  What I cannot figure out is why my electronics read 11.9v and low volt warning displays when starting, in addition, to not having enough juice to start after having the auto circulate on.  I am puzzled at this point because I have started my motor with 10.5v before.  The only thing that all 3 incidents have in common is the auto circulate being on. 

 

This past weekend I threw in the towel and took the battery to the graveyard.  I upgraded to 2 31 blue tops and started to make room for the second battery.  I plan on hooking the 31's up in 12v parallel (not displayed in photo) once my cables arrive.  Hopefully this solves the problem and it does not turn out to be a wiring issue.

 

 

 

 

 

 

[BrianinMD]

Just because the trolling motor batteries charged up fine does not eliminate the bank charger from being the issue. It could be one of the banks is bad while the others work normally. You could test voltage after charging to see if it was truly being charged or swap the cables from the starter battery bank to one of the trolling batteries to see if it charges or issue follows the bank.

 

 

[YUT18]

9 minutes ago, BrianinMD said:

Just because the trolling motor batteries charged up fine does not eliminate the bank charger from being the issue. It could be one of the banks is bad while the others work normally. You could test voltage after charging to see if it was truly being charged or swap the cables from the starter battery bank to one of the trolling batteries to see if it charges or issue follows the bank.

 

 

This was the first steps I took in troubleshooting the issue.  At first I thought I had a lose wire but the batteries had full charge. 

[iabass8]

I can't tell by your post but I hope you aren't hooking up your cranking battery in a 24v series....

 

Assuming the only thing that is on your TM batteries is your TM (Nothing should ever be on your TM batteries except your TM) and your cranking battery runs your big motor and electronics, it sounds like your cranking battery is shot at first glance but it could be a couple things. Very simple test. Charge your battery to full. Take it off the charger and take a reading at the terminals /w a volt meter. Should be 13.1 or so right off the charger. Let it sit for 12 hours with nothing hooked up to it. Battery should read 12.6-12.7 after rest. If it's lower than that, your battery is dead. Drop the low voltage alarm to 11. Your voltage will drop some when you crank the big motor but it will immediately recover to full after it cranks. If your battery is dropping to 11.9 while your fishing for a couple hours, that's only a battery /w 40% juice. 12.2 is only 60%. 

[YUT18]

1 hour ago, iabass8 said:

I can't tell by your post but I hope you aren't hooking up your cranking battery in a 24v series....

 

Assuming the only thing that is on your TM batteries is your TM (Nothing should ever be on your TM batteries except your TM) and your cranking battery runs your big motor and electronics, it sounds like your cranking battery is shot at first glance but it could be a couple things. Very simple test. Charge your battery to full. Take it off the charger and take a reading at the terminals /w a volt meter. Should be 13.1 or so right off the charger. Let it sit for 12 hours with nothing hooked up to it. Battery should read 12.6-12.7 after rest. If it's lower than that, your battery is dead. Drop the low voltage alarm to 11. Your voltage will drop some when you crank the big motor but it will immediately recover to full after it cranks. If your battery is dropping to 11.9 while your fishing for a couple hours, that's only a battery /w 40% juice. 12.2 is only 60%. 

The cranking battery is not set on a 24v series.  I will have it set as a 12v parallel (top picture).  The TM is the only thing hooked up to the TM batteries (24v Left side of bottom picture) The problem I was having out the gate was I had 12+volts after coming off charge and anytime I turn the key my low voltage alarm would go off.  Now I've owned this boat since 2004 and never had the issue of the voltage warning going off unless I was down below 11v.  What I cannot figure out is whether I had a cell going bad in the battery or if I have a short somewhere in the livewell wiring.  In my OP I mentioned that 3 out of 5 times the battery would die immediately after turning on the auto circulate.  At first I thought I had a loose wire to the motor and after ruling that out I changed out the battery.  Now I just have my fingers crossed that the problem is fixed and it is not a wiring problem.

 

 

[TheRodFather]

If you have a DVOM you can check for parasitic draw.  Then if you find something drawing current, start disconnecting systems until you find what is drawing the current.  Half an amp draw is considered normal in the automotive industry.  On a boat, I wouldn't think there would be much of any since there aren't very many things that need power to store any memory.

[Way2slow]

First thing you need to check is making sure the battery is being fully charged by the charger.  If the charger has a float mode, the charger's float voltage should be approx. 13.4 VDC and should be approx. 14.4-14.6VDC while in charging mode.

Since this is the cranking battery, you also need make sure the outboard's charging system is working properly.  At 2,000 rpm, you should be reading at least 13.8 volts across the battery with the motor running. If you are only reading in the 12 volt range, the motors charging system is not working.

Once you have verified the batteries are being charged.  Then you have to start working from the battery out and see if you are loosing the voltage through a bad connection. 

All this is very basic trouble shooting and if you understand the electronics part, then it should be no problem. 

[YUT18]

Thanks everyone for your input. All of you have provided valuable input and you are absolutely right.  Testing the battery is very first step and basic troubleshooting of the issue.  I've been troubleshooting this issue for several weeks now.  Each time the battery has been fully charged and volts tested after at least 48 hours at rest.  Every time the volts stayed at 12.7.  I was thinking that maybe I had a cell going bad in the battery because every time I hit the auto circulate while running electronics the battery would die.  So I bite the bullet and got a new battery.  This time I upgraded to a 31.  After getting the battery I got a hook on another 31 and at first was going to hook them up as a parallel 12v system and since decided against it.  Last night  I installed a battery switch at the console and installed a voltage meter that allows me to switch between batteries.  This is probably an over kill since I could monitor voltage at the console or through my electronics but I tend to go a little overboard when fixing a problem.  So while I was in overboard mode I replaced all electrical connectors and checked all the fuses.  The last remaining item to troubleshoot is the auto circulate.  I plan on filling up the livewell tonight and will run the auto circulate to see if am losing voltage. 

 

Again thanks for the input.  Just hope the problem was due to the battery.

 

 

 

[A-Jay]

Does your on board battery charging system have a bank designated to charge the cranking battery ? 

If not, it's something to consider if & when the time is right. 

Clearly not a solution to a bad circuit somewhere but definitely keeps the one battery (arguably the most important one) that's depended upon to power several items, very healthy.

A-Jay

[Way2slow]

I would not connect the batteries together.  If the old battery has a shorted cell, it can pull the new battery down very quickly.  Also, connected in parallel, the voltage is always going to read the same on both batteries, so it does no good to switch a voltmeter between the two.

The best way to test a battery at home is to connect a head lamp to it.  That's 55/65 watts (approx. 5 amps) and then time how long it takes to drain the battery to 11.8VDC.  Do the math and that will give you the RC value of the battery.

[YUT18]

9 minutes ago, Way2slow said:

I would not connect the batteries together.  If the old battery has a shorted cell, it can pull the new battery down very quickly.  Also, connected in parallel, the voltage is always going to read the same on both batteries, so it does no good to switch a voltmeter between the two.

The best way to test a battery at home is to connect a head lamp to it.  That's 55/65 watts (approx. 5 amps) and then time how long it takes to drain the battery to 11.8VDC.  Do the math and that will give you the RC value of the battery.

After researching the pro's and con's of connecting the batteries together I decided against the original plan.  I did install a battery switch in order to switch from Battery 1 and Battery 2.  I also installed a rocker switch with voltage meter so I can monitor battery levels.  I installed the switch to have a secondary means to monitor volts.