Need some advice from the battery wizards!

[Rattletrap2]

Guys, the last couple of times out, the two graphs have killed my starting battery! It never happened before. I keep a maintainer on it all the tine between trips. It is a “Mercury group 24” that came with the boat in 2017. This battery appears to be sealed with no removable caps. I pit a load tester on it after my last trip and it looks good. Could it be that it is just getting tired and does not keep as deep of a charge? I hate to trash it if it does not need to be replaced yet. My graphs have voltage displayed and I watched it go down to 9.6 volts on about 4 hours!

[Terry]

2 graphs should not kill that battery that fast. And you did a load test and shows fine  I would turn the graphs off and see if anything else is drawing down the battery. 
use a meter to see the standing voltage and the voltage with motor charging it. You could have a bad cell. 

[AKRISONER]

i run 3 graphs, +livewells fishing tournaments on my group 24 and have never had an issue. Something seems up!

[Garnet]

The first thing clean those terminals and all other connections .

Tighten all connection .

If you had a dead cell it would show 11.3 volts when discharged.

Do you charge your cranking battery after each trip . What happens if you don't is your battery gets less and less because we don't run far enough for complete charge.

[Garnet]

Sorry I reread your post.

So take your load tester when battery is discharged.

Hook it up same thing if it reads 11. anything that's a dead cell.

With load tester hooked to battery plug your maintainer in.

It will take a minute the load test will increase volts.

Your maintainer is working.

I never really like these things.  

You can start motor and watch the volts jump up more and your Alternator is working.

If it doesn't Stainer or alternator. 

Edited September 23, 2020 by Garnet
more info

[Rattletrap2]

Garnet, the alternator on the motor is definitely working. When the motor is running, you see almost 14 volts displayed on the graph. I have an isolation switch on the battery that i turn off immediately after each use. I found that the graphs sometimes stayed on after switching off and drained the battery a few years ago between trips. When the maintainer is on, it is only the battery that is in the circuit. Everything else is isolated.

I agree Akrisoner, it never drained the battery before. Just this last couple of outings. My Daughters bought me a booster for Father's Day this year and I was very fortunate to have it with me. They work great for such a small package!

[grimsbylander]

I’d give the battery a good solid charge with a 10amp charger. I’m not a fan of the trickle charge units during the season. 

[Dan668]

My Mercury group 27 battery constantly had issues when running multiple finders, nmea network, livewell, radio. If i didnt make long enough runs during say an 8 hour fishing trip. The battery towards mid/end of day would always end up dead. Switched to a Northstar Group 31 AGM, have been problem free for years now. Im actually surprised some are running Group 24's with all listed. For reference purposss, i have an Optimax, which requires high CCA and tends to be finicky. 

[Terry]

Considering my fishfinder goes portable in the winter with a 9 ah and it lasts all day 

a 27 group 100 amp battery will have no problem with 2 graphs

i ran a HDS 8 on a single battery for a week 12 hours a day fishing from a 14 ft boat with no charging system  and no power at the cabin  and it lasted so there is a problem with his battery or system 

Something is draining his battery or the battery has issues 

[Garnet]

So it's even more likely your terminals both side of breaker switch need to be cleaned.

I've seen guys lose the stainless nut on there battery and get a galvanized nut that immediately rust.

  

  

[DanD]

I'd fist do a parasitic draw test on the boat's electrical system.  

• Begin with a fully charged battery
• Make sure everything is turned off (Other then the isolation switch)
• Disconnect the negative battery terminal
• Connect a multi meter. Negative lead to negative battery post, positive lead to the negative cable terminal. 
• Turn the meter on and set it to amps.
•  50ma (0.050) is the maximum allowable draw that will not drain a battery over 3-5 months; depending on the battery's condition.

Then if you want, turn on your graphs (one at a time) and see what it is drawing. You can then compare your reading to what the graph is supposed to be drawing.  Just make sure you do not exceed the multi meter's amperage capacity. If you do, you'll let the smoke out of the meter or blow the meter's fuse.

Next pull the battery and have a proper load and if needed a charge test performed. The battery needs to be fully charged before these tests would be valid. With a carbon pile connected to the battery; load the battery down to 1/2 of the Cold Cranking Amperage (CCA) rating; for no more then 15 seconds. With the load still applied take a voltage reading. A reading of 9-9.5 volts is a good test result and the battery is good. If the voltage drops below 9 volts; you then need to do a 3 minute charge test. With a charger that is capable of a 30 amp charge rate. Turn charger on and watch the voltage; at the 3 minute point take a voltage reading, with the charger still on. The voltage should not exceed 15.5 volts. If the voltage is higher then the 15.5 the battery is sulfated and needs to be replaced. A sulfated battery will seem to charge normally; but it is only a surface charge.

Sorry for the noel of a post; but didn't know how else to explain the different tests.

Dan.

 

  

[fisherman7]

I had the same isse with my boat. Was stranded a few times. I got a cranking/deep cycle battery. The finders draw off the deep cycle side and the motor pulls off the cranking side. Never had a problem since. Wasn't that much more expensive than a regular cranking battery. 

[AKRISONER]

23 minutes ago, fisherman7 said:

I had the same isse with my boat. Was stranded a few times. I got a cranking/deep cycle battery. The finders draw off the deep cycle side and the motor pulls off the cranking side. Never had a problem since. Wasn't that much more expensive than a regular cranking battery. 

I went group 24 ultra AGM from canadian tire for the size savings while maintaining huge reserve capacity and cranking amps

Industry leading 4 year all encompassing full replacement warranty and I have absolutely loved mine so far. Thing turns my two stroke over like its firing a machine gun.

Edited September 25, 2020 by AKRISONER

[tbayboy]

Hey all, going to bring this oldish topic back to life because the same thing happened to me today and I'd love your thoughts. 

 

I've had this boat for 3 years, brand new so new batteries etc. Never had a problem but I recently upgraded the helix 7 to the helix 10 and its higher power transducer (800mv to 2.7a draw according to specs).  My guess is that the extra draw of the bigger transducer/display killed the battery when I wasn't watching (didn't have low voltage alert set). 

Luckily the trolling motor has its own set of batteries that held up to get us back to the dock while I googled how to pull start an etec 90 (its not pretty).

So... I actually thought the dealer had the finder hooked up to the trolling motor batteries but when the finder shut down every time I tried to get the motor to turn over it was pretty clear that wasn't the case (sometimes you should just do you're own wiring so you know...).

Anyhow, I've never charged the starter, figuring the alternator would take care of it.  The boat has a minkota 2 bank charger but from what I can tell thats only set up for the trolling batteries so yeah... dumb me.  And honestly I spend way more time on the trolling motor than the big engine so I guess it was never getting enough time for the alternator to charge it up and now with the higher draw it killed it I guess?  I've got it on a 10a charger now and will see how it goes after it juices up but had a couple questions:

1) If I've got 2 group 31 deep cycle batteries in series for the trolling motor: (https://labatteries.com/product/00/dc31dt/Deka-DC31DT-Marine-Master-DeepCycle-Group-31-12-Volt-650-CCA190-Res-Cap). The trolling motor is an ulterra 80 w/ipilot auto stow and deploy etc. Should I hook the finder up to that that bank to keep the starter battery for just that one use or is it normal to use the motors battery?

2) I see notes above about cranking batteries that are a mix cranking/deep cycle.  If I've managed to kill this battery (3 years old so I hope not but...) should I consider one of these (happy to pay money to reduce chance of this fun day happening again)? The current battery is a Deja 24M7: https://www.nationwide-battery.com/deka/24m7.php. Fairly generic flooded battery by the looks of it.

So... what would you all do?

 

 

 

Edited July 25, 2021 by tbayboy

[Sinker]

Keep a set of jumper cables in the boat as a worste case scenario. At least then you can jump the main off your bowmount batteries. 

Also, charge your cranking battery once in a while if your not running the main engine much. 

a bigger dual purpose battery would certainly help. 

 

S. 

[tbayboy]

14 minutes ago, Sinker said:

Keep a set of jumper cables in the boat as a worste case scenario. At least then you can jump the main off your bowmount batteries. 

Also, charge your cranking battery once in a while if your not running the main engine much. 

a bigger dual purpose battery would certainly help. 

 

S. 

Good thinking Sinker. The truck had cables and 2 different booster batteries of course - lot of good those do in the truck   After charging the battery overnight its back to its old self - ran everything for about an hour or so (both graphs, radio, bilge bump on and off, etc) while starting up the motor several times and it seems to be ok (voltage didn't take any nose dives) but definitely going to drop the charger on it whenever I have a chance especially if its one of those heavy electronics, not much main motor days.

[Terry]

What voltage is the battery before you start it for the first time of the day. What volts when running the motor at trolling speed and up on plane.   What  is the volts after you shut the motor off to start using the electric. The reason I ask it could tell you if the motor  isn’t putting out enough or if the battery isn’t holding a good charge. Or if something is draining the battery 

[tbayboy]

4 minutes ago, Terry said:

What voltage is the battery before you start it for the first time of the day. What volts when running the motor at trolling speed and up on plane.   What  is the volts after you shut the motor off to start using the electric. The reason I ask it could tell you if the motor  isn’t putting out enough or if the battery isn’t holding a good charge. Or if something is draining the battery 

Hi Terry, that'll be the next real test when I get it back on the water. This morning fresh off the charger the multimeter shows 13.0, with everything on was 12.75(ish).  When cranking (in the driveway with mufflers) it would drop to 11.8 or so and then pop back up. At the end of a couple hours of playing around with stuff I was in the 12.65 range (with no alternator as I just started the motor for a few seconds to ensure it would turn over).  Next time on the water I'll get some better "real" measurements.  Might also try measuring each item individually when I get a chance.

[AKRISONER]

Don’t run graphs off of the trolling motor battery. You are asking for a pile of interference. 
 

keep your graphs connected to the starting battery but you should also be keeping your batteries all fully charged any time you are not fishing. You may have wrecked your 3 year old battery by basically keeping it discharged for over a year.

 

the amount of time running On the alternator is nowhere near enough to totally charge up your batteries that have had two graphs running on them for days.

id personally bite the bullet and get a three bank charger and try out the old battery once it’s been fully charged and see how you go. If the batteries toast, lesson learned.