Nitro z20 battery issue

[GoneFishingLTN]

Humminbird Helix 10 at the console, Humminbird Helix 9 at the bow, along with a Garmin 10 used for LiveScope. The boat is a Z20 with a 250 Mercury 4-stroke engine.


The main batteries are two Interstate AGM 31M.


The batteries will not last longer than 3 hours without running the main motor. When I run the motor, it charges them up for a bit but then they quickly

[Tennessee Boy]

How old are the batteries?

[GoneFishingLTN]

Less than 6 months I took them out and interstate put a load test on them and said they are perfect

[Tennessee Boy]

So after 3 hours they are still able to crank the motor but not run the electronics?   How long did your previous batteries last?

[GoneFishingLTN]

 

 

I bought the boat last year, and the batteries lasted the entire year. However, Bass Pro said it was time for new ones, so they installed them.

 

After 3 hours, I notice the voltage drops down to 12.1. When I start the main motor, the voltage jumps up to 14, but after I turn off the motor, it quickly drops back down to 12.8 and then returns to 12.1 within about an hour.

 

 

[Tennessee Boy]

I’m thinking everything is working as designed.   The 14 volts is coming from the engine to charge the batteries.  I would expect to see a voltage drop when the batteries drop down from a full charge.   12.1 volts is low.  I’m assuming you’re getting the reading from your fish finders.  Fish finders are not very accurate voltage meters.  You will also have some voltage drop in your wiring.  The smaller the wires the more voltage drop you will see.  If the wiring was installed at the factory it’s probably on the small side.  If your electronics are working okay and your motor always starts then I wouldn’t worry about it.  
 

If you have one wire running from the battery to bow that is powering both fish finders then turning off one fish finder should reduce the voltage drop in the wiring and you should see a voltage increase on the other fish finder.  If this change is significant then you might consider rewiring with bigger wires.

[GoneFishingLTN]

Yeah the electronics will shut off after 3 hours if I don’t drive the big engine due to low voltage I do agree they are not a true tell of voltages but last year when I got the boat I never went below 12.8 voltage with the factory wiring but now I am with these new interstates. 
 

I'm fine investing into new wiring if this is the fix just why do you think it worked fine last year? 
 

am I running the correct batteries for my set up?

[gulfcaptain]

So I run a completely different battery for my electronics,  used to run 2 27 series in parallel for my cranking and electronics.  Had a couple times where had to come back to the ramp on trolling motor(now carry a jump box) so this season ran a separate battery for my electronics and ffs(2-10",12", and a 9") and after 9hrs went down to 11.4v. Livescope won't work after 11.6v....lol. thinking I am going to run a 100ah 12.8v lithium for screens and find a 50ah to just power my black box since the black box draws the most. I use 6awg to the fuse panel, then 12awg to each console and black box, 10awg to bow units. Unfortunately newer electronics use more power usage then the older ones ever did. But if I were you I'd add a small lithium 100ah to your set up to run your black box and 10" unit .

Quote

 

 

[Tennessee Boy]

If all of the fish finders are shutting off after 3 hours and the problem started when you got new batteries,  that strongly suggest the batteries are the problem not the wiring.  It seems very odd to me.   Are you running deep cycle batteries?   Even if you're using cranking batteries I would not expect 3 fish finders to drain them in 3 hours.   Without looking up the specs on your fish finders I would guess you have about 10 amps total of power draw.   That would mean your two batteries combined have about 30 amp hours of capacity or 15 amp hours each.  When I first got my boat I was running two Solex 10s,  360, and all the accessories on my group 27 cranking battery.  I could go 12 hours with no problems but I spend a lot of time graphing which charges the battery.  Now I run three Solex,  360,  MEGA Live on a 75ah Lithium and have never run out of juice.

 

Some thoughts

If it's a battery issue I would think only one of the batteries is bad.  Seems very unlikely that you got two bad batteries.  My best guess is you have one bad battery  which is draining the other battery.  If you leave the batteries on the charger until you leave to go fishing this would make it more likely that it's a bad battery.  Disconnecting the charger after the batteries are charged and then checking the voltage after a day or so might tell you something.

 

You could charge both of them separately and then run your electronics (off the water) for a few hours off of each one separately to see if there is a difference in run time between the two batteries.  

 

There are other things you could check if you have the right tools like a multimeter or a load tester. 

[airshot]

Check all the batteries with a good von to be sure the readings are accurate.  My boat runs two group 31 deep cycle batteries for the trolling motor which draws far more than your electronics and I can run for 8 hours !  On the few occasions I have used Interstate batteries, I have had results similar to yours, which is why I stopped using them years ago.  Many folks have had great success with them, but not me or my two neighbors.  My current batteries are "walmart" from 2019 and still going strong.  Go thru your wiring and check co for good clean solid connections...poor connections can cause weird things to happen..

[gulfcaptain]

If you're running 2 31's in parallel you shouldn't have issues. I read the post wrong to start on my first response. Somethings not hooked up right. Something is drawing current. This is where understanding how your boat is wired is needed.  You need to look at your batteries first, check the jumper wires, they should be regulation battery cables to run them in parallel.  Your positive connections should be on one battery and negative on the other one. Not all loaded up on one. Start at your batteries and see how everything is connected. 

[WRB]

Look up Interstate 31M battery reviews and you have the same compliant as multiple boats are having. The 31M isn’t a AGM it is apparently a new hybrid dual put purpose cranking battery.

My advice exchange the battery’s for Optima Blue top AGM batteries.

Tom

[Jig Man]

So you are using 2 batteries as cranking at the same time?  Is that correct?  Are they connected parallel to each other?  What amp hour are they and how many reserve minutes?  
 

I have been down that same rocky road that you are on.  Mine was with Lowrance units and blue tops.  Then H bird units and interstates.

[GoneFishingLTN]

Here is a pic I honestly don’t know if everything is hooked up right I’ve paid B.A.S.S. pro 1000 dollars in labor and it’s been nothing but headaches with promises it’s fixed. I would love to learn if I’m doing something wrong

[F14A-B]

I would wager a bet in Vegas you have inferior batteries.. and that wiring job, well it doesn’t look very professional. I see two batteries not three, BPS isn’t exactly known for having great service either. When I bought my Skeeter many years ago.. I went thru it completely, all new switches, pumps, I pulled new wiring, new tires etc that boat was solid for 15 years except the batteries.. every two years it got new batteries.. couldn’t tell you why but I just sucked it up.. I should say the start of the third year, but yes, you can and will get a bad battery. Good luck to ya. 

[Tennessee Boy]

When I have a problem like this I look at the evidence and make my best guess at what the problem might be.  Then I try to prove or disprove that guess.  If I’m right I proceed in fixing the problem.   If I’m wrong I look for what else could cause the problem.  
 

My best guess is you have a bad battery.   That contradicts what Interstate found when they tested your batteries.   Either they screwed up/lied or I’m wrong.  If I was you I would determine for myself if it’s a bad battery/batteries.  There are many way you can test this.   You could buy a $20 battery load tester at Harbor Freight and test each battery separately with them disconnected from each other.   You could take them to another place to be tested.   You could connect everything up to just one battery and see how long the battery last then do the same for the other.   Other folks here might have additional suggestions.  It shouldn’t take long to determine with certainty if it’s a battery problem.

[airshot]

Can't see enough in your pic to tell if batteries are wired correctly or not. The cables disappear from the pic to know where they go.  On my boat..there are two deep cycle batteries for trolling motor only !  One group 31 deep cycle for accessories, fish finder, lights, radio etc and have yet to run it down over an 8 hour day !  One group 24 start engine only battery.  Start battery is charged off of outboard, others have built-in chargers that I plug in while boat sets in my barn.  Never have I run the batteries down where power is to low to run my stuff. 

[J._Bricker]

I don’t know if this makes a difference, but judging by the above picture @GoneFishingLTN it shows the Interstate batteries are “dual purpose” batteries and not “deep cycle”. And according to the information I attached from the inter web, the batteries you currently have are functioning properly and could be why you’re not getting longer run time with your electronics. I hope this is helpful.
 

The main difference between deep cycle and dual purpose batteries is that deep cycle batteries are better for long-term power, while dual purpose batteries are more versatile:

• Deep cycle batteries

  These batteries are designed to provide a steady power supply for extended periods of time. They are ideal for powering devices like fish finders, radios, and trolling motors. Deep cycle batteries can be recharged and discharged many more times than dual purpose batteries because of their thicker plates. 

   
• Dual purpose batteries

  These batteries can perform both starting and cycling tasks. They are a good choice for smaller boats with limited space because they can reduce weight and save space by eliminating the need for a separate starting battery. 

When choosing between a deep cycle and dual purpose battery, you can consider things like:

• Application: What will you be using the battery for?

• Longevity: How long will the battery last?

• Versatility: Do you need a specialized or versatile solution?

[airshot]

While dual purpose batteries don't last as long as a true deep cycle, he should not run out of battery after three hours !!  

[J._Bricker]

Agreed @airshot and that’s the problem. All I was trying to point out was two dual purpose batteries to run what I understood as two graphs on the bow (helm graph on “sleep” mode) and trolling motor on a 20ft boat is under powered battery. And after spending over a grand at BPS most of us would probably drop in a group 31 AGM on the big motor/electronics side and still have two batteries for the trolling motor. After all with the fall bite turning on, got to get @GoneFishingLTN back on the water.

[Bird]

Perhaps I'm somewhat confused, happens often.

I've only had 2-bank chargers that only charge the 2 deep cycle trolling motor batteries, 10 amps.

The cranking battery is independently charged at home in the garage regardless of how much I've run the motor.

There is quite a bit of demand put on the cranking battery besides cranking the motor.......graphs, live well, running and console lighting, bilge.

A long day of fishing my cranking battery is exhausted and I don't rely on the alternator for a full charge.

Note: 

Your 24V trolling motor batteries are not being charged on the water by the alternator.

 

[airshot]

You are demanding to much from your starting battery !  Deep cycle batteries normally do not work well as a cranking battery and are not recommended for that by most mfgrs.  A cranking only battery is a safety so you don't get stranded on the water. Your alternator will keep that battery topped off.  You need a good deep cycle battery to run your electronics !  Trolling motor should have its own batteries and chargers. Deep cycle batteries don't care for high charge rates from alternators. I run a single group 31 deep cycle for all my accessories, charts, bilge pump, aerators, lights, radios etc and can run all day with power left over.  Cranking an engine really sucks power from a deep cycle battery as they are designed for lower continuous power draw. 

[GoneFishingLTN]

There seem to be a lot of options available, and I’m trying to figure out the best course of action. If you were in my shoes and had two batteries that both tested good, but they’re from Interstate and have received poor reviews, what would you do?

I don’t want to just waste money replacing them, but at the same time, I want to avoid potential issues when I’m out on the water. I typically spend 8-10 hours out there and need reliable power for the entire trip.

Would it make sense to invest in a deep cycle battery, and get rid of one of the interstate?

[Tennessee Boy]

35 minutes ago, GoneFishingLTN said:

There seem to be a lot of options available, and I’m trying to figure out the best course of action. If you were in my shoes and had two batteries that both tested good, but they’re from Interstate and have received poor reviews, what would you do?

If you’re convinced that both batteries are good then you need to determine what is causing your problems.   Replacing a good battery with a new battery doesn’t fix anything.   Something is wrong.  You could pull a 4 year old battery out of a car and get more than 3 hours of run time on your electronics.

[Way2slow]

Here's how I would chase this rabbit.  

The first thing I would do is get my hands on a battery tester, something like one of these.  Amazon.com: TOPDON BT100 Car Battery Tester 12V Load Tester, 100-2000 CCA Automotive Alternator Tester Digital Auto Battery Analyzer Charging Cranking System Tester for Car Truck Motorcycle ATV SUV Boat Yacht : Automotive

and check each batteries actual capacity/percent of charge.  First check them before using them.  Then check them again after using them until they are showing the 12.1 VDC.  12.1 VDC is typically about 30% charge, you want to see if that is what the battery is actually testing at.  

It's not uncommon to have a bad connection that's creating a voltage drop between the battery and the electronics, causing the electronics to show a lower voltage than the battery actually is.  

If the batteries are actually at approximately 12.1 volts as the electronics is showing, then you have to look at the batteries, because one or both are bad.  Connected in parallel, if one is bad, it's going to pull the other battery down with it, so they have to be checked individually, so disconnect them from parallel and only run on one battery at the time.  If you have a load tester, you can just load test each one separately, but without one, you just need to run each one individually. 

I would not think all the electronics combined would be drawing more that 3 - 5 amps, (without live well pumps running) and just one battery should run that for 20 hours or more. 

Another thing to consider, just because BPS installed them new, does not mean they were new.  If they sat on the shelf for months before getting sold, they could very well have been junk, right from the start.    If they have the date stickers on them, see what it shows.  

One thing, if you are going to own a bass boat, a good battery tester is one of those must have devices if you want to save yourself some headaches. 

I just noticed they advertise that unit as a LOAD TESTER, that's not exactly correct, so don't know how they call it that.  A LOAD TESTER places a very heavy amp load on the battery to see how well it will hold its voltage and how quickly it recovers afterwards.  That unit is not going to load a battery.