Boat battery wiring and charging questions

[nixdorf]

Hi folks,

I have a 2004 Tracker Pro Team 190TX with a 90 HP two stroke Mercury. It has a 12V, 48 ft-lbs Motorguide trolling motor, Lowrance HDS 9 Gen 3 at the console, and Lowrance Elite HDI 7 at the bow. I have two batteries on the boat: starting/cranking and deep cycle. I have an on-board single bank charger wired into the trolling motor battery.  I use an external trickle charger on the starting battery.  I store my boat at a storage business away from my home; the rented parking spot does not have access to power.  Each evening before a fishing trip, I bring my boat home to charge over night.  I charge the deep cycle via on board charger every time (charger light turns green), and put the starting battery on an external charger at 2 A setting (10A is the other option).  My boat is used/charged at least once a month, year round.

I have been having battery issues for as long as I have owned this boat (4+ years). I have replaced both deep cycle and starting batteries 2-3 times each.  Both are less than 4 months old at this point. I am starting to have cranking issues again after a full day on the water.  My dash voltage reading while on the water never shows above 12 V (even when running at WOT for a few miles) and frequently dips to 10V when not cranking. I'm ready to pull what little is left of my hair out.

My first question pertains to battery wiring. As noted above, I have the trolling motor and on board charger wired in to the deep cycle. Everything else is wired into the starting battery.  Is this the right setup?  Should I wire everything but the engine into the deep cycle?

My second question is about my battery charging. Should I be doing something different?  Perhaps charging the cranking battery at 10A overnight before a trip? Buy a dual bank charger?

I'm starting to think I am definitely doing something wrong. My budget (read: wife) has required me to buy lower end batteries. I'm currently using Excide and EverStart. I'm inclined to buy higher end batteries, but only if I can have confidence that I'm not doing something else wrong first.

Any other thoughts? 

[iabass8]

you are set up correctly wiring wise. I don't have an issue using a cheap walmart MaXX 29g for my trolling motor batteries because if they fail, there's a walmart almost everywhere where I can get them replaced. I do however never go cheap on the cranking battery as it runs all my pumps, motor, electronics, etc. You want something with the most reserve you can afford. I like something 200+ reserve. You don't make long runs it sounds like so the more reserve you can find in a cranking battery in your budget, the better. Just make sure it has enough CCA/MCA to start your motor. I don't know the specifics of a 90h merc but I can't imagine the requirements are too high. I 

You should be charging your batteries directly after you get off the water. You are running them down low, letting them sit for what sounds like a few weeks at a time, and then charging them. You're killing the batteries. 

You're having cranking battery issues because your motor isn't charging the battery. A few mile run generally isn't enough to fully charge a cranking battery. Yours don't seem to be holding a charge for the reason I stated above. However...it doesn't sound like your rectifier/ regulator is working anyway.  Your engine should be charging your cranking battery after 1500 rpms(ish) to WOT. You should see a voltage of 14.5 give or take when cruising and then, assuming it's charged and your battery is good, a reading of 12.6 at rest. You aren't seeing anything. That's bad. Even if it was working it doesn't sound like your batteries are holding a charge anyway. I'm guessing you need 2 new batteries and a, hopefully, just a new rectifier that is very simple replacement. Hopefully it isn't a combination of the stator, rectifier, voltage regulator, etc.  

[nixdorf]

Awesome response, iabass8.  Thank you!

I never considered that storing the boat without recharging batteries was putting the batteries through a brutal cycle.  Excellent point.  

So after reading your post, I broke out my Seloc book to take a look at how to test the rectifier/regulator.  Unfortunately, it doesn't have any info for my model.  It has tons of detail for other models of Mercury motors, but it has a bland statement that mine isn't easily testable.  On a lark, I decided to go take a look under the cowl at the regulator/rectifier and related wiring.  The pic below is what I found: the wiring harness where the rectifier/regulator connects into the engine harness is completely fried.  Both yellow wire connectors are burnt; same for red.

I'm guessing the regulator went bad, causing resistance to spike, heat to build up at the connector, and the heat melted the connectors causing a short.  I didn't notice any other suspect wiring.

Thoughts?

[iabass8]

Looks like you caught that bad boy just time. 

I too would guess the voltage regulator and rectifier went bad but it's just a guess. Based on your info I can't see it being anything else. I believe the 2 red, 1 gray, and 2 yellow  should go directly to your voltage regulator.  If you have the engine manual it can walk you through step by step on how to test each component to make sure you didn't do any more damage to the Stator or rectifier. You can purchase it through Mercury's website I believe if you don't have it. I would recommend getting it. They are ridiculously handy. Checking the system is pretty straightforward stuff that involves a multi meter. Personally, I always go OEM replacing anything. I don't like to go cheap. Make sure you clean your battery connections, too. Use locking nuts over wingnuts to keep those connections tight.  Hopefully your only out a couple hundred bucks instead of thousands for a new motor. If you aren't handy, just take it into a Mercury Dealer. Assuming it is indeed just your voltage regulator/rectifier, it shouldn't take any qualified mechanic longer than 1 hour of shop time + parts. 

Always, always, always charge your batteries up after each use. 

[nixdorf]

So I finally got a chance to get back out on the water with the new resistor pack. Installation was simple, even after cutting out the old fried wiring. 

The boat voltage was definitely better. It started off around 12V to start the day and ended up at 13.6V at WOT just before I had to leave the water. I think it would have kept going up had I spent more time on the water. Based on that, I would guess my stator was not fried (thankfully). 

Just posting a follow up in case someone with a similar problem finds this thread in the future. 

Thanks again iabass8!

[iabass8]

 You should be seeing 14.4(ish)v at WOT on your HDS9 while running. Assuming your battery was fully charged prior to going out, your battery should read 12.6-12.7 when put in gear at idle, 13.3-13.6(ish) when in neutral and it should go up when in gear and revving the engine/moving at RPMS above 1500 or so to 14.4 give or take .1-.3. Since you only started at 12v (which is pretty close to a dead battery. If you read 12v, your battery was only 25% full which is really, really bad for it.-a fully charged battery with no load should be 12.6-12.7) you may want to look into a new cranking battery if it hasn't been charged/charging properly for a while. Hopefully you see a higher voltage next time out if it was charging.  Charge your batteries after every use! 

[Skeeter Dan]

11 hours ago, nixdorf said:

So I finally got a chance to get back out on the water with the new resistor pack. Installation was simple, even after cutting out the old fried wiring. 

The boat voltage was definitely better. It started off around 12V to start the day and ended up at 13.6V at WOT just before I had to leave the water. I think it would have kept going up had I spent more time on the water. Based on that, I would guess my stator was not fried (thankfully). 

Just posting a follow up in case someone with a similar problem finds this thread in the future. 

Thanks again iabass8!

Stator was good Voltage regulator was Bad

[nixdorf]

Thanks gents. 

Yes, the battery was close to dead when I got out on the water. I knew it was going to be low to start the day.  I was traveling for work until just before I hit the water, so I didn't have a chance to charge it before going out. It's charging now, and will be ready to go for the next trip. I plan to see 14V+!!

Thanks again,

Pete