Battery keeps dying - Maxum Boat Owners Club

viper12161 · 05-21-2021, 02:23 AM

Hello,

So new to me 01 2400SCR. This is my first time having a boat with shore power. It's all hooked up correct. Breakers are on for battery charger. Everything 120v wise works fine. But tonight, the battery only had 8.9v in it for some reason. The bottom green light is on for the battery charger, so I think that is working correctly. I'm guessing something is obviously drawing the power, but I would think that needs to be a hell of a draw that the charger can't overcome it. So question....should I be putting the battery selector switch to OFF every time I leave the boat? I used to have to do this on an 1800sr3 I had. The only real new addition is a Raymarine Axium 9. Any thoughts where i need to start here? Battery is 2 weeks old and is a starter/Deep cell combo battery.

Thanks!!!

mmwjr · 05-21-2021, 12:33 PM

The green light just tells you the charger is getting power and nothing about it’s output. You need to use a voltmeter to actually measure it’s output to be sure it’s working. To determine the source of the power draw use an amp meter on the batteries positive cable to see how much current is being drawn when the boat is shut down as you leave it. Then try pulling fuses to see if you can find the source but see if the current draw goes down. I always turn my switch off when not using the boat.

viper12161 · 05-21-2021, 01:43 PM

Thanks Mike. I did try to test the charger output. Followed the orange wire coming from it to the battery. Disconnected from the battery and tested and was getting 12v. However, where I'm not sure was correct, I had my son turn off the shore power switches, and it was still reading 12v. So not sure it was somehow pulling off the other battery. Maybe they both need to be disconnected. I did replace the charger connector at the battery while I had it apart. They had used this giant O connector that was way too big for the battery post. I turned off the battery switch last night before I left with battery at 10v. So I will check later tonight to see if it is charged. That should at least verify if the charger is working correctly or not.

mmwjr · 05-21-2021, 02:58 PM

The chargers output should be 13-14V. The two banks should be isolated and not allowing voltage bleed through. Some chargers will turn off if it doesn’t have a load.

viper12161 · 05-21-2021, 03:04 PM

Hmmmm, that's weird then. Not sure where that 12v to that orange line is coming from even with charger off. I wonder if there is some sort of capacitor in the charger that holds some power and I gotta let that bleed off first or something. I'll see what happens today when I head down before I start going nuts diag-ing the charger.

viper12161 · 05-22-2021, 02:42 AM

Ok, so a little update. Went down tonight. After leaving the battery switch off and shore power connected, charger on for roughly 24 hours. Battery was at 11.5v. I'm thinking charger is bad here. Only charging 1.5v over a 24 hour period seems off to me. Just for the heck of it, I started the boat and let it idle for about 5 minutes. Checked battery after and it was at 12.5v. So I know the battery is taking a charge. (It's only a week or two old, so I would hope so.) If it is the charger, is there a good recommended replacement? Prefer something that is relatively drop in replacement. Current charger is a Truecharge 10hw. I'd rather not have to rewire everything (I will if I have to, but prefer not to)

Thanks!!
Dave

jparsons121 · 05-22-2021, 03:54 AM

That charger has a sense circuit that varies output voltage based upon the batteries charge state. To measure if it’s putting out proper voltage, the leads from the charger must be attached to the battery. Check the voltage across the battery terminals with the charger on and see if you have 13-14v. Charger should be connected directly to battery, so leaving battery switch in off would also make the test more accurate.

Be sure to check both the positive as well as negative leads for good connections..

viper12161 · 05-22-2021, 03:59 AM

So when I tested tonight, I tested right as I got on the boat. Switch off position, charger was on...and got the 11.5V. That was tested on the terminals.

jparsons121 · 05-22-2021, 12:28 PM

So onto your next question..
I’m partial to the ProMariner line of chargers.
Since your factory unit was only a 10a (which really means 5a per bank) your options would be a 12a or even a 20a. Selection is up to you based on how fast you need to recharge and cost. I use a prosport 20 dual bank for my small boat to recharge the trolling motor batteries which allows for full recharge overnight (actually a few hrs). On the 3000, it has a Pronautic 12-30 which is a 3 bank heavier duty charger. For youR application, the Prosport 12 or the 20 would be a solid replacement.