Battery charger

[biggerseagar]

My turn to ask a question.....

I am getting ready to put 2 new batteries in our 3000 and last week had a chance to run an extension to the boat and turned the charger on see if the old batteries will take one more charge. This is via shorepower connection. Long story short one of the batteries got charged (12.82) while the other did nothing and is at 12.2.....dead. These batteries are 6 years old ....I am not complaining

While looking at all the charger connections just to see if something wasn't connected right.......First I have noticed I have a three bank charger. Then I also noticed that the ground wire coming from the charger goes to just one battery (negative post) which that one got charged while all that is connected to the dead battery is the red lead. Is this a normal setup?

Now mind you I have had no problems before keeping these two batteries charged. I did check the inline fuse on both red leads and the glass was so brittle on the fuses when I pulled them apart they fell apart. I replaced them with two new fuses.

So I got the directions out for boat battery charger and their diagrams does show a black (gound) wire going from one negative post to the other negative post for two batteries but I don't have one.........

So will I get a better charge if I install a ground wire from the negative post of one battery to the other negative post of the second battery or

It works just find like it is ...leave it alone........


Roger

[pascavone]

my original charger died last fall, and so did my two batteries.

So i took the old one off that the fan is so loud you can here it run in the cabin, to get it looked at and they said throw it away and get a new solid state electrinic control unit for $150.00

The new one come with all wires and loops right down to the battery posts, so abandon the old wires.

To answer you question, my boat two batteries negativites are jumped together for a common ground.

[mcoffey]

Hey Roger, is that battery tied into the same common ground as the other battery? That is normally the engine block.
I do not see your 3000SCR manual on Maxum Customer Care but looking at the 2001 2700SCR it does show a jumper between the 2 negative posts on the batteries.
Now it is possible they are connected together right at the block ground point, may want to check that.
Basically, both batteries must be connected to ground or they won't work at all.
Looking at the attached diagram for the 2700, it shows 2 positive leads from the charger with one connecting to each battery.
It also shows just 1 negative lead connecting to one of the 2 batteries.
Then the 2 batteries are tied together on negative.
Easy way to test this is connect your meter ground to the engine block somewhere and then connect the positive to each battery positive and see if you read 12v.

As far as your readings go, 12.2V is not all that bad. It really all depends on how long it can hold 12V while under load.
You can test with a battery load tester (you work for Interstate so I am sure you have one of those laying around) or you can turn on everything for 15-30 minutes and take another reading.
If still in the 11.5-12v range, not bad at all, if below 11.5, may want to consider replacing.
As you said, they are 6 years old and that is about all you normally get out of good batteries (4-5 on the cheaper batteries).

[biggerseagar]

Mac..........each battery ground (twin engines)is connected to each engine separately, so the battery ground is not the same. When I get my new batteries installed next week I am going to add a ground wire from negative post to negative post for the battery charger. I have the battery charger manufacturer's phone number and I am going to give them a call and see what they say.

By the way I do not work for Interstate anymore....got let go day after april fools day and all days. I will be pursuing full retirement now.... what a strange trip it has been!

Roger

[Scott]

Hey Roger,
I'd say run the jumper. If there connected at the engine block it wouldn't matter?

[mcoffey]

Sorry to hear that Roger. Enjoy the retirement and spend as much time as you can on the boat
As far as your issue goes, I don't see why a ground jumper could not be used here. I am actually surprised they have seperate grounds on the 2. I see no benfit to this and would have though the blocks would be tied together on a ground bus or something. I never have worked on anything with 2 engines other than an old Cat D3 dozer with a pony motor (used for starting the big boy diesel).

[pascavone]

I pulled my old charger off and all the wiring. The original positive leads connect under the main battery switch posts and was fused, using those little weather proof fuse holders that ring the main battery switch.

The negative is bundled with the other wires running to the negative battery post.

The original 110 volt on the boat has three loops on the wires end, not a standard outlet plug. The new charges have an typical 3 prong male plug like your coffee maker.

So, the new "Guest chargers" come with all wires that run directly to the battery posts.

My original was 30 amps, but they suggest amp size is 10% of the battery amp hours, which is 85 per a number 24 battery.

so, 8.5 x 2 = 15amp charage, or 20 amps to be overkill.

For $200 bucks on ebay or amazon, $350 at the local boat store you can get a 3- battery unit with an extra.....

[9Ball]

All this discussion made me go look at my battery charger wiring. I have a two Battery bank, and the Charger is a ProTech1210i. The wiring from the charger goes to the Battery switch as well, but the Manual shows the POS wires going to the Batteries and NEG to a Common ground. Think I'm going to fix this tonight.

Todd

[biggerseagar]

Todd.......Makes you wonder .....I know my battery charger worked without the common ground to the other baterry, but added one yesterday when I put my new group 29's batteries in the boat. We have a regional store called Farm and Fleet and I picked up these Marine deep cycle batteries group 29 800 cca and 185 RC with a 2 year warranty for $75.00 a piece. The diagram from the charger instructions has that common ground wire from batery negative to the other....so see what happens...

Roger