Deep Cycle Battery

[Steve B]

Yeah the 24 month warranty was a bonus too. The Landmark place I get them here in Gin Gin has them for $121.00...best value I have ever seen. They sell hundreds of them. Not very handy for anyone really unless u live around here...or travelling thru!!!.

Cheers Steve

[cormorant]

I'd want a explaination from the people who sold you the other batteries as well if your charging and motor have all been OK.

I'd be checking your set up especially if it has battery switches or a automatic switch as it may not be right or you may not be using it correctly. . You don't want to get stranded with both new batteries dead if one fails. Some alternators are able to charge 2 batteries seperately.

Most batteries have a set shelf life and some can't be recovered past that if they haven't been charged so have a look on your dead ones and see if they were old stock or something??

A propper charger may recover the deep cycle one so it could be used as a spare.


Edit

I second what Rayken says below. Battery shops love mug punters ( and we are all mugs at some point) A deep cycle would be a 6 hr recharge overnight and then a discharge tester down to a set voltage.

[rayken1938]

It would appear to me that you had a problem before you purchased the new deep cycle batteries if the original batteries would not hold charge.
No way in the world would 2 3month old deep cycle batteries fail without some underlying cause.
I would predict that you are going to have the same problem with your new batteries.
Did battery world recharge the batteries before testing them?
If the batteries were discharged no way in the world can they successfully do a load test.
It is a favorite ploy of battery shops and if it turns out there is another problem they will state that the battery is stuffed anyhow.
Has anyone done any in depth testing including leakage tests or just concluded that everything is ok because there was no massive spark when the battery was connected.
Cheers
Ray

[PADDLES]

i reckon that's good advice from cormorant and rayken

[MEG-A-BITE]

I have checked all the connections on the boat and tested to see if there is any draw on the battery once the isolator switch is set in the off position. 0 reading on the meater, so happy there is nothing drawing current when the isolator switch is off. Started the motor and checked the alternator is charging at the correct voltage 14.3 so all good according to my motor mac.The old batteries that got the boat with were not deep cycle but cranking batteries and I used them for 4 months before changing them as they were over 4 years old. They never let me down but for peace of mind got new ones. Only now when I started using the new N75 Century deep cycle battery have I had a problem.
Well will see how the new marine Pro last, will soon see if they do the same, as it only took two outings before the last lot were flat.
Just in case I do carry a third 120AMP battery as a spare for kids DVD, so it’s a good backup for a jump start if necessary. And its always charged.

[cormorant]

I'll guess there is something up with the alternator or even as simple as astuffed battery switch?

I'd run on bat 1 position only so you can only stuff 1 battery and then have the other 2 to get home with.

Not a fan of trail and error on the water but it works as long as you know you have a possible issue.

It may just be a battery you have removed.

Does the manual have any other tests for alternator output especially as it may only be charging for a very short period or getting very hot? I don't know mercs .

[MEG-A-BITE]

Hi Cormorant,
Im sure the alternator is working,when i did a long run out to Hutchies last the battery was low when I left Bribie.And was fine all day from the charge it got during the 1 hour trip out there. But when I got home charged it up for a day on the charger,then went to use the boat on the weekend and its flat, It just did not hold the charge once it was fully charged. Must have been a bad battery.

[rayken1938]

Be interesting to place both the 75ah deep cycles on charge and then do a load test.
Cheers
Ray

[MEG-A-BITE]

I was told its not good to run the motor when you have the isolator switch set to both batteries, is this true?

[cormorant]

Yes and no

Firstly never change the isolation switch with motor running. You can do it with some "make before break"ones but most aren't. It can kill motor computers , electronics on boats and stuff alternators.

The yes and no bit.
Running the motor with both batteries connected just makes one bigger battery. No problem with that if both batteries are good. If one battery is bad it means both will not charge and the good one will die faster. Gives you no backup if something goes wrong. I assume the alternator is capable of putting out a reasonable charge suitable for the "one big battery" with the above.

Running the battery switch on 1 or 2 position keeps the batteries isolated. The "1 or "2 " battery will only be charged when the switch is on its' position not both.. This means the battery used to start the motor gets recharged and topped up quite fast. Later you can with the motor switched off switch over to "2" and a run on that will charge it.

Having the switch on both is a issue with accessories as well as they can drain both batteries and leave you no way to start the motor. Best to have all accessories off only one battery so if you leave a pump or light on it only drains one battery.

In our larger boat we had a system where we could select which battery bank we would choose to use as the house battery so all batterys got a reasonable use and drawdown

A solution is to use a automatic switch that isolates the batteries when the motor is not running and only opens the relay between them only when the master battery is fully charged. A lot of cheaper ones don't do this well so watch out what you are getting.


The big mistake with battery switches people make

Both is only for emergencies is my feeling. Basically try and start on pos 1 and if it doesn't start go to off then to pos 2. If it doesn't start only then try both. The reason for this is that if you go straight to both then if one battery is flat ( left radio on for a week) and the other fully charged then it will drain the good battery into the bad so you at best only then have 2 half charged batteries. You may not have enough to start.

[MEG-A-BITE]

Thanks Comorant for the infomation. Will take you advice.