Charging Dead Battery

[joey nathan]

Hello,
So, I tried to help a buddy with a dead battery. Smart charger would not come on until battery cables disconnected. Does this make sense? What would cause this? I remember back in the contact breaker points era we always disconnected one lead to avoid burning the points. This engine does not have points though.
Any thoughts appreciated, thanks...
Jon

 

[alldodge]

Hello,
So, I tried to help a buddy with a dead battery. Smart charger would not come on until battery cables disconnected. Does this make sense? What would cause this? I remember back in the contact breaker points era we always disconnected one lead to avoid burning the points. This engine does not have points though.
Any thoughts appreciated, thanks...
Jon

Yes this sounds normal. The smart charger will not allow itself to charge a battery which is shorting out. If it senses it is pulling more amps then the charger is trying to put in, it shut off so to speak to save it self. Sounds like your buddy needs a new battery

Edit: either that or the buddies boat has a short somewhere. Try putting charger on just the battery

 

[achris]

I guess if the points are closed and the key ON, then yes, the charger will see a short. Or everything AD said.

When I'm done with my boat after each trip, I leave the battery switch on BOTH and hook a small (1.6A) charger to one of the batteries. If I hit the trim switch (drive the leg UP or DOWN) the light on the charger goes from green (maintaining) to orange (charging). Few minutes later it drops back to green. When I connect it up I don't disconnect anything, it just works.

May be your smart charger is alluding to why the battery is dead in the first place. If, as AD suggests, the wiring does have a short, that will be why the battery's dead. :noidea:

Chris.........

 

[bruceb58]

Which smart charger do you have? Many smart chargers will not begin a charge if the voltage is below a certain voltage. An unloaded almost dead battery may still have a voltage of around 8V. By just having the slight tiny load of the battery cables hooked up to an extremely low load circuit could bring that 8V even lower which would put it under the threshold that the charger wants to see.

 

[joey nathan]

It's a Schumacher, but I don't have it here, so not sure model #. Multimeter showed 1.5 volts on a very dead battery, plus hydrometer check showed in the red as well. Thanks for your insight...

 

[Grub54891]

Some of them smart chargers have to sense voltage before they will charge.I've hooked up a jump box and the charger will kick in,then remove the jump box and good to go. Thats if the battery is ok,only dead from lights left on or stuck bilgepump.

 

[Outsider]

Put a 2 amp trickle charge on it for a few hours, then hook up the Schumaker ...

 

[UncleWillie]

... Multimeter showed 1.5 volts on a very dead battery, plus hydrometer check showed in the red as well...

A battery that measures 1.5 volts is DEAD in the sense that it will never be ALIVE again.
1.5 volts means one cell is fatally weak and the other 5 are shorted.
Don't bother trying to recharge it. It will never reliably hold a charge again.
It is time to replace it.

 

[NYBo]

Uncle Willie is correct. Time for a new battery.