Battery charge question

[investor2009]

Hi all, I recently traded in my old ride on mower for a new John Deere (which is really good by the way!) and used to use a 12v float charger to keep the battery in tip top shape for many years.

With the deere, I plug the charger in but it never floats so is always charging.. I remove the charger and test with a meter and watch the voltage slowly drop down millivolt by millivolt to just under 12v. Do these possibly have a bleeder circuit or something, why can't I charge the battery to 13.5v like others?

 

[eXc]

I'll talk car and bike batteries here...but they are still 12v.

Not sure I understood the scenario completely, however...

You should disconnect your battery from the vehicle when charging. It seems you are leaving it connected to the vehicle?

It's rare for a battery to hold over 12.2v when not on charge. They might for a short period, but not long term. I would expect to charge at ~14.4 if on the vehicle, and on my bench charger (cheap) I get 13.2v trickle, but never used fast charge - assuming it will be 14.4v.

As soon as I unplug the charger after it is 100%, the battery will drop to 12.2v or so. Re-connecting the vehicle, it stays at 12.2v or so, at least for a few days.

I'd say the battery is on its way out if it drops below 12v. A mate just replaced his last week - it dropped from 13.2v charging, to 11v immediately after stopping charge.

As a side note - for those that don't do it - it is recommended that you trickle charge your car batter at least once a year - apparently it makes them last much longer.

 

[redwing]

There is a slight draw (milliamps) to run the odometer/engine hr clock on some models. First impression as per eXc is that the battery is u/s and will not hold a charge, it will not reach 13.8 volt 'float' and self discharges whilst under no load.

My suggestion would be to undo and remove one battery lead - charge the battery - check the voltage (no load of any sort on the battery as it is now disconnected).

Let us know how you go