Re:Now Battery Care

[turbodmc@xxxx]

I'm the original author so I'll clarify this.
A Float charger is not a Trickle charger. 
A trickle charger will eventually over charge a battery thus it
should not be left on indefinitely.
The float charger only tops off a battery and can be left on 
indefinitely. A Float charger is not a good choice for charging a
dead battery.

Float chargers are available for as little as $10 or $15 dollars, the 
more expensive ones have short circuit protection and some other
bells and whistles I'm sure.

I use the low-end $15 float chargers and you do have to be careful
of two things with the low cost float chargers.

1. If you draw too much current when the Float charger is on (like 
leaving the key in the on position when your DeLorean is in storage 
(the dash lights draw a lot of current) you will burn out the float 
charger because they are only meant to put out about 50-100 ma max. 
After you burn out the cheap float charger then you kill the battery 
next. So don't leave the keys in the ignition its bad practice.
Don't ask me how I know this!

2. The low cost float chargers have one other draw back and that is, 
if you loose ac power, the car battery now acts as the power source 
and back feeds the charger slowly discharging the car battery.
If you just add a diode to prevent this it will throw off the output 
voltage by 0.6vdc so you would have to re-calibrate the unit to put 
out the right voltage (a float charger is a constant voltage device 
not constant current device like many tritional battery chargers). 

The general thumb rule for charging a battery is 10% of the ampere 
hour (AH) rating is an acceptable charge rate thus a typical car 
battery with an 80 AH rating can be charged at a maximum of 8 Amps 
safely.
Don't confuse this with the CCA rating on the battery!

Trickle chargers usually have a maximum charge rate of 1 to 2 amps 
thus they don't charge the battery too quickly, slower charging is a 
preferred method if time is not a factor. 

Note: A trickle charger can over charge the battery if it is left on 
after the battery is fully charged!

I have heard about electrolysis of the engine and am not sure how
much of a problem it is.

I think I heard Ferrari's have a sacrificial anode that is built into 
the engine to prevent this and is even on the maintenance schedule to 
be replaced at some interval. If some one knows about this I would 
love to know the details.

If you are worried about electrolysis disconnect the battery and keep 
a float charger on the battery while it is being stored, this will 
give you the best battery life and keep a full charge on it at all 
times. 

Regard,

Mike D.


> ALSO - note that you want a battery TENDER (aka battery buddy, 
etc.) not a float charger. Based on the price range given, that is 
probably what the author meant. The difference is that the
tender-type 
of device actually cycles on and off, whereas the float/trickle 
charger keeps a constant current flow to the battery. The constant 
current flow is not as healthy for the battery. The difference in
cost 
between the two is slight. 
> 
> 
> Dave Swingle
>