Re: [MV] Battery Charging rule of thumb

From: Andreas Mehlhorn (a.mehlhorn@t-online.de)
Date: Sun Apr 15 2001 - 02:47:09 PDT


Ron schrieb:

> While wandering through the manuals I've down loaded, I came across this
> info on recharging rates:
>
> a. When uncontrolled, a high charging rate (current flow) will generate
> excessive heat...

You are right, "when uncontrolled". The good old rule was to charge the
battery with 1/10th of the capacity:

Capacity 20 Ah = Charge with 2 A(mperes)
Capacity 50 Ah = Charge with 5 A
Capacity 80 Ah = Charge with 8 A
etc...

At this charging current you need 14 hours to charge an empty battery.

If you controll the battery during charging, you can use much higher
charging currents. "Controll" can be checking the temperature, voltage
and acid density during charging or using a automatic charger.

Note: My car has a generator (to be more precise: a three phase alternator)
wich produces 2 kW (2000 Watts) at 14 Volts = 142 A. When the car
is running without light or any other big electrical consuming devices
(only ignition and injection) there is much more elctricity left to charge
the battery than these lousy 8 A for the 80 Ah battery. The alternator
is voltage regulated, so you can't overcharge the battery, but if the
battery is low, there will be a very high charging current.

Best regards
Andreas
http://www.kettenkrad.de



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