Date: Mon, 31 Jan 94 15:25:31 EST
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From: "Fred G. Martin" <fredm@media.mit.edu>
To: Multiple recipients of list <robot-board@oberon.com>
Subject: Re: Battery charger 

> What kind of DC power adapter do I need to buy to power the 
> battery charger board (6.270 kit)?  It has to be a 6-Volt
> supply, right?  Thanks.

No it has to be greater than 6 volts in order to charge the battery.
If you used a 6 volt supply, your batteries would be charging the
adapter (well not really, but you get the idea).

Figure a couple of volts above the desired battery voltage, and add a
couple volts for the diode drops in the bridge rectifier.  We use 12
volts supplies for 6 volts batteries.

Also, get the strongest (i.e., greatest ampere capacity) adapter you
can get your hands on.  We use a 2 amp adapter, which is pretty hefty.
If you go below an amp, your charge rate will be limited by your
adapter, and your adapter will be pushed to its limits.

	-Fred

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Date: Mon, 31 Jan 94 17:00:19 EST
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From: John_Cook_at_USNUS08@usnus05.usnus.abb.com
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Subject: Re[2]: Battery charger 
X-Listprocessor-Version: 6.0b -- ListProcessor by Anastasios Kotsikonas


>> What kind of DC power adapter do I need to buy to power 
>>the  battery charger board (6.270 kit)?  It has to be a 6-Volt
>> supply, right?  Thanks.
     
>No it has to be greater than 6 volts in order to charge the battery. 
>If you used a 6 volt supply, your batteries would be charging the 
>adapter (well not really, but you get the idea).
     
>Figure a couple of volts above the desired battery voltage, and add a 
>couple volts for the diode drops in the bridge rectifier.  We use 12 
>volts supplies for 6 volts batteries.
     
 >Also, get the strongest (i.e., greatest ampere capacity) adapter you >can get 
 your hands on.  We use a 2 amp adapter, which is pretty hefty. >If you go below 
 an amp, your charge rate will be limited by your >adapter, and your adapter 
 will be pushed to its limits.
 
 >-Fred


I use a spare PC power supply with a 10 ohm 20 watt load on it to preload it
and maintain good regulation.  They're typically rated at around 5 to 10 amps
on the 12 V output and work well.  Plus they're VERY common.

-John C.