[ARC5] Dynamotor Regulation

[Christopher Bowne]

For the ARC-5 /274 systems you can easily get by with 2 20 buck garden tractor batteries from Walmart in series each floated with a separate 10 amp 12 battery charger.  I have been using that type of set up for over 30 years with two basic Sears chargers.  I also use the small garden tractor batteries in series across my PP-7773 60A 28vdc supply to run my ART13/DY17A setup.  However, the small batteries don't have quite enough oomph to prevent the DY-17 starting surge from tripping the 7773 output breaker, l usually have to reclose it once the dyno is running.  With fully charged bigger deep cycle marine or car batteries the breaker usually will not trip.  I have also found from experience with the 7773 that you need to physically disconnect the batteries from across the output of the supply when it is shut down.  There is some drain on the batteries from the 7773 even with its output breaker open, from at least the voltmeter circuit,  which will drag down the batteries over several days.  I just disconnect the lead between the two batteries to put them on open circuit.

Sent from my iPhone

> On Jul 29, 2017, at 08:39, Cliff Miller <cliff52 at gmail.com> wrote:
> 
> please add to my last - I reread the original message and you did mention the BC-456 so we're talking the dynamotor power supply for the modulator.  I hope someone updates my notes with what size batteries/ charger/ DC Power Supply works with the larger dynamotor.  The server power supplies I mentioned are available in quite large current ratings.
> 73 - Cliff W4HGR
> 
>> On Sat, Jul 29, 2017 at 8:19 AM, Cliff Miller <cliff52 at gmail.com> wrote:
>> Have we clarified if we're talking about just a receiver or a receiver-transmitter system?  I have no experience with the dynamotor on the modulator for the transmitter so I can only speak to using the receiver dynamotors, which is smaller.
>> I have successfully used 2-12V gel-cell batteries of 7A-h or more capacity, series-connected, to start the receiver dynamotors.  I've also used my 13.8V 25A ham power supply and a 12V gel-cell to run them / no problem.
>> 
>> The RC folks have pioneered the use of two 12V computer server power supplies, series-connected, to charge 24V model airplane batteries.  These are readily available in high current values since the server people just install new ones periodically because failure-is-not-an-option, etc.  The negative side is shorted to ground so you have to separate that on one of the supplies if you're going to connect them into 24V.  Lots of details on using these on some of the RC forums.
>> 
>> I bought two of these to experiment but have yet to try them.
>> 
>> Of course, eBay is your friend with various 24-28V high current power supplies available just about all the time.  I tried the server units since they're cheap (two for 15 bucks plus shipping).
>> 
>> 
>> 73 Cliff W4HGR
> 
> 
> 
> -- 
> Cliff Miller
> cliff52 at gmail.com
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