Ground Power

[jaylw314]

Whoa guys, we're overthinking this a little too much!  @flyboy0681's goal seemed to be to be able to run his electrics on the ground for about an hour or so.

ANY battery charger would be fine, even the original one he pictured--that one looks like it has a 50 A max boost current (limited by duty cycle), 10A max constant current charge and 2A max float charge.

If you're drawing more than 10 amps, the battery just makes up the difference, since it's still connected.  My radio and cockpit stuff runs off 15 amps or so, IIRC, so after an hour my battery will be discharged by 5 Ah.  Since it has a capacity of 29 Ah, that's fine, and I'd just leave the charger attached after for another hour or so.

I don't think the Sears power supply pictured cycles automatically on 50 A, since there's a current switch.  I suspect the listed duty cycles assume the operator will follow them.

IIRC, 14.0V will fully charge lead acid batteries at hotter temps, so voltage regulators aren't set to 14.2V to make sure there's some leeway for hot days.  A little overcharging is not terrible for lead acid, though, since it simply electrolyzes the water, which you can replace or recombine.  Unless you overdo it and overheat the battery, of course, then it's bad...

Edited June 4, 2021 by jaylw314

[bradp]

For reference my avionics pull about 15-18 amps   
 

[Ulysse]

I plugged a 30A 24V battery charger to the external receptacle to play with the avionics but it doesn't seem to work as the battery voltage went down quickly. 

Can anyone provide a schematic of the external plug/battery system? (M20K)

 

[Warren]

There is a relay that must be powered to engage power delivery to the battery.

This is the diagram from the last of the 231's with 12V systems.

Just noticed you have an Encore.  Here is is for the last K serial numbers with 24V.

[Ulysse]

Oh, that is what the third pin is for !

Looking at the schematic, it seems that attaching the third pin to + would energize the relay. Is this what people are doing ?

[carusoam]

10 minutes ago, Ulysse said:

Oh, that is what the third pin is for !

Looking at the schematic, it seems that attaching the third pin to + would energize the relay. Is this what people are doing ?

This is a natural safety system for keeping somebody from connecting a battery up with reverse polarity…

Proper plug, with proper polarity… results in the relay closing allowing electrons to flow… the proper way…

 

What people are doing… is get a plug that is pre wired to do all this… connect ordinary jumper cables and battery… and voila!

Best regards,

-a-

[EricJ]

10 minutes ago, Ulysse said:

Oh, that is what the third pin is for !

Looking at the schematic, it seems that attaching the third pin to + would energize the relay. Is this what people are doing ?

That's also why the third pin is shorter, so that the two power pins are connected before the relay is energized.

[Mooney Dog]

That says charger and starter on it, i wouldnt use it as a GPU. I would assume it would be for short term use. 

 

On 6/3/2021 at 7:42 AM, flyboy0681 said:

I'll run down to Radio Shack and get one today.

Oh man, thats a blast from the past.