bradp Posted August 13, 2019 Report Share Posted August 13, 2019 Hi all, Wanting to run avionics / be able to test electrical devices in the aircraft. Thinking about a used HAM radio type 13.8V power supply to do this. I’ve seen the stupid expensive power pacs on spruce. There’s some stuff on csobeech and a guy on cirruspilots.org that makes switching units with a 3 plug. I’d like adjustable in order to avoid charging the battery indiscriminately. Not looking to charge - just keep from discharging battery when fiddling with radios / updating databases etc. Deciding between an Astron unit and an MFJ unit. Without me looking up my latest electrical load analysis, is 30A reasonable to run avionics and intermittent electrics (ie pitch trim, autopilot servo?). I’m not looking to crank and I’m not looking to swing the gear (and if I did swing the gear all the other stuff would be off anyway). Just ballpark ...25A continuous use should be plenty right? Next step up is about 50A... seems with both these brands RF noise should be a non issue for either linear or switching models. thanks much! Brad Quote Link to comment Share on other sites More sharing options...
wishboneash Posted August 13, 2019 Report Share Posted August 13, 2019 I use a ham radio supply myself when I need to run avionics, test the autopilot etc.. Mine is a variable 0-20V, and 0-30A supply (have to check the make and model, can't remember at the top of my head). Unfortunately the potentiometer has deteriorated so the voltage is not quite settable accurately (so I double check with a voltmeter before connecting to the 3 pronged plug). I use the Concorde batteryminder when I need to properly charge the battery when I am not actively monitoring the charger or if it involves a long charging time. 1 Quote Link to comment Share on other sites More sharing options...
larryb Posted August 13, 2019 Report Share Posted August 13, 2019 I tried a cheap 25 A LED power supply from amazon which had enough noise to break squelch on my GTN. Now I have a MeanWell supply which is much better but still not perfectly quiet. 25 A is fine. Quote Link to comment Share on other sites More sharing options...
MIm20c Posted August 13, 2019 Report Share Posted August 13, 2019 I’ve recommended the Iota power supplies in the past but never actually used one. I’d want a unit that had a very stable voltage output all the way to the rated amperage limit. Quote Link to comment Share on other sites More sharing options...
carusoam Posted August 13, 2019 Report Share Posted August 13, 2019 So I looked up the BatteryMinder version... to see their specs... 28V 25A 0.8AMU... Does everything including charge and desulfate... A regular BatteryMinder can provide 4Amps at 28V If you have 14V system... 8Amps are available... If you are only going to run a few radios... The load needed is roughly described by their collective CBs... Try connecting you BatteryMinder up to your battery... Have your JPI on displaying Voltage... See how far you get..? Nothing charges the battery as indiscriminately as the old voltage regulators from the early days, made up from sticks and stones and springs... PP thoughts that you have covered already... but, I did the homework, so I am showing it too... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
EricJ Posted August 14, 2019 Report Share Posted August 14, 2019 (edited) I made one last year just for running the panel to do software updates, etc., and to be a simple constant-voltage charger if/when I needed it (I have a couple times). This is *not* the same thing as a batter tender or battery minder, which are *not* made to hold the system voltage up when running things. FWIW, I did make mine 30A capacity and just used a decent generic power supply that has good regulation and adjustable output. This is the one I used:https://www.amazon.com/gp/product/B01EWG6YT8 ...but any supply that will regulate properly across the load range (i.e., up to 30A or whatever you want it to do) will work, and most decent supplies will do that. FWIW, I did it just because I thought it would be a fun project, but I still wound up with a fair amount of $$ in it, so if you're not handy with this stuff and are looking to save a ton of $$, this is probably not the low-hanging fruit for that outcome. For a 12V system the output should be in the 13.5V to 14V region, which will run everything like the alternator was running, and will charge the battery like the alternator would. Pics below. In hindsight I should have used a larger project box, but it did all wind up fitting. It works great, I've used it a lot, and used it as charger when the avionics installer hosed me with the current-sucking clock that would kill my battery in a few days and to subsequently top of the Gill as it was dying many months later. Edited August 14, 2019 by EricJ 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.