Paralleling Power Supply Units Made Easy ???
I am considering paralleling a couple of 20a variable adjustable psu's for 40a charging. According to what I have read on the world wide inter-web, it can be done quite easily, provided the following ...
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I hooked up both the Turnigy 1080w and the Gophert 1620 on a 215Ah bank at 12.16v, ~45% soc. The Turnigy was set at 13.62v, and the 1620 was set at 14.9v and 19.8a.
I started charging with the 1620. Within 2 minutes, the batts were up to 13.75v, so I turned on the Turnigy. It came on, without going into over-current protection, and output 0 amps. As I slowly turned up the voltage (it takes about 15 full turns per 1v) it started outputting current once I came withing 1v of the 1620's output voltage. As I continued to raise it's voltage, the 1620's voltage rose accordingly, staying between 0.5v - 1.0v above that of the Turnigy.
Once the Turnigy was dialed up to 14.82v, the 1620 reached it's 14.9Vabs setting, and switched from cc to cv, and its amps started tapering. The Turnigy's amps rose as the 1620's tapered. Between them they maintained the total the batts would accept... but only up to the Turnigy's 60a limit? So, if the 1620 was at 20a, the Turnigy was at 40a, and likewise 15 and 45, 10 and 50, and so on, until such time as the total amps began to taper below 60a.
If I raised the 1620's voltage 0.1v above that of the Turnigy, it would start to raise its amps, and start doing a higher percentage of the total. At 1v above, it would max out its amps at its 19.8a setting, but remain in cv. If I lowered the 1620's V to 1v below the Turnigy's, its amps would go to zero.
Two things that surprised me were, 1) the fact total amps never exceeded 60a (I expected total amps to be 80a; 60+20), and 2) total amps began to taper very early on in the charge cycle. Although 60a on a 215Ah bank is a fairly high C/3.6 rate, it still seemed a little early for amps to start tapering at about 60% soc?
After playing around with a few settings,I turned off the 1620, and let the Turnigy continue on its own.
So, simply hooking up the 1620 for a few minutes will keep the Turnigy from going into OCP on power up. I actually thought it would take a lot longer for the 20a 1620 to get the 12.2v batts up to over 13.7v. (This is why I hadn't tried it sooner). So, hooking up the 1620 for a few minutes is no big deal as I have lugs I can quickly attach a small pair of clamps on to, inside the inverter cabinet. So now I just need to figure a way to attach a knob to the tiny screw on the Turnigy's pot, for fast and easy adjustments; or better yet, have an electronics guy change out the pot for one with a knob. And once I get solar going, hopefully I won't need to gen charge too often, anyway, and thus save wear and tear on the pot.
Next, I will wire the 430Ah bank back together, and try the same charge routine. I'm curious to see if the larger bank will draw the full 80 amps, instead of 60, at 50% soc?
I started charging with the 1620. Within 2 minutes, the batts were up to 13.75v, so I turned on the Turnigy. It came on, without going into over-current protection, and output 0 amps. As I slowly turned up the voltage (it takes about 15 full turns per 1v) it started outputting current once I came withing 1v of the 1620's output voltage. As I continued to raise it's voltage, the 1620's voltage rose accordingly, staying between 0.5v - 1.0v above that of the Turnigy.
Once the Turnigy was dialed up to 14.82v, the 1620 reached it's 14.9Vabs setting, and switched from cc to cv, and its amps started tapering. The Turnigy's amps rose as the 1620's tapered. Between them they maintained the total the batts would accept... but only up to the Turnigy's 60a limit? So, if the 1620 was at 20a, the Turnigy was at 40a, and likewise 15 and 45, 10 and 50, and so on, until such time as the total amps began to taper below 60a.
If I raised the 1620's voltage 0.1v above that of the Turnigy, it would start to raise its amps, and start doing a higher percentage of the total. At 1v above, it would max out its amps at its 19.8a setting, but remain in cv. If I lowered the 1620's V to 1v below the Turnigy's, its amps would go to zero.
Two things that surprised me were, 1) the fact total amps never exceeded 60a (I expected total amps to be 80a; 60+20), and 2) total amps began to taper very early on in the charge cycle. Although 60a on a 215Ah bank is a fairly high C/3.6 rate, it still seemed a little early for amps to start tapering at about 60% soc?
After playing around with a few settings,I turned off the 1620, and let the Turnigy continue on its own.
So, simply hooking up the 1620 for a few minutes will keep the Turnigy from going into OCP on power up. I actually thought it would take a lot longer for the 20a 1620 to get the 12.2v batts up to over 13.7v. (This is why I hadn't tried it sooner). So, hooking up the 1620 for a few minutes is no big deal as I have lugs I can quickly attach a small pair of clamps on to, inside the inverter cabinet. So now I just need to figure a way to attach a knob to the tiny screw on the Turnigy's pot, for fast and easy adjustments; or better yet, have an electronics guy change out the pot for one with a knob. And once I get solar going, hopefully I won't need to gen charge too often, anyway, and thus save wear and tear on the pot.
Next, I will wire the 430Ah bank back together, and try the same charge routine. I'm curious to see if the larger bank will draw the full 80 amps, instead of 60, at 50% soc?
