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Old 02-12-2016, 08:08 AM   #1
338federal
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Default PSU 37.5V drops to 24.4V

Hello. New dude here. And new to Powerlab8 charger. I have DPL charger. 3x12.5V power supply. Brand is hp dsp-600pb. I take power parallel from these psu. 37.5V shows unload from both ec5 ends. Power up both and V drops to 24.4V. Only with one channel powered it shows 37.5V.
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Old 02-12-2016, 08:18 AM   #2
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Sounds like one of your DPS-600PB server supplies is dropping out under load. You should be able to see the fan stop and the supply that's failed will get hot.
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Old 02-12-2016, 08:55 AM   #3
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Originally Posted by JetPlaneFlyer View Post
Sounds like one of your DPS-600PB server supplies is dropping out under load. You should be able to see the fan stop and the supply that's failed will get hot.
I will check this out. I hove ordered hp dsp-800 1200w 3 of these maybe they will give the power i need.
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Old 02-12-2016, 09:19 AM   #4
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The combination of the DPL (Dual power lab) and the regular PL8 could for sure be exceeding the output of the power supply, which could cause them to trip out. But that would only happen if you were using both chargers at high output.
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Old 02-12-2016, 09:29 AM   #5
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I was only tested to storage charge one 7s lipo with 10A. Not hard charge. Limit on DPL software current 21A on both channels. I get mine 1200W power supply next week. Thanks dudes for answers.
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Old 02-12-2016, 11:31 AM   #6
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Now i have tested with no load at all. I plug 1 side from DPL. It shows 37.5. I plug both sides power supply fails. The first one. Tested the same with power supply 2-3-4. The last "4" fails. These supplys don't like parallel hook up.
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Old 02-12-2016, 12:36 PM   #7
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The supplies have no way of 'detecting' that two chargers are connected. I think it must be the way you have it wires. Can you take a photo?
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Old 02-12-2016, 10:51 PM   #8
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Hello. I am not chore if this is right. Tested with only 2 power supplys. It works parallel. Both channels powered. Manual says with parallel hook up one or two power supplys. This DPL is not working with 3 power supplys. Like i wrote before. 3x1200w 100A is soon home. Will test then.
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Old 02-13-2016, 12:23 PM   #9
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Hello! I figured out what was wrong. I calculated the power supply current limits like this. 47A/2 x 0.9 = 21.15A. I put the current limit tp 24A now all supplys is working. But i am not charging like this because afraid to blow over 47A. Waiting for my bigger supplys.
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Old 02-14-2016, 12:19 AM   #10
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I find the reason why one psu drops out. My english and manual. I must think with my brain not the shell. I had the lowvolt limit at 18.1V. Manual says little lower than real output. Like mine 37.5V out. I put the lowerlimit to 36V. I think this was my problem.
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Old 02-14-2016, 08:55 AM   #11
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DPL randomly drops one psu. I think these chargers are not made for 3 or more psu in series and parallel hook up. One charger is OK but not two.
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Old 02-14-2016, 10:18 AM   #12
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More likely a problem with one of the PSU's... have you done the modifications to disconnect the ground connection inside the PSU?
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Old 02-14-2016, 11:18 AM   #13
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No. I will check the ground. I have not done this psu packs. Bad with this.
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Old 02-15-2016, 11:57 PM   #14
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Originally Posted by 338federal View Post
I had the lowvolt limit at 18.1V. Manual says little lower than real output. Like mine 37.5V out. I put the lowerlimit to 36V. I think this was my problem.
Low supply limit should be 50%-75% of the supply voltage. If you set it at 36v, the chargers will start limiting as some as a the load causes the supply voltage to drop.

There are at a lot of users with that setup. It most certainly can me be made to work. As others have said, its most likely and issue with the way the supplies are wired together, or perhaps one of the supplies is going bad.
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Old 02-16-2016, 01:01 PM   #15
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Maybe one are giving up. It works nice with one charger plugged but not both. Now i have 25V and 25V. I manage until i get the bigger ones.
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Old 02-22-2016, 05:23 PM   #16
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Hello! I have now 3x1200w 100A power supplys. All is working OK. Now only happy charging and flying.
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Old 02-22-2016, 09:19 PM   #17
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Sounds like something about "isolating the ground" in the secondary and/or tertiary PSU. This is the part that made me run away from linking my PSU in series. It can be, and from what I understand, has to be done. I do not have enough understanding of the process to go any further.

I don't have a short temper. I just have a quick reaction to B.S.
Rob
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Old 02-22-2016, 09:30 PM   #18
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I think with my first psu dropping voltages issue was to much current in startup. When i plugged second time all works. But now no issue with this new HP 1200w.
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