is series 2x switchingmode power supplies safe for charging at 1C

bike4life

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Apr 10, 2020
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i have a 36v 1000w supply i would like to series with another 36v 1000w supply of the same model to yeild 72v 2000w... anything i should know. does series SMPS work that well and wont damage the supplies that much.
thx
 
I'm not expert enough to say if there will be long term damage but I've done it many times with server PSUs, before you do anything though you have to make sure you won't have a ground loop. Most of these PSUs have the output negative tied to case and wall ground so you have to disassemble them and isolate the them, normally this means disconnecting the output ground from the case but every PSU will be different and I'm sure some you can't easily disconnect them. That being said I can't recommend doing this, they are really not designed to be operated in series and the isolating thing is a bit of a hack so this may be one of those do as I say not as I do situations, at least unless you really understand what you are doing.

Edit: Also should wait on someone more expert than I to chime in here.
 
It would depend on the psu
I know for some of the Meanwell psu's (HRP) you can series them no problems.
I know for some Dell server psu's people use to power big powerful rc chargers you need to isolate the ground.

Its probably a whole other story when you're talking about off brand generic chargers.
 
its a generic 1000w switching supply from china... The grounds are isolated. I actually ran a series system for a few seconds and had it turn an motor and it worked, so i suppose its ok. I never open and remove case ground, i simply dont wire a ground to the supply 2 prong plug and i make sure the 2 supplies are not touching.
 
If you can take a quick peek inside and see if you can isolate the case that would be safer, if you just don't connect the ground on the case then that exposed case is now live and something metal could easily touch it at the other case. On many server PSUs at least it's just a matter of removing one of the board mounting screws and putting something under the pad around that screw hole that connects the output ground to the case there.
 
If it didn't immediately blow up when you tested them in series, that's a good sign. An easy way to double check is to use an ohmmeter and measure resistance from the case to either output terminal. It should look like an open circuit if it is isolated.
As long as the outputs are isolated, you can run supplies in series with no issues.
 
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