Ebuilt said:
Can someone who charges their batteries with a computer power supply instead of the everyday Chinese style chargers help me figure out if this power supply would work for my 72v?
https://www.ebay.com/itm/Smartbuy-1000W-1000-WATT-LED-Fan-Silent-PC-ATX-Power-Supply-PSU-SATA-12V-PCI-E/284079549368?hash=item422475ebb8:g:t04AAOSwN4ZfsxPy
A low-voltage computer PSU like that can't directly charge your 72v battery. You could possibly use it, with some modifications (that add more cost), to power an RC charger to charge part of your battery at a time. (how much of it depends on how many series cells the RC charger in question can handle, but probably only half the pack at a time at best, if it's a 10S RC charger).
*IF* that computer PSU is electrically isolated from it's wall AC plug to it's DC outputs (some are, some aren't), then you could series the 12v outputs of 7 of them to get a voltage high enough to be able to charge your 72v battery. But you would still have to build or buy a current-limiting circuit, so you don't just blow the fuses (or the electronics) in the PSUs when you connect your discharged battery to it. So you'd have the cost of 7 x $70, or $490, plus taxes and shipping, plus the cost of the modifications necessary to make the PSU run without a computer attached, plus the cost of the current-limiting circuit. It'd probably end up costing at least as much as two Satiators at that point.
If you want to use a power supply, instead of an actual charger, to safely charge your battery, you need one that does *all* of the folowing things:
--it must have a voltage *at least* as high as the fully charged voltage your pack needs to reach.
--This voltage should be adjustable to reduce it to match your fully-charged voltage. (otherwise you risk overcharging your pack and starting a fire)
--it must be capable of the current rate you want to charge your battery at.
--it must have current limiting that is *not* a crowbar or hiccup type; it must be the type that lowers the voltage to reduce current to whatever you have set the limit to.
--This current limit should be adjustable so you can reduce it to the maximum your battery can safely be charged at.
If it can't do all of those, you can't safely use it as a charger. (it *might* charge your battery...but not controllably).
So the type of PSU you are looking for is generally called a "laboratory PSU" or Lab PSU, that has both adjsutable current limit and adjustable voltage. These can be fairly expensive, unless you find them used. Sorenson makes good ones that I have used for this...but they're not cheap.
Alternately, you can use *some* of the LED PSUs, like the ones Meanwell makes in their sealed (weatherproof, like the Satiator) HLG and ELG series, *as long as* you get the versions that have adjustable voltage and current (they do not all have this! If they don't, they won't do what you want!). But these don't usually go as high a voltage as you want, so you would need to series some of them to do it.
For example, you could use two HLG-600H-48A units in series, adjusting their voltages down to about 42v each for the 84v total your pack needs for full charge, and adjusting their current limits to be whatever rate your pack is safely chargeable at. At a guess that's probably anywhere from 2A to 10A, depending on the cells in it, how many there are in parallel, and the BMS in it. These PSUs are capable of up to 11-12A or so, so you would probably not be running htem at their max for your pack.
Mouser has them for only about $184 each
https://www.mouser.com/ProductDetail/MEAN-WELL/HLG-600H-48A/?qs=5pLaOnqdcwMTG4LuGsfZDA%3D%3D
so it would only cost about $400 with shipping/tax/etc most likely. This sounds expensive, but it gives you at least twice the available charge current that a 72V Satiator can do. (though two of these HLGs are about three times the size of a single Satiator.) I'm sure you can find them cheaper somewhere else.
You can get cheaper "open frame" Meanwell LED PSUs that do the same job; I don't know which specific models work for this, though. There are a number of good threads around the forum discussing using Meanwell LED PSUs for charging, if you poke around, that do have those details.
