S-350 range of meanwell power supplies work well and are easy to mod.
I am using 3 x 48v units modified to provide 60v at 5.5A to charge a 20ah x 50 cell pack in 4 hours.
The info comes from this thread on the endless sphere forum.
http://www.endless-sphere.com/forums/vi ... =14&t=4125
I bought them from the below, came in about 10 days from china. Three chargers came to about $110 which is very cheap compared to a 'proper' EV battery charger. I paid over £500 for my last Zivan charger and it took two months to arrive
48v items - Get great deals on Tools, Prototype PCBs items on eBay.co.uk Shops!
I'm using them to charge my 50 x 20ah A123 cell pack. I have them running at 60v and 5.5A output.
They seem pretty easy to mod, with all the bits identified in the endless sphere forum threads in the right places on the pcb.
The three supplies all have the following mods.
1) Fan mod to activate fan as soon as psu is turned on. Simple 470R resistor inserted instead of thermistor.
2) Raised output voltage mod. Simple replacement of 2k resistor with a 1.2k device to push up the operating voltage range window.
2A) Replacement of over V voltage detection zener with a 68v device to enable 2) above.
One of the psu's (Let's call it the Master) has three further mods.
1) Current limit mod to lower output current so total supply power does not exceed 350w or so. I started by removing one of the three shunts on the pcb reducing output current by a third.
2) I then removed R33 and added a 500R pot into the free space on the pcb at SVR2 and a link at R27. Gives fully variable current limit.
3) I also brought out two connections which bridge the output voltage pot to use that to remotely control the operating voltage later. Perhaps via a digital pot.
All three psu's in series should run at the current as determined by the Master.
The charger is controlled in three ways.
1) The total output voltage of the combined psu's is adjusted to the pack full voltage limit or a tad below. So they limit themselves when output voltage rises to the preset maximum. So if the BMS fails and the pack is reasonably balanced it should be impossible for them to overcharge the pack.
2) The BMS controls the output voltage of the Master Psu. If a cell goes over V it can cutback the voltage of the the master PSU reducing charge current.
3) The BMS controls the solid state mains relay which powers up all three Psu's. If a cell goes over V and it can not be corrected by 2) above then the mains can be cut.
You can make higher current charger using a higher number of the lower voltage supplies.
I used to have giant 50A charger for my 200ah TS cells made using two 3kw 48v server psus in series. It worked very well!