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lipo battery charger

yinny1

hi all i would like to build my own charger for a nominal 72v full charged 84v lipo pack but i would like it to be able to charge with up to 60 amp and i would like it to have the ability to have its amprage going out to be controled via a micro controler any help would be nice

i am thinking about a buck converter as the mane architecter but i cant seem to find a buck controler to do this task

i would also like it to oparate based on constent current constent voltage both being able to be set by the micro controler via a nextion display were i can also change some settings like

it would be nice to also have soafty features like over temp reduce output power as charger gets hotter short curcit protection over voltage protection over current protection over and under temp protection

  • What is the input voltage desired for your charger build ?

  • in reply to robogary

    input voltage would be 230v ac 50hz

  • That will be a beast of a charger - over 5 KW.

    Even with an efficient power supply it will still have to dissipate over 500 Watts as heat.

    Be sure to factor in a big forced-air heatsink system.

  • in reply to dougw

    i have taken that in to consideration and i am going to use 9 pwm controled 40mm server class fans

  • I'm a professional power electronics engineer with 45 years experience and I can tell you this project will be no easy task. I'm not sure if you're planning on using a 230 VAC to say 100 VDC power supply, or design and build your own offline power supply as part of the job. I highly recommend that you keep safety in mind at all times. And if you're going to use this to charge otherwise disconnected batteries, it would be technically possible to do it without isolation, but that would be highly dangerous if anyone touched either battery lead while the power was switched on. One way to get around that problem is to start with a 230VAC to 100 VDC (or similar) isolated output power supply and follow it with a 5 KW buck converter. The inductor will be your biggest problem component as there generally are no off-the-shelf inductors of that type available. That means you must design your own and get the proper core material for it. The switching frequency should be in the range of 100 KHz to 250 KHz, but not higher than that or the losses and switching voltage spikes can be hard to control.

     

    You could also possibly modify the AC-DC power supply and put in a digital control, but it won't be easy. This way, you don't need a second converter stage. The output of the 230VAC to 100 VDC power supply can be directly controlled to regulate voltage, current, or both (not at the same time).

     

    All I can say is do your homework and good luck.

  • in reply to kkazem

    hi there thank you so much for your helfull advice and i know its a big chalange and i have beign looking round for close to 3 month for help/info on somethign like this and found nothing hens why i am asking here
    and yes i understand all safty concerns and precortions and in a way what i am after isent too far differant from chademo ev dc fast charge onaly lover voltage and current

    for instants i would have a always active 12v logic controle voltage wich inturn would controle contacters to turn the main power on

    and i am looking in to a isolated charger as it is the safest (well as safe as it can be round high ac voltage and relativly high dc voltage)

    and i am wanting it to be digitly controled as i would have it again work simmeler to the chademo standerad were the charger will recive infomation from the EV controle unit so it can adgust the current acordingly and also make sure the voltage stay in acseptable limits

    like i say i have put a lot of thought in to this is just the actual build of the charger that is difficult