48v PSU for charging

[iangreenhalgh]

Hi folks

My bike has two 48v 20ah batteries I made from 18650 cells, they are 12s8p so 50.4v fully charged.

They each have a BMS for charging, I have wired them both to the same socket.

Now I need to select a PSU. There are lots of 48V 7.5A units on ebay cheap and they have a adjustment pot that can turn them up by 5%, which to my maths would give 50.4V.

http://www.ebay.co.uk/itm/48V-Switching-Power-Supply-7-5A-360W-AC-PSU-110-220V-For-LED-Lights-TV-/262491058847?hash=item3d1dafb29f:g:Ge0AAOSwMNxXZ5rD

Is this suitable?

 

[amberwolf]

What kind of current limiting does it use?

If you're not sure, or don't know what I mean, I highly recommend that you look up and read the various Meanwell and Server PSU threads, including Fechter's mini-meanwell current limiter thread, which discuss that and what kinds of PSUs have the right kind of current limiting (what to look for when shopping).

 

[iangreenhalgh]

Hmm, I kinda know what you mean. I guess I have some reading to do....

 

[KINNINVIEKID]

NO

I have one of these fake Meanwells and its no good as a charger as it just cycles on and off all the time.
I use genuine Meanwells NES 350-48.
http://www.ebay.co.uk/sch/sis.html?_nkw=Mean+Well+MW+48V+7.3A+350W+AC%2FDC+Switching+Power+Supply+NES-350-48+UL+PSU&_id=370887902167&&_trksid=p2057872.m2749.l2658

 

[iangreenhalgh]

Cheers, that's the kind of experience I was hoping to glean.

I bought a proper Meanwell as you suggested, at 32 quid it's not that much more than a copy at 20.99 and surely worth the extra tenner.

BTW, do you happen to know what the max voltage is on that Meanwell when the pot is turned up fully? I'm going to use it to charge a 13S 18650 pack and was hoping it might get a bit over 50v out of the Meanwell.

 

[Drunkskunk]

The NES 350-48 is the way to go. Most PSU shut down when you try to pull too many amps from them. The NES 350 series limit the current output at the peak, and don't shut down. I use 2 of them in series for my 88V charger.

The NES 350-48 is can be adjusted from 41 to 56 volts. here's the spec sheet : http://www.meanwell.com/mw_search/NES-350/NES-350-spec.pdf

 

[iangreenhalgh]

Cheers, that adjustment range is perfect - 13S is 54.6v fully charged so the Meanwell sounds like an ideal match to the 156 cell 13s12p battery pack I've built.

 

[friendly1uk]

Hi folks
My bike has two 48v 20ah batteries I made from 18650 cells, they are 12s8p so 50.4v fully charged.

That doesn't quite add up. You have 44v batteries.

 

[iangreenhalgh]

12S = 50.4V, 13S = 54.6V, what's the confusion?