Bulk charging via digital DC-DC boost Minghe BST-900W

Batteries, Chargers, and Battery Management Systems.
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Re: Bulk charging using a digital DC-DC boost module

Post by Overclocker » Aug 25 2016 12:22pm

bobc wrote:OK mine says STPS30L80CT - looks like an 80V part. I guess I'm lucky I didn't take it over that then!!!
But I might need to one day, I'd better get hold of some 100V shottky's before I do....

It's not assisting china's reputation for quality is it....

That must be the MOSFET on the left - any chance you can read the number on yours? Mine's screwed to a wall & a real pig to read..... (as a low voltage part here would have a similarly amusing effect)

strange... google isn't turning up anything about STPS30L80CT. but judging from the naming scheme it does seem like it's an 80v part

yeah it's a MOSFET, fairchild FQA70N15, 150v at least they got that one right :roll:

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Re: Bulk charging using a digital DC-DC boost module

Post by Alan B » Aug 25 2016 12:29pm

Be sure to derate everything, whatever they claim reduce at least 20%.

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Re: Bulk charging using a digital DC-DC boost module

Post by bobc » Aug 25 2016 12:38pm

EBRT in place of STPS works... Thanks for that - I will need 80V in the fullness of time so I should swap that diode. I can't believe I was happily running it at 80V, like dancing on a cliff edge....

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Re: Bulk charging using a digital DC-DC boost module

Post by Bouteille51 » Aug 25 2016 4:08pm

Nice catch !

For safety reasons though, you want to be sure that your converter works as advertised.
This guy found some interesting behavior in some (specific) conditions for a quite similar device :
https://www.youtube.com/watch?v=Xp6uDBMn3cY

Not sure about the relevance of the peak output voltage and peak input intensity at startup for your charging setup.
The 0v setting behavior however is quite worrying for any setup...
IMO this bug is most likely a firmware problem and the "manual/analogic" versions with a simple potentiometer should be safer.

I'll give a try to this one that he also tested and seem "safer"...
https://www.youtube.com/watch?v=cUpJs6Z41YM

One should note that the advertised "Watts" are only reachable at higher input voltages (there is a 15A fuse at input).

Can you comment about similar tests with the one you bought ?

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Re: Bulk charging using a digital DC-DC boost module

Post by Overclocker » Aug 25 2016 10:21pm

bobc wrote:EBRT in place of STPS works... Thanks for that - I will need 80V in the fullness of time so I should swap that diode. I can't believe I was happily running it at 80V, like dancing on a cliff edge....

http://ph.rs-online.com/web/p/products/7660353/

ON Semi NTSV30120CTG, Dual Schottky Diode, Common Cathode, 120V 30A, 4-Pin TO-220AB

i might replace with this. cheap too :)

will let you know how it goes. although it takes about a week to get parts from RS Components...

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Re: Bulk charging using a digital DC-DC boost module

Post by Doctorbass » Aug 25 2016 11:18pm

Mine also blew up after i used it with 53v input. ( the mosfet is now short...)

this is the same 900W capable for up to 120VDc out..


Mine use Fairchild FDH055N15A (150 V, 167 A, 5.9 mΩ) mosfet and a STPS20150CT diode ( 2x 10A 150V)

It worked well at 75V out for charging my zero 2012.. but it blew after couple hours... :roll:

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Re: Bulk charging using a digital DC-DC boost module

Post by bobc » Aug 26 2016 2:08am

Is that 4 respondents, and every one with a different diode.....!!!!
I must say that (having not blown up at all) the thing has been absolutely perfect for what I need, and so cheap too.
I did look at it with my cheap thermal camera &only the choke and one of the resistors seemed to be getting warm (not hot) and the capacitor total looks quite generous, build quality looks fine; so I'd expect it would last well enough.
They must have a bargain bucket shottky assortment for the customers to play boost level roulette....

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Re: Bulk charging using a digital DC-DC boost module

Post by Overclocker » Aug 26 2016 11:14am

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it's alive! i soldered in a temporary schottky. everything seems to be working fine...

i'll be ordering a proper one ASAP. it seems a higher voltage diode also has a higher forward voltage, which is going to hurt efficiency e.g. the the 150V part has a Vf of almost a volt, while the 120v one is only 0.522. the 100v one is 0.471

i guess i'll go with the 120v part

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Re: Bulk charging using a digital DC-DC boost module

Post by Overclocker » Sep 02 2016 4:42am

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:)

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Re: Bulk charging using a digital DC-DC boost module

Post by Overclocker » Sep 02 2016 10:58am

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charging great at 48v, but output is limited to about ~2.7a at ~12v input. so i just ordered a 36v power supply:

http://www.aliexpress.com/item/400W-36V ... 22784.html

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Re: Bulk charging using a digital DC-DC boost module

Post by Overclocker » Sep 02 2016 11:20am

bobc wrote:Is that 4 respondents, and every one with a different diode.....!!!!
I must say that (having not blown up at all) the thing has been absolutely perfect for what I need, and so cheap too.
I did look at it with my cheap thermal camera &only the choke and one of the resistors seemed to be getting warm (not hot) and the capacitor total looks quite generous, build quality looks fine; so I'd expect it would last well enough.
They must have a bargain bucket shottky assortment for the customers to play boost level roulette....

it's remarkable that yours hasn't blown up :mrgreen: which probably means that you've got the "correct" MOSFET i.e. with the correct parameters. what's your part number, if you don't mind. i might preemptively upgrade mine to the MOSFET you have

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Re: Bulk charging using a digital DC-DC boost module

Post by bobc » Sep 02 2016 3:04pm

You have a 70A 150V part there - I think you're in clover :)
I'll try to read the number when I'm home in daylight... yeah the nights are drawing in...

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Re: Bulk charging using a digital DC-DC boost module

Post by Overclocker » Sep 03 2016 2:09am

bobc wrote:You have a 70A 150V part there - I think you're in clover :)
I'll try to read the number when I'm home in daylight... yeah the nights are drawing in...
thanks! but mosfets have a bunch of other specs like Rds(on), Crss, etc that have to be matched for the particular application.

Doctorbass' mosfet blew so it's probably not the optimal one. so it would be really interesting to see what mosfet you have

PS Julian Ilett on youtube also has a BST900. guess what, his output capacitors are also different from mine :roll: this MingHe factory in china is doing guerrilla supply management :roll: which isn't uncommon. i've ordered the same BMS four times from Greentime@aliex and i got four different BMSes w/ slight variations

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Re: Bulk charging using a digital DC-DC boost module

Post by Overclocker » Sep 11 2016 9:05am

bobc wrote: What I've learned about controlling such a boost converter:
1) RH button switches output on, LH button switches it off
2) when 'on' RH button toggles between Volts and Amps display
3) up/down buttons alter setpoint for volts or amps (whichever is being displayed)
4) "save" an altered setpoint by a long press on LH button - display should flash once

check this out, it seems you missed a few more functions 8)

https://www.dropbox.com/s/4vldh7bpp4u6q ... l.pdf?dl=0

store/recall presets to 10 memory slots. useful, since it's so easy to overshoot your target when scrolling w/ the up/down buttons

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Re: Bulk charging via digital DC-DC boost Minghe BST900

Post by whereswally606 » Sep 12 2016 2:02am

thanks for the post overclocker. I like the idea of comes on straight after electricty mode 0. means I can use one for a load on my PSU which is hooked up to solar panels. Also confirms something I saw with input voltage. 12v input got me half the amps of 24v roughly. now I use 36v minimum input to charge 54v pack.
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Re: Bulk charging via digital DC-DC boost Minghe BST900

Post by bobc » Sep 12 2016 3:44am

nice one!
The linked manual talks about power and capacity modes on the display (P and C prefix) - this is not something I've seen; I would be interested in a amp-hours display..... How do I make that happen?

OK - it looks like a long press on the RH button to get into the various "function" options (I need '1') I'll try it later

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Re: Bulk charging via digital DC-DC boost Minghe BST900

Post by Overclocker » Sep 12 2016 9:31am

bobc wrote:nice one!
The linked manual talks about power and capacity modes on the display (P and C prefix) - this is not something I've seen; I would be interested in a amp-hours display..... How do I make that happen?

OK - it looks like a long press on the RH button to get into the various "function" options (I need '1') I'll try it later


yeah it needs a bit of chinglish-to-english translation. press and hold OK while powering on to get to the settings

Funtion 0, 1, 2 are all configurable with yes or no

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Re: Bulk charging via digital DC-DC boost Minghe BST900

Post by parabellum » Sep 12 2016 12:43pm

Is input low V limit programmable? To avoid over discharging source battery.

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Re: Bulk charging via digital DC-DC boost Minghe BST900

Post by bobc » Sep 12 2016 1:02pm

It looks as though it is (prefix u on display), but the manual is in full gobbledegook at that point.....

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Re: Bulk charging via digital DC-DC boost Minghe BST900

Post by Overclocker » Sep 13 2016 10:48am

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just got the 36v power supply. rated 400w, 11A

i didn't want to overload the PSU so i limited the charging current to 8.0A at 48v

Smun brand, seems to be pretty good quality. a lot heavier than your typical cheap 400w PSU. http://www.smun.cc/en/

i think i just built a poor man's Satiator 8)


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Re: Bulk charging via digital DC-DC boost Minghe BST900

Post by Overclocker » Sep 13 2016 11:59am

apparently it IS a meanwell clone :roll: like they copied the PCB layout. here's the Smun:

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now here's a Meanwell (photo by DrkAngel https://endless-sphere.com/forums/viewt ... =2&t=55658 ):

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Re: Bulk charging via digital DC-DC boost Minghe BST900

Post by Samd » Sep 14 2016 12:28am

A few of us been using these on ES facebook for awhile. There is a known fault though in the software that if you set the output less than the input, the output voltage tries to fly away to infinity. Which isn't ideal for charging lipo.
Other than that I love the simplicity and have now mounted one inside my bike case so I can charge at work.

Also handy solar regulators when using solar panels.
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Re: Bulk charging via digital DC-DC boost Minghe BST900

Post by Overclocker » Sep 15 2016 2:07am

Samd wrote:A few of us been using these on ES facebook for awhile. There is a known fault though in the software that if you set the output less than the input, the output voltage tries to fly away to infinity. Which isn't ideal for charging lipo.
Other than that I love the simplicity and have now mounted one inside my bike case so I can charge at work.

Also handy solar regulators when using solar panels.

yeah i've seen that on youtube. i think the 400w version.

this BST900 has a similar issue if you set the voltage to like 1.5v

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Re: Bulk charging via digital DC-DC boost Minghe BST900

Post by Punx0r » Sep 15 2016 2:41am

I've been running a different boost converter but with the same MW clone (running at 8A) for a couple of months now. The PSU died at power-on yesterday - no noise, smoke or fuss and no damage inside, just a quiet death. The only difference I can see between mine and yours is the big ferrite on mine is about twice as wide.

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Re: Bulk charging via digital DC-DC boost Minghe BST900

Post by bobc » Sep 15 2016 5:10am

I tried the "Amp hours" reading after yesterday's ride to/from work. Looks pretty good - the journey is 27.5 miles & the charger stuffed 25.2Ah in (from the display), but I had to switch off before end of charge as I was leaving the house (to work today) - It had got up to 61.3V - I normally stop at 61.5V so room for a few more electrons.....
So it's looking like 1Ah per mile - travelling with the throttle 'pinned' everywhere.... :)
Makes the sums easy......
Considering the season I'll do a run with the headlights on - see if it makes much difference

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