BMS Battery Alloy Shell Charger Problems

[deVries]

49.2v output at 7.5 amps

Subject: BMS Sold... EMC-1000 900w Units...

Is this the amp-setting you requested, or is this an actual amp measurement you took? That's quite a conservative setting for your 900w unit.

Does anyone know where to adjust the amp settings up/down on these 900w units? I've decided to drop down the amp setting from 15A @ 48v to 11A, which is about 25%+ further "de-rating" of the spec max.

Thanks.

Btw, @ 48v w/max spec amps of 15A this is only 720w, so it seems this 900w charger is "de-rated" already??? Call it about 810w "burn rate" total by adding-in heat loss inefficiency of 87-88%. That's at least 11% under the charger's 900w rating IF it can be believed.

49v @ 11A is about 540w which is "de-rated" 40% from its 900w rating, so that should be super low stress on the charger, hopefully!!!

[elmannen]

Hello! all forum members, i am a new member from Sweden and i have just bought two of those Alloy shell 600w charger.

I have one at work and one at home, charging 49V 8A just under 400W.

They get barely worm at all. Later on i will slighly raise the voltage to maybe 50V.

So far so good.
/Lasse

[captain387]

Well, the charger was second hand and the previous owner had it set at 72v, 11 amps, I think.
Everything with my bike I have set it to be extremely conservative from charging at below 1 c and running my speed control at 60% its rating.
I do plan on enlarging my battery pack in the future and wanted to get a charger that could meet those needs.

Here is the inside of my charger and the adjustment pots I used.

Bms charger v and c.jpg (79.16 KiB) Viewed 975 times

[dnmun]

yep, great picture, you can see the daughter board that carries the TL494 chip that controls the feedback to the front end.

if you follow the traces through the trimpot, the wiper will go up to one of the pins on the 494, for both the V and current. go google up the TI pdf technical sheet for the TL494 and save that file for use. you can follow the pinout in the pdf to see where the V&I feedback pins are.

about the power, i understand the power numbers are based on what the transformer can handle at max. derating may also benefit the other components, but i think it is the transformer size that determines power handling.

ok, i went and looked for it. right here in my documents. the inputs are at pin 1 and pin 16.

the voltage trim pot will be in the resistor divider bridege between the ouput and the ground and the current trim pot will be in the cicuit that includes the shunt resistor in the negative traces with the output negative as ground, and the voltage on the shunt high end the input to the 494.

editors note: ask questions about the IC diagram in the pdf if you want, the initial schematic kinda encapsulates what the pwm chip does, how it controls those output transistor that then turn on and off the push pull transistors heath was talking about, in the front end.

that's how it knows to switch more current through the transformer, and the input switching transistors stay on longer because of the pwm making them do it.

edit some more, i just looked at this Vpower charger with the daughter board carrying the 494. the current sense connection from the high side of the output shunt resistor is at pin #3 from the right on the bottom of the daughter board, and since this is a 36V charger instead of a 48V charger it has a small 1/4 watt through hole resistor on the pcb next to the daughterboard to set the voltage, and that connects to the voltage from the high side of the schottky diode in the positive side of the output comes on to the daughter board at pin#4 from the right on the bottom, so see if that is the same as on your daughter board

[jateureka]

This person has reverse engineered the E-400 charger and posted the circuit schematic and some mods. May help someone.
http://www.avdweb.nl/solar-bike/electronics/portable-lightweight-lifepo4-ebike-battery-charger-800g.html

[dnmun]

that was really useful to analyze the circuit for the TL494 based charger. i have a Vpower charger open and it is almost identical to the schematic. different resistor values but some of the ceramic caps are the same. my charger has two schottky diodes to the output, one before and one after the choke, the inductor in the back end.

i can see where the two transistors on the daughterboard causes the current in the small feedback transformer to switch on and off according to how much the TL494 is commanding it to. this feedback transformer then drives the base voltages of the two NPN transistors in the front end. and they have diodes so that one transistor is on while the other is off and the two together keep the main transformer cycling more or less current depending on the height of the voltage induced on the base by the feedback transformer so that determines how much current goes into the main transformer to induce the current to flow in the back end part of the main transformer. this current then flows out into the back end through the schottky diodes and the current flow through the shunt in the negative trace of the back end gives the feedback for current onto the daughterboard.

[amberwolf]

interestingly, I thought the page looked familiar, and when I went to save it locally, it said it already existed, from last year. So I searched ES to see where I probably found it from, and found this thread by the website owner:
viewtopic.php?f=14&t=26859&p=388000

[nonlineartom]

Here's my story.

1200W charger, 49.8V out the factory for a 4.15V per cell end voltage with 12s of Lipo.

Worked great for 6 months charging 12s2p pack up every day. Left it unused for a week, turned it on to charge again and POP tripped out the ring main in my house

Now it won't turn on at all. Fuse in plug and in unit remains intact. Took the lid off, everything looks intact inside, no burnt out components of visibly broken connections.

Just before it died it "clicked" on and off 3 times I could hear the relay engaging and disengaging before it tripped the power. Any ideas?

[dnmun]

was the battery already plugged into the charger when you plugged the charger into the wall outlet?

did it actually charge during the periods it was clicking the relay. was the red light on and off as it clicked? are there any burned traces or shorts on the other side of the pcb? if the fuse did not blow there should be voltage to the diode rectifier bridge and then through that onto the input caps.

[nonlineartom]

the battery was not plugged in, my process remained the same as ever. turn mains socket on at the plug, turn toggle switch on back of charger, wait until LCD display shows correct voltage (guess thats caps charging up) That's when i usually plug in the battery, but before i reached that stage the relay clicked on and off a few times and the screen flickered on and off before finally dying completely ( and taking the whole ring main with it)

I havent unscrewed the PCB to see if any traces are burnt on the underside but as I say the top of the PCB and all components look factory fresh, what else should I look out for ?

[deVries]

You paid about $250+ including shipping. I suggest if you can't get a quick fix here or with Jack at BMS, then ask for a warranty replacement.

P.S. Their shipping prices are waayyy tooo high, IMO. These guys need to offer Sea Shipping now!

[dnmun]

fuse did not blow. the clicking of the relay is normal as it charges up the output caps i assume. but the current draw blew the circuit breaker.

with that much shorted, but the fuse not blowing implies the main power cord has shorted. test continuity between each leg including ground and the also to the housing of the charger.

[nonlineartom]

I replaced the main power cable with one I confirmed to work on a different device. Wires from socket in charger to PCB look intact

Tom

[GCinDC]

if your torn between 600W vs 900W, the 600W is much smaller, fyi:


my 900W seems to be working fine.

[999zip999]

A.W. that's a great tutorial by Avandalen.

[rui_fujino]

okay this is my first youtube video so please dont criticise too much on quality ect..
looks like how people charge may be the cause of charger braking so I filmed myself charging mine.

[dnmun]

I replaced the main power cable with one I confirmed to work on a different device. Wires from socket in charger to PCB look intact

Tom

did you get this resolved?

i am slow, but now thinking about this and how you mentioned that the relay clicked, but never engaged the battery to the charger.

the relay coil current is coming from the battery so i wondered if it has a bad connection between the battery and the plug.

you can do this while every thing is turned off by measuring continuity between the negative lead on the pack, and the negative output on the pcb. and then measure continuity between the positive terminal of the pack and the place where that diode is on the pcb next to the bottom of the relay. that diode is there to prevent the charger from being reversed when plugged into the battery so the end of the diode should be connected to the B+.

it did click though, see if it clicks when you apply the battery again, without the charger powered up.

[nonlineartom]

No life from it at all. No relay clicks on battery connect, no LED or LCD life either.

emailed BMS battery, quoted them my order number and explained the symptoms, they asked for pictures which I provided, 24 hours later they emailed me back and said they would send out a replacement and pay shipping if I shipped them the faulty unit so they could give it a poke and see what went wrong. Seems a fair deal

Stupid me hasn't got round to posting it off yet but I'll report back with how long the turn around is, fingers crossed.

I replaced the main power cable with one I confirmed to work on a different device. Wires from socket in charger to PCB look intact

Tom

did you get this resolved?

i am slow, but now thinking about this and how you mentioned that the relay clicked, but never engaged the battery to the charger.

the relay coil current is coming from the battery so i wondered if it has a bad connection between the battery and the plug.

you can do this while every thing is turned off by measuring continuity between the negative lead on the pack, and the negative output on the pcb. and then measure continuity between the positive terminal of the pack and the place where that diode is on the pcb next to the bottom of the relay. that diode is there to prevent the charger from being reversed when plugged into the battery so the end of the diode should be connected to the B+.

it did click though, see if it clicks when you apply the battery again, without the charger powered up.

[dnmun]

interesting that they will pay shipping.

[nonlineartom]

Still haven't got round to posting back my faulty 1200W unit, bought another one in the meantime, I need a second one anyway. Took 3 weeks to arrive, plugged it in... BANG big flash of light out the plug and that oh so familiar smell of cooked electrics. Tripped the ring main in my house, turned the power back on and began diagnosing the fault. The fuse in the charger had not popped, it had vaporized.

I noticed the toggle switch was in the "on" position when I had plugged it in, so turned it off, replaced the fuse with another 10A fuse, plugged it in and turned it on at the socket, BANG exploded the fuse again, the unit wasn't even switched on at this point. Odd?!

Seems like a dead short in the AC side of the circuit then, opened it up to see if there were any lose wires inside, it looked ok. Until I noticed something..

I really know very little about AC electrical stuff, but should the live and the neutral line really be connected to the same "IN" point on the PCB like that?

Can't see any visibly loose connections or charred components, really annoyed this charger was DOA especially as it was replacing another dead unit. I want to get back on my dam bike!

[dnmun]

does the charger have a 115/230 selector switch? was your battery plugged in at the time?

i don't see what you were worried about in the picture. i can see the ground but do not see how the neutral is tied to it.

[nonlineartom]

The charger doesn't have a 110/230V switch on it, it's marked on the top of the case that it's for 230V though. The photo doesn't illustrate my concern very well. I think I'm being daft anyway, the live goes through a fuse then onto the PCB onto the "IN" point but it's a seperate solder point than the neutral, just both labelled IN

[dnmun]

maybe go look and see if the IN is really LN for line.

i assume since you got the 230 model you used it on 230V, but you don't see any burn marks on the sides where the transistors are snugged up under the bar? nothing blown up?

[nonlineartom]

No burn marks on the transistors, there are two inputs on the PCB titles "IN" separate solder points but both in a box called IN.

I am using it on 230V, tried a different power lead to rule out that as the problem. Hmmmmm what now?

[heathyoung]

Time to get the multimeter out unfortunately. Check the transistors for shorts, but if this is brand new, you should hit up the vendor. This isn't right...