[poltergiest]

Plugged in my elcon 1.5, which is in my golf cart conversion from may 2015, and there was a few red blinks and a pop, then nothing. I did not count the blinks it was late, I wanted to get home.
I unplugged the mains and waited a few minutes and tried again, nothing, no lights but could hear the "normal" crackle when I plug in. I took out the charger but have not opened it yet, its 11;15 pm and I have a 6 am meeting in a different time zone.

Yes my cart is my only vehicle, that is what everyone has on the island.

 

[Coulomb]

Plugged in my elcon 1.5, which is in my golf cart conversion from may 2015, and there was a few red blinks and a pop, then nothing.

I'm sorry to hear that. If it's a pre-2014 model, and you have the time and resources to fix it yourself, then you can use this guide:
http://www.diyelectriccar.com/forums/showthread.php/tcch-elcon-charger-troubleshooting-and-repair-90162.html

 

[poltergiest]

Oh boy most of it so far is way beyond my electric ability. I ordered another charger, and so my hurried diagnostic can be more leisurely.
The problem with troubleshooting link is 23 pages of no order or progression. Guess I will need to spend the next month re-reading. sigh.

 

[pdove]

Did you give up fixing the charger?

 

[poltergiest]

Personally yes, outside my wheelhouse. PM'd ya

 

[kennybobby]

This charger is a lead-acid version 1.8 control board that was reprogrammed for 57 Lithium cells at 1Vpc.

The board has none of the black conformal coating we have seen in most chargers--this is actually good for troubleshooting since we don't have to scrape it off.

There is a bit of arc flash debris inside the mains relay cover but the parallel 150R resistors don't appear overheated, and the diode bridge appears okay.

On power up the mains relay doesn't engage, so there is no 12V supply from the ViPer circuit.

There appears to be no output fuse--or it has blown off at the leads right at the board. Didn't see any fuse residue floating around inside.

Will reserve some space to edit and add photos as this problem gets resolved.
[EDIT]
1. Pulled the filter inductor on the +12(+15V) volt supply near the Viper, L10, it was good.
2. Pulled the D11 diode, also good and short was still present downstream of the capacitors C22,C42, but caps measured ok.
3. Pulled L1 on the control board, now the short was 330 Ohms to ground on the main board, but was ~1.8 Ohms to ground in the central section of the control board (across the cap near the FET drivers). The caps on either side of L1 didn't appear bulging (C1 and C2 100uF, 50V).

The 330 Ohms to ground is likely the ac relay coil plus the inline resistor, R29.

So the short is in the filtered 15_VDC_PS supply for the FET driver circuit on the control board.

4. The 2 output pins of U14, the SMPS chip are showing a low impedance short to both the 15V and ground.

5. De-soldered the control board from the main board. Removed C2 (50V, 100uF) it appears okay. Removed U14 and the A and B output pins are not shorted on the chip but they still are on the board. Didn't see any blown chip residue in the vicinity of the FET drivers, but the short has to be in that section. Need to check all the ceramic chip capacitors.

6. Pulled the steel heatsink clamp and inspected the pfc and boost FETS on the main board--didn't see any evidence of damage. Checked for shorts and found none so i think the FETS and pfc diode are okay--that's good news.

7. Pulled the U15 and U16 fet driver chips, and found that pins 1,2,3, were all shorted, while 6,7,8 were shorted on U15. The short was measuring ~ 3 Ohms on these triplets. So U15 and 16 are blown.

8. Haven't pulled U12 yet, but nearly all the pins are shorted to ground and to the solder pads of U14 for the A and B output. U12 is blown.

Maybe the popping sound was the output fuse being blown off the main board--i'm not seeing any damage so far that we would expect to see with a "pop"

more later...

 

[kennybobby]

[Reserved for repair photos]

control board shows no obviously blown parts, but tracing it out has found U12, U15, U16 are blown and shorted internally.

Wish we had a clean board like this without the black conformal goo when we were tracing the schematics--would have saved a lot of time scraping...

 

[pdove]

Check the inductor on the 12 volt line on the main board the powers the daughter board. We have seen that blow on several.

 

[poltergiest]

Just a note, nothing was inside floating around when I opened the case...

 

[kennybobby]

i found a slight error on the control board schematic related to the 15VDC_Aux supply, and the 15_VDC_PS which is a filtered supply after inductor L1 and the C2 electrolytic 50V 100uF at the top middle section on the back side.

The power for U2 and U13 comes from the 15VDC_Aux supply before the filtering.

The power for U12, U14, U15, U16 comes from the filtered supply, 15_VDC_PS.

Troubleshooting note: Removing L1 from the control board provides a quick way to determine which power supply section is shorted to ground. It is very easy to access this inductor and is a good place to start when troubleshooting the low voltage supplies.

 

[Coulomb]

i found a slight error on the control board schematic related to the 15VDC_Aux supply...

Ah! I have this change, among many others, marked in red on my "master" paper schematic; it somehow didn't make it to the digital file and the post. Fixed now.

 

[kennybobby]

@Mike

do you think the FETS would be blown by an internal short of the IR fet driver chip? pins 1,2,3 were shorted on both U15 and U16, while 6,7,8 where shorted on U15?

Nothing appears out of line, but the "pop" makes me think something had to blow.

 

[pdove]

A large transient on the gate of a MOSFET will certainly blow the device.

 

[kennybobby]

All the FETs (boost and pfc) measured open between G-S and G-D with 4MegOhms beween D-S, so i think they are not blown. The PFC diode measured good also. The 1R resistors from the control board to the gates were all intact.

Still searching for the source of the "pop"

 

[poltergiest]

Wow sounds like there is now way I was ever going to track this down..definite absence of a giant ON/OFF switch inside!

 

[Coulomb]

@Mike

do you think the FETS would be blown by an internal short of the IR fet driver chip? pins 1,2,3 were shorted on both U15 and U16, while 6,7,8 where shorted on U15?

I can only guess, but my feeling is that there is a good chance the MOSFET would have survived. All it can do it put 15 V from gate to source. If the opto-isolation was breached, then could easily blow the MOSFET, but I'd expect other carnage on the U12 (NOR gate) side if that was the case. I find U12 does blow up moderately often, but you'd probably have noticed if that wasn't working.

A mysterious case, huh?

A large transient on the gate of a MOSFET will certainly blow the device.

Certainly. But I think without more carnage, just shorting 1,2,3 and not these to 5,6,7 should not create such a transient.

 

[kennybobby]

What would happen if the connection to the battery was disconnected while charging at full current, or half, or quarter, etc.? Maybe dirty contacts caused an open circuit and blew the fuse?

i'm adding a photo of the board in a post up-thread.

 

[kennybobby]

...I'd expect other carnage on the U12 (NOR gate) side if that was the case. I find U12 does blow up moderately often, but you'd probably have noticed if that wasn't working.

U12 is definitely blown internally, pins 1,2,4,6 thru 13 all shorted to ground and to the A and B out of U14 solder pads.

What chip blew first and took out the others, looking for cause and effect and if it would be isolated to the control board.

i was thinking about powering up the digital side of the control board to see if the processor is okay. Since it runs on the "isolated" supply i'm thinking it may not have been involved in the "aux" supply carnage...

 

[Coulomb]

With respect to the output fuse being missing; they started doing stupid stuff like using blade fuses instead of real DC rated HRC fuses in the later models. I suppose that there are ~80 V rated blade fuses, so this might be ok on a nominal 48 V charger. But I thought they were doing this on higher voltage chargers as well, and thet might have noticed that they were not worth having. So maybe they just skip the output fuse these days to save a little money. Is the position for the output fuse shorted under the board? I'm finding it hard to believe that there was a fuse there that completely vaporized.

 

[kennybobby]

Looked at the underside of the main board and found that there is a copper wire soldered across the fuse pads--so there is no fuse but a big-ass jumper.

Applied 12 V to the output relay coil and it is working properly. The continuity between the green and red output wires responds as expected.

Applied 3.3V to the header above the micro, and the processor came up with the red led slowly blinking, so i think the digital section is okay.

Replaced U12, U15, U16 in the central section and there is no short circuit between the 15V and ground anymore.

If possible i would like to test the viper low voltages before re-soldering the control board to the 32 header pins. May use a variac to bring up the mains at a low voltage.

In a previous failure like this one, the IR2110 fet drivers had a hole burned thru the case near pin 6. It was a 300V charger, but no such damage has been found in this 48V version. Maybe punch-thru damage is related to voltage and the loudness of the pop.

Wish we could find some visual damage related to the 'pop'. We jumped the gun on an early repair by powering it up too soon, and it promptly blew up the fresh repairs--don't want to repeat that trick...