DMHC DC Motor Controller for Electric Quad

[Bloopeta]

Hi, I was given a Funbikes 96 36v 800w Electric Quad.
Problem is the guy who had it connected the batteries wrong. It has 3 12v batteries in series, but he connected the 3 batteries in a complete circuit (diagram attached to explain, please excuse my drawing lol) and connected them to the quad, and said the motor controller made a fizzing noise and smoked lol.

Funbikes no longer stock a replacement controller, and I am unable to locate one online with the part number.

I opened up the controller, and immediately could see some blown caps, so I have replaced all the caps, however it still does not seem to work.

I am litterally clueless where to even begin with this, so any help and advice greatly appreciated.

[petehall347]

he most likely connected it backwards .

[eccerr0r]

Shorting out the batteries like drawn will protect the controller and should not fry it. The batteries will take the brunt of the damage in this case -- but as petehall347 says, this is not what happened. It was reverse connected, sparks flew, capacitors exploded, silicon melted.

Likely all semiconductors like the controller succumbed to the backwards voltage. So past the capacitors, the controller probably melted. The switching transistors may have survived, don't know but you may have to replace them too.

[Bloopeta]

Originally Posted by eccerr0r

Shorting out the batteries like drawn will protect the controller and should not fry it. The batteries will take the brunt of the damage in this case -- but as petehall347 says, this is not what happened. It was reverse connected, sparks flew, capacitors exploded, silicon melted.

Likely all semiconductors like the controller succumbed to the backwards voltage. So past the capacitors, the controller probably melted. The switching transistors may have survived, don't know but you may have to replace them too.

The most annoying part is im strugging to plug the controller back up, as was unplugged when I got it, so am having difficulty working out what plugs go where as alot are the same, however the colours of the wires on the controller dont match up to the colours of the wires on the quad :/

Looking at the board I can see initials where wires are connected, i.e. GND, but struggling to work out what the others mean

SL
SB
GS

KEY (ignition)
GND (ground

But dont know what these are

SL (3 wires go to this one)
SB
GS
DS
+5V

[eccerr0r]

not enough to go by for someone who's only familiar of the general structure of such control boxes - can assume fat wires goto the motor or battery and thin wires to the throttle and brake controls... past that, you need to scrutinize the board to figure out what goes to what.

TBH it might be easier to just buy another generic controller and replace the burned one.

[Bloopeta]

Originally Posted by eccerr0r

not enough to go by for someone who's only familiar of the general structure of such control boxes - can assume fat wires goto the motor or battery and thin wires to the throttle and brake controls... past that, you need to scrutinize the board to figure out what goes to what.

TBH it might be easier to just buy another generic controller and replace the burned one.

I seem to have worked out where the wires all go now.

I get power to ignition switch, and to forward/reverse/off switch, and the horn works lol.

But apart from that, I havnt got it to move yet.

One battery seems pretty shot, im only getting a total of 28v, but would assume it should still work with that but underpowered/slow??

I have emailed the company who makes the controller to see if they can advise where to get one, but if not I think n new generic one may be the only option if I can get one thats compatible. Just depends on the cost, as may not be viable, especially if need a replacement battery also. Plus, due to contoller problem Im not even sure the motor is good.

Just seems a shame to scrap it

[R_J]

There should be a voltage regulator ic on the board, likely that to220 near the caps, If the voltage was reversed and blew the caps it may have damaged the input to the regulator ic and if that is the case it may have protected the rest of the circuit, so check the number on the to220 parts to see if one is indeed a low voltage regulator and check its output voltage

[petehall347]

charge batteries separately

[Bloopeta]

Originally Posted by petehall347

charge batteries separately

I am with a car battery charger, one battery doesnt seen to want to charge past aprox 7 volts, and holds around 5.49v standby

[Bloopeta]

Originally Posted by R_J

There should be a voltage regulator ic on the board, likely that to220 near the caps, If the voltage was reversed and blew the caps it may have damaged the input to the regulator ic and if that is the case it may have protected the rest of the circuit, so check the number on the to220 parts to see if one is indeed a low voltage regulator and check its output voltage

Which is that please?

[R_J]

Originally Posted by Bloopeta

Which is that please?

It might be this one, post the number that is printed on it. Also post the number of that ic next to it, that might help with what voltage the circuit needs. Likely around 5vdc

[Bloopeta]

Originally Posted by r_j

it might be this one, post the number that is printed on it. Also post the number of that ic next to it, that might help with what voltage the circuit needs. Likely around 5vdc

lm317t
g4091 vw
chn 321

[petehall347]

https://uk.farnell.com/stmicroelectr...317/dp/9756027

[R_J]

Oh Great, an adjustable LM317t, You should be able to check its output voltage between the metal tab and ground

[Bloopeta]

Originally Posted by petehall347

https://uk.farnell.com/stmicroelectr...317/dp/9756027

Ive ordered one

[eccerr0r]

A "good" AGM SLA will charge back up if discharged completely and recharged right away, you probably have bad or worn out SLA packs and probably need to replace those, too. If you don't recharge right away, you increase the chance of it becoming unrechargeable fairly quickly -- I wonder how long the battery sat discharged.

Note that one dead battery can kill the whole pack making the vehicle unusable, especially if the controller detects battery issues. I have a 24V ⅓HP scooter, battery pack is shot. Powers up, no motion despite still being close to 24V. It droops below 24V for a moment when the motor starts and the controller will stop trying to power the motor before the voltage goes any lower.

[Bloopeta]

Originally Posted by R_J

Oh Great, an adjustable LM317t, You should be able to check its output voltage between the metal tab and ground

I had to remove it from board to read the number, so will just replace now with new one

[Bloopeta]

Originally Posted by eccerr0r

A "good" AGM SLA will charge back up if discharged completely and recharged right away, you probably have bad or worn out SLA packs and probably need to replace those, too. If you don't recharge right away, you increase the chance of it becoming unrechargeable fairly quickly -- I wonder how long the battery sat discharged.

Note that one dead battery can kill the whole pack making the vehicle unusable, especially if the controller detects battery issues. I have a 24V ⅓HP scooter, battery pack is shot. Powers up, no motion despite still being close to 24V. It droops below 24V for a moment when the motor starts and the controller will stop trying to power the motor before the voltage goes any lower.

Think I best get a new battery, as one is only holding 6v at best.

Not sure how long they were left discharged, but I suspect it was quite a while

[Bloopeta]

Originally Posted by Bloopeta

I had to remove it from board to read the number, so will just replace now with new one

Just to update, it arrived today, installed that, and have a replacement battery for the bad one, and still not working

[eccerr0r]

Well you'll have to go and test each device on the board and see if any are dead. Not enough data here for us to really give any additional suggestions at this point, picture angles are insufficient.