24v charge controller help

[petehall347]

Re: 24v charge controller help

guess i need to draw a schematic to figure out the zener bit . saying that i am thinking cathode of one half goes to op amp . pin 4 + . not sure on other half yet .

[petehall347]

Re: 24v charge controller help

dont know why i said zener ..its not ..its bat54s . and new one didnt fix it ..pwm controller coming soon . so far as i can work out it should be driving that fet all resistors appear good . no shorted or open semiconductors . no shorted caps .

[petehall347]

Re: 24v charge controller help

new controller ic fitted ..still not charging ... aaaarrrgghh
. am going to see if i can get voltages at controller pins .. am thinking it might be in protect . or i am missing something .

[petehall347]

Re: 24v charge controller help

pin 3 FB 782mv .
pin 6 DR 0v

[petehall347]

Re: 24v charge controller help

pin 7 FA/SD 6.52v ..
pin 7 has a 100k resistor to ground

am wondering if the fet is ok .. its not shorted . but might be open .

[petehall347]

Re: 24v charge controller help

tried switching fet on with my meter and it stays off . its still in circuit though .

[petehall347]

Re: 24v charge controller help

after lots of studying i decided to test the inductor 22UH 1.6A SMD . my meter doesn't read it as a coil . on any setting . thought i would give the sniff test and it smells burned .. now to find one to use for testing .
it is still in circuit . not sure if that would affect testing it at all .

[petehall347]

Re: 24v charge controller help

DOH silly me forgot how to use my meter .. its testing as .021mH

[petehall347]

Re: 24v charge controller help

ok so i worked out the feedback for the controller goes to the other circuit with the op amp which is actually a comparator . it seems to end up at the charge light .
looks like the comparator might need changing next ..
although i dont understand these things very well but how will feedback happen properly until there is something to feedback ?

back to why the controller wont start . or why its shutting down and its faster than i can measure it . 30ns is pretty quick .
output 1 and 2 are shorted together .. they end up at that red battery fault light that fails to go off

[petehall347]

Re: 24v charge controller help

just need to be sure what this ezdd device is to replace it . or first diagnose it properly .. without a schematic its not easy .. drawing it out is beyond me .
trying to work out out how its supposed to work and how its working now .. not knowing that part is holding me up now .

[petehall347]

Re: 24v charge controller help

search says its lm324 .. input shorted to output if so ..
scratch that ..vcc is pin 3 .

[petehall347]

Re: 24v charge controller help

ezdd 339
lm339 ..

[petehall347]

Re: 24v charge controller help

ok 25 comparators ordered along with 5 fets .. min order .. good job they are cheap enough to buy .
if this dont fix it i wont have much of a clue what to do .

[redwire]

Re: 24v charge controller help

I'm taking a guess at how the charger works.

Normally, the LM3478 and mosfet boost the input to ~27.5V charging voltage for the battery pack.

If the battery mid-point voltage is out of spec, light the fault LED and shut off the boost converter by turning on its shutdown pin 7. If pin 7 is over 1.35V the converter goes to sleep. The pcb via goes to the comparator which can turn the converter off.

The three 0.22R set peak current to back off above 1A and seem to activate that mangled transistor if peak current is higher. That would maybe indicate bulk charging.

It (comparator) might also look for too low or too high a battery voltage.
It's hard to tell if it's mainly for the LED's or does a bunch of charge control too.

[petehall347]

Re: 24v charge controller help

mangled transistor is a dual schottky . i replaced that for a new one .

[petehall347]

Re: 24v charge controller help

this is turning out to be fun .. changed the comparator and constant blue light on batteries .. charger not connected .
connected charger and red light on with blue .. disconnected charger then connected it again . this time the dual diode that supplies the comparator power decided to smoke .. just put in new dual diode .
one thing i noticed this time is 4 input - is now 1.2 ohms to ground ..it was like this before i connected any power .. looks like the comparator needs another new one .
i might even see if it charges or smokes with comparator removed .

[petehall347]

Re: 24v charge controller help

and we have a result .. another new comparator later .. battery only no lights .. charger connected and batteries blue light on .it went up to around 30v then dropped to around 27v . then tiny sparks at dual diode . then charging at 26v ..left it a few mins and went to 26.1 then 26.2 .. dual diode tests ok so maybe my soldering is bad there .. will touch it up tomorrow .its too late tonight to do it ..

[redwire]

Re: 24v charge controller help

Is the battery pack OK, the mid-point is ~12V?
I would stop and trace out the circuit around this dual-diode to see why it keeps roasting.

[petehall347]

Re: 24v charge controller help

Is the battery pack OK, the mid-point is ~12V?
I would stop and trace out the circuit around this dual-diode to see why it keeps roasting.

its not roasting now ..it tested fine after second new comparator fitted .. was arcing from my bad soldering .. well i hope its just that . still need to look at it some more ..

[petehall347]

Re: 24v charge controller help

job done and seeming to be working as intended ..voltage creeps up to 28.5v and charge light goes out .. left it with the owner and he is going to run batteries down and see if low voltage light comes on .