iMax B6 Clone from Ebay - INPUT VOL ERR for charging > 2A

[Pietro Alberto Cultrona]

Hi guys, I recently buyed from ebay an iMax B6 Clone, the mainboard reports version VER1.8, I actually get the error "INPUT VOL ERR" when I try to  charge a battery to more than 2Amps. I have tested different power supplies and different batteries (Turnigy Nanotech 1800/2200 mAh 3s 65-130C). If I set the charging current to something like 4000mAh, the error appears immediately. I have read about firmware flashed and Mofset/ resistors replacement as well as shortcirquiting the input mosfet,but in my case, this mosfet is missing. Does anyone have the correct schematics or the final solution form this problem? In attachment is a picture of my  hardware. Sorry if this problem as already been discussed, but I did not find a specific solution fomr my hardware.

[diggit]

Hi,

what does voltage on input look like when you get this error? Are you sure, you have enough power on input?

[Pietro Alberto Cultrona]

Hi, thanks for your quick reply, my input power supply is an old 350W Fixed PC. Nominal values are 24A on 12V for this power supply, I did not measure the voltage drop under load,.. 

[diggit]

It is necessary to have good wiring. Not sure what is input low threshold voltage in stock FW. (I guess 11V) ATX(PC) power supplies have not the best output regulation for this usage. You should definitely measure input voltage.

[Pietro Alberto Cultrona]

Ok, I will make the test between this evening and tomorrow with my power supply, in the meanwhile my frined made some tests with his charger, bought together with mine, he as an industrial stabilised power supply set at 17,7V, and under load the voltage loss is lower than 1/2 Volt so the problem should not be related to the input power but more on a thermal problem of a component inside, this because if we set it a 2A it requires 10 mins to get the error, if we set at 4A the error is immediate. 

[diggit]

As written e.g. here, ATX feedback is mostly common to 5V and 12V rail. If you load 12V rail and 5V remains unused, ATX can't add too much power to not get overvoltage on 5V rail. Your ATX may supply for example 11.6V in idle, you van get to 11V easily. (Input wires and terminal loss (and heating) and crappy ATX regulation)

Set output current to not trigger input low error (slightly lower than when you get error) and measure voltage on input.

[Pietro Alberto Cultrona]

Hi We made some tests with 2 different power supplies, with different results. Attached is the picture of our setup:

-1 one B6 connected to a Laptop PSU with some diodes in series to reduce the input voltage

-1 one B6 connected toan ATX PSU.

The results seems to be that in one case the power for some reasons excedes the B6 upper threeshold input (nominal should be 18V, but in the reality at 17,8 we have already problems). In the other case, the problem seems to be an insufficient voltage when the B6 is under load (the lower limit seems to be 10V and not 12V as from label), so I have to modify the ATX PSU to increase the voltage at at least 13,5V.

Also discharge (even if the nominal should reach 1A) seems to be limited to 0,5A

In any case B6 case becomes very hot, thus I was looking for some mods like adding a fan to decrease inner temp

Any suggestion?

[diggit]

Hi We made some tests with 2 different power supplies, with different results. Attached is the picture of our setup:

-1 one B6 connected to a Laptop PSU with some diodes in series to reduce the input voltage

-1 one B6 connected toan ATX PSU.

 

The results seems to be that in one case the power for some reasons excedes the B6 upper threeshold input (nominal should be 18V, but in the reality at 17,8 we have already problems).

This is not best solution, Voltage drop on diodes is dependent on current. Also default calibration of these chargers is not best.

 

In the other case, the problem seems to be an insufficient voltage when the B6 is under load (the lower limit seems to be 10V and not 12V as from label), so I have to modify the ATX PSU to increase the voltage at at least 13,5V.

12V is nominal, it is possible, that lower limit is 10V. Find different PSU. Many people use server power supplies which deliver 12 only on high current. Look here and try searching the web.

 

Also discharge (even if the nominal should reach 1A) seems to be limited to 0,5A

Discharge is limited to 1A and  5W I believe. You probably hit power limit.

In any case B6 case becomes very hot, thus I was looking for some mods like adding a fan to decrease inner temp

Any suggestion?

Even during charging? There are mods, try searching this group.

[diggit]

BTW if you want to calibrate your charger and more, you can try cheali charger FW. (this group is about it, your thread is kinda OT :) Just keep in mind, there is no supported way to move back to stock FW unless you do original FW backup from unlocked device.

[Igon]

Hello Pietro

Can you share a link to the seller?

[Pietro Alberto Cultrona]

Hi, of course: http://m.ebay.it/itm/IMax-B6-Multifunzione-digitale-Lipo-NiMh-Battery-LCD-balance-Caricatore-DE-N3B1-/111992252849 is it possible to load the firmware of this group on it? How do I unlock it to backup actual fw?
Thanks

[diggit]

 is it possible to load the firmware of this group on it?

You need to verify, what microcontroller your charger use. Bend LCD slightly upward to read label on chip below it. If it is ATmega32 or Nuvoton MCU, your charger is probably supported and you just need programmer (1$ or so from ebay).

 

How do I unlock it to backup actual fw?

When it is locked, it is not possible to read stock FW, you can overwrite it. If it is unlocked, you can read stock FW as backup. Howto is dependent on MCU.

Nobody forces you to do so, but IMO it's worth it. There are no warranties. Read through project page I linked.