[OlliFromGermany]

I used a B6 mini charger. 1S 1A for charging. That will take a while – but the lipo stays cool. USB charger have much less power and may be not as accurate as the B6.

[OlliFromGermany]

I had the same problem. No sign of life and the battery at 3.1v – fully discharged. (at 3.1v stops the pmic – axp288c)

First of all: the BIOS Chip is a Winbond FW Type. That means: 1.8V. Most programmers (the ch341 for example) are only for 3.2v eeprom types. so you have to use a level converter from 3.2v to 1.8v. If you didn’t do that, you have inserted 3.2v on the motherboard where only 1.8v were expected……

I had to desolder my bios chip and change it to a new one. the old chip was possible to program and verify but it doesn’t work. a new one was able to start my tablet with the same bin file. it seems that my old bios chip has problems at normal working frequencies (20mhz).

After changing the chip and charging the lipo with an external lipo charger my chuwi works well since a couple of weeks.

[OlliFromGermany]

I think they are only used for power supply. The flex cable from MB to docking port is too thin for 10W charging power……

[OlliFromGermany]

Bevore ordering a new battery i would desolder the old one and put it to an external lipo charger. with the charger you can measure the true capacity of the lipo. i had a similar problem. my lipo of the hi12 was discharged to 3.1v (bad). the hi12 only wanted to charge it with 450mA. but the lipo of the hi12 survived. the charger measured a capacity of round about 9500mAh.

[OlliFromGermany]

Programming the eeprom is done at very low frquency. the SOC of the Z8300 reads the data at about 20MHz. I’ve read about a Winbond series that had problems at higher frequencies. it may be possible that the used 26q64 produces errors at working frquencies. i will change it on my board and see what will happen. did you make a dump of the stored data? is it equal to the bin file in the bios package?

[OlliFromGermany]

You have to be carefull. The eeprom in my Hi12 is a Winbond 25Q64FW. that’s a 1.8V type. most programmers are 3.3 and 5v. my tablet is also not booting (see my post in the chuwi forum). the SOC tries to boot an retrieves data from the eeprom. but no sign of life. i also want to reburn the eeprom or change it. i hoped that helps but your post makes me sad…… ;((((

[OlliFromGermany]

That’s true, but if your battery is dead – you may want to change it.

[OlliFromGermany]

Hi, the Hi12 is relatively easy to open: 4 little torx screws and a (old) credit card or something equal to disassemle the back-cover from the snaping-plastic holders.

Inside there are two 3.7v lipos. parallel together for 3.7v and round about 11000mAh. The battery is soldered to the mainboard with to wires (+ and -). the lipos are glued to back of the screen. hot air from an air gun will help.

The lipos are very thin. i would think round about 4mm. so your choice seams to be right.

Good luck!

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