Chinese low cost solar charger controller for lead-acid battery - Don't restart. - Page 1
Forum section: electronics / general

author: jcfoto
author_rank: Contributor
timestamp: August 17, 2023, 02:30:40 pm
content: Hello.I have been testing this solar charger/controller for lead-acid battery since 2019. It is a Chinese product with no brand name.When the battery drops below a threshold ( ex 10,8v), the controller switches off the consumers.When it rises above another threshold (e.g. 12.8v), the controller theoretically switches the load back on.The problem is that the load is never switched back on, whatever the model (10 or 30A)!The main microcontroller (2x10 SMD pins) is unbranded, and manages the LCD display and all other functions. I'm looking for its reset pin...The PCB has only one mark: W88-v2.0Could someone who has worked on this device tell me the type of µC?Thanks

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 17, 2023, 11:02:28 pm
content: mine is only version 1 and uC is scratched out.. no reset pin/button avail...

author: Shonky
author_rank: Frequent Contributor
timestamp: August 18, 2023, 01:00:27 am
content: Microcontroller could be anything. May be worth looking at some of the more common ones like STC but you're unlikely to have much luck. Also the pictured one is 2 x 12 pins so they may have even replaced the CPU. It's common for Chinese manufacturers to change hardware and firmware completely in between versions of product such that they're incompatible.Looks like it might have a serial port on that 4 pin edge connector. Looks like a GND, power and two lines to the CPU

author: jcfoto
author_rank: Contributor
timestamp: August 18, 2023, 08:30:54 am
content: Hello.Thank you, Mechatrommer and Shonky for your replie.My PCB don't have the four pins port ... I've tryed to force each pin ( without LCD pins) at Vdd or GND with 2.2K and 1K resistor to search reset pin directly on µC. No reset => no result ! Later, i'll transmit PCB photos.

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 18, 2023, 11:51:34 am
content: Quote from: jcfoto on August 18, 2023, 08:30:54 amassuming the uC has one, then i guess you need to find one pin with only pull down or pull up resistor that does nothing... if you cant find one, why dont just install mechanical switches on solar and battery input? you turn off both, you turn off everything including uC.

author: Shonky
author_rank: Frequent Contributor
timestamp: August 18, 2023, 12:36:38 pm
content: I would think 1k should be enough to override any onboard pull up/down for a reset but who knows.Based on the description it does seem like the v1 and v2 are significantly different which doesn't surprise me.Also even if you do identify the chip how will that help? You want to add some kind of one shot reset pulse?

author: jcfoto
author_rank: Contributor
timestamp: August 21, 2023, 03:48:26 pm
content: Hello Shonky and Mechatrommer.I can't have a mecanical switch : my system is in a natural zone, far of access. It's impossible to move switch ...I think the issue is an automatic reset with an extern classic quad NAND ( schmitt trigger CD4093B ...). Perhaps the reset pin is connected on power line ( Vdd or GND). I've Vdd on pins 4 and 20 and GND on pin 1. Later, i'll test these pins with a scope to be sure they have no signal and only power. In this case, i've a doubt about pin 4.

author: jonovid
author_rank: Super Contributor
timestamp: August 23, 2023, 07:52:02 am
content: one requirement for this type of low cost Chinese solar charger controllers is the battery must always be connected & the battery must have a working minimum voltage.if the solar is connected without the battery the unit can be permanently damaged.

author: Mechatrommer
author_rank: Super Contributor
timestamp: August 23, 2023, 10:00:07 pm
content: i removed and replaced batteries too many times during the day without problem... i remember one time the unit suddenly switched off as if its damaged, iirc it was while the load is turned on. but removing everything (solar, battery, load) and reinstalling in correct order turned on the unit again... but i agree, removing battery while solar is charging is not recommended.

author: jcfoto
author_rank: Contributor
timestamp: August 24, 2023, 02:11:56 pm
content: @Jonovid : Yes . The solar panel output can be up to 20-22v. If the controller isn't powered by the battery, this voltage can go everywhere ... and damage anything. My problem is different and i've always followed the procedure. All my controllers have the same fault including those in reserve.