Auto Ah Capacity Tester & Logger for 12V lead acid Batteries - Safe, autonomous Ah capacity testing with auto shutdown & recharge option.
This is an intermediate DIY project that is great for determining 12V lead acid battery AH capacity up to 127 Ah. Suitable for batteries found in road vehicles, military, marine, UPS and avionics.
The attached zip contains all the instructions, schematics and microcontroller code to get it working. the BOM is in the Battery Load Sample document. There is an ICSP programming header built on the PCB for convenient code flashing. View attachment 85944
I observed some comm. errors with PL2303 HX cables. The PICKIT2 has no probs. After much digging it seems there is significant drift on the PL2303 bit pulse duration which causes unpredictable comms. @ 9600 bps.
I attach updated hex code running RS232 at 2400 bps as a more error tolerant means of data uplink. The speed loss is under a second as the data is small. The PL2303 cables work fine now.