schroederjd
Solar Enthusiast
- Joined
- Nov 12, 2020
- Messages
- 175
Hi Everyone,
While waiting for my cells to come in (16 x 272Ah Lishen) from China, I've been working on a top balancing setup. Objectives were 1) don't damage the cells, 2) get the job done in < 2 wks, 3) don't spend more than $100. After reading several threads related to top balancing with Mean Well power supplies, I decided to go in that direction. I purchased a HRPG-300-3.3 from TRC Electronics. Price was $98 after shipping. I went with the HRPG over the HRP because it has the remote on/off and remote voltage sensing features.
The more interesting part of this is how to meet objective 1 (don't damage the cells) without constantly checking the voltage. That's where the microcontroller comes in. I used a Node32s (ESP-32), as I had one on hand, and it has multiple analog inputs (ESP8266 only has one). I used Arduino IDE for the programming along with the Blynk iOS app for remote monitoring. Wiring diagram of the system is shown below. I'm using an open-loop hall-effect current transducer (LEM DHAB S/133) that came with my TinyBMS for current monitoring. I've coded in a non-reversible remote shut-off for when the current reaches a pre-defined set point. This set up allows me to remote monitor the charging from anywhere, and kills the charging automatically so I don't risk overcharging.
I'll post the code once I have it cleaned up. Probably the most complicated part was trying to get the ESP-32 to provide accurate volatge reading (the ADC has a non-linear response). The Blynk app made the remote monitoring setup super easy.
After a lot of testing and tweaking, the system seems to work great. Voltage and current readings are spot on, and the remote shut-off kicks on reliably. I would really appreciate any feedback (risks, design flaws, ideas for additional functionality, etc.).
Circuit diagram:
Here's the dashboard I've set up in the Blynk app. Nothing too spectacular, but it allows me to see what's going on...from anywhere.
While waiting for my cells to come in (16 x 272Ah Lishen) from China, I've been working on a top balancing setup. Objectives were 1) don't damage the cells, 2) get the job done in < 2 wks, 3) don't spend more than $100. After reading several threads related to top balancing with Mean Well power supplies, I decided to go in that direction. I purchased a HRPG-300-3.3 from TRC Electronics. Price was $98 after shipping. I went with the HRPG over the HRP because it has the remote on/off and remote voltage sensing features.
The more interesting part of this is how to meet objective 1 (don't damage the cells) without constantly checking the voltage. That's where the microcontroller comes in. I used a Node32s (ESP-32), as I had one on hand, and it has multiple analog inputs (ESP8266 only has one). I used Arduino IDE for the programming along with the Blynk iOS app for remote monitoring. Wiring diagram of the system is shown below. I'm using an open-loop hall-effect current transducer (LEM DHAB S/133) that came with my TinyBMS for current monitoring. I've coded in a non-reversible remote shut-off for when the current reaches a pre-defined set point. This set up allows me to remote monitor the charging from anywhere, and kills the charging automatically so I don't risk overcharging.
I'll post the code once I have it cleaned up. Probably the most complicated part was trying to get the ESP-32 to provide accurate volatge reading (the ADC has a non-linear response). The Blynk app made the remote monitoring setup super easy.
After a lot of testing and tweaking, the system seems to work great. Voltage and current readings are spot on, and the remote shut-off kicks on reliably. I would really appreciate any feedback (risks, design flaws, ideas for additional functionality, etc.).
Circuit diagram:
Here's the dashboard I've set up in the Blynk app. Nothing too spectacular, but it allows me to see what's going on...from anywhere.