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OlRowdy01 V2 Grid Charger Build (Illustrated)

18318 Views 46 Replies 12 Participants Last post by  olrowdy01
I'm starting a fresh thread on this because I'm going to be posting detailed step-by-step info and photos about my build of Ol' Rowdy's V2 grid charger. Spoiler alert: it works.

Ol’ Rowdy DIY V2 Grid Charger/Discharger

Huge thanks to Ol' Rowdy for revising his design for current components and providing great support along the way.


When I bought my Insight (2002 MT) January 3, 2019, it had 248k miles and what the previous owner said was a weak battery. I reset the IMA by pulling fuse #15 under the dash and generally was okay driving around town, but any long hills or extended high speed interstate driving would eventually trip the IMA warning light and disable the system again.

After looking at the commercial grid chargers available, I decided to give Ol’ Rowdy’s homebrew charger a shot to save money. The cheapest reputable grid chargers seemed to start at $150 and go up. Ol’ Rowdy suggested his version could be built for about half that.

At the time, though, the key component to Ol’ Rowdy’s design – the current-limited LED power supply – was no longer available. Over the summer I got a local tech college to do a free battery conditioning on my car which worked wonders. By January 2020, my IMA was starting to act flaky again. Fortunately, Ol’ Rowdy now has a version 2 grid charger design using a widely available Mean Well power supply. Bonus – it is even simpler than his first version!

This thread documents my experience building the V2 Grid Charger, with extensive photos.

Baseline: I enjoy tinkering and building things, and can follow directions. The case construction was done using a Dremel, a drill, and some hand tools. I'm okay with basic circuits and soldering, but don’t understand electronics theory.

If this sounds like you, you can do this.
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Great thread. I can’t remember why I only skimmed through this before, maybe because it was before my first battery charging and cycling and I didn’t understand everything here. This thread deserves more replies.

So, as you’ve found, the voltage drops very quickly around the 140V point and it’s difficult to catch it at the desired voltage when you’re discharging manually. It’s a lot of checking. This is why I started the Simple Arduino Discharger project so you could connect it up and walk away. I reckon if you’re competent enough to build an OlRowdy grid charger you’ll be competent enough to to build a SAD discharge controller.

I’m also still of the opinion that the first discharge on a badly out of balance pack should only be to 140V. Maybe even higher on a pack triggering the IMA light. The logging from my first SAD discharge showed that the first cells were dropping out at this point. Despite opinions on here, I don’t like holding cells reversed, even at low current. If you were to shut off the discharge at this point, fully recharge and repeat, the next discharge will be a lot cleaner and much more even throughout the pack. This is because you’ll have significantly improved the performance of the weakest cells in the pack by reversing the memory effect and at least boosted the performance of the ones following closely behind them.
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