Honda Insight Forum banner

OlRowdy01 V2 Grid Charger Build (Illustrated)

18334 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.
See less See more
  • Like
Reactions: 1
1 - 1 of 47 Posts
Whoops. Discharge #2 turned into a deep discharge on accident.

I left the discharge process in the care of my brilliant grad student daughter. She dutifully logged data all day, and I showed her how to use the pull-chain switch on the discharge load to turn off the lights and change to 25W bulbs when the voltage hit 120V.

The battery lingered for a loonng time over or close to 140V, then tipped over a cliff. In one 85 minute interval, it dropped from 136.5 to 128.2V. In the next 76 minute interval it fell from 128.2 to 30.22V.

At that point my daughter called me for advice. I told her to turn off the light bulbs. Unfortunately, she turned off the grid charger instead of the pull-chain on the discharge load. So over the next 69 minutes the battery dropped from 30.22 to 8.4V, and did so without a cooling fan. Ouch. At least the discharge current was fairly low, and my garage is pretty cool.

So far the battery is recovering well on charge #3.

The good news is that it looks like my battery can hold a nice long steady discharge at a pretty consistent 140V+.


- Park
I noticed on my first discharge, it took 2 hours to go from 144 to 130, then only 30 min down to 120 volts..... yeah...falling off a cliff is a good description....
  • Like
Reactions: 1
1 - 1 of 47 Posts