Honda Insight Forum banner

OlRowdy01 V2 Grid Charger Build (Illustrated)

18316 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 - 7 of 47 Posts
Hi Insight People,
I have an 08 Toyota Highlander and I want to accomplish the same thing with an appropriate power supply to reach 360 V which I've found. My question is: Does the circuit depend on the batteries to limit the high voltage to the maximum, in my case 360v, much like a zener diode or will the charger overcharge the batteries to a higher voltage? There is no voltage limiter on these Mean Well supplies.
This cc power supply doesn't have an adjustable voltage limiter. I think you happened to find one that has the same voltage limit as your battery, about 175V. This one will go to 400 V in its safe operating area. I can add a simple voltage regulator that won't kick in until the output goes above 360 volts, the upper limit of my battery. The Prolong for my HiHy has a voltage limit of 360, same as the battery so it is a bit more sophisticated.

So what do you all do when your battery is fully charged? It doesn't appear there is an auto shut off in the DIY design. So how long are you comfortable running charging current through a fully charged battery, or to be more precise, how long is the battery comfortable??

The one I'm looking at is the Mean Well HLG-185H C500 which can be adjusted for constant current of 350 ma and is rated at 200W. I calculated my battery needs 216 watts. Probably close enough. I have not bought it yet.

I may have just answered my own question but I wanted to know what you folks are doing.
And thanks for the reply.

Font Material property Parallel Number Screenshot
See less See more
You're just the guy I want to talk with. Thank you for getting into this. I posted on this thread because I thought you might still be monitoring it.

I don't have a Prolong. I am reverse engineering this thing from the specs I see on the Prolong website and your plans. The only difference between our batteries is probably the voltage and current ratings.

From the Prolong Website
The Prolong pro charger has a 3 digit meter. "ProlongPro Battery Charger – Will fully charge a NiMh hybrid batteries pack in 1-3 hours – Works with all common NiMh battery sizes up to 240 cells – User selectable charge/balance mode vs. charge only (PHEV) modes.- User programmable cell balancing time – Compatible with all Prolong Car Harnesses – Audible alert when finished to minimize shop idle time – Reverse polarity protection to prevent system damage from incorrect battery connection – Thermal protection to prevent against excess heat damage ProlongPro Battery System User Manual"

That tells me charging current can be a lot higher. Maybe we're pussy footing around at 350 ma?? Or is 350ma required for cell balancing? 350ma seems to be the current from the round hocky-puck version of the Prolong

Thanks again.
See less See more
Thank you for your "Insight", olrowdy01!

The Prolong puck is a 350 ma charger, probably to avoid battery damage. It has a 12 V output for the fans. I just have to figure out the right connector to hook up the fans.

As I say the charge voltage isn't settable, so I can add a transistor voltage follower to limit the voltage out. I'll have to heat sink it. It should only have to dissipate 10-12 watts.

As for the battery, not only is there the chemistry to deal with but there is charge migration which is why the battery no load voltage can rebound to over 100 volts after a discharge. The migration is slow in both directions, I would assume.
I have a few voltmeters & ammeters that have 4 digits so no problem there. They're also dirt cheap online.

If you have a link to the bat testing by Mike Debrovsky could you send that along? Thanks.

As far as I can tell I have the original battery. My Dr. Prius app is showing a rise over the last year on internal cell resistance, now up to 35 milliohms and is operating at about 60%, so that's why I want to do this. It's a very useful app, I also recommend Blue Driver app which costs some $ but gets codes that a regular OBDII reader can't access, like speed sensor and CPU communication errors. At least for the Toyota hybrids. It's made trouble shooting a breeze so far.

I've been riding without the 5 rear seats for the last year. When I got the HiHy it was missing rear under bumper chassis plugs and filled up with water in a heavy rain. The water got into the battery and caused HV leakage to the chassis. They HiHy has a detector for that and shuts it down. So I had to take it apart, plugged the leaks and left a fan in the car for a few days to dry out the battery and rugs. Also had a bad connector that caused a fault code so I cleaned all the com connectors in the battery case to cure that. That said, I put the battery cover back but left it accessible just to wire up a charger. I also get 1 mpg better mileage not hauling the extra weight of rear seats. I'm a jazz bassist so I'm usually just carrying my bass and amp around. It's more like a truck for me.

As for the discharge light bulbs, the resistance drops as the voltage drops but not enough to make them a constant current load. But it's a cheap, no hassle way to discharge the battery.

So I guess I'm ready to get this gizmo going. I thank you for all your time and help and posting your schematic. My background is designing and modifying hi end vacuum tube audio amps so 360 volts isn't scary but is to be respected. If it's of any use to you I can post my version of your version. I not planning to build a fancy box, just maybe breadboard it with a fan and some jacks to hook up meters.

I just went through having Covid for 5 days so I thank all the scientists that figured out how to make a vaccine and drugs to fight it in record time. If I had gotten it before vaccines I might not be here today. I'm 70 and it was just like having the flu. So please stay safe, however you do that. This latest variant is highly contagious.

See less See more
"Why are you worrying about the max power supply voltage (400 volts) being more than the battery will allow at 350 ma (your posted number, 360 volts at full charge)?"

I'm not familiar enough to know how much and for how long over voltage can damage a battery. It would be a giant PITA if I have to fix it unnecessarily. The Prolong chargers have a maximum V output = to the voltage of the intended battery, 360 V for my HiHy. So they see fit to limit the voltage. So that raises my concern. Obviously you are getting good results with your setup.

"And to top it off, the Insight discharges the SOC down (into some load) to ~80% when you next use the car. The Insight runs the IMA pack from 20% to 80%, not 100% SOC."

I assume my Toyota will do the same or just run until the SOC goes below 80%. My battery SOC is between 50-65% right now. So the on board computer doesn't give it much range due to its reduced performance.

About the bulbs - I'm not implying anything about what you may want or what is desirable, just commenting on how an incandescent bulb works. A cold 60 W bulb is 17.9 ohms, a hot one is 240 ohms.

Thanks again. Will check out your website again. I'm still getting over covid. My personal SOC is currently limited.
See less See more
Get well and be carefull my friend.
Thank your for your time and support. I'll let you know how it goes when it goes.
And stay safe.
Finally past the covid but some residual fatigue is still there for me. But I did do a home made reconditioning. In the photo you can see I breadboarded the whole thing and used alligator clip jumpers to make connections. I am an experienced audio designer working with vacuum tubes so I didn't bother to package this and 360 volts doesn't scare me. Also you pull the disconnect plug on the side of the pack and it breaks the battery pack into 2. Since it floats, i.e. not grounded to the chassis, that makes it relatively safe to work on.
Also I didn't plan to keep doing this so breadboarding was enough packaging for now.

I used the directions from Prolong to hook up the high voltage. I had to research on my own how to get the fans to run. I bought a 3 amp 12 volt power supply and hooked the fans up with 5 ohm resistors in series with each. I had to ground the speed control pin in the connectors to enable them to spin. The fans draws 2.5 amps at full speed and around 1amp with the 5 ohm resistor. However the power supply would run 5 seconds shut down for 1 and turn back on as the overload protection kicked in and out. No harm to the power supply and the fans ran fast enough to do the job.

Also note that I had a larger fan blowing on the whole battery pack but it wasn't enough to keep it cool until the I had built in fans running during a sunny day.

My initial charged reached 339.4 volts and would not go higher. So I did a discharge as per the Prolong directions. I had to use 3 200W bulbs in series to start then dropped to 2 60 W bulbs when the voltage was low enough for them. I went through the whole procedure 3 times and the last charge got up to 344 volts max.

When I did a deep discharge the 3rd time I took some voltage readings on the battery modules in the HiHY. There 2 blades in each one 15 modules total, i.e. 30 blades. I found at least 7 modules that drained down to a few volts or less and some others held up to around 15 volts. So knowing that I dialed back my expectations for a revival of the battery. Although it did improve.

While I did this I used Dr. Prius app to obtain readings. It has a nice recording feature of the parameters so I was able to dump them into spreadsheets.

Attached are photos of the charger and the whole mess at work.
Electrical wiring Gas Machine Electrical supply Wire

Electrical wiring Electricity Electronic engineering Audio equipment Circuit component
Electrical wiring Engineering Motor vehicle Control panel Machine
Motor vehicle Hood Audio equipment Electrical wiring Electronic component
Motor vehicle Wood Gas Machine Engineering

Rough schematic. I used a 1 ohm resistor in the ground leg to monitor current, which allowed me to also switch to voltage easily. However I didn't include switches or or the fan circuits. I hooked up the fans with alligator jumpers. Also it shows 2 ways to build fan control modules for a Toyota fan but doesn't show the 5 ohm resistors or a necessary 555 pulse width modulator to control fan speed fi you don't want to do the 5 ohm resistor.

I could not find the connectors online to hook to the fans or I would have built a more complete circuit. If anyone knows where to get them let me know, though I know this isn't a Toyota forum.
Schematic Rectangle Font Material property Parallel

Here are some Dr Prius screen shots.
Before, heavy discharge, and after.
Line Font Screenshot Parallel Pattern
Product Font Material property Parallel Rectangle
Green Font Rectangle Parallel Design

Again, thanks for all the help and inspiration. I will be looking for some decent blades to rebuild the pack or I may just spring for a rebuilt battery with a warranty with gas is at $5/ gal.

All in all, I have a much deeper picture of the health of this battery however this just took a lot of time.

Yours truly,
See less See more
  • Like
Reactions: 1
1 - 7 of 47 Posts