Honda Insight Forum banner

OlRowdy01 V2 Grid Charger Build (Illustrated)

18332 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 - 10 of 47 Posts
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.
Excellent write up with lots of detail. I'm glad you were able to work through the project to completion.

I commend you for offering your spare Mean Wells to others to build their chargers.

It's interesting to see how you mounted the smaller power supplies and even left the original 120Vac plugs on them. Also mounting the Mean Well on its side allows the use on a normal computer power supply case.

As a safety precaution I would not use a penknife to adjust the 4 digit meter pots since they may have 200 Vdc on them.

For some reason my Mean Well power supply will power the two 60 watt light bulbs with no drama.

I will put a link to this thread on the forum and on my website.
  • Like
Reactions: 1
Whoops. Discharge #2 turned into a deep discharge on accident.


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
Man that charger looked like a bowl of spaghetti before you buttoned it up. :D

Otherwise a great thread and I'm sure it will give other readers confidence to build their own charger.

What voltage did the battery recover to after the discharge to 8.4 volts? We were worried about that when Park's Mean Well power supply wouldn't power the two 60 watt bulbs.
You're referring to the end of discharge #2. I'm not sure what the recovery voltage was, because my daughter was implementing my (apparently not very clear) directions by text message, and the only data I have is what she wrote down. She couldn't explain it to me very well, but here's what I think happened...

What she described doesn't make a lot of sense to me.

According to your description of the Mean Well on your website, it shouldn't start charging unless the battery is at a minimum of 100V. Maybe it automatically kicked in once the battery recovered to 100V+, sometime between 17:04 and 18:11?

It was definitely charging at 18:11 last night. As of 9:11 this morning it had pushed the battery up to 164.6V. The charge curve looks the same as the previous two charge cycles so far.

We'll see. I definitely appreciate the more detailed write-up of the charge and discharge cycles you added to your website.

- Park [/QUOTE]

I misread the Mean Well data sheet and based on your initial experience with turning the charger ON & OFF in our private emails when it wouldn't output voltage with the 60 watt bulbs I thought you had to switch the supply ON/OFF to get to work again.

But based on what you found when the voltage was 9 volts and rising, I now realize what the HLG-60H-C350A data sheet means in this specification,

"PROTECTION - SHORT CIRCUIT ............ Hiccup mode, recovers automatically after fault condition is removed."

i.e. The power supply will not charge the battery if it is below 100 volts. But the charger will automatically power back on when the voltage rises to more than 100 volts. That's actually a good thing if necessary so the battery can recover on it's own before the charging starts again after a discharge.

I think my power supply may have a longer Hiccup fault time constant than yours that allows my 60 watt bulbs to light up right away.

I have already changed the following in the "Do a rejuvenation" section of the V2 DIY charger article.

"Here's why:
The power supply will not charge the battery if it is below 100 volts because a protection mode called 'Hiccup mode' kicks in. The charger will power back up when the voltage rises to more than 100 volts."

So that clears up why your charger started working by itself by the time you came home.
See less See more
  • Like
Reactions: 1
Thanks! I remember seeing your posts when you were starting the Arduino discharger project. Glad to see you finished it...

I absolutely would be interested in building it. What would be helpful would be a finished circuit diagram and list of parts. I’m more of a “mechanic” when it comes to electrical stuff - I can follow directions well but don’t grasp much of the theory.

- Park
Lately some of us have been slow discharging to zero volts and even leaving the battery overnight with the light bulb load on it.

A few months ago I was talking to the owner of an aircraft battery maintenance business and he said he discharges Ni-Mh aircraft batteries to zero volts and leaves a dead short on them over night. I would not go to that extreme though.

My last discharge on my 8 year old Honda warranty replacement IMA battery was a grid charge & single discharge to zero volts and left overnight with the load connected. After a final grid charge the battery is definitely acting better than with a discharge to 12 volts.

So I'm not so sure partial discharges are the way to go with Insight batteries.
  • Like
Reactions: 1
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.
Please give us the supply name and part number you 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.
I know nothing about the Toyota's battery system (or the cooling fan voltage etc requirements).

Good storage batteries will normally charge to some fully charged voltage and try to limit further voltage rise. BUT the battery(s) will also start dissipating the heat generated by the overcharge and can (in extreme cases [think of the exploding hover boards!]) vent, explode and or start fires. Depending upon the batteries chemistry, some lithium batteries can be ruined by over voltage charging and too low a discharge voltage.

Part of the apparent higher battery pack charged voltage will be the internal resistance of the pack's cells and wiring due to the charging current and ambient temperature.
  • Like
Reactions: 1
Sorry to hijack the thread guys. This ought to be pulled out to a new thread.

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.
The max voltage of my V2 DIY supply is 200 volts.

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.
Probably not necessary, depending upon your battery chemistry and it's end of charge characteristics.

The Prolong for my HiHy has a voltage limit of 360, same as the battery so it is a bit more sophisticated.
Will it charge your battery OK?

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??
We charge for 24 to 30 hours or a little longer until we see (hopefully) 174 volts at ~350 ma. With a good battery above ~170 volts the battery voltage rises ~2/10 of a volt per HOUR! The slow rise in voltage gives us plenty of time to stop the charge with the simple grid charger.

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.
If your battery tops out at ~360 volts and the supply is putting out 1/2 A the supply will be delivering 180+ watts. You ought to use a good air flow fan on the charger itself. My V2 supply at 100% SOC is outputting ~60 watts and runs at the cabin ambient temperature with a small computer fan for cooling it.

I may have just answered my own question but I wanted to know what you folks are doing.
And thanks for the reply.
See more details of my V2 DIY charger by going to my website. The link can be found by clicking on the 'CRX'' area below this post.

Out of curiosity, how many digits does your Prolong charger meter have?
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.
After reading up on the Ni-Mh battery that your car seems to use,
In affect all you have to do is set the supply voltage to be (perhaps) 10 volts above the 100% full charge rating of your hybrid battery and use 350 ma charge current. I don't know what power source your battery cooling fan uses, so that's left up to the student. ;)

quote]From the Prolong Website
The Prolong pro charger has a 3 digit meter.[/quote]

That isn't going to show the 1/10s of a volt change above the charge creep voltage point.

"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"
One hour to balance charge a Ni-Mh battery !?! o_O

– 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.
There was a lot of testing done years ago by Mike Debrosky(spelling?) that involved various charge/discharge rates for deteriorated cells etc. He settled on 350 ma charge/discharge rate that was safe for our IMA batteries. The info is still on his website.

I bow to Mike's research and will stick to a slow charge of 24 to 35 hours at 350 ma. [edit to time to charge 5/26/2022 ]

Chemical reactions can take time to happen. I've found that you should keep the IMA cooling fan running all the time while cycling the battery. There's lots of heat being radiated for many hours after a 350 ma charge to 100% SOC.

I use two light bulbs at the start of the discharge at ~350 ma discharge rate. The discharge current automatically tapers off as the battery voltage gets lower. This relieves the stress on the reverse charged weak cells. I do a complete [slow] discharge to 0 volts in one step. When the discharge current gets very low, I change the load to use one bulb and leave it on the battery overnight.

My 9-1/2 year old Honda warranty replacement battery is still working fine for my driving style. Yes several of the cells have low capacity but they still work OK.
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.
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)?

If your Ni-Mh battery responds near the end of charge similar to the Insight battery, (2/10 volt change/hour) all you have to do is turn (or program) the charge power supply OFF when the 100% SOC point occurs.

Believe me, we don't know absolutely for sure when the Insight packs are 100% charged either. We have educated guesses, but the battery voltage varies with temperature, IR etc etc as to when 100% SOC has been reached.

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.


If you have a link to the bat testing by Mike Debrovsky could you send that along? Thanks.
I did a quick forum search for Mike's website. All I can find in his forum posts is his email address. I also did a quick search on the web, but no luck finding his website either. Perhaps if you send him an email he will point you to his site.


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.
I don't want a constant current discharge load. I am trying to simulate a pack long term self discharge. As the battery voltage goes down, the bulbs change the [effective] load.

I have a chart on my website that shows the current change effect of different wattage light bulbs vs the battery pack voltage.
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.
I think you are misunderstanding what the max unloaded voltage of the supply is about. I'm sure you know that to charge any kind of rechargeable battery the charger has to be able output at least a little more (and sometimes even a lot more) voltage than what the charged voltage of the battery will end up being.

In your case the 400 volts represents the absolute max battery voltage the supply is capable of charging

As long as none of your cells are completely open you will never see 400 volts while charging your battery. The battery in affect loads your power supply enough to set the constant current to 350 ma at the voltage that the battery is at the time.

Assuming your Ni-Mh pack responds to a charge like the Insight pack does, here's is what should happen when doing a charge.

When the charger is first connected, and then turned ON, the power supply voltage will start charging at whatever voltage your battery is at (just guessing here, maybe 330 volts) and will output the constant current of 350 ma while charging. The voltage will quickly rise to some newer value (still below 360 volts). After an hour or so the voltage rise per hour will start to slow down. Eventually (after going through the 2/10s volt per hour stage) the battery will be charged to 360 volts but the charge will continue at 350 ma and ~360 volts (never at 400 volts). The supply and battery will both be dissipating a lot of heat though if the charge continues.

It's been recommended on the forum to make sure all the cells are fully charged to 100% SOC, to continue the charge for another few hours.

After you get the charger working, record the pack voltage every 1/2 hr for awhile and then every hour to really see what is going on.

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.
No problem. I just wanted to explain why I like bulbs as the load.

Thanks again. Will check out your website again. I'm still getting over covid. My personal SOC is currently limited.
Get well and be carefull my friend.
See less See more
I am looking to build a simple grid charger for rebalancing on my 2006 civic IMA. I saw some post about the meanwell drivers had changed and are not constant current.. I found these really cheap and in series would be correct volts, need about 200v.
Can you tell me if these should work? I am not sure how to tell if constant current or what happens if I use one that is not?
Typically the output current of these LED power supplies are either current limited or constant current. From the specs shown on the picture I would expect both of them to be constant current. But truthfully with cheap Chinese power supplies you can't be sure until you test them yourself.

I figured I'd ask before I just tried it.

The problem I see with those two supplies is that the output voltages and power output ratings aren't the same. You're in uncharted ground trying to use them in series.

As a test I would wire a 40 watt, 120 volt light bulb to the output of one supply at a time and measure the output voltage and current to see what they actually do. The higher voltage supply should output 300 ma at some voltage around 120 volts. The lower voltage supply may require a lower wattage bulb to test at 60+ volts.

Either way, I doubt the lower voltage supply will work with the large voltage difference in ratings between the two supplies as a series connected pair because the two power supplies have different maximum output -power- specifications when the the battery pack will be charging.

By the numbers shown on each supply, one is rated at ~37 watts output and the other at ~18 watts. That's not a recipe for a good match when wired in series.

I would definitely use output protection diodes (as my two charger designs do) to prevent the higher voltage supply from putting a reversed voltage into the lower voltage supply even as a test!
See less See more
  • Like
Reactions: 1
1 - 10 of 47 Posts