One KiloWatt 18S Bulk Charger

I picked up three of these 24V 320 Watt LED power supplies:



Datasheet

They are well suited for Lithium battery charging, and much better quality than some of the available chargers, and easier than a hacked up power supply.

They are out of the box adjustable in voltage and current, available from many suppliers, and come with a 5 year warranty. They are silent, potted and very efficient. They just get warm when silently putting out 25 volts at 12 amps into a 6S Lipo bank. You can set the voltage and current and plug one of these into your 6S pack, or series two or three of them and plug them into your 12S or 18S pack and they will bulk charge them nicely. You might want some more features added on for a really top notch charger, but just these supplies will do most of the job. Three of these will draw a bit over 1,000 watts from the power line, which is about as much as one wants to draw from a 120V standard circuit without danger of popping a breaker or overloading inexpensive extension cords.

What these LED power supplies lack to be first-class bulk chargers is end of charge shutoff, and data collection (time, voltage, current and integrated current, eg amp-hours). I would also like some "safety checking" to verify that the voltage is within spec and the charging is proceeding normally, and disconnect if anything goes wrong.

Edit - the first pages of this thread are about building the controller to shut off the charge and measure the energy put back into the batteries. On page six I went ahead and set up the supplies for bulk charging for my GreyBorg without the controller. My plan is to build the controller, but it has taken too long so I forged ahead on the charger setup. So for the time being I use a WattsUp and manually disconnect the charger when the current drops below about one amp which is 5% of my pack's amp hour rating.

To that, I set one at 25.000 volts with a Fluke 189 meter, and each time I check it I get either 25.000 or 25.001. Still, with time, temperature, vibration, etc it would be good to have a "monitor" of the value.

One solution advocated by acuteaero is to use a Standalone Cycle Analyst to do this. It will provide the information, but not the shutoff or safety monitoring. But it is an easy way to go.

Another solution is to use a Watts-up, but this only works to its max voltage which is not sufficient for the 75 volts of my 18S packs. I did connect it to the first 6S block and that works, but still not all the features.

So what to do. It would be nice to have a purpose designed little board that had a CPU, LCD display, voltage and current measurement hardware and high current switch. How about an Arduino?

Sure, could do that, but would have to build or hack together most of it anyway, so why not toss the whole thing on a board, and make it Arduino open software compatible? This gives a lot of options for programming it. Then folks can customize their software for their own needs.

It might look something like this:



The board layout is not complete, but it is probably 75% there, though this rendering is earlier in the process. Basically a 16x2 LCD, a current sensor, some voltage sensors, a high current FET switch, an Arduino compatible AVR CPU, a knob and some pushbuttons.

I was thinking it might be nice to use this on the other available bulk chargers (or power supplies made into bulk chargers) to provide extra monitoring and safety. If we made some hardware with sample open software folks could do their own customization for various purposes. I can think of a few other uses for this hardware as well.

Comments? Suggestions? Worth completing??

That's something missing for all the ebike community.

And what's missing the most is an high voltage step-up DC-DC converter. If I was able to use any charger to charge my lipo up to 100V that would be so much simpler!

I was thinking it might be nice to use this on the other available bulk chargers to provide extra monitoring and safety. If we made some hardware with sample open software folks could do their own customization for various purposes. I can think of a few other uses for this hardware as well.

Comments? Suggestions? Worth completing??

Click to expand...

Hi Alan, this is a fantastic idea and contribution. We needed this years ago... yeah, this is a top 1-3 contribution to ES & ebikes for 2012. In fact, I'm rating it the number one contribution for 2012 if you can offer this before the end of August or September.

PLEASE offer this ASAP. PLEASE.

From the MeanWell spec page;

"B" Suffix: IP67 rated. Constant current level adjustable through output cable with 1~10Vdc or PWM signal or resistance."

Could this feature be used to, if not achieve complete shut-off, reduce current flow to Zero or near zero?

Bulk Charger Analyst

There's one vote!

What to call it. The BCA? That's Justin's naming, I don't plan to go that way. Maybe call it ABCC for Alan's Bulk Charge Controller. Whatever.

Well, my projects have a habit of getting slowed down by other pressures, but this is a pretty high priority for me, too. Most of this whole weekend has gone into it, but I can't keep doing that.

The PCB layout is at 80% now. Need to do some Arduino research to make sure that it is compatible enough. Plan is to use a separate USB to serial adapter, one of the standard Arduino ones. Need to put that connector on the board.

I also need to do some research on solving one problem I'm having, needing one more ADC channel. Perhaps a little CMOS 2:1 mux would do the trick.

Need to add a crystal for Arduino compatibility.

Should get all the parts to check against the board layout.

Need to finish the schematic and check the board layout. Twice.

Then pull the trigger and get boards made.

Then write software.

Build up a board - the first article. (Skipping the whole prototype phase by going straight to PC board).

And begin the debug process.

Etc.

End of August is possible for a working first article.

Anyone interested in helping with any of this? Board checking, building the first article, writing software? Maybe someone would like to build the production hardware?

motomech said:

From the MeanWell spec page;

"B" Suffix: IP67 rated. Constant current level adjustable through output cable with 1~10Vdc or PWM signal or resistance."

Could this feature be used to, if not achieve complete shut-off, reduce current flow to Zero or near zero?

Click to expand...

Maybe. I didn't get that variant of the supply so I can't test that. Does it adjust all the way to zero? The datasheet may answer that question.

The variant I picked up has two pots, one for voltage, one for current. Set the terminal voltage, and drop the current a little below full for good reliability and you're set to charge.

The current drops off anyway when the battery becomes charged. The current drops way down. Then a switch or relay should disconnect the battery from the charger. All you have to do is monitor the current and shut off when it falls below some value. The chargers I've been testing drop at 5-10% of max current. Other sources mention those percentages of the C rate of the battery. So far I've seen 300-700 mA cutoff on the chargers I've tested.

motomech said:

From the MeanWell spec page;

"B" Suffix: IP67 rated. Constant current level adjustable through output cable with 1~10Vdc or PWM signal or resistance."

Could this feature be used to, if not achieve complete shut-off, reduce current flow to Zero or near zero?

Click to expand...

Perhaps in conjunction with the Aux. Voltage Function of the CA-SA?

End of August is possible for a working first article.

Anyone interested in helping with any of this?

Click to expand...

I'm certainly willing to have a go at assembly & beta testing. I think this something most of us should use...

Thanks for your efforts to get it together so soon...

Can you assemble surface mount?

Alan B said:

Can you assemble surface mount?

Click to expand...

I wish. Sorry, I just have basic solder skills & monkey see monkey do abilities with this type of "beta test" process. Avoiding tedious assembly and squinting eyes would be a good thing if this is going to be packaged in kit form like Fechter & Goodrum did. I suggest following their example with a thread topic for the development work, beta testing, and feedback to learn how to use and assemble these. Certainly, it's not nearly as complicated a project task as their BMS R&D was.

From your description, it sounds as if Fechter's Mini Meanwell Limiter V.3 can provide the charge-limiting and termination you require along with optional per-cell HVC by CellLog, etc. Have you determined that it is incompatible or is the integrated Ah meter a critical part of the desired solution?

I was planning to use through-hole parts, but the availability of parts these days has mostly shifted to SMT. Also the cost of parts and the cost of assembly is much lower. And there is not enough room on this size board for through-hole parts.

Ham Radio folks have found many ways of doing SMT without fancy equipment, using head mounted or desk lamp magnifiers, small soldering pencil tips, hot air embossing tools, and mug warmers as well as electric skillets and toaster ovens.

When I discovered that I needed to do some surface mount I picked up a low power stereo microscope, a board heater, and a hot air rework station. So I can assemble a few prototypes but I don't have time/interest to do very many.

But we are stuck with SMT. I just selected a 2:1 cmos switch and there were no products with through-holes. For the hall effect current sensor I didn't see any either. There is very little market for through-hole parts anymore, and the lead-free rules forced a lot of old through-hole old parts to be dropped off the market. It just was not worth re-tooling for the sales volume, and the old stock was no longer saleable so it was junked. Through hole is dying.

As to the complexity compared to the BMS, it is hard to compare. They are so different. There's more on this board than I expected when I started. But this is more software based, so the hardware is in some sense simpler. But it is not quite simple.

teklektik said:

From your description, it sounds as if Fechter's Mini Meanwell Limiter V.3 can provide the charge-limiting and termination you require along with optional per-cell HVC by CellLog, etc. Have you determined that it is incompatible or is the integrated Ah meter a critical part of the desired solution?

Click to expand...

The Fetchter Mini Meanwell Limiter is not needed with these LED supplies, they already do that part - current limit and constant voltage. I don't see a shutoff there, it just keeps at a constant voltage as the current drops down.

I want the features it lacks, however. Amp-hour monitoring, Voltage verification, Charge time limiting. Shutoff at end of charge, or at any fault detected. Whatever else makes sense to add to the software.

Edit - note that the Fetchter board in conjunction with a power supply would make an appropriate charger to work with this Charge Controller. The Controller would provide the readouts, safety, shutoff, etc to make a "basic charger" into a "deluxe charger".

The Fetchter Mini Meanwell Limiter is not needed with these LED supplies, they already do that part - current limit and constant voltage. I don't see a shutoff there, it just keeps at a constant voltage as the current drops down.

I want the features it lacks, however. Amp-hour monitoring, Voltage verification, Charge time limiting. Shutoff at end of charge, or at any fault detected.

Click to expand...

I like your feature set. The Fechter board does have some "switch mechanism" that you can trigger something with like using a Celllog to monitor HVC & then you could "trigger" based on that "switch alarm" from the Celllog "alarm". I don't know any detail about it, though to go beyond 8s with more than one Celllog like 2 x 8s = 16s monitoring requires isolating/protecting the setup.

Your feature set is way more advanced & is exactly what we need, imo.

Yes, the Fetchter has a boolean HVC input which lowers the voltage setpoint that effectively stops charging current under most circumstances. It does not disconnect or shut off though, from what I looked at.

Anyway, I'm not trying to compete with that circuit (which is extremely cost effective), but provide something that provides a different, much larger set of features. (Edit - Actually they work well together, more details later).

So here it is with the parts and traces on. It needs review and tidying up. The components are not all numbered yet. Everything's there unless I decide to add something.



I don't know that I'd call it simple.

Of course, it is 1,000 times simpler than your basic garden variety laptop.

My inspiration to use the HLG power supply in the first place is attributable to Shane Colton. http://scolton.blogspot.com/2010/05/super-mean-well-scooter-fast-charger.html , and since reading that post back in 2010 I have heard of several instances of people using LED power supplies (HLG and otherwise) as CC/CV Lithium chargers.

Just wanted to make that clear

Shane is the man.

Thanks for the reference acuteaero.

I made a little progress this morning and evening. Found a few errors on the PCB. It'll probably take a week to finish the schematics and check this board. Perhaps it will be ready for etching a week from today.

Alan B said:

I made a little progress this morning and evening. Found a few errors on the PCB. It'll probably take a week to finish the schematics and check this board. Perhaps it will be ready for etching a week from today.

Click to expand...

Thanks for making the extra effort to complete this so soon. This really & truly is a "must have" item, imo. 8)

Made a little more progress. Changed a couple of chips to reduce assembly effort. Improved routing. Added Endless Sphere text to the bottom layer, top is too full.

I'm sorry to disrupt your interesting thread but is this something similar to what you're talking about or am I confused?

http://www.ebay.com/itm/300W-DC-DC-0-60V-5A-CC-CV-BUCK-step-down-regulated-power-supply-stable-297-/160838343490?pt=LH_DefaultDomain_0&hash=item2572b65b42

That is an adjustable buck regulator good to 5 amps with an LCD display. It takes in a higher voltage and puts out a lower voltage. It requires some kind of DC power for the input that is higher than the output value by a few volts. It is basically an adjustable power supply regulator.

This Charge Controller project is a 15 amp FET switch with voltage and current measurement capability, LCD display and open user programmability. This is designed to manage power supplies that are voltage and current limited into a deluxe bulk charger with readouts of charge time, voltage, current and integrated current (amp hours). It can also be programmed to provide safety features like checking the power supply and battery voltage and disconnecting if anything is off normal or if a charge time limit or integrated amp hour limit is exceeded. It will provide an extra layer of protection on top of the power supply circuits to insure that the voltage on your Lithium Battery Pack doesn't get higher than you have chosen.

So you can add this Charge Controller to a Meanwell or other supply that has voltage and current limiting (perhaps built in like the first post LED type supply, or use Fetchter's board on a standard or clone Meanwell), or one of the BMS alloy chargers, or other existing charger. This will provide the readouts and safety features, as well as the end of charge cutoff feature (which the bulk chargers may not need, but the other supplies do).

Thanks Alan! Still confused (normal) but 'little less so...

OK. Sorry if I have not been clear enough.

You can take a Meanwell and add a Fetchter board, or you can get voltage and current regulated LED power supplies as mentioned in post #1 or you can buy a bulk charger from various sources including BMSBattery. Then you will have a basic bulk charger. But no voltage, current, etc readouts, and in some cases no end of charge shutoff.

Just how critical is end of charge shutoff? It is a good idea to have one, the current drops down to pretty much zero when the charging is complete anyway but according to many sources leaving the pack on charge voltage is not good and will shorten pack life after awhile. But a few minutes here and there is not likely to be a significant factor in the life of the pack, from what I have been able to find. Ideally recommended is to have a shutoff at some low current value like 5-10% of the 1C rate. So for a 20 amp hour pack the shutoff would be one or two amps.

Then you add this controller board to the basic bulk charger. It provides displays of voltage, current, charge time and amp-hours. It can shut off the charge when it is done (which some of the chargers can already do but the LED supplies and many Meanwell type supply setups don't). It can check the voltages of the pack and the supply and disconnect if anything is out of limits, providing some extra safety.

It takes a "basic" charger and makes it into an "advanced" or "deluxe" charger.

Alan B said:

OK. Sorry if I have not been clear enough.

You can take a Meanwell and add a Fetchter board, or you can get voltage and current regulated LED power supplies as mentioned in post #1 or you can buy a bulk charger from various sources including BMSBattery. Then you will have a basic bulk charger. But no voltage, current, etc readouts, and in some cases no end of charge shutoff.

Just how critical is end of charge shutoff? It is a good idea to have one, the current drops down to pretty much zero when the charging is complete anyway but according to many sources leaving the pack on charge voltage is not good and will shorten pack life after awhile. But a few minutes here and there is not likely to be a significant factor in the life of the pack, from what I have been able to find. Ideally recommended is to have a shutoff at some low current value like 5-10% of the 1C rate. So for a 20 amp hour pack the shutoff would be one or two amps.

Then you add this controller board to the basic bulk charger. It provides displays of voltage, current, charge time and amp-hours. It can shut off the charge when it is done (which some of the chargers can already do but the LED supplies and many Meanwell type supply setups don't). It can check the voltages of the pack and the supply and disconnect if anything is out of limits, providing some extra safety.

It takes a "basic" charger and makes it into an "advanced" or "deluxe" charger.

Click to expand...

so, it's the add-on board I've been looking for.

Too bad I can't deal with building tiny circuits no mo'.