Fechter's Mini Meanwell Limiter Board

[kjparker]

Any chanceo f this being provided in a "kit" form?

I'm happy to assembe myself, but paying international postage on the board, then the parts, is probably going to be pricey! One postage cost would be good!

[kevo]

Fetcher,
What is your paypal address for ordering/paying for these?
Thanks,
Kevo

[fechter]

Any chanceo f this being provided in a "kit" form?

I'm happy to assembe myself, but paying international postage on the board, then the parts, is probably going to be pricey! One postage cost would be good!

I could probably do that. Shipping to Australia is pricey. Send me a pm.

[neptronix]

erm.. can you explain to a newbie why one would need one of these? is there something inherently wrong with the meanwell powersupplies to begin with?

[amberwolf]

Wrong? No, but they aren't designed to limit current in the way a charger needs to do, so this board (and other ways of doing it) helps it do that.

Often enough, power supplies will react to an overcurrent by just turning off for a moment, then turning back on (hiccup mode) to see if the "short" has cleared, then continuing to repeat the cycle to protect itself from blowing something up.

It's a nice cheap way of doing it, but it does not work well for charging, since that's going to by nature have a very heavy current draw on a discharged pack at a lower voltage, compared to the current draw it will have at it's fully charged voltage which should be at or near the rated voltage of the power supply/charger.

[fechter]

Another reason to use one is the supply will try to run at its maximum current rating during bulk charge. This often overheats the supply, especially if it's running at a higher than normal voltage. By cranking down the amps, the supply can run for long periods of time without overheating.

[kevo]

Another reason is to use for slowly charging puffed packs. Also to use the Meanwells in vehicles with a DC inverter running off a 15A fused cigarette plug without blowing the fuse. Also charging a single 5000 mAh 2C Lipo at 13 amps is bad for it.

[fechter]

Good point. Many packs may not be able to handle the full rated current during charging. This is especially true of the cheaper LiFePO4 pouch type cells.

[kevo]

Currently (excuse the pun), using Fetcher's Mini Meanwell Limiter Board charging a puffed Lipos 6S 5000mAh pack at .25 amps.
This pack was down to 2.1 volts/cell or 12.6 for the pack. Based on LFP's advice I'm cautiously trying a very slow charge.

Without the limiter, the Meanwell would be putting out 13.5 amps, a dangerous experiment I would not be willing to try.
With the limiter, we will see if the pack is revived. I'm optimistic, knowing the life of the pack will be greatly reduced.

Thanks for the excellent board,
Kevo

PS: You might explicitly update the Mouser BOM (Bill of Materials) list to emphasize two .1uF caps are needed per board.
I had bought parts for two Mini Meanwell's so was OK, but now have to run out for two more caps for the second board.

If this should be in the Battery or Review section, please feel free to move this post.

[fechter]

OK, here's an updated BOM that reflects the updated schematic.
For over 35v operation, we just add the 24v Zener diode and no longer use the FET or 100K resistor.

652-3362F-1-102LF|1
594-K104K15X7RF5TH5|2
512-1N914B|1
66-OAR5R005FLF|1
270-160K-RC|1
270-4.7K-RC|1
512-LM358AN|1
512-LM78L12ACZX|1

For the updated schematic over 35V, add:

78-1N5252B|1

Yes, be sure to order 2ea of the capacitors, however I have run it without them and it seems to be OK. They are not critical values either, probably anything with a 35+V rating will work fine.

For under 35v, place a piece of wire through the 24v jumper holes. You can use a piece of wire snipped off of one of the resistors. The jumper goes here:

24V jumper location.jpg (47.56 KiB) Viewed 985 times

For over 35v, place the zener diode like this:

Zener Diode placement.jpg (45.49 KiB) Viewed 985 times

It won't hurt if the zener diode is installed and the 24v jumper is added. It will be in the under 35v mode with the jumper.

For odd voltages, the value of the zener might need to be changed. To calculate, take the highest output voltage for the supply the board is connected to, and subtract 35v. This is the value you should use for the zener. If this doesn't work out to an available value, use the next higher zener voltage. Multiple zeners can be put in series to increase voltage. Try to keep the input of the LM78L12 between 24v-35v.

[fechter]

Currently (excuse the pun), using Fetcher's Mini Meanwell Limiter Board charging a puffed Lipos 6S 5000mAh pack at .25 amps.
This pack was down to 2.1 volts/cell or 12.6 for the pack. Based on LFP's advice I'm cautiously trying a very slow charge.

PS: You might explicitly update the Mouser BOM (Bill of Materials) list to emphasize two .1uF caps are needed per board.
I had bought parts for two Mini Meanwell's so was OK, but now have to run out for two more caps for the second board.

Wow, that was fast! Cool that you can dial it down to that low.

Anyway, if you copy and paste the BOM into Mouser, two caps will show up. Like I mentioned earlier, the caps aren't critical.

Also, I have determined that shipping to overseas costs $12.78 USD. I sent one to Jeremy in the UK and one to Greg in Australia. It cost the same for both.

[number1cruncher]

overseas costs $12.78 USD.

JC! It cost that much??? I received my board yesterday evening via regular mail. It only cost 88 cents for domestic shipping. Did you send the international package with a lot more padding?

BTW - You freaked my wife out(good ). She starts to open the envelope, sees the folded paper and hands it to me and says, "not sure if its anthrax, but you're opening it." I saw Fechter on the return address, so I knew it was cool. Pregnant women are sooo picky...

Thanks for this awesome little solution Fechter!!!!

[Alan B]

If you can ship in first class envelope then shipping is much cheaper. This should be okay for the PC board at least, and some folks ship kits this way.

[fechter]

Yeah, I'm not much of an expert at shipping things. It looks like I if I can put it in an envelope the overseas shipping will be a lot less. For bare boards, an envelope works fine. With parts, it could get smashed if it's not protected.

Update: Sold out for now.
I'll place an order for another batch of boards. This usually takes about a week. I can update the layout for the simplified regulator.

Also, these boards are designed for 24v and up. For 12v or 15v operation, a couple of parts can be changed to make it work at lower voltage. I'll have to do some calculations and make a schematic for the low voltage variant. The same board layout will work for either, just a couple of parts need to change.

[fechter]

For 12v or 15v supplies, U1 is changed to a LM78L05, R2 changes to 1K and R3 changes to 49K for a 0-20A adjustment range. For a 0-10A range, R3 should be 100K. Keep in mind that at 20A, the shunt resistor will run hot, but it is designed to withstand a lot of heat.
The 12v version is not tested, so could require a bit of tweaking.
The LM358 may not provide enough output swing, so the TLC2272 or TLC2262 may be better for U2

Also, I have determined that the input side capacitor on the 78Lxx regulator is unnecessary in any version since the input is feeding right off the output filter caps in the supply. The next version of the boards will reflect this change.

I'm revising the layout so I can get another order of boards placed soon.

MW Mini Limiter_12v version schematic.jpg (33.25 KiB) Viewed 577 times

[kevo]

Fetcher,
This is probably laziness on my part, but I have a question on your limiter board. On my S350-36 Meanwell (modified to 24volts) without your board the Meanwell tapers to 0 amps as I approach full charge on my 6s Lipos. When I charge it limited to 1Amp using your Mini Me board the tapering no longer occurs. Is this what you would expect from the circuit. It is still very useful, I just have to keep a closer eye on the end of charge currents. Just wondering, if I may have assembled it slightly off. Otherwise it has been great for reviving some slightly puffed Lipos.
Thanks,
Kevo

[fechter]

The amount of tapering is going to be a function of the voltage setting and the cells. If you lower the voltage slightly, it will taper off more. It's possible the cells are damaged. I don't think the limiter will affect this. Check the voltage near end of charge.

[kevo]

Appreciate the quick feedback. Testing the taper now on my good Lipos, but your response makes sense.

[kevo]

YES! Looking good on the current taper for both good Lipos and the puffed (but not greatly puffed) packs as well. I was being extremely conservative bringing the voltages up with about .1 to .2 amps. The taper doesn't seem to work for such low current settings. My voltages were up to 24.4 and after your post I used a starting current of 2 amps which tapered just fine. I'm currently at 24.6 volts with a current of .75 amps. Success!
Thank you so much for an excellent product,
Kevo

[etard]

Fechter,
Those ebay supplies you linked to in OP are sooo cheap! I want to get the S-350-48 and one of your boards for charging my 12S lipo, total cost: $75 shipped! That's a supreme deal for this many amps, amazing how things are getting so cheap for top of the line stuff. My question is, before I pull the trigger and order the supply, is this the supply that goes into hiccup mode instead of CC/CV? It mentions something about hiccup mode for overload etc... Is this a different function, or is this the unusable supplies that cannot be used for charging? If you give me the green I will order a board today.

Thanks for offering this great mod to those that don't want to piece the thing together on their own.

[fechter]

I've placed an order for another batch of boards. These will be updated for the simplified voltage regulator section and take out C1. New batch should be in next week.

I'm also researching less expensive shipping options for our overseas friends. $12.78 is ridiculous. It looks like if I use a padded envelope (a 'flat' as they call it), the shipping will be much less expensive. I still need to figure out the right customs forms to use, which varies depending on where it's going. So far it looks like it should be around $3 depending on what the total weight ends up being and how much the envelopes cost.

The super cheap Meanwell clones may have some minor differences but I expect they will be nearly indentical. Beware that some of them have horizontal terminal blocks instead of vertical ones. The boards should still fit, but would need to be upside down and stick out the front. I'd perfer the vertical blocks myself.

[fechter]

New batch of boards has arrived!

Getting to the post office before they close is pretty challenging, so please expect some delay for any international orders. I'm going to try a different service next time and from what I can estimate it should be more like $5 instead of $12.78 for most countries. For orders in the US, I can just drop them in the mailbox, so it's much easier.

[fechter]

I think I'm almost caught up with the shipping. For international orders, I can get a $1.50 padded envelope and the postage is about $1.50 to most places. It's pretty time consuming, so I think $5 shipping/handling is fair. Much better than the $12.78 flat rate box anyway.

[marty]

I download this program from http://www.usps.com/shippingassistant/welcome.htm
It prints all the shipping labels and customs forms. At the post office they just scan it and it's done. Saves time. I pay cash. But it's cheaper if you pay online.
________________________________________________________________________
USPS Shipping Assistant
Print and ship faster and smarter...from your desktop!
USPS Shipping Assistant® is a free desktop computer program that combines all the functions you need to create a variety of barcoded USPS shipping labels:
Domestic
International
Merchandise Return
Priority Mail Open and Distribute
Custom Forms

[fechter]

Thanks Marty. I'm using that to print the customs forms now. There is a learning curve though.