Fechter's Mini Meanwell Limiter Board

[fechter]

Here it is:

4.2.3 Limiter board built.JPG (142.25 KiB) Viewed 4348 times

This attaches to most Meanwell and Meanwell clone power supplies to give an adjustable current limit. This prevents overloading the supply at elevated voltages and prevents 'hiccup' mode limiting from kicking in.

It works by tapping into the voltage sensing line in the supply and lowers the output voltage when the current tries to exceed the set point dialed in on the adjusment pot. The sensing line can be easily located in most models and a single wire needs to attach to that point.

There is a discussion of it around page 33 of this thread: http://endless-sphere.com/forums/viewtopic.php?f=14&t=4125

Here's how it looks installed:

4.2.3 Limiter board installed.JPG (148.39 KiB) Viewed 3036 times

For 24v models running up to about 35v, the first regulator stage is not needed. For higher voltages, either the original regulator parts or a simple zener diode can be used to drop the voltage going into the regulator.

Right now, I'm doing the bare boards for $10 and fully built (less wires) for $35. I hate to charge practically what the supply costs, but my labor time is not cheap as I have many other projects to work on. Prices do not include shipping.
If you are interested, please pm me.

For cheap Meanwell clones, search eBay. I did a search on "27v power supply" and found most of the likely suppliers of Meanwells and Meanwell clones

Here's one of the cheapest: http://stores.ebay.com/stoneined2009/_i.html?_nkw=power+supply&_arm=1&_armi=Electronics+Accessories&_armm=351&_ruu=http%3A%2F%2Fstores.ebay.com%2Fstoneined2009%2FElectronics-Accessories-%2F_i.html%3F_nkw%3Dpower%2Bsupply%26_arr%3D1%26_fsub%3D1903645010%26_sid%3D868665070&_sid=868665070&_rdc=1

$32.75 including shipping. I don't know how they do it.
Genuine Meanwells are going for around $40.

[fechter]

Here's the schematic:
If you are really cheap, you can easily build one on a small piece of perf board.

Meanwell Limiter 2.0.0 schematic.jpg (43.87 KiB) Viewed 4387 times

More technical info to follow....

[fechter]

There are limitations to this setup. When the current tries to exceed the set point, the output voltage drops, but it can only drop so far. On the 24v versions I tested, it would drop to around 16v. For battery charging, this should be more than ample range to get effective limiting action.

You can place two 24v supplies in series to get 48v and only use the limiter board on one of them. I don't think it would matter which one, but I'd generally place the one with the limiter on the negative side. You might be able to push this to 3 supplies, but you could run out of "compliance" if the pack voltage was very low, like after a complete discharge.

In shopping around for Meanwell supplies, I noticed there is a S-350-27 version that runs 27v. Since I need around 29.2v for 8s LiFePO4, these supplies might be able to go that high without mods.

[bigmoose]

Nice design! Is the 0.005 Ohm shunt you specified hard to find?

[fechter]

Nice design! Is the 0.005 Ohm shunt you specified hard to find?

No.
Mouser # 66-OAR5R005FLF
4,323 In Stock
$0.60 ea.

[cassschr1]

Will this work with the sp-320-48 also? I have 12s moli on one bike (48v) and another with28s a123,M1 cells that I bulk charge with 2, 48v meanwells in series for 102 volts. Would this eliminate the hic-up mode?

[El_Steak]

You can place two 24v supplies in series to get 48v and only use the limiter board on one of them. I don't think it would matter which one, but I'd generally place the one with the limiter on the negative side. You might be able to push this to 3 supplies, but you could run out of "compliance" if the pack voltage was very low, like after a complete discharge.

So for a 100V solution (4 x S-350-24) this would not work?

[fechter]

Will this work with the sp-320-48 also? I have 12s moli on one bike (48v) and another with28s a123,M1 cells that I bulk charge with 2, 48v meanwells in series for 102 volts. Would this eliminate the hic-up mode?

Yes. I tested with a SP-320-24. No more hiccups.

So for a 100V solution (4 x S-350-24) this would not work?

It would work, but could run out of compliance if the pack was really dead. If you installed limiter boards on two of the 4 supplies, it would have more compliance.

I'll try to explain differently: At 100v the supply with the limiter can only drop by about 10v when the current tries to exceed the set point. This still leaves you with 90v, which might give you more than the desired current and throw things into hiccup mode. You could also run the risk that one supply shuts down and gets fed in reverse by the other ones (causing failure). This would not necessarily be the supply that has the limiter board on it. All of these things would only happen if the pack voltage was significantly below 90v.

[number1cruncher]

Will there be BOM like Gary has for the lvc boards?

[cassschr1]

Whats BOM? Also , in the first picture of this thread, the positive terminal says 24v. Your saying it could also be 27,36,48 etc....that it don't matter what MW your running, is this correct?

[fechter]

BOM is a bill of materials, the list of parts you need to build it. I'm working on it. Mouser doesn't have a BOM export tool, just an import tool.

The 24v jumper is used for supplies running under 35v. For under 35v, you don't need a couple of parts and you install the jumper. I'll try to get the instructions up soon. I've decided that for higher voltages it's cheaper/easier to just add a couple of zeners ahead of the 7812 regulator.

Here's an unedited Mouser parts list for the under 35v setup:


Mouser #: 78-1N5252B
Mfr. #: 1N5252B-TR
Manufacturer: Vishay
Desc.: Zener Diodes 24 Volt 0.5 Watt
$0.03 $0.03

Mouser #: 652-3362F-1-102LF
Mfr. #: 3362F-1-102LF
Manufacturer: Bourns
Desc.: Trimmer Resistors - Single Turn 1/4 SQ TRIMPOT 1K ST CERMET
$0.75 $0.75

2ea. Mouser #: 594-K104K15X7RF5TH5
Mfr. #: K104K15X7RF5TH5
Manufacturer: Vishay
Desc.: Multilayer Ceramic Capacitors (MLCC) - Leaded Axial 0.1uF 50volts X7R +/-10%
$0.06 $0.12

Mouser #: 512-1N914B
Mfr. #: 1N914B
Manufacturer: Fairchild Semiconductor
Desc.: Rectifiers 100V Io/200mA BULK
$0.02 $0.02

Mouser #: 66-OAR5R005FLF
Mfr. #: OAR5R005FLF
Manufacturer: IRC
Desc.: Current Sense Resistors - Through Hole .005 OHM 1%
$0.60 $0.60

Mouser #: 270-160K-RC
Mfr. #: 270-160K-RC
Manufacturer: Xicon
Desc.: Metal Film Resistors - Through Hole 160Kohms 1% 50PPM
$0.15 $0.15

Mouser #: 270-4.7K-RC
Mfr. #: 270-4.7K-RC
Manufacturer: Xicon
Desc.: Metal Film Resistors - Through Hole 4.7Kohms 1% 50PPM
$0.15 $0.15

Mouser #: 512-LM358AN
Mfr. #: LM358AN
Manufacturer: Fairchild Semiconductor
Desc.: Op Amps DIP-8 Dual Op Amp
$0.33 $0.33

Mouser #: 512-LM78L12ACZX
Mfr. #: LM78L12ACZX
Manufacturer: Fairchild Semiconductor
Desc.: Linear Regulators - Standard Pos Voltage Reg 3Term 0.1a
$0.17 $0.17

[jason701802]

Will this work on a mean well 48V supply? What modifications would be required?

[fechter]

Here's an updated schematic showing the simplified voltage regulator setup for over 35v. This should be good for 48v supplies. Anyone wanting to run somewhere between 35v and 40v could use a 15v zener instead of 48v. Just subtract the zener voltage from the supply voltage and make sure it is under 35v for other voltages.

Meanwell Limiter 2.0.0a schematic.jpg (35.28 KiB) Viewed 4136 times

[shinyballs]

Thank you for making this available! Except for the diode change, I guess this would work "as is" on my Cosel ADA600F 36V psu, yea?
Word of caution regarding the (-)wire. Use a proper strain relief on the black wire or the board "legs" could snap like twigs.

[AndyH]

Will there be BOM like Gary has for the lvc boards?

Here's the BOM file for Mouser that matches the last schematic - under 35V. Parts total is $2.40.

78-1N5252B|1
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 first schematic over 35V, add:

863-BS107ARL1G|1
270-100K-RC|1

[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 1056 times

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

Zener Diode placement.jpg (45.49 KiB) Viewed 1056 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.