Fechter's Mini Meanwell Limiter Board

[wineboyrider]

Yes, although it was my original suggestion, I do tend to agree that maybe it is work that is not a good use of time.

A few months ago, I would have said different, but now with the appearance of these Alloy shell chargers from E-city/BMS battery, building a high power charger from multiple Meanwells is not as cost effective.

When I originally built my 100volt twin S-350-48 supply. I had ideally wanted a 20 amp supply at 100volts, so that was going to be 6 x S-350-48's
in three parallel strings.
I have just ordered a 2kW Alloy Shell charger from BMS for around $350 dollars delivered to me in UK from China..plug and play..no competition.

buying 6 Meanwells, combined with the hassle of building the system up .. would have made it not worthwhile.
Suppose if someone laready had a stack of Meanwells/ PC server supplies etc going cheap and free it would be a useful idea, but probably a bit limited now, you are right Richard

Are you still using and plan on using the pc power supplies as chargers? Because, I have a few pc power supplies I'd like to set up for charging my kids lipo powered scooter and my lipo packs? Just want to know of any trouble with the pc power supply idea if any??

[fechter]

I agree that trying to make a 2kW charger from a bunch of Meanwells is not the most elegant solution, especially if there is an off the shelf solution that is not more expensive.

For me, a measley 350W is fine and I'm cheap, so the Meanwell makes sense.

I also have one of those 600W HP server power supplies (12v, 47A) I was using with an iCharger. I might see if the limiter board is compatible with one of those. I suspect it will be, other than the current rating of the shunts. That's a great supply for running Lipo chargers BTW. Just needs a minor mod to make it run independently.

[NeilP]

[
Are you still using and plan on using the pc power supplies as chargers? Because, I have a few pc power supplies I'd like to set up for charging my kids lipo powered scooter and my lipo packs? Just want to know of any trouble with the pc power supply idea if any??

Yes I do still use PC supplies regularly to charge random packs in the workshop..All still very dodgy.
I have a string of 8 I think..all with bare wires ends, sitting on a piece of rubber underlay from some flooring system, ALl the output wires are bare, so i have 12v, 3 volt and 5 volt otputs I try and use all the 5 volt outputs, as they tend to have the highest current output, but if I am charging a 100volt pack, i need two or three of them running on the 12 volt output, to make up the voltage. The past one in series is a Meanwell 12 v S-350, with SVR2 current mod and 5 k pot voltage mod. This allow fine tuning of the voltage to exactly what I need for the pack, once I have roughly adjusted the voltage with as many of the supplies as I need. I use a standalone Cycl analyst to measuere current. One day I may fit plugs to the outputs of the supplies . Even the green to black connection required to fire the supplies up, is done by twisting the bared ends to the nearest bare end of black wire


Fetcher, yes, apart from the above experimental 25 amp charge string..all my charging is either doen with a single s-350-48 for the gf's bike or a pair in series for my bike. The alloy shell charger is for the new build. 34 or 35 series with 5405 in 17 inch with 24 FET 4115 Just ordered batteries yesterday. I did not order a complete pack, but just enough extras to make my current 20s Nano tech pack up to 34 S, plus few spares. Wold liek to have ordered a full 35s4p set of Nano techs, but the budget is overstretched as it is. OK did not need nano tech..but since that is what I already have, it means repairability of packs and in future and interchangeability etc

[fechter]

OK, I'm back from vacation now, so I can take a look at updating the board layouts. Hopefully I can get this done in a couple of days.

[wineboyrider]

So if I had two 15amp PC psu in series at the 12v connector that should give me a 25v lipo charger capable of 15 amps....!

[cor]

So if I had two 15amp PC psu in series at the 12v connector that should give me a 25v lipo charger capable of 15 amps....!

Correct. Make sure that the ground (case) of the supplies are not connected, it may be that the negative output is connected to the case, I am not sure but good to look out for (measure with a multimeter) as it is easi to bolt both to a metal frame, then if you connect the first +12V output to the next negative output, you may short out the first supply...
(That is why Neil has all supplies on an insulating mat)
NOTE that this gives you a fixed 24V supply, not a battery charger unless you add current limit! PC supplies normally do not have a good current limit from itself...

[NeilP]

So if I had two 15amp PC psu in series at the 12v connector that should give me a 25v lipo charger capable of 15 amps....!

Almost Cor..the insulating mat is to stop all the bare wires from shorting out on the metal bench.

My supplies have all been hacked inside..traces cut on the PCB's to isolate the negative line from the chassis. All out mains plugs here are earthed, which would put the negative line on the output side common to all supplies via the chassis and earth.

So yes, a pair of PC supplies would give you about 15 amps...jsut depends on the output the 12v line would put out. if you can get more, go for 5 of them on the 5 volt line


Either search my posts for PC supply type threads, or google for PC PSU mods..not a lot to it

, it may be that the negative output is connected to the case, I am not sure but good to look out for (measure with a multimeter) as it is easi to bolt both to a metal frame, then if you connect the first +12V output to the next negative output, you may short out the first supply...

Yes, at least in UK, the negative black output line is common to the case.

NOTE that this gives you a fixed 24V supply, not a battery charger unless you add current limit! PC supplies normally do not have a good current limit from itself...

You can sometimes getaway with not having a current limiting source. I have had limited success doing it ..but often you end up chasing the supplies along the line..as you power one up, another drops out...I have a huge stack of dead PC PSU..30 or more..and have probably zapped a good few..10 or so at least.

That is why my current setup includes a current limited meanwell...current limiting as well as fine voltage adjustment

Will try and find the correct threads in a moment

[NeilP]

here are a few threads to get you going...have had a quick look,, only one has a bit of info on which wire does what and how to start them up...green to black

viewtopic.php?f=14&t=25298

viewtopic.php?f=14&t=28632

viewtopic.php?f=14&t=28891

What you also need to do is open up each one, remove the pcb from the case, then cut and remove any trace that is connecting any electrical part of the board to the mounting posts.

Follow each trace and see if you are isolating any parts by cutting the traces. if so then solder jumper wires across the breaks you have made..keeping the mounting post corners free of connection to the negative line

[cor]

Almost Cor..the insulating mat is to stop all the bare wires from shorting out on the metal bench.

Ah, you already took care of the cases=ground. Good.

So yes, a pair of PC supplies would give you about 15 amps...jsut depends on the output the 12v line would put out. if you can get more, go for 5 of them on the 5 volt line

That would likely give you 25V, 30A or something like that.

You can sometimes getaway with not having a current limiting source. I have had limited success doing it ..but often you end up chasing the supplies along the line..as you power one up, another drops out...I have a huge stack of dead PC PSU..30 or more..and have probably zapped a good few..10 or so at least.

Yes, PC supplies are not so well regulated, so the voltage varies quite a bit with load - this "soft" behavior helps in cases of overload as in battery charging.
However, the simplest way to use PC supplies (or other fixed power supply) and charge a pack with them is to set the supplies to the maximum charge voltage by tuning the output voltage if possible or by combining different voltages - for PC supplies you can choose from 12V, 5V and 3.3V and with multiple supplies you can make a lot of combinations, for example to charge a 4s LiPoly pack (up to 17V max if it is well balanced and each cell goes to 4.25V) you can add the 12V from one supply to the 5V from another supply (usually you cannot combine the voltages from the *same* supply as they are tied together at the negative side) or use 3 supplies for more current: place 2 12V supplies in parallel to double their current and add the 5V from the third supply.
Note that if you can't get the right voltage then you can create a voltage a little higher and add heavy duty low voltage diodes in series to drop the voltage by about 0.8V for each (silicium) diode.
Note also that the 12V supplies might not be the exact same voltage and so they might not share the current evenly.
Also, to charge a pack that is quite empty and has a low internal resistance, the voltage of the charger will need to drop. Power supplies do not like this, they try to deliver all they have, overheat and die.
One simple way to solve this if the voltage difference between your pack and power supplies is no more than 15V is to place a few car headlights between the supply and the battery. Incandescent bulbs are pretty good current limiters and a typical 55W headlight will give you a current between 4 and 5A over a wide range of voltages, probably from lower than 8V to above 15V. So, to limit a PC supply setup to a max of 15A you wire 3 headlights in parallel between the string of supplies and the pack. No more blown supplies and the headlights give a visual indication of the charging progress: first bright, then slowly extinguishing while the pack comes up in voltage (charge). When the current drops below 1 or 1/2A then the charging is done.
If you can scrounge a couple headlights from a junkyard (or from your garage) then you only need to wire them in and off you go. No modern electronics required

[fechter]

BTW, the mini limiter board should work with most PC power supplies as they are very similar to the Meanwells. The hard part will be finding the OVP pin equivalent spot to tie in the feedback line. There seems to be a million different varieties of PC supply, but they are all similar.

[wineboyrider]

I have been charging my 6s scooter with my ping chargers, which are set to 45 volts. Is this a problem? I know I can't overcharge the lipo batteries, but I am monitoring the cell charge level with a cell log.

I think I'll just use the power supplies I have as a power supply for my hyperion.....

[Ykick]

I have been charging my 6s scooter with my ping chargers, which are set to 45 volts. Is this a problem? I know I can't overcharge the lipo batteries, but I am monitoring the cell charge level with a cell log.

I think I'll just use the power supplies I have as a power supply for my hyperion.....

I hope you mean 2qty 6S in series for 12S? Other wise you'd be charging each cell to 7.5V.

If 12S, you're only getting to 3.75V/cell so that's not gonna be much of a charge. I try to do my 12S around 49-50V.

Perhaps I missed something you're not talking RC Lipo?

[wineboyrider]

I have been charging my 6s scooter with my ping chargers, which are set to 45 volts. Is this a problem? I know I can't overcharge the lipo batteries, but I am monitoring the cell charge level with a cell log.

I think I'll just use the power supplies I have as a power supply for my hyperion.....

I hope you mean 2qty 6S in series for 12S? Other wise you'd be charging each cell to 7.5V.

If 12S, you're only getting to 3.75V/cell so that's not gonna be much of a charge. I try to do my 12S around 49-50V.

Perhaps I missed something you're not talking RC Lipo?

What I have done a couple of times is charge my 6s lipo with my 36v lifepo4 charger while watching the cells on my cell log monitor. I'm still alive and I know the voltage is higher than the lipo so I need to monitor them closely, but what I really want to know is if there is a problem with it other than over charging my lipos which could be easy to do with a higher voltage charger. I have a turnigy watt meter in line with it to monitor the wh, watts, amps etc...?

[Ykick]

I have been charging my 6s scooter with my ping chargers, which are set to 45 volts. Is this a problem? I know I can't overcharge the lipo batteries, but I am monitoring the cell charge level with a cell log.

I think I'll just use the power supplies I have as a power supply for my hyperion.....

I hope you mean 2qty 6S in series for 12S? Other wise you'd be charging each cell to 7.5V.

If 12S, you're only getting to 3.75V/cell so that's not gonna be much of a charge. I try to do my 12S around 49-50V.

Perhaps I missed something you're not talking RC Lipo?

What I have done a couple of times is charge my 6s lipo with my 36v lifepo4 charger while watching the cells on my cell log monitor. I'm still alive and I know the voltage is higher than the lipo so I need to monitor them closely, but what I really want to know is if there is a problem with it other than over charging my lipos which could be easy to do with a higher voltage charger. I have a turnigy watt meter in line with it to monitor the wh, watts, amps etc...?

As long as you don't forget or pass out from too much Wine, that does work. But if you forget, holy smokes! Did you ever rig up an off timer for AC power? That could be a last line of defense but using this setup as described is risking Lipo over voltage, IMO.

[wineboyrider]

I remember seeing your post on this. I bought 2 ezip scooters for $150.0 on cl and I want to keep one pretty much stock on 6s lipo for the kids to ride. I know the lipos can charge easily 1c and since I have my ebikes running on 36v lifepo4 and 12s and 10s lipo mostly is buy a 600w charger for opportunity charging when I'm traveling. The 600w charger I could also use when we go to the park and ride the scoots so we can get some extra rides out of them. There is an electrical outlet at the park where we ride that I know is live so I'm hoping to kill 2 birds with one stone. I also plan on buying a regular 2 amp charger from BMSbattery.com set to 24.5v so I can keep the 24v scoot ready to go when the kids get out of school....?

[cor]

I also plan on buying a regular 2 amp charger from BMSbattery.com set to 24.5v so I can keep the 24v scoot ready to go when the kids get out of school....?

Hi Wineboy,
That would be very adviseable.
Even when you *plan* to watch careful while charging the 25V pack with the 36V charger, the charger will take an hour to replenish an empty battery (BTW, are you running a BMS or voltage monitor? Discharging the LiPoly too far is equally destructive to the cells as overcharging them) so it is like watching paint dry and you might get distracted at some point, or an emergency happens and you come back to a cooked (on fire?) pack...
BTW, where did you get your 36V charger? I have a 8s pack and need about 34V charger while I only have 48V units. Turning them down to 34V is OK but they do not go much lower or start hiccuping, so I can't charge an empty pack with those.

[fechter]

As long as Lipo cells are well balanced, it should work OK to just set the maximum voltage of the charger to 4.15v / cell or maybe a little lower if you want to be safer. Once the cells reach that voltage, the current will drop to near zero essentially stopping the charging process. The charger could stay on for a really long time without overcharging any of the cells.

[wineboyrider]

I also plan on buying a regular 2 amp charger from BMSbattery.com set to 24.5v so I can keep the 24v scoot ready to go when the kids get out of school....?

Hi Wineboy,
That would be very adviseable.
Even when you *plan* to watch careful while charging the 25V pack with the 36V charger, the charger will take an hour to replenish an empty battery (BTW, are you running a BMS or voltage monitor? Discharging the LiPoly too far is equally destructive to the cells as overcharging them) so it is like watching paint dry and you might get distracted at some point, or an emergency happens and you come back to a cooked (on fire?) pack...
BTW, where did you get your 36V charger? I have a 8s pack and need about 34V charger while I only have 48V units. Turning them down to 34V is OK but they do not go much lower or start hiccuping, so I can't charge an empty pack with those.

I have 2 36v chargers from ping. They both can adjust up or down just like the BMS battery ones (I suppose). The 2.5 amp ping chargers are great in that I ca adjust them for 10s lipo or 12s lipo (62v max I think).

[cor]

I have 2 36v chargers from ping. They both can adjust up or down just like the BMS battery ones (I suppose). The 2.5 amp ping chargers are great in that I ca adjust them for 10s lipo or 12s lipo (62v max I think).

Sounds good. I guess they can't adjust down to 24.5V for the other bike?

Thanks for the reference - I asked around at work and an IT guy told me that he was getting rid of 2 drawers of laptop chargers, except the newer ones.
Fine with me - I rummaged around and came up with a 15V Toshiba charger and a 19V HP charger. In series that is 34V, exactly what I need.
I know that these supplies are already current limited and will handle overload reasonable well, so I think I have found my "charger" for free
Now I only need to build a BMS and a Charge Controller to throttle back the current once a cell gets around 4.25V (LiPo pack). Zephyr sounds good, though I have not seen a schematic of the charge control part yet.

[fechter]

I'm reviewing the design of the mini limiter board now.

It looks like by adding 2 resistors and a transistor, I can make an interface for CellLogs or HVC boards that will drop the charge current to zero when active. These parts can be left off the board for those who don't need this function.

Does this sound like a useful feature?

Another thing I'd like to test is to replace the output diode with a red LED and see if it is bright enough to see. This would provide the diode function needed in addition to indicating when the limiter was active. My guess is the LED would light up during bulk charge getting gradually dimmer as the pack approaches the CV point, then go out. This would give a visual indication of when the pack was done.

[wineboyrider]

I have 2 36v chargers from ping. They both can adjust up or down just like the BMS battery ones (I suppose). The 2.5 amp ping chargers are great in that I ca adjust them for 10s lipo or 12s lipo (62v max I think).

Sounds good. I guess they can't adjust down to 24.5V for the other bike?

Thanks for the reference - I asked around at work and an IT guy told me that he was getting rid of 2 drawers of laptop chargers, except the newer ones.
Fine with me - I rummaged around and came up with a 15V Toshiba charger and a 19V HP charger. In series that is 34V, exactly what I need.
I know that these supplies are already current limited and will handle overload reasonable well, so I think I have found my "charger" for free
Now I only need to build a BMS and a Charge Controller to throttle back the current once a cell gets around 4.25V (LiPo pack). Zephyr sounds good, though I have not seen a schematic of the charge control part yet.

Actually I think the 24v charger is different as I tried to trim the voltage down and the lowest I got was 34volts. But, other ES members say the BMS battery chargers can be trimmed (adjusted) up or down? Since I want a faster opportunity charger anyways and the price is right I decided to go ahead and order one set for 24.5v.

[NeilP]

It looks like by adding 2 resistors and a transistor, I can make an interface for CellLogs or HVC boards that will drop the charge current to zero when active. These parts can be left off the board for those who don't need this function.

Does this sound like a useful feature?

Useful, yes, I have jus ordered a pair of Cell Logs, so using them instead of building extra in to the circuit would be a good thing. Just to be clear, this is a re design of the single pot or the three pot board?

[teklektik]

... It looks like by adding 2 resistors and a transistor, I can make an interface for CellLogs or HVC boards that will drop the charge current to zero when active. These parts can be left off the board for those who don't need this function.

Does this sound like a useful feature?

You betcha. Please also arrange for a free pad to pick up Vcc to facilitate twin lead hookup to outboard opto(s).

Also - many different flavors of DIY HVC circuits always seem to end up with a tiny annoying 'glue board' with little but some limiting resistors and paralleled optos. To minimize the PITA factor, I would gladly pay to get a three channel isolator board modeled to be driven with the CellLog alarm interface with maybe a standard 9 pin pcb balancer connector for 3 alarms and FMM limiter hookup. This is an embarrassingly simple board but it would provide a quickie plug and play solution where alarm isolation is an issue.

[fechter]

Does this sound like a useful feature?
You betcha. Please also arrange for a free pad to pick up Vcc to facilitate twin lead hookup to outboard opto(s).

The CellLog and most HVC boards pull to ground when active, so I will have a ground pad and the HVC line is pulled up by a resistor (to 12v).

I have a layout for the CellLog isolator board. As you say, it is very simple. The real trick is to power on/off more than one at a time. To do this, a small multi-pole switch seems to be the easiest. A 4P switch could power 3 CellLogs and use the 4th pole to turn on the controller power for example. This is an entirely separate project though.

[teklektik]

The CellLog and most HVC boards pull to ground when active, so I will have a ground pad and the HVC line is pulled up by a resistor (to 12v).

Good - it wasn't clear what you meant by 'when active' (asserted low) so I was looking at an outboard Vcc+pull-up rather than onboard pull-up. I forgot the ground reference anyway, so you're still at two pads: signal and gnd.

I have a layout for the CellLog isolator board. As you say, it is very simple. The real trick is to power on/off more than one at a time. To do this, a small multi-pole switch seems to be the easiest. A 4P switch could power 3 CellLogs and use the 4th pole to turn on the controller power for example.

Hmmm, I think you had more in mind than I did for this board - I was just going after the isolation and was leaving the CellLog power, etc to the DIYer because of packaging/use case variations.

For instance, in my case I have an onboard CellLog with each 8s2p Headway pack and CellLog alarm leads running out from the pack balance charger connector. The CellLog on/off business is in the pack. Adding a simple isolator to the multi-pack balance charger would allow it to slave a MW bulk charger + your new limiter. (To make this more idiot-proof, the existing CellLog switch in the pack could be paralleled with two jumpered pins in the balance cable M/F connectors so the CellLog would power up whenever the pack was connected to the balance charger.)

In another thread recently, a poster had gutted and mounted Vphreak charger boards as part of a combined bulk/balance charger. With everything already exposed, he could use this isolator board to pick up the Vphreak green 'charge complete' LEDs directly w/o using CellLogs at all.

I think this may be a case where 'less is more' but as long as it's all optional board population, it looks good .