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Author Topic: Meanwell + server PSU charger  (Read 773 times)

nedfunnell

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Meanwell + server PSU charger
« on: June 07, 2016, 10:57:18 PM »

Howdy folks,
I was going to reply to this thread where this subject is discussed, but decided not to necro it and derail it from the OP's build.

I would like to double my bike's charging speed. I have a 22s Leaf cell pack and charge it to about 91v using two Meanwell RSP-1000-48s trimmed for the desired ending voltage. This gives me 21A charging, which is great, but I want more.

I ordered a HP ESP-120 server power supply which provides 51.2v and is commonly modified to provide power for 48v input chargers by the model flight crowd. My hope is that I can put the RSPs in parallel with their current sharing mode enabled, and put that unit in series with the server PSU- so I'd get 51v from the HP, and then the pair of Meanwells would provide the remainder of the voltage and current control.

I was warned that this could be a problem, as I've been told that the RSP-1000 units will only let the voltage sag 9v or so from their setting in constant current mode. Can anyone confirm that? If so, I couldn't use this to charge from 0% on my pack without re-trimming the voltage. Do I have that right?

This will also get interesting because I 'hacked' one of the RSPs to provide a half-power mode by removing one of the two sense resistors on the underside of the PCB and replaced it with a switch on some short wire that provided similar resistance. I'll have to remove that and hope that it works as originally built.

For reference, here is my original build thread.
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alexanderfoti

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Re: Meanwell + server PSU charger
« Reply #1 on: July 13, 2016, 03:57:10 AM »

did you ever get anywhere with this?

I want to use 2 Elcon Flatpack2 HE 2000Watt psus in parallel and then another 2 x 1000watt 24v psu in series with them to give 7300 total charging power (including onboard) but read that there might be issues doing in this?
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Doctorbass

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Re: Meanwell + server PSU charger
« Reply #2 on: July 13, 2016, 10:20:50 AM »

Yes guys you have to make sure that the power supply you use can take voltage drop of your empty battery pack otherwise it will enter in protect and you will need to reset these ( unplug and plug back)

3 years ago when i made the first post about Quick Zero charging using CC-CV power supply i used the RSP-2000 witch have a voltage adjust feature that can go as low as 40% of their rated voltage. . If you use a 2013+ zero a empty pack is 28 x 3.0V = 84V minimum voltage. and from a 116v full that's 32V delta that your power supply have to tolerate. This mean that the power supply that you will connect in serie to get the desired voltage will have to take a drop of 32V at their output when in constant current mode and pack is empty. and you want that power supply to be the one with the highest voltage.. ex if you use two 48V  and one 24V in serie, then the 48v will have to be the one that fall in constant current first so the current  they supply must be less tahan the 24v so the 24v will remain at 24v and one of the 48V will take the drop  of 32V. As well the 24V MUST not have to take the 32V drop as it would need to go in reverse voltage...

in other words when you serie multiple power sppply in serie, make sur ethatthe one that will take the voltage drop when connecting your empty battery will be the one that have a voltage that is higher than that drop.. and that this is the one that will have the lower current limit.

Doc
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alexanderfoti

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Re: Meanwell + server PSU charger
« Reply #3 on: July 13, 2016, 04:27:01 PM »

Ah ok I get it.

So the real question is, how much voltage drop do the Flatpack2 take before they go into protect mode?

That I will have to find out, because I can then look at the voltage cutout spec (for example the rsp-2000).

Thanks.
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nedfunnell

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Re: Meanwell + server PSU charger
« Reply #4 on: October 24, 2016, 04:36:56 AM »

Yes guys you have to make sure that the power supply you use can take voltage drop of your empty battery pack otherwise it will enter in protect and you will need to reset these ( unplug and plug back)

3 years ago when i made the first post about Quick Zero charging using CC-CV power supply i used the RSP-2000 witch have a voltage adjust feature that can go as low as 40% of their rated voltage. . If you use a 2013+ zero a empty pack is 28 x 3.0V = 84V minimum voltage. and from a 116v full that's 32V delta that your power supply have to tolerate. This mean that the power supply that you will connect in serie to get the desired voltage will have to take a drop of 32V at their output when in constant current mode and pack is empty. and you want that power supply to be the one with the highest voltage.. ex if you use two 48V  and one 24V in serie, then the 48v will have to be the one that fall in constant current first so the current  they supply must be less tahan the 24v so the 24v will remain at 24v and one of the 48V will take the drop  of 32V. As well the 24V MUST not have to take the 32V drop as it would need to go in reverse voltage...

in other words when you serie multiple power sppply in serie, make sur ethatthe one that will take the voltage drop when connecting your empty battery will be the one that have a voltage that is higher than that drop.. and that this is the one that will have the lower current limit.

Doc

So do you know how much the RSP-1000-48 will sag without failing? For my bike, I need about 12v of sag. Can the RSP-1000-48 sag that much?
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nedfunnell

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Re: Meanwell + server PSU charger
« Reply #5 on: October 25, 2016, 04:28:55 AM »

I asked Meanwell, here is the answer I got:

Quote
If the RSP-1000-48 is loaded to the maximum current, the output voltage will be maintained until the current draw is increased beyond the overload protection point.
Once the overload protection has been triggered, the output voltage will fold back to a very low value.
The RSP-1000-48 will only operate in constant current mode if the output voltage is clamped by the load, such as in charging or LED driving applications.
The clamped output voltage has a under voltage protection value about 70~80% of the current PV set voltage.
For example, if output voltage is not adjusted, then the 48V default will support constant current operation for voltage down to around 33.6V.
A output voltage clamped to values lower than 33.6V will cause the power supply to shut down.
This value can be lowered by using the PV function.

I presume that "PV" refers to setting the output voltage with the trim pot. Right?
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nedfunnell

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Re: Meanwell + server PSU charger
« Reply #6 on: October 26, 2016, 06:36:14 AM »

Further clarification from MW:

Quote
PV refers to the output voltage programmable function, for which you apply a DC signal to the control pins to trim the output voltage.
Adjusting the output voltage with the trimpot will have the same effects on the under voltage protection limit.
However, the tirmpot can only go to a certain value, whereas the PV function can go all the way down to 40% trimming.
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