Convert your 48V charger into 100V for 24s for CHEAP !
- Thread starter Doctorbass
- Start date
liveforphysics
100 TW
Doctorbass said:
This is not how it works.
The DC/DC's just drop-out if input voltage drops below the minimum threshold. You can not current limit upstream of the DC/DC, it will just turn off and go into 'hicup mode'.
The smart way to charge 24s on a budget is to buy one of these:
http://www.serversupply.com/POWER S...Y/3000WATT REDUNDANT/HP-COMPAQ/253232-001.htm
And stack a couple of these in series with it depending on the voltage you want:
http://www.serversupply.com/MFGR/HP-COMPAQ/POWER SUPPLY/SERVER POWER SUPPLY/575 WATT/335892-001.htm
And then for your current limiting, you need something to top off the stack with that can operate in CC/CV mode, as the other 2 supplies are just CV.
So, you find something like this:
http://cgi.ebay.com/MW-12V-DC-29A-350W-Meanwell-Switching-Power-Supply-/350473428035?pt=LH_DefaultDomain_0&hash=item5199d81c43#ht_5025wt_972
Two of these in series would work well for packs for 24s packs if you wish to charge at 2900w. Or do 4 of them 2p2s to charge at a more manly 5,800watts.
Nuts&Volts
100 W
LFP,
That is my off board charging plan
I have the HP 51V57A and 3 IBM 12V48A supplies to try to get a 90V 48A setup. To make sure I understand, Do i have to current limit if I want to charge at full current, 48A? Will the server type power supplies simply blow their tops off if connect say a 75V battery to their ~90V output? (ie they have no current or power limiting)
Doc, I have a RSP-1000 that I am doing this with, do i need to modify it at all to limit current or power? I sounded like the unit was capable of current limiting itself. I have it set to 41-42V out
That is my off board charging plan
I have the HP 51V57A and 3 IBM 12V48A supplies to try to get a 90V 48A setup. To make sure I understand, Do i have to current limit if I want to charge at full current, 48A? Will the server type power supplies simply blow their tops off if connect say a 75V battery to their ~90V output? (ie they have no current or power limiting) Doc, I have a RSP-1000 that I am doing this with, do i need to modify it at all to limit current or power? I sounded like the unit was capable of current limiting itself. I have it set to 41-42V out
liveforphysics
100 TW
Server supplies will trip off if you pull the voltage down. This is why you gotta have something with current limiting in series that handles the change in voltage that the pack requires as it charges.
Doctorbass
100 GW
Nuts&Volts said:LFP,
That is my off board charging plan
Doc, I have a RSP-1000 that I am doing this with, do i need to modify it at all to limit current or power? I sounded like the unit was capable of current limiting itself. I have it set to 41-42V out
Tehe RSP serie are Power limited and also depend on the AC input voltage. but for the same AC input you always get the same power until the load equivalent resistance decrease..
These power supply have a current sence transformer on the HV dc section and thatMs what monitor the power input.
it can be modified as well
Doctorbass
100 GW
liveforphysics said:
Luke.. The problem is that if you only have a 120V AC 15A socket.. it is difficult to use one of those beast 2900W :lol:
My suggestion is more for people that want a compact portable solution. It work well for me with the psu and the DC-Dc
Most important is to put a parallel protection diode with each source i serie.
The way my psu+ dc-dc work is that when the battery are empty or are under 100% soc.. Their voltage is lower than the psu and DC-Dc are regulated for ( CC-CV) . the psu take the voltage drop and the dc-dc stay regulated to their preseted output.
Doc
cwah
100 MW
Not sure to completely understand, but can I use my 500W power supply with 3 of theses to reach 82V (20s lipo):
http://www.ebay.co.uk/itm/DC-DC-10-32V-12-35V-150W-Power-Supply-Boost-Adjust-Module-Mobile-Laptop-Car-/110842505154?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item19ceba67c2#ht_4076wt_956
http://www.ebay.co.uk/itm/DC-DC-10-32V-12-35V-150W-Power-Supply-Boost-Adjust-Module-Mobile-Laptop-Car-/110842505154?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item19ceba67c2#ht_4076wt_956
IBScootn
100 W
Subscribed
docnjoj
1 GW
Hey Dr Bass
Could you do this with a 12 volt power supply to make it 24 volts just using some // D/c-DC 12 volt converters? Would the sam principles apply?
otherDoc
Could you do this with a 12 volt power supply to make it 24 volts just using some // D/c-DC 12 volt converters? Would the sam principles apply?
otherDoc
Doctorbass
100 GW
docnjoj said:
Yes!
cwah
100 MW
I'm trying to understand this chart but I still don't get it:
How come you have 3 DC-DC converter to reach 96V output? I suppose you would need 2 to have 48V*2 = 96V? And what's the grey line connection for?
Thanks
How come you have 3 DC-DC converter to reach 96V output? I suppose you would need 2 to have 48V*2 = 96V? And what's the grey line connection for?
Thanks
deVries
100 kW
cwah said:I'm trying to understand this chart but I still don't get it:
How come you have 3 DC-DC converter to reach 96V output? I suppose you would need 2 to have 48V*2 = 96V? And what's the grey line connection for?
Thanks
The grey wire connection is the Isolated Series Step-up (3 Parallel DC/DC 48v + 48v Meanwell) to get to 96v.
3 Parallel 48v DC/DC * 250w = 750w output @ 48v in Parallel.
cwah
100 MW
So if I understand it correctly, the wiring is:
1) 3*48V DC-DC in parallel to reach 750W
2) The 48V meanwell in series with the 48V750W DC-DC converter. How is it displayed in series? Doesn't look like the wiring in series I used to do with my lipo
3) And why the isolated series step up is connected between the + and - ?
Thanks
1) 3*48V DC-DC in parallel to reach 750W
2) The 48V meanwell in series with the 48V750W DC-DC converter. How is it displayed in series? Doesn't look like the wiring in series I used to do with my lipo
3) And why the isolated series step up is connected between the + and - ?
Thanks
deVries
100 kW
cwah said:
1) Yes, 750w on just the DC/DC.
2) That's because the inputs/outputs are isolated. Grey wire is the Series step-up.
3) Well, Series is a connection with +/-, otherwise it's parallel as is shown with the 3 DC/DC in parallel.
Hey, even if you don't understand it, you can still follow and do the wiring diagram anyway. It works! :lol:
What's really "psycho" or "mind warping" about this is BECAUSE everything is isolated the 750w output ADDS to the 1500w output too... Sooo, that's how you get to 20A output at 96v too ASSUMING the 37A output noted below. Freaky, Freakin Awesome. IF true.
Now, I don't understand how Doctorbass claims his 48v 1500w Meanwell can output 37A, since it can only be 31A with my math at 48v 1500w. IF I am correct, then the maximum you can charge at 96v is 15A. For a higher Meanwell 37A output maybe Doctorbass is thinking 55v (Meanwell maximum voltage setting) + 48v DC/DC output too??? :?
cwah
100 MW
Thanks Devrie. Much clearer now.
I'm trying to find these module online but they seem to be impossible to find.
Can't see any 12V isolated high current DC-DC converter online?
The one proposed is not sold anymore. Where can I find them?
I'm trying to find these module online but they seem to be impossible to find.
Can't see any 12V isolated high current DC-DC converter online?
The one proposed is not sold anymore. Where can I find them?
deVries
100 kW
cwah said:
These will be on ebay probably even 'now'... the problem with ebay is how to search to find the dang things!!! You will have to search using many different methods of key words. Also, if you find something close, then go to that sellers online store at ebay too. Often the item can be found in the store inventory, when you can't find it on the ebay search.
You're pretty good at finding things, so I'm sure you can do it within a few days or a week at most.
cwah
100 MW
lol!
Until I find a cheap 12V isolated high current DC-DC converter, I think the most flexible solution is still the non-isolated one as I can even use them on laptop power supply
Until I find a cheap 12V isolated high current DC-DC converter, I think the most flexible solution is still the non-isolated one as I can even use them on laptop power supply
Doctorbass
100 GW
deVries said:Now, I don't understand how Doctorbass claims his 48v 1500w Meanwell can output 37A, since it can only be 31A with my math at 48v 1500w. IF I am correct, then the maximum you can charge at 96v is 15A. For a higher Meanwell 37A output maybe Doctorbass is thinking 55v (Meanwell maximum voltage setting) + 48v DC/DC output too??? :?
Ok.. so the RSP serie have a 105 ~135% rated output power so you can get more than the rated current. I saw mine reach 37A output and over 1700W of DC output… and it can hold that 1700W continuously no prob.. the 1500W is only the rated power
See the specs: http://www.meanwell.com/search/RSP-1500/RSP-1500-spec.pdf
