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Seeking: ~120V DC 20A supply

Started by David Lesher November 4, 2012
Three of us are working on an electric car conversion.  We're
now working on the "home" charger for it. For that, we are
seeking a digitally controllable switcher supply with ~120V
output, at up to 20-30A. At these power levels, 240VAC supply is
more likely.

Obviously new this will be $$$$, but I wonder if anyone knows of
a surplus candidate.

We currently ^H^H^H presently have a 48V 750W supply with remote
sense but would prefer something the charge controller can
directly manage [We now use a D-A to fake the sense input into
giving us our desired output...] as well as being able to charge
the whole string at once.

{Question: If you have 3 EE's is that 6E, or (EE)^3?}
-- 
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
On Sun, 4 Nov 2012 18:19:52 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

>Three of us are working on an electric car conversion. We're >now working on the "home" charger for it. For that, we are >seeking a digitally controllable switcher supply with ~120V >output, at up to 20-30A. At these power levels, 240VAC supply is >more likely. > >Obviously new this will be $$$$, but I wonder if anyone knows of >a surplus candidate. > >We currently ^H^H^H presently have a 48V 750W supply with remote >sense but would prefer something the charge controller can >directly manage [We now use a D-A to fake the sense input into >giving us our desired output...] as well as being able to charge >the whole string at once. > >{Question: If you have 3 EE's is that 6E, or (EE)^3?}
Why do you want an electric car? -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
On Sunday, November 4, 2012 10:19:52 AM UTC-8, David Lesher wrote:
> Three of us are working on an electric car conversion. We're > now working on the "home" charger for it. For that, we ar > seeking a digitally controllable switcher supply with ~120V > output, at up to 20-30A. At these power levels, 240VAC supply is > more likely.
The closest 'standard' item would be a speed control for DC motors; these are intended for inductive loads, a series choke might be appropriate. This one is good for 180V/26A <http://www.baldor.com/products/detail.asp?1=1&page=2&catalogonly=1&catalog=BC155&product=DC+Controls&family=One+Way%7Cvw%5FDCControls%5FOneWay> It's not digitally controlled, though. I'd think your charger would best be part of the vehicle, you'll want to charge in a remote location someday. Safe connection of 120VDC with a wire and plug is ... difficult (even a fuse is hard to manage for high DC voltage).
On 11/4/2012 12:27 PM, John Larkin wrote:
> On Sun, 4 Nov 2012 18:19:52 +0000 (UTC), David Lesher > <wb8foz@panix.com> wrote: > >> Three of us are working on an electric car conversion. We're >> now working on the "home" charger for it. For that, we are >> seeking a digitally controllable switcher supply with ~120V >> output, at up to 20-30A. At these power levels, 240VAC supply is >> more likely. >> >> Obviously new this will be $$$$, but I wonder if anyone knows of >> a surplus candidate. >> >> We currently ^H^H^H presently have a 48V 750W supply with remote >> sense but would prefer something the charge controller can >> directly manage [We now use a D-A to fake the sense input into >> giving us our desired output...] as well as being able to charge >> the whole string at once. >> >> {Question: If you have 3 EE's is that 6E, or (EE)^3?} > > Why do you want an electric car?
That's beside the point. Can you help with the requirement?
John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> writes:


>Why do you want an electric car?
We want to *build* an electric car for the same reason people enter the NYC Marathon, walk on the Serengeti, go to the Moon, and many other challenges. There are many people who may buy one; that holds no interest to us. As engineers who alas seldom get to actually create, we decided to do just that. -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433
whit3rd <whit3rd@gmail.com> writes:


>It's not digitally controlled, though.
That is a reason to change from our existing thinking. I was hoping someone made a 488 controlled PS, or such.
>I'd think your charger would best be part of the vehicle, you'll want to >charge in a remote location someday.
There will be a lighter, smaller, lower current one on board. -- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433
David Lesher wrote:
> Three of us are working on an electric car conversion. We're > now working on the "home" charger for it. For that, we are > seeking a digitally controllable switcher supply with ~120V > output, at up to 20-30A. At these power levels, 240VAC supply is > more likely. > > Obviously new this will be $$$$, but I wonder if anyone knows of > a surplus candidate. >
A good candidate might be a multi-kilowatt VF drive and then hack it. Sometimes called VFD, other times just "drive". Even big ones have become quite inexpensive. They come for inputs of 120VAC, 207VAC, 230VAC, 240VAC, 277VAC, and so on. You'd have to remove or disable the bridge at the oupt so you get DC, and then also hack the control circuitry so it doesn't scribe a sine. Another good candidate could be a huge UPS. One of those server room versions. There are companies that routinely switch them out almost like the batteries, one of the reasons being (like with VF drives) that the electrolytics in there have a finite life span. This would also need to be hacked.
> We currently ^H^H^H presently have a 48V 750W supply with remote > sense but would prefer something the charge controller can > directly manage [We now use a D-A to fake the sense input into > giving us our desired output...] as well as being able to charge > the whole string at once. >
Afraid there is no market for what you are looking for, so not likely surplus gear. What's wrong with faking signals for the sense lines? I do that all the time.
> {Question: If you have 3 EE's is that 6E, or (EE)^3?}
For a loner type nerd that would be a crowd :-) -- Regards, Joerg http://www.analogconsultants.com/
David Lesher wrote:

> John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> writes: > > > >>Why do you want an electric car? > > > > We want to *build* an electric car for the same reason people > enter the NYC Marathon, walk on the Serengeti, go to the Moon, > and many other challenges. > > There are many people who may buy one; that holds no interest > to us. As engineers who alas seldom get to actually create, we > decided to do just that. > >
I think if you are going to work with that level of voltage you should incorporate some sort of ground fault sensor to terminate the output immediately if some one comes in contact with it, even if it is floating. It does not take much to stop the heart. Jamie
On 11/4/2012 10:19 AM, David Lesher wrote:
> Three of us are working on an electric car conversion. We're > now working on the "home" charger for it. For that, we are > seeking a digitally controllable switcher supply with ~120V > output, at up to 20-30A. At these power levels, 240VAC supply is > more likely. > > Obviously new this will be $$$$, but I wonder if anyone knows of > a surplus candidate.
Presumably, you have a high-current variable supply to run the motor. Can you stick in a relay to flip it around to take rectified line input and charge the battery?
> > We currently ^H^H^H presently have a 48V 750W supply with remote > sense but would prefer something the charge controller can > directly manage [We now use a D-A to fake the sense input into > giving us our desired output...] as well as being able to charge > the whole string at once. > > {Question: If you have 3 EE's is that 6E, or (EE)^3?}
3 EE's are useless. It's like having three watches. One watch and you know what time it is. Three and you're never quite sure. They can't agree on anything.
In sci.electronics.design David Lesher <wb8foz@panix.com> wrote:
> Three of us are working on an electric car conversion. We're > now working on the "home" charger for it. For that, we are > seeking a digitally controllable switcher supply with ~120V > output, at up to 20-30A. At these power levels, 240VAC supply is > more likely. > > Obviously new this will be $$$$, but I wonder if anyone knows of > a surplus candidate.
Xantrex and Sorensen (now ametek) made exactly the sort of monster power supplies you need. I think xantrex dropped out of the power supply business, but the tiny bench ones were just rebadged units from the TTI, in the UK. check test equipment dealers. The really old sorensen stuff will be 1980s goofy linear power supplies with SCR preregulation. Those will be giant, and probably stuffed with obsolete parts. The newer ones are real switching power supplies.