# [EVDL] homebrew switch mode charger



## EVDL List (Jul 27, 2007)

Hi - I would like to build an EV charger. Switch mode if possible for
efficiency but any design is OK. Could any one please point me at any
homebrew designs out there? I have a 144V pack of 12 x 75AH Yellow Tops
I would like to charge.

To get started something low power (< 1 kW) is quite OK. In fact I
would rather start that way to lower the risks. 

Thanks,

David


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## EVDL List (Jul 27, 2007)

> David Rowe wrote:
> > Hi - I would like to build an EV charger. Switch mode if possible for
> > efficiency but any design is OK. Could any one please point me at any
> > homebrew designs out there? I have a 144V pack of 12 x 75AH Yellow Tops
> ...


----------



## EVDL List (Jul 27, 2007)

Your question is kind of general. I'm sure you will
get the usual bad-boy family of charger suggestions. 
I'm not sure what your goals are. Learning
experience? Reliable charger and save money? If you
want to experiment with charger algorithms, a couple
of ideas. One could be to put some sort of motor
(stepper motor, or DC servo motor) on a variac, and
control it via a computer, basic stamp, analog
circuit, etc. Or maybe buy a power stage off ebay. I
like the Sorensen DCS series power supplies. All of
them have analog control of the voltage and current
limits, some come with various other optional
interfaces. There is an isolated analog interface,
some GPIB interfaces, RS-232, RS-485, and ethernet. 
I've only used GPIB, RS-232, and the analog
interfaces, though. They are generally 1 KW, and
there is a 300V version that would work for you. It
shouldn't be too hard to get one under $300 or so.

But first thing I would do is go to the hardware store
and get a 12 hour wind up mechanical timer, like the
ones sold for attic fans. Use this as a backup
shutoff for your charger. Mount it in a box with a
circuit breaker, and maybe a GFI. I'd also put in a
separate circuit, like maybe modifying a Rudman
Regulator, that will also shut down your charger if
the output goes above some upper voltage limit. This
will help protect your batteries if (or rather when)
something goes wrong when you are not there to see it.

If your interest lies in building a power stage, I'll
let people with more experience give suggestions.

- Steven Ciciora



> --- David Rowe <[email protected]> wrote:
> 
> > Hi - I would like to build an EV charger. Switch
> > mode if possible for
> ...


----------



## EVDL List (Jul 27, 2007)

> David Rowe wrote:
> > Hi - I would like to build an EV charger. Switch mode if possible for
> > efficiency but any design is OK. Could any one please point me at any
> > homebrew designs out there? I have a 144V pack of 12 x 75AH Yellow Tops
> ...


----------



## EVDL List (Jul 27, 2007)

> To get started something low power (< 1 kW) is quite
> OK. In fact I
> would rather start that way to lower the risks. 

1kW isn't that low of a power level to do a SMPS
design with. That's actually a lot of power. It can be
done. However, if you have the knowledge and ability
to actually get one going, you probably can design
one. Check manufacturer's application notes for
suggestions. Magnetics are an issue at these power
levels. You need some big magnetics.

At these power levels, I usually end up blowing
up many power transistors between just getting it to
deliver the power, and testing out all of its failure
modes and protection circuitry. The first big charger
I designed and built took me a rail of MOSFETs to get
going. Since I work for companies designing SMPS supplies
I can't share my designs - they are 'theirs'.

Wear ear protection.

Transistors this size don't just go 'pfft', but
go 'bang' and can make your ears ring for days. Do
that enough times and you won't be able to hear at
all.

-Dale

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## EVDL List (Jul 27, 2007)

I'm making something of an assumption here so please forgive me if it's 
unjustified. However, it may help some other people even if it doesn't help 
you right now.

Many EV beginnners look at the prices of EV components and get sticker 
shock. TVs, computers, and other consumer appliances don't seem any more 
complex, and yet the EV bits cost several times as much!

EV parts such as chargers are expensive because they aren't manufactured in 
large quantities like TVs, computers, and DVD players. 

Really good components are not trivial to design or build, and that's 
another reason they cost a lot - the costs of design (in engineering person-
hours, and in components destroyed and wasted in trials) have to be spread 
over a few hundred or perhaps a few thousand units, not over hundreds of 
thousands.

Personally, I think that the cost of a good commercial EV charger is 
justified because in the long run it will save you money on battery 
replacement. But I have not tried to confirm this or compute exactly how 
much it might save.

That said, you >can< make a charger yourself, but it will most likely have 
to be quite a bit simpler than a factory-made charger. It will be heavier, 
will probably charge more slowly, and will treat the batteries more roughly 
so they don't last as long.

The simplest EV charger I can think of is a power cord, a large Variac 
(variable autotransformer) chosen for your battery voltage, a large bridge 
rectifier, a couple of fuses, and some cables to connect it to the battery. 
This charger is totally manual - YOU are the charge controller! Ideally, 
you check it every couple of hours and adjust it for the proper current and 
voltage as the battery charges. 

If you don't set it correctly, you're apt to have poor range, or ruin your 
batteries. With gross neglect, it could even start a fire. There will also 
be some shock hazard from it, though you can mitigate that with a GFI. But 
it will be fairly easy and inexpensive to build - probably just a couple 
hundred of dollars, or less, depending on how good you are at scrounging 
components.

If you build a charger like this, you really should use it only for golf car 
batteries. It can be used for sealed batteries if you are VERY careful and 
watch it almost every second. It can be >dangerous< to use for some kinds 
of lithium batteries, which require very precise charge control, and is 
likely to ruin them in short order in any case. But if you can afford 
lithium, you can probably afford a proper charger!

Hope this helps.

David Roden - Akron, Ohio, USA
EVDL Administrator

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## EVDL List (Jul 27, 2007)

Hi Steve,

> Your question is kind of general. I'm sure you will
> get the usual bad-boy family of charger suggestions. 
> I'm not sure what your goals are. Learning
> experience? Reliable charger and save money? 

My main aim is to develop a low cost "open hardware" charger for the EV
community. It occurred to me that there might be one (or the seeds of
one) out there already, hence this post.

Thanks for the tips on a backup cutoff timer, and the Rudman type
regulators for each battery - excellent idea.

- David



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## EVDL List (Jul 27, 2007)

> I have been working up a controller design that albeit isn't yet tested 
> should work. I figure it should work for charging as well.
> www.zev.dk/misc/diagram5.gif

Thanks Dan - that design looks like a good starting point. So I guess
we could rectify the mains (with a GFI for safety), then using the PWM
signal to control the voltage and hence current applied to the pack. An
isolation transformer could also be used for safety (with some losses I
guess).

I live in Australia, so have 240VAC mains.

Rather than straight PWM switching, perhaps we could add an inductor and
diode to make a:

http://en.wikipedia.org/wiki/Buck_converter 

This will have smoother output (less AC) that straight PWM.

Idea: perhaps a similar circuit (or perhaps the charger reconfigured)
could be used for an in-car DC-DC converter for the 12V circuit.

Cheers,

David


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## EVDL List (Jul 27, 2007)

Hi Dale,

Thanks for the practical tips - the ear protection is a great one .
Yes, the requirements for magnetics are an area I only dimly understand
and need to research more.

I am an electronic engineer (so OK with power supply theory, software,
signal processing, low power stuff), but need to learn a lot about the
practical aspects of high power electronics. I have designed some small
microcontroller based DC-DC converters (like ring generators for
telephones). I plan to scale up _slowly_ and carefully.

What would your recommend for a dummy load for testing? I was thinking
of something like a old electric radiator.

Thanks,

David



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## EVDL List (Jul 27, 2007)

Hi David,

Thank you for your comments. I guess I am partly motivated by sticker
shock, but mainly I would like to contribute to the EV community. You
see you guys have been very helpful to me (I have been lurking on the
list for months), and I figure an open charger design is one way I can
contribute to the community.

Yes, I understand that the price of current chargers is very justified -
I have started my own electronic manufacturing companies in the past and
have even been the guy doing all the R&D  

However I think they may be a gap between the current commercial full
featured chargers and the current open bad boy designs that I can fill
in just a little.

I am also a strong believer in the power of community - by putting our
heads together it is often possible to out-do or at least equal
traditional commercial product development models.

> That said, you >can< make a charger yourself, but it will most likely have 
> to be quite a bit simpler than a factory-made charger. It will be heavier, 
> will probably charge more slowly, and will treat the batteries more roughly 
> so they don't last as long.

Yes, I anticipate most of those. That's OK for a start I think. One
requirement I do need to watch is that it treats my AGMs (D31 Yellow
Tops) well. So I need to make it behave, say with a Rudman type shunt
regulator or equalisation scheme, and careful monitoring of individual
battery voltage. That bit I know how to do (low voltage and micro
controllers I am OK with).

So here's one draft design I have in mind:

1/ Manual timer, breakers, GFI or isolation (2:1 step up for the US)
transformer, Rectifier, filter caps, maybe inductor. Gives us 400VDC.

2/ microcontroller0 based switch mode step down stage, outputs 0-200VDC
at 5-10A. Or perhaps SCR based switching stage as per Lee's suggestion.

3/ microcontroller(1-12) across each battery to measure voltage, talks
to microcontroller0 via isolated (floating) RS232 type bus. Sends "stop
charging" type command if V(1-12) exceed a threshold.

4/ Series regulators across each battery, perhaps controlled by
microcontroller(1-12).

> Hope this helps.

Sure does - thanks David.

Cheers,

David


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## EVDL List (Jul 27, 2007)

> David Rowe wrote:
> > Rather than straight PWM switching, perhaps we could add an inductor and
> > diode to make a: http://en.wikipedia.org/wiki/Buck_converter
> > This will have smoother output (less AC) that straight PWM.
> ...


----------



## EVDL List (Jul 27, 2007)

> David Rowe wrote:
> 
> > Hi David,
> >
> ...


----------



## EVDL List (Jul 27, 2007)

To start small, I would be really tempted to make a charger
in 300W 'bricks' that can be put in series or parallel.
That power level is quite a bit easier and the magnetics
and design should be straightforward. You only have to look
as far as your local desktop PC them make it tougher. I
always found the 400W region to be where it gets a bit strange.

-Dale

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## EVDL List (Jul 27, 2007)

> Hi David,
>
> Thank you for your comments. I guess I am partly motivated by sticker
> shock, but mainly I would like to contribute to the EV community. You
> see you guys have been very helpful to me (I have been lurking on the
> list for months), and I figure an open charger design is one way I can
> contribute to the community.

About every year or two someone wants to develope an "Open Charger". You
can search the archives
for "Shep the charger" and "Open Source Charger" {I think those are the
right names}

The often generate a lot of discussion, but never go anywhere. Cheap
chargers are easy to build, the "Bad Boy" charger is nothing but a bridge
rectifier and bunch of extension cords, add and remove extension cords to
adjust charging current.

Good chargers are much more complicated to build and by the time you've
pruchased the components, purchased a few more to replace the ones you let
the smoke out of, and caculate minimum wage for your own time, you are at
or above the cost of buying one.

The folks who are building EV chargers, controllers, etc. aren't getting
rich, far from it.

if you really want to try it, go for it, just don't have any delusions
about saving a ton of money.
>
> Yes, I understand that the price of current chargers is very justified -
> I have started my own electronic manufacturing companies in the past and
> have even been the guy doing all the R&D 
>
> However I think they may be a gap between the current commercial full
> featured chargers and the current open bad boy designs that I can fill
> in just a little.
>
> I am also a strong believer in the power of community - by putting our
> heads together it is often possible to out-do or at least equal
> traditional commercial product development models.
>
>> That said, you >can< make a charger yourself, but it will most likely
>> have
>> to be quite a bit simpler than a factory-made charger. It will be
>> heavier,
>> will probably charge more slowly, and will treat the batteries more
>> roughly
>> so they don't last as long.
>
> Yes, I anticipate most of those. That's OK for a start I think. One
> requirement I do need to watch is that it treats my AGMs (D31 Yellow
> Tops) well. So I need to make it behave, say with a Rudman type shunt
> regulator or equalisation scheme, and careful monitoring of individual
> battery voltage. That bit I know how to do (low voltage and micro
> controllers I am OK with).
>
> So here's one draft design I have in mind:
>
> 1/ Manual timer, breakers, GFI or isolation (2:1 step up for the US)
> transformer, Rectifier, filter caps, maybe inductor. Gives us 400VDC.
>
> 2/ microcontroller0 based switch mode step down stage, outputs 0-200VDC
> at 5-10A. Or perhaps SCR based switching stage as per Lee's suggestion.
>
> 3/ microcontroller(1-12) across each battery to measure voltage, talks
> to microcontroller0 via isolated (floating) RS232 type bus. Sends "stop
> charging" type command if V(1-12) exceed a threshold.
>
> 4/ Series regulators across each battery, perhaps controlled by
> microcontroller(1-12).
>
>> Hope this helps.
>
> Sure does - thanks David.
>
> Cheers,
>
> David
>
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>


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## EVDL List (Jul 27, 2007)

Just a small suggestion. It's probably safer to flip that signal
around. Instead of a "stop charging" signal, it'd be a "keep
charging" signal sent periodically. The main controller would
automatically stop charging if it lost contact with a secondary
controller. That way, if the secondary controller should fail, you
won't destroy that battery.

-Steven



> David Rowe <[email protected]> wrote:
> > 2/ microcontroller0 based switch mode step down stage, outputs 0-200VDC
> > at 5-10A. Or perhaps SCR based switching stage as per Lee's suggestion.
> >
> ...


----------



## EVDL List (Jul 27, 2007)

I have some experience in cheap chargers,
though my EV has a bit higher voltage pack (312V): 

The easiest, fastest and cheapest way to charge this
high pack voltage, is to use surplus power supplies
that are PFC (Power Factor Corrected) and can be found
in nearly any power level.
I selected a Dell server's power supply after my work
discarded two old Dell servers (with redundant power supplies)
so I ended up with 4 of them.
I later bought a few more for a low price, in case I wanted to
grow a bit to a large charger, but I realized that when
starting with these 700W chargers, that using just two of them
would allow me to charge anywhere from either 110V or 240V and
likely even from a Prius' battery in case of an emergency, 
because the PCF just takes the input voltage, fits the current
form to the input voltage and generates a switching output to
create 400V output with a simple inductor and switch
(boost configuation)

The cheapest and simplest way to match the 400V output to my
pack voltage is a bank of 120V lightbulbs.
Sure, that is more wasteful than a current-regulation of the
PFC, which is what I intend to add soon, but it works.
It also lets the current taper off while the pack gets full
so I can rest assured that my batteries will get full and not
overcharged.
If I forget the charger then a day later I will see that the 
bulbs are starting to light up a bit again, as the pack is
getting warm from the overcharge and the voltage drops, so the
bulbs are coming on again. (for a normal charge, the pack rises
close to 390V = 15V per battery, so the bulbs are not visibly
glowing any more.

So, if you are interested in a $25 charger that can send up to
700W into your pack, drop me a line as I have a stack of those
and I want to let them go.

Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of David Rowe
Sent: Thursday, February 21, 2008 10:30 PM
To: Electric Vehicle Discussion List
Subject: [EVDL] homebrew switch mode charger

Hi - I would like to build an EV charger. Switch mode if possible for efficiency but any design is OK. Could any one please point me at any homebrew designs out there? I have a 144V pack of 12 x 75AH Yellow Tops I would like to charge.

To get started something low power (< 1 kW) is quite OK. In fact I would rather start that way to lower the risks. 

Thanks,

David


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----------



## EVDL List (Jul 27, 2007)

I need something to charge my 72 volt.. Qould this work?

-----Original Message-----
From: Cor van de Water <[email protected]>
Sent: Monday, 25 February 2008 04:09 PM
To: Electric Vehicle Discussion List <[email protected]>
Subject: Re: [EVDL] homebrew switch mode charger

I have some experience in cheap chargers,
though my EV has a bit higher voltage pack (312V): 

The easiest, fastest and cheapest way to charge this
high pack voltage, is to use surplus power supplies
that are PFC (Power Factor Corrected) and can be found
in nearly any power level.
I selected a Dell server's power supply after my work
discarded two old Dell servers (with redundant power supplies)
so I ended up with 4 of them.
I later bought a few more for a low price, in case I wanted to
grow a bit to a large charger, but I realized that when
starting with these 700W chargers, that using just two of them
would allow me to charge anywhere from either 110V or 240V and
likely even from a Prius' battery in case of an emergency, 
because the PCF just takes the input voltage, fits the current
form to the input voltage and generates a switching output to
create 400V output with a simple inductor and switch
(boost configuation)

The cheapest and simplest way to match the 400V output to my
pack voltage is a bank of 120V lightbulbs.
Sure, that is more wasteful than a current-regulation of the
PFC, which is what I intend to add soon, but it works.
It also lets the current taper off while the pack gets full
so I can rest assured that my batteries will get full and not
overcharged.
If I forget the charger then a day later I will see that the 
bulbs are starting to light up a bit again, as the pack is
getting warm from the overcharge and the voltage drops, so the
bulbs are coming on again. (for a normal charge, the pack rises
close to 390V = 15V per battery, so the bulbs are not visibly
glowing any more.

So, if you are interested in a $25 charger that can send up to
700W into your pack, drop me a line as I have a stack of those
and I want to let them go.

Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of David Rowe
Sent: Thursday, February 21, 2008 10:30 PM
To: Electric Vehicle Discussion List
Subject: [EVDL] homebrew switch mode charger

Hi - I would like to build an EV charger. Switch mode if possible for efficiency but any design is OK. Could any one please point me at any homebrew designs out there? I have a 144V pack of 12 x 75AH Yellow Tops I would like to charge.

To get started something low power (< 1 kW) is quite OK. In fact I would rather start that way to lower the risks. 

Thanks,

David


_______________________________________________
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_______________________________________________
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----------



## EVDL List (Jul 27, 2007)

Well, first question to ask is if you really need isolation. If not, there are plenty of buck/boost power supply chips out there with "reference designs" for constant voltage, current-limited switching supplies. They are fairly straightforward if you follow the design. Do not mess around with thinking you don't need this-or-that or that an electrolytic will work when it specifies ceramic or whatever. They don't usually put unnecessary parts or unnecessarily costly parts in reference designs.

There are also plenty of driver chips with reference designs for isolated chargers with high freq transformers. HF transformers are essential to avoiding huge 60hz transformers. I mean even 100VA (100W) is sort of a monster. The problem is that transformers must generally be custom designed and wound for the task and that gets to be problematic for many home builders. There are many issues of skin effect, core losses, core saturation, core material selection, I2R wire losses, not having enough room for the wire, having too much room not covered by wire, and winding technique to consider and there's not a quick way to learn how to work this stuff out. Plus with the wire and core involved it's definitely gonna be the most expensive thing on the board.

Danny

> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf Of David Rowe
> Sent: Thursday, February 21, 2008 10:30 PM
> To: Electric Vehicle Discussion List
> Subject: [EVDL] homebrew switch mode charger
> 
> Hi - I would like to build an EV charger. Switch mode if possible for efficiency but any design is OK. Could any one please point me at any homebrew designs out there? I have a 144V pack of 12 x 75AH Yellow Tops I would like to charge.
> 
> To get started something low power (< 1 kW) is quite OK. In fact I would rather start that way to lower the risks. 
> 
> Thanks,
> 
> David
> 
> 
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
> 
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
> 
> 
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

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## EVDL List (Jul 27, 2007)

<<<< Well, first question to ask is if you really need isolation. If 
not, there are plenty of buck/boost power supply chips out there with 
"reference designs" for constant voltage, current-limited switching 
supplies. They are fairly straightforward if you follow the design. 
Do not mess around with thinking you don't need this-or-that or that 
an electrolytic will work when it specifies ceramic or whatever. They 
don't usually put unnecessary parts or unnecessarily costly parts in 
reference designs. >>>>

If you are adept enough to build a charger or controller yourself, you 
should add every safety feature (and plenty of headroom) to work under 
the pressures of high current and nasty road environment. Going cheap 
ends up costing more in the end, and if you aren't *that* adept, you 
may as well pay for a professionally-made unit.

People who use stuff from China, especially without a warrantee, are 
misguided. For OEM use, you have to send your own QC personnel to test 
every item off the line. Brand name products, even high end ones, may 
say "Made in China", but you cannot trust a **Chinese** brand to be 
just as good.

So, build it, or buy it from people with a reputation (several of whom 
are on this list).

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## EVDL List (Jul 27, 2007)

Hi Eduardo!

So, your beloved Citroen is going to becomes a 72V system?

My suggestion is certainly not going to be a good way to resolve your issue.
It may be interesting if you use GolfCart batteries to check if you can
split your pack in two strings of 36V, and charge those, either by
paralleling them and using one GolfCart or ForkLift charger, or by
charging them with two separate GolfCart chargers, which means that
the two strings don't need to be disconnected, you only need to attach
one wire to the connection halfway the pack from each of the two chargers 
and the other wire to the pack neg or pos.

There is also the option to get 6 12V chargers and wire each across
12V of battery (1x12V or 2x6V) though the jury is still out if this
is a good option: one failing charger means a damaged battery, but 
these chargers are usually very cheap.

I have received many private replies with questions, so I'll write a
separate email with a how-to use the PC supply.

Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Eduardo K.
Sent: Monday, February 25, 2008 4:56 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] homebrew switch mode charger

I need something to charge my 72 volt.. Qould this work?

-----Original Message-----
From: Cor van de Water <[email protected]>
Sent: Monday, 25 February 2008 04:09 PM
To: Electric Vehicle Discussion List <[email protected]>
Subject: Re: [EVDL] homebrew switch mode charger

I have some experience in cheap chargers, though my EV has a bit higher voltage pack (312V): 

The easiest, fastest and cheapest way to charge this high pack voltage, is to use surplus power supplies that are PFC (Power Factor Corrected) and can be found in nearly any power level.
I selected a Dell server's power supply after my work discarded two old Dell servers (with redundant power supplies) so I ended up with 4 of them.
I later bought a few more for a low price, in case I wanted to grow a bit to a large charger, but I realized that when starting with these 700W chargers, that using just two of them would allow me to charge anywhere from either 110V or 240V and likely even from a Prius' battery in case of an emergency, because the PCF just takes the input voltage, fits the current form to the input voltage and generates a switching output to create 400V output with a simple inductor and switch (boost configuation)

The cheapest and simplest way to match the 400V output to my pack voltage is a bank of 120V lightbulbs.
Sure, that is more wasteful than a current-regulation of the PFC, which is what I intend to add soon, but it works.
It also lets the current taper off while the pack gets full so I can rest assured that my batteries will get full and not overcharged.
If I forget the charger then a day later I will see that the bulbs are starting to light up a bit again, as the pack is getting warm from the overcharge and the voltage drops, so the bulbs are coming on again. (for a normal charge, the pack rises close to 390V = 15V per battery, so the bulbs are not visibly glowing any more.

So, if you are interested in a $25 charger that can send up to 700W into your pack, drop me a line as I have a stack of those and I want to let them go.

Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of David Rowe
Sent: Thursday, February 21, 2008 10:30 PM
To: Electric Vehicle Discussion List
Subject: [EVDL] homebrew switch mode charger

Hi - I would like to build an EV charger. Switch mode if possible for efficiency but any design is OK. Could any one please point me at any homebrew designs out there? I have a 144V pack of 12 x 75AH Yellow Tops I would like to charge.

To get started something low power (< 1 kW) is quite OK. In fact I would rather start that way to lower the risks. 

Thanks,

David


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## EVDL List (Jul 27, 2007)

> Cor van de Water wrote:
> > Hi Eduardo!
> >
> > So, your beloved Citroen is going to becomes a 72V system?
> ...


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