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Discussion Starter · #1 ·
Hi All,

this is a thread branched out of our 10kW DIY charger thread (http://www.diyelectriccar.com/forums/showthread.php/10kw-60a-diy-charger-open-source-59210.html). That thread details how to build your own 12kW 70A charger with full microcontroller control and complete flexibility for less than $1,000.

Now, some of you have asked if it would be possible to maybe trade some of the smartness for more power. This is what this thread is about.

We have just tested a pre-production version of the 40kW 240VAC charger designed for batteries above ~300V nominal. It is a full PFC unit (as it should at this power level) and supports proper CCCV charging profile and J1772-compatible.

We are working on putting a kit together now to let any of you to build your own for less than $1,500. Target size: 12x11x8" box, air cooled up to 25kW, liquid-cooled up to 40kW. Weight ~30lbs, which makes it possible to use as a primary in-vehicle unit.

I'd like to get an idea of how many people might be interested in something like this. Also, I'd like to understand how valuable would adding some of the intelligence back would be. Right now, the voltage and current cutoffs are being set by fixed resistor networks. Adding a micro control is relatively straightforward but will increase the cost by a few $100s.

Let us know what you think. A 40kW charger means 30 min full recharge for a small EV. And it is a power level available in most new US homes without doing any major electrical work.

Thanks,
Valery.
 

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I think this is a great idea, and I'm really interested in the liquid cooled option. The added cost of a microcontroller is not a huge concern when compared to the utility offered:

-CAN bus control
-Scheduled charging (To take advantage of time of use pricing)
-Slower charging to extend battery life (when you're not in a hurry)
-Act as a charge controller for a generator while driving

Does this charger require three phase input? 40kW at 240V... that's a lot of amps for single phase.
 

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Hi Valery,

as already 10 kW would be sufficient for me, the high-power version is not too important for me.

However, what I do need, is ability to charge a pack of 500-600 V. Is this something that is doable with the 10 kW charger, and if yes, what would it cost.

If only feasible with the high-power version, then I might be interested, and intelligence would be OK as I do have a CAN BMS in mind.

Regards,

Huub
 

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I'm pleased to see that you've continued development of your charger! I was quite tempted to buy one of your kits for the follow up to mine - but mine now just refuses to die (I'm only charging at 5kw) and I cannot justify something new with a perfectly good charger in the truck already!

Well done!

Si
 

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Discussion Starter · #5 ·
I think this is a great idea, and I'm really interested in the liquid cooled option. The added cost of a microcontroller is not a huge concern when compared to the utility offered:

-CAN bus control
-Scheduled charging (To take advantage of time of use pricing)
-Slower charging to extend battery life (when you're not in a hurry)
-Act as a charge controller for a generator while driving

Does this charger require three phase input? 40kW at 240V... that's a lot of amps for single phase.
Still single phase. This is about the max you can get from 240V service (most new houses in the US are built with 200A 240V service ready to go).
 

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Discussion Starter · #6 ·
Hi Valery,

as already 10 kW would be sufficient for me, the high-power version is not too important for me.

However, what I do need, is ability to charge a pack of 500-600 V. Is this something that is doable with the 10 kW charger, and if yes, what would it cost.

If only feasible with the high-power version, then I might be interested, and intelligence would be OK as I do have a CAN BMS in mind.

Regards,

Huub
Hi Huub - I would definitely suggest this design for your case - it is more efficient than our main design at these voltage levels. However, we do not yet have the intelligence built into that so if you need that, you might have to wait for a month or so.

V
 

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I love the first one, but a water cooled 25kW version would be handy. I like the configuration options on the normal version and I think it would be worth the extra cost to make it programmable. You could probably drop the display in favour of a web interface or something similar for programming. LED's would work just fine for status.
 

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A three phase version would be the best to sell it to europe.
230V is typically hedged with 8A (switzerland), 10A in germany, not uncommon 16A.

When we need real power, we take the 3phase (400V) 16A, 32A or 63A outlet.
So it would be 11kW, 22kW or 44kW max.

That 25kW/40kW charger would definitely an option to me, if it is programmable/switchable so I could charge f.ex. at 10% over night or 100% at a quick charge on a trip to get home.
 

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Discussion Starter · #9 ·
A three phase version would be the best to sell it to europe.
230V is typically hedged with 8A (switzerland), 10A in germany, not uncommon 16A.

When we need real power, we take the 3phase (400V) 16A, 32A or 63A outlet.
So it would be 11kW, 22kW or 44kW max.

That 25kW/40kW charger would definitely an option to me, if it is programmable/switchable so I could charge f.ex. at 10% over night or 100% at a quick charge on a trip to get home.
Yes, it will be natively 3-phase (we are using 3-phase bridges and our PFC controller can deal with 3-phase rectified, as well). However this version can only output higher voltage than rectified mains. That's why we need 310+V nominal battery to operate off 240VAC.

V
 

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Discussion Starter · #10 ·
ok some update & pics.

Added:
1. Hardware temperature protection
2. Provision for current (via J1772 protocol - whether from a J1772 EVSE or simulated by a micro)
3. Provision for voltage control by a micro

Will probably add a kit product to our store soon (1-2 weeks).
 

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This looks pretty great Valery. I haven't finished my 10 kW charger kit yet and you've already got me dreaming about 40kW:)

Can you give a bit of a run down as to how you make those C brackets for the inductor?

Do you have any pictures that show a close-up of the inductor mounting?

thanks,
Shane
 

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Discussion Starter · #12 ·
This looks pretty great Valery. I haven't finished my 10 kW charger kit yet and you've already got me dreaming about 40kW:)

Can you give a bit of a run down as to how you make those C brackets for the inductor?

Do you have any pictures that show a close-up of the inductor mounting?

thanks,
Shane
Thanks Shane - the brackets are 1" thick HDPE. We make a 'C' shape with a cutout just big enough to fit the inductor. Then put a piece of rubber between the inductor and metal box when fastening to the box. We found that this configuration results in an optimal cooling of the inductor.

V
 

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Discussion Starter · #15 ·
Valery, I agree with RWAudio. Drop the display and go with programmable web interface.

I almost ordered your 10kW, but I'm still building so I can wait for this gem :)

Thanks for the update!
Thanks guys. I think we are going to go with Bluetooth interface and upgrade our Android EV Dashboard app to add a tab managing the charger.

Also, we are now ready to accept orders for the first batch of these 25kW air cooled units - pot-controlled voltage and current limits only for now. Please PM if interested.

Thanks,
Valery.
 

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Looks good...

For use in Europe on 240v with 16amp fuse for instance, which mode could it be used on? And if on 3 phases? How would it be wired?
Also, how long would it take to charge 24 or 28 100Ah LifePo4 cells in series
then at those scenarios?

Thanks!
 

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Discussion Starter · #17 ·
Looks good...

For use in Europe on 240v with 16amp fuse for instance, which mode could it be used on? And if on 3 phases? How would it be wired?
Also, how long would it take to charge 24 or 28 100Ah LifePo4 cells in series
then at those scenarios?

Thanks!
16A would give you ~4kW, 3.7kW output which is a serious underutilization of this design's capability.

Also, this version would only work with 310V or higher nominal packs. So at least 95 LiFePo4 cell in series.

For more flexible voltage output and full programmability, check out our 12 kW charger at http://www.diyelectriccar.com/forums/showthread.php/10kw-60a-diy-charger-open-source-59210p44.html and http://www.emotorwerks.com/cgi-bin/VMcharger_V9.pl

Thanks,
Valery
 

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Discussion Starter · #19 ·
OK. Thanks. Can you give me an answers for same questions for a system with a 220v pack? Because I may get one of those shortly also.

Thanks!
same as above. as long as below 310V nominal battery voltage, the answers would be the same.
 

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Yes, it will be natively 3-phase (we are using 3-phase bridges and our PFC controller can deal with 3-phase rectified, as well).
Um, won't that only provide good power factor for the top 60 degrees of each phase's waveform? [ Edit: 60 degrees of each half-cycle, so 120 degrees total. ] Only one pair of the 6 diodes in a 3-phase bridge can be conducting at once, right? (Otherwise the bridge would short the phases.) So for 2/3 of the time, each phase has zero current, after a 3-phase bridge rectifier.

So to get decent power factor (low harmonic distortion), you'd need three PFC front ends, would you not? Each only have to be one third the power, but still, it has to increase the cost a bit and take up a bit more room.

So for decent power factor, it seems that 3-phase can't be a near-trivial change from a single phase model. Assuming I'm not missing something here.

Oh, I suppose you could have three one-third power PFC stages, and run them in parallel for single phase mode. Is that how you're doing it?

My apologies if this is a FAQ.
 
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