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Author Topic: DC-DC charger  (Read 1484 times)

yhafting

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DC-DC charger
« on: February 09, 2017, 03:53:25 PM »

Along with the growing number of DC-Chargers popping up around the roads, i was pondering on why we don't see many attempts on using a DC-DC converter to charge the Zero fast.

I was thinking along the path of combining a CCS plug with something like this:
http://www.tronico-alcen.com/en/products/dcdc-energy-converters/converter-dcdc-10kw-80-150v

But there must be something prohibiting this?
- There may be some physical reason; I thought of a step down converter since i believe the charging stations for cars mostly would start at a too high voltage for the Zero (200-450V).
- I admit having hard time finding a product with a price tag, so the cost may be prohibiting?
- In a way it is doing what the charging station already does for a car for the bike, so it should be unnecessary, however i don't think it is realistic to get DC charging from 70 to 120V  as infrastructure when all cars use higher voltages.

Anyone have some thoughts on this?
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remmie

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Re: DC-DC charger
« Reply #1 on: February 09, 2017, 04:57:22 PM »

An Eltek Flatpack S has an DC voltage input range of 85-250 Vdc (85 - 305 Vac) So it could be used for AC charging stations and DC charging stations.
An Eltek Flatpack 2 HE can handle even higher DC input voltages 140 - 275 Vdc

In fact most (AC) rectifiers used in home-brew chargers can handle a DC input.

However, according to a quick search CSS uses powerline communication to tell the charging station what voltage and current to supply. That's a lot more difficult to interface compared to the J1772 or Mennekes type 2 (AC) charging stations where a diode and a resistor are sufficient.

But still interesting

 
 
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Zero SR 2014
Homemade "Supercharger" 4x eltek Flatpack S (8.5 kW including the onboard charger)

Erasmo

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Re: DC-DC charger
« Reply #2 on: February 09, 2017, 05:37:24 PM »

I've dabbled with a ChaDeMo top case, it sorta works but in the end I decided to go for a SC.
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olle.eriksen2

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Re: DC-DC charger
« Reply #3 on: February 09, 2017, 11:40:50 PM »

I think the ChaDeMo standard goes down to 50 V. Would be much simpler and cheaper to use than a onboard AC charger if someone could make a cable/interface.
Here is another tread on the subject http://electricmotorcycleforum.com/boards/index.php?topic=3308.msg17640#msg17640


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Erasmo

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Re: DC-DC charger
« Reply #4 on: February 09, 2017, 11:59:09 PM »

You can source the cable pretty much everywhere, interface, inlet etc can be purchased from EVTV.
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yhafting

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Re: DC-DC charger
« Reply #5 on: February 10, 2017, 01:05:46 AM »

I think the ChaDeMo standard goes down to 50 V. Would be much simpler and cheaper to use than a onboard AC charger if someone could make a cable/interface.
Here is another tread on the subject http://electricmotorcycleforum.com/boards/index.php?topic=3308.msg17640#msg17640


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I don't think chademo has any future in europe. It seems the only sensible thing is CCS-combo or some kind of AC. Since those chademo chargers that already exist likely doesn't work with the bike, some add on circuitry will be needed.

I guess the Eltek rectifiers are one of the best solutions around, but i'd like to get something that allow ~10kw without taking too much space and money from my wallet. I wonder how easy it is to get hold of the ccs protocol. Perhaps i could make an arduino solution or something similar.
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ElectricZen

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Re: DC-DC charger
« Reply #6 on: February 10, 2017, 02:07:41 AM »

I think the biggest problem is the ChaDeMo standard isn't really a standard.  Pretty sure if you do some searching you should find articles about Zero working on ChaDeMo charging back in 2013. 

While yes, supposedly the ChaDeMo "standard" supports 50v charging so theoretically it should support the 116v that we need for our batteries.  The issue, to my understanding, is 50% or so of the ChaDeMo charge stations don't support charging at the lower voltages that we need.  So Zero canned the development.  Basically, charge station networks not following the "standard".  Licensing to use the ChaDeMo standard is not cheap either.

With that said, it sounds like a future with CCS is more likely.  Probably why Energica supports CCS.  So hopefully it's easier to work with.  No idea if the liscensing is any cheaper. 

 

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Electric Cowboy

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Re: DC-DC charger
« Reply #7 on: February 11, 2017, 07:39:50 PM »

DC charging is a lot different than AC to DC charging. The power output is based on voltage rise. A ChaDeMo can only charge 6.2 kW at 50v IF it follows the spec, which most do not.

Sadly most chargers, ChaDeMo and CCS, in practice, do not go below 200v meaning you have to fake the system out. In doing so, you get an immediate voltage rise causing the DC charger to think you have completed your charge nearly immediately.

A ChaDeMo is no different from an offboard SC which would also result in the same thing. If you plugged the output of one SC into the input of another SC, the first SC, which is powering the second SC would turn on and off again immediately. The nature of DC charging uses the battery itself as a load causing voltage drop. This is the premise of how we control the SC power and voltage output, and how it knows when to slow down and by how much.

CCS is actually more complex than ChaDeMo by far, but that complexity also makes it super secure. It uses encrypted TCP sockets over the power lines themselves with security cert transfers etc. Where ChaDeMo is simple canbus messages.

As far as making it less expencive, the I inlets which can handle reasonable power run around 800 for the incomplete plug alone excluding control board's, wiring harnesses etc. Which would bring the cost up more.

DC charge stations are nothing more than offboard SC programmed for higher voltages. We are also building SC based DC fast chargers for Zeros ;)



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yhafting

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Re: DC-DC charger
« Reply #8 on: February 11, 2017, 11:05:40 PM »

CCS is actually more complex than ChaDeMo by far, but that complexity also makes it super secure. It uses encrypted TCP sockets over the power lines themselves with security cert transfers etc. Where ChaDeMo is simple canbus messages.

Thanks for the input Electric Cowboy. I guess encrypted TCP over power lines requires slightly more effort than i would put into a hobby project at the moment. I guess a decent rectifier solution will be easier then..   
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Electric Cowboy

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Re: DC-DC charger
« Reply #9 on: February 12, 2017, 02:26:27 AM »

I would recommend against a simple rectifier solution. The zero contactor will open in a slew of situations. When this happens, depending on your charge rate you will get a small arc which raises your voltage a lot. And if that voltage spike goes over say 144v several internal components of your controller will explode. This is true no matter where your rectifiers are connected, aux or controller.

I honestly this the IP67 solution we have is a lot cheaper than the dangers of trying to hobby this kind of charging on a 15k motorcycle. I mean the SC is built to charge your bike safely in a tsunami basically...

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yhafting

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Re: DC-DC charger
« Reply #10 on: February 12, 2017, 05:29:39 AM »

I would recommend against a simple rectifier solution. The zero contactor will open in a slew of situations. When this happens, depending on your charge rate you will get a small arc which raises your voltage a lot. And if that voltage spike goes over say 144v several internal components of your controller will explode. This is true no matter where your rectifiers are connected, aux or controller.

I honestly this the IP67 solution we have is a lot cheaper than the dangers of trying to hobby this kind of charging on a 15k motorcycle. I mean the SC is built to charge your bike safely in a tsunami basically...

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I am sure the diginow SC is a great product, but i cannot justify using that kind of money at the moment. IF i am going to have a charging solution faster than the onboard 1300W, i will most likely decide on product then wait until i can find it cheap enough- no matter how long time that takes.

I will of course take into account every advice i get, but i still believe i will be capable of building a solution if i can get my hand on the components.

When you bring up the cost of damaging a 15k$ bike, and derating hobby projects, you should thread carefully, because every trade is a wager. When i see the diginow charger closing in on 3k$ in the US for the 7.9kW solution, i know having this shipped to Norway and adding taxes i end up near 5k$. We're talking about 30% of the bikes initial cost or more- if i was about to sell the bike, perhaps more than 50% of the bikes cost... Now i can hold the wager of such a product holding what is warranted against a self made solution that i have carefully planned/considered thoroughly through months, that cost 1/3?. What are my stakes for disappointment, shipping problems, components failing, loss of money, death or injury? I'm not going to fill in numbers on these, but i'm not certain that the odds are in favour of the SC, even if the product in it self is great.

If i had the money (and then some), and needed the solution NOW, i would definitely consider the SC, but the stakes are always higher on what you cannot fix yourself, especially when the only help you can get is overseas. There is also a certain amount of satisfaction by doing things by myself, experiencing, rather than blindly trusting someone elses experience and judgement.
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Electric Cowboy

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Re: DC-DC charger
« Reply #11 on: February 12, 2017, 06:49:23 AM »

Good answer. Just to clear up some details the 7.9 is $2700 shipping to Oslo is $227 including customs with a reported value in favor of shipping... if purchased from Norway or online there should be no sales tax at the time of purchase.

So the total cost would be around $2927 USD or 24,495 krones to get the 7.9kW in Norway.

For between 4 and 5k USD you can get 1C charging from mennekes connectors. There are a few people in the EU doing this already.

If you want to build your own, it is a great experience and a lot of fun, just be careful. And if your bike turns on, but  does not react when you plug in the onboard for some reason, remember to replace the 100A inline fuse with a breaker at that point. It blows really easy while learning about back flow into caps of larger charging systems.
So just be prepared to spend a lot more to get it the way you want and mounted. Most people forget to add in the cost of all the parts.

All my projects started as hobbies that I decided to just go head down and charge forward no matter how much it cost. And boy has it cost a lot!

I encourage your electric riding and fast charging no matter how you do it! And I hope you have a TON of fun!! 🤠 .

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Erasmo

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Re: DC-DC charger
« Reply #12 on: February 12, 2017, 08:30:35 PM »

yhafting, I have been to Norway a lot and you have one of the best charging infrastructures. Mennekes everywhere and DC is also rolling out.
If the SC might not be the thing for you, why not go for the official Zero auxiliary charger? It is still far from 1C but you practically double your charging speed. 
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Electric Cowboy

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Re: DC-DC charger
« Reply #13 on: February 13, 2017, 01:10:41 AM »

@erasmo I don't think you can get that in EU. Also, the single Super Charger module puts out more power and is $200 cheaper.

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Erasmo

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Re: DC-DC charger
« Reply #14 on: February 13, 2017, 03:33:25 AM »

Edit: I misread. You must be thinking of the Charge Tank, which you can get here ready for Mennekes btw.
 I was talking about this one: http://www.zeromotorcycles.com/shop/index.php?main_page=product_info&zenid=5rpnifiojlnfbim5jompu49i90&cPath=5&products_id=194
« Last Edit: February 13, 2017, 03:41:55 AM by Erasmo »
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