6.6kW effective charging?

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Pegasus

Well-known member
Joined
Jul 12, 2013
Messages
126
Location
Las Vegas, NV
Okay, here's one. Does anyone know the physical location of the stock on-board charger? And is there any communication between the on-board charger and the pack or is it just the DC power leads?

I'm wondering if there's room to connect a second stock 3.3kW charger in parallel with the existing one to be able to charge about twice as fast from a 40+ amp 240V circuit. The major hurdles I see, assuming there is no pack-to-charger communication (which would make this a no-go) are 1) physical space on the car to mount a second unit and 2) compatibility: will the two chargers get confused as they independently monitor the pack voltage & current draw? (I assume the BMS is integral to the pack so hopefully the chargers are just fairly dumb energy pumps. If the $1000+ for the wall units don't buy any intelligence, then that's quite a racket!)
 
the way that i know, while charging, the battery heats up, and needs to be cooled. the reason why faster chargers are more expensive is not electronics, but the cooling system of the battery. rather than adding a charger, you could probably hack the existing charger to admit a higher current, but you may turn your beautiful chevy spark into a disgusting fried fisker karma.
 
That's very interesting, thank you. But if that's really a concern, how is DC fast charging even going to be an option? That would really heat things up!
 
Pegasus said:
That's very interesting, thank you. But if that's really a concern, how is DC fast charging even going to be an option? That would really heat things up!

I think I've heard that while plugged in, the power source can provide extra cooling...not sure where i heard that though
 
i heard it on my own car ;) a few minutes after i plugged it in, you could clearly hear a humming sound, like fans were rolling.

my suspicion is that a faster charger, either 6.6kW or DC, will not be an out-of-factory option.
 
Hybrid and EV Engineer and Spark EV owner here.

The same cooling that is used during driving on a hot day or Fast Charging is available during J1772 charging. The limitation is indeed the on board charger itself. Unless specifically designed to operate in parallel an additional charger is not feasible. A CANbus hack and charger swap or bypass would be required.

I'll be poking into this problem myself as I will be doing about 24k miles a year on my Spark!

On the flip side the DC fast charging hardware is essentially in place even without the purchased option, so doing an upfit for that may be very feasible.

Do not attempt anyodifications of a high voltage system or CANbus without the knowledge and training to do so, you could cause damage to your vehicle and injury or death to persons.

60V can kill you eventually, but there is nothing eventual about it with 360VDC!
 
Skullbearer said:
Hybrid and EV Engineer and Spark EV owner here.

The same cooling that is used during driving on a hot day or Fast Charging is available during J1772 charging. The limitation is indeed the on board charger itself. Unless specifically designed to operate in parallel an additional charger is not feasible. A CANbus hack and charger swap or bypass would be required.

I'll be poking into this problem myself as I will be doing about 24k miles a year on my Spark!

On the flip side the DC fast charging hardware is essentially in place even without the purchased option, so doing an upfit for that may be very feasible.

Do not attempt anyodifications of a high voltage system or CANbus without the knowledge and training to do so, you could cause damage to your vehicle and injury or death to persons.

60V can kill you eventually, but there is nothing eventual about it with 360VDC!
Glad to have you here. I really hope you stay on the board.

I always assumed the on-board chargers location would be critical to how upgradeable it will be.

Do you know if the charger is water-cooled like the batteries? Assuming that it's air cooled an upgrade is going to be difficult because the heat sink will need to get substantially larger. Most of this vehicles technology is very well engineered so I wouldn't put a water cooling loop for the charger. If it is a water cooled system, the most you would need to do is upsize the coolant lines for more flow.

I really think the reason they don't offer a 6.6kw charger is to keep the initial price as competitive as possible. Handling more current is just more expensive. If 480V wasn't used so rarely here, developing chargers that could handle it would be worth it. Everyone in Europe is going to have 10KW Level 2 charging before us.

The Spark EV is only masking as a compliance car. I have high hopes for the next Spark platform too. I can tell GM has big plans for that powertrain especially. Nissan is more short sighted than they seem.
 
FutureFolly said:
Do you know if the charger is water-cooled like the batteries? Assuming that it's air cooled an upgrade is going to be difficult because the heat sink will need to get substantially larger. Most of this vehicles technology is very well engineered so I wouldn't put a water cooling loop for the charger. If it is a water cooled system, the most you would need to do is upsize the coolant lines for more flow.
https://www.chevrolet.com/content/dam/Chevrolet/northamerica/usa/nscwebsite/en/Home/Help%20Center/Download%20a%20Brochure/02_PDFs/MY14%20Spark%20EV%20eBrochure_091813.pdf says "Charger: Liquid-cooled onboard".
 
drivefast said:
the way that i know, while charging, the battery heats up, and needs to be cooled. the reason why faster chargers are more expensive is not electronics, but the cooling system of the battery.
Ummm.... the Leaf has optional DC fast charging via CHAdeMO port and has NO battery cooling.

As for your second statement, the '13+ Leaf S w/charge package and '13+ Leaf SV and SL have 6 kW on-board chargers and again, no battery cooling. http://www.mynissanleaf.com/viewtopic.php?p=279458#p279458 indicates that '13+ Leafers (w/6 kW OBC) charge at C/5 rate.

I used a CHAdeMO DC FC today w/my Leaf today and even though I didn't arrive w/very low SoC, the DC FC the car was still drawing ~42 kW at the 5 min mark.

At ~25:45, I disconnected as the dealer was about to close. By that time, the car had ramped down to 8.295 kW and had accepted 9.7 kWh.
 
FutureFolly said:
Do you know if the charger is water-cooled like the batteries? Assuming that it's air cooled an upgrade is going to be difficult because the heat sink will need to get substantially larger. Most of this vehicles technology is very well engineered so I wouldn't put a water cooling loop for the charger. If it is a water cooled system, the most you would need to do is upsize the coolant lines for more flow.

I meant Most of this vehicles technology is very well engineered so I wouldn't put a water cooling loop for the charger past them.

Very different meaning. Lol

Thanks for your help cwerdna.
 
FutureFolly said:
<snip>
I really think the reason they don't offer a 6.6kw charger is to keep the initial price as competitive as possible. Handling more current is just more expensive. If 480V wasn't used so rarely here, developing chargers that could handle it would be worth it. Everyone in Europe is going to have 10KW Level 2 charging before us.

The Spark EV is only masking as a compliance car. I have high hopes for the next Spark platform too. I can tell GM has big plans for that powertrain especially. Nissan is more short sighted than they seem.
Re the highlighted section, you're right that they did it to keep the cost down, but wrong about the rationale. The Spark EV has a 3.3kW charger because it's the same one used by the Volt, i.e. they can increase production and cut the price while keeping the separate parts count down. Assuming that SAE-Combo stations start popping up everywhere fairly soon, that may be a reasonable plan, but realistically that's not going to happen very fast or very widely.

While 3.3kW is fine for a PHEV like the Volt, it handicaps a BEV like the Spark EV compared to its competitors. Even though it costs more, offering a faster OBC is needed to make the Spark EV more competitive and more useful. I was hoping that GM would do it on the 2014s, but instead they made minor cosmetic changes. Hopefully they'll get a clue with the 2015 MY.
 
gra said:
I was hoping that GM would do it on the 2014s, but instead they made minor cosmetic changes. Hopefully they'll get a clue with the 2015 MY.

It would probably help to know when the Spark oil burner gets an update. I doubt they'll change much now, since the car sells in the required volume (less than 100 per month) in the required regulatory states.
 
Sticking to the topic of feasibility here and the reasoning behind the 3.3kW choice from an Engineering perspective;

There is a general case set of charge rate numbers based on the rate in cell capacities that a battery cell may be designed to operate at safely and reliably in the very long term. A 1C rating means that at this rate the cells/battery will fully charge or fully discharge in one hour (excluding balancing and assuming constant power at all times).

For a general case lithium cell, a common maximum 'no wear and tear' rate for charging is 0.1C, or 10 hours. The batteries will never be discharged fully, so for the Spark's 21kWh pack you may only use up to 16-18kWh (we can easily get a better estimate at another time, this is just for the hypothetical). If you were to charge at 0.1C it would take roughly 7 hours, which matches their 3.3kW. They probably did it for manufacturing cost reasons, but the lower rate also will extend the battery life.

Generally 0.5C is a high, 'almost no wear', rate for lithium polymer. This corresponds to roughly 15kW, or about 1.7 hours to charge your battery usable storage. This would probably be fine on a cool day with minimum cooling for the battery, but only new large chargers can do that from AC. The SAE standard plug can do it, but likely the on board wires are only sized for a safe 4kW. Most EVSE stations can only do at most 7.2kW.

I expect that at up to ~9kW this pack and chemistry is fine for no effective wear and tear at under 90F ambient, probably more than safe at 6.6kW at 110F with cooling.

Also, we could potentially install a communication gateway between the current and an additional charger, and the J1772 communication and the chargers, to create a parallel charging system at 6.6 or 9.9kW. The battery will broadcast its charging current limit and the gateway splits that to each charger. That could work if you could fit a second liquid cooled charger, like the Brusa. Key thing with the Brusa is it must be placed flat, which can make underside mounting hard.

On charger cooling, increasing line size isn't as important as the pump and the radiator. Higher cooling requires higher flow, which is usually dictated mostly by the constant flow coolant pump. More heat output requires a larger radiator or more air flow. Maybe the stock cooling system is fine, they appear to have kept the ICE vehicle radiator, which is easily 4 times too large. Thus the reason they could eliminate the front grill.

Replacing the on board charger completely is a possibility then without necessarily changing the cooling at all. I just purchased my 2LT three days ago and haven't got it up on the lift at work yet to poke at it. Two other engineers leased Sparks over the weekend so I guarantee they will be poked, prodded, and maybe gradually CAN hacked if someone else doesn't do it as was done on the Leaf.

For now I recommend those not familiar with these types of systems excersize the best method of staying safe with high voltage and high power... Stay clear! Discussion doesn't hurt, but these are not shade tree type projects so please don't take any of my thoughts towards a solution as reasons to monkey with it!

On the fast charge option:

Fast charging is definitely going to wear your battery a little bit, not a noticeable amount in any one time, but don't plan to do it more than once a week as a good rule of thumb. If you do it more, make sure you don't do anything that will let them void your battery warranty, or in 70,000 miles you may regret it to the tune of an out of pocket battery replacement.

If you are in the Sacramento area and have a fast charger installed, I may want some specific pictures taken so I can verify what needs to be added to make it functional on the ones without. Not urgently though, baby on the way so I don't have loads of time.
 
Ok, a simple case for doing 6.6/7.2kW charging or quicker is to install a dedicated 'on-board' charger at your home and utilize a communication gateway to translate from the GreenPHY and J1772 standards on the pilot pin to the CAN or analog communication expected by the stand alone charger. In this manner we can design a hybrid Charger/EVSE station at decently low cost for home or business use using the so called 'Frankenplug' or as I'll refer to it, the SAE J1772 CCS.

The CCS allows simultaneous 1 phase, split phase, or 3 phase AND/OR DC charging with the combined J1772 and GreenPHY J1901 based communication for control. I need to dig into the J1901 standard to see how reproducible it is. An ElCon charger for example, combined with the CCS could be used to provide up to 3.3kW via the existing Spark charger plus 3.6 or 7.2kW via the DC ports.

What's everyone think about that? Your looking at a standard EVSE setup for at least 30A of charging (40A breaker) plus the charger... around $1,500-$2,000 with parts at a small resale profit. Maybe I might be able to spare the time for doing the design by the end of summer, 2014. The system could be portable, but that would be a big heavy thing to lug around, so mostly a dedicated station. Could be made so that you plug your J1772 EVSE into a port on the 'boost' unit (ie the charger), then plug its CCS into the car, which would keep the two units separate and modular.


Maybe we should start discussing price points here. How much is 4 hour charge from 0 worth to you Spark EV owners? I can work with MetricMind or do something separate, however there is no getting around a $750+ cost for a reliable 3.3kW charger at reseller costs, plus you need to add in some margin. Let's rank it like this:

-6.6kW J1772 (Fully on-board) Charging is worth $XXXX to me if I install it from a kit, and $YYYY to me professionally installed.
-6.6kW J1772 CCS (3.3kW on-board, 3.3kW DC off-board) Charging is worth....
-9.9kW J1772 CCS (3.3kW on-board, 6.6kW DC off-board) Charging is worth....

Give realistic pricing here, assuming a 3 year warranty and no decrease in the life of your Spark EV on board equipment. After sufficient feedback I'll look into it more.
 
gra said:
Re the highlighted section, you're right that they did it to keep the cost down, but wrong about the rationale. The Spark EV has a 3.3kW charger because it's the same one used by the Volt, i.e. they can increase production and cut the price while keeping the separate parts count down. Assuming that SAE-Combo stations start popping up everywhere fairly soon, that may be a reasonable plan, but realistically that's not going to happen very fast or very widely.

While 3.3kW is fine for a PHEV like the Volt, it handicaps a BEV like the Spark EV compared to its competitors. Even though it costs more, offering a faster OBC is needed to make the Spark EV more competitive and more useful. I was hoping that GM would do it on the 2014s, but instead they made minor cosmetic changes. Hopefully they'll get a clue with the 2015 MY.
That's a very good point. They had a charger already on the shelf and it saves them money on production and development.

They should buy a 6.6kw from Bosch or GE type company that will fit in the space allocated as a short term solution. Even if any price increase will turn most people away, all the marketing and journalists will have them. It could be bundled with DC-FC potentially too.

Meanwhile they should be working on a 9.6kw charger that can be used for more than this generation of EVs. Developing their own 6.6kw charger would be only on par with most of the competition. With good thermal management there is no reason all GM's EVs shouldn't be able to hook up to a NEMA 14-50 like a Model S.

When it comes to the best places to put their money, they chose well with the powertrain. For the second round of development, an amazing OBC would be the best follow up to the DC-FC because they can work so well together.
 
Skullbearer said:
Fast charging is definitely going to wear your battery a little bit, not a noticeable amount in any one time, but don't plan to do it more than once a week as a good rule of thumb. If you do it more, make sure you don't do anything that will let them void your battery warranty, or in 70,000 miles you may regret it to the tune of an out of pocket battery replacement.

A recent government study on the LEAF just showed that with nothing but DC quick charging one car and slow AC charging another, the difference in battery wear was minimal.

More important variables were battery heating and cycles.
 
TonyWilliams said:
Skullbearer said:
Fast charging is definitely going to wear your battery a little bit, not a noticeable amount in any one time, but don't plan to do it more than once a week as a good rule of thumb. If you do it more, make sure you don't do anything that will let them void your battery warranty, or in 70,000 miles you may regret it to the tune of an out of pocket battery replacement.

A recent government study on the LEAF just showed that with nothing but DC quick charging one car and slow AC charging another, the difference in battery wear was minimal.

More important variables were battery heating and cycles.
For those who are interested, here's the slides from the presentation of that report:

http://avt.inl.gov/pdf/prog_info/SAEHybridSymposium2014.pdf

Note that the vehicles are only charging twice per day: Tony essentially broiled his second LEAF's battery (which unlike the Spark isn't liquid-cooled) by making multiple QCs in a single day.
 
Great link for that paper, I look forward to the 50k lab results. Obviously Nissan did a good job with the LEAF battery, especially given that it isn't liquid cooled.

I wouldn't consider the difference shown at 30k and 40k to be insignificant, not with the vehicle range as it is. Beyond 50k, though is generally where I think the most interesting results will be, which unfortunately is an area with sparse to no reliable and comparable data. My experience, and the much greater experience of my co-engineers at my place of employment, is that doing a DCFC from no remaining range every day, 5 days a week, for your ~46 work weeks a year, will end up with a significant (ie >10%) decrease in battery capacity. So my Spark EV warranty allows for up to 35% decrease in capacity after 8 years or 100,000 miles... this is probably so high to allow for DCFC. The battery is well constructed and charging is almost always charged at low rates (3.3kW and under). I would expect the pack to see <20% decrease in capacity at 8 years or 100,000 miles, maybe even on the order of only 10%. That's an EPA estimated 12.3+ miles combined of driving range difference on the Spark EV. Significant, by my standard. (My commute is 37 miles each way, and I've been going about 85 miles a day, all EV fyi)

That being said, there's still such limited data that Chevy may very well be surprised along with us all, with much lower battery degradation than the warranty covers. (Cross my fingers)

We can keep to the topic of 6.6kW or greater effective charging though. Has anyone by chance taken any pictures of the cable connecting the DC port on their SAE CCS to the 'DC Fast Charge Controller' module? According to the first responders manual, the charger is the top-rear most unit, but the 'DC Fast Charge Controller' is a similar looking cast aluminum unit top-front most. Both are vertically the top of the drivetrain stack. I can take a picture in the next few days of what it looks like in mine, without the DCFC option installed. This is with the intent of adding charging capacity as an external unit, rather than the more difficult method of putting it on-board. I unfortunately didn't get the DCFC option on my 2LT.
 
Skullbearer said:
Ok, a simple case for doing 6.6/7.2kW charging or quicker is to install a dedicated 'on-board' charger at your home and utilize a communication gateway to translate from the GreenPHY and J1772 standards on the pilot pin to the CAN or analog communication expected by the stand alone charger. In this manner we can design a hybrid Charger/EVSE station at decently low cost for home or business use using the so called 'Frankenplug' or as I'll refer to it, the SAE J1772 CCS.

The CCS allows simultaneous 1 phase, split phase, or 3 phase AND/OR DC charging with the combined J1772 and GreenPHY J1901 based communication for control. I need to dig into the J1901 standard to see how reproducible it is. An ElCon charger for example, combined with the CCS could be used to provide up to 3.3kW via the existing Spark charger plus 3.6 or 7.2kW via the DC ports.

What's everyone think about that? Your looking at a standard EVSE setup for at least 30A of charging (40A breaker) plus the charger... around $1,500-$2,000 with parts at a small resale profit. Maybe I might be able to spare the time for doing the design by the end of summer, 2014. The system could be portable, but that would be a big heavy thing to lug around, so mostly a dedicated station. Could be made so that you plug your J1772 EVSE into a port on the 'boost' unit (ie the charger), then plug its CCS into the car, which would keep the two units separate and modular.


Maybe we should start discussing price points here. How much is 4 hour charge from 0 worth to you Spark EV owners? I can work with MetricMind or do something separate, however there is no getting around a $750+ cost for a reliable 3.3kW charger at reseller costs, plus you need to add in some margin. Let's rank it like this:

-6.6kW J1772 (Fully on-board) Charging is worth $XXXX to me if I install it from a kit, and $YYYY to me professionally installed.
-6.6kW J1772 CCS (3.3kW on-board, 3.3kW DC off-board) Charging is worth....
-9.9kW J1772 CCS (3.3kW on-board, 6.6kW DC off-board) Charging is worth....

Give realistic pricing here, assuming a 3 year warranty and no decrease in the life of your Spark EV on board equipment. After sufficient feedback I'll look into it more.
I think you're really onto something here....

This has a lot of potential as the basis for residential L3 charging. I think it would really only be practical with the CCS plug too. I'm not sure you could license the plugs or protocols from Tesla or CHAdeMO very easily. Also, with both your costs would go up dramatically because you couldn't use the OBC to speed up charging.

Since the Americans and Europeans are supporting CCS you should really be thinking about a broader market than just the Spark. The i3 uses the rare 32 amp J1772. People that want the most out of their vehicle will probably spring for the more expensive home charger and the higher quote from the electrician for installation. When they find out that their car was designed with a DC socket that will eventually be useful at DC-FC stations that might exist near them someday, they will be apathetic. When they find out that their car was designed with a DC socket that can work with a home charger that cuts the charging time in half because it uses the OBC and a garage installed DC charger at the same time, range anxiety will start to melt away.

Price isn't as important as you might think when realistically this is a green replacement for a range extending gas motor. At over 10kW of total charging capacity, stopping at home for 20-minutes in between errands is enough to add a significant amount of range.

Realistically, you wouldn't have to stop at 6.6kW of DC-FC capacity either. You're only limited by how many amps there main service box can draw, and how much power they can get permitted for. Someone in the i3 demographic could easily have a $5,000 budget if the change was significant enough. You shouldn't be afraid of a healthy margin on a top shelf model.

Upgrading the OBC on the Spark will probably never make you money for a few reasons. The Spark EV is more of an appliance car than some of the competition that let price run away with them. There are lots of reasons to love the Spark EV, but a strong percentage of owners are very price conscious. You probably couldn't sell an upgrade kit for the OBC for less than $1,500, and it would cost at least $2,000 installed. GM is bound to come out with a 6.6kW OBC eventually and your market would shrink to the owners of used Sparks that are even more price conscious. The modification would also have to be depreciated in the resale process too.

Residential L3 chargers could also have a lot more appeal for committed EV buyers that know they will buy another EV. You also might get some business owners interested too. Even if it isn't an 80% recharge in 20 minutes, your charger could easily undercut the $25K-$50K that most DC-FCs cost at present.

To speculate with you about the value of a Residential L3 charger, I would say that 6.6kW of off-board charging is worth:
$4,000-$5,000 to someone that will use it daily.
$2,500-$3,000 to someone that will use it weekly.
$1,500-$2,000 to someone that will use it monthly.
$1,000-$1,500 to someone that just thinks it's cool and really only uses it to show their friends.

I wouldn't try to sell a 3.3kW off-board charger for more than $1,500.

I think 3.3kW off-board charging would be much less appealing. It's just not dramatic enough of an improvement for only working at home. 6.6kW charging is dramatically more useful when you're out of the house because you rarely are going to be there long enough to make a difference. 10-13kW charging is useful enough to work stopping by your house into your plan.
 
Skullbearer said:
The CCS allows simultaneous 1 phase, split phase, or 3 phase AND/OR DC charging with the combined J1772 and GreenPHY J1901 based communication for control. I need to dig into the J1901 standard to see how reproducible it is. An ElCon charger for example, combined with the CCS could be used to provide up to 3.3kW via the existing Spark charger plus 3.6 or 7.2kW via the DC ports.

As far as I know, the J1772 connector can do 1-phase (120V to 240V) but not 3-phase. Also, I don't think the protocol allows AC and DC at the same time. There is an option that allows the pins used for AC to support L1 DC charging, but I haven't heard of any plans for cars or chargers to support it. This lower power DC charging might be a reasonable residential option.

If you have > 3kW power available at the EVSE, what benefit would there be in splitting it between AC and DC over just putting it all on the big L2 DC pins?

-Nate
 
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