Enginer plug in hybrid kits coming to the market

[krousdb]

Originally Posted by Dan

OK... so I've dug through PC and CMPG and come up with the software guy's question deck. Feel free to answer as many or few questions as you wish...

1. I looked at the manual and they install a little switch. What does it do? Looked like it was an EV switch, but the other docs imply that it somehow turns the curcuit for the AUX pack on or off. Does it do either of these, or both of these? Can you turn the AUX pack off or is it always feeding into the OEM pack?

1. The switch turns the system on and off and doubles as the EV button. You can keep your existing EV switch. I will be keeping mine.
   
   

   Originally Posted by Dan

   I'm a bit concerned about the thermals on the OEM pack with the AUX pack installed. This summer I had my trunk tray full of miscellaneous junk. I noticed on a number of occasions my pack would go all thermal on me and kick on the little fan in the back seat. Easy to hear in a glide. So what I figured out was that the junk in my trunk tray was acting as a heat sink. Since my car in Texas in the sun will hit an internal temperature of 130+ on most days, anything other than air sitting over my spare will thermally transfer as heat down into the OEM pack. My solution was to remove my trunk tray and tray cover for a few days. Worked great. So now the thought of putting another heat sink back in that cavity fills me with a bit of concern, not so much for the AUX pack, but rather for the OEM pack. Having a steal box heated to 130F will surely be enough to through the OEM pack into it's thermal spiral. When it goes all thermal, there is very little EV and other goodness since that is only allowed when the OEM pack is "healthy". So A bit of concern from the Texans here I guess.

   After your pack gets up to 7 bars, I doubt that much energy will be moving in and out of your pack. The energy will go straight to MG2 except during regen (no energy from the converter) and at a standstill. Even if it is too hot to use EV, you still get the benefit of a high SOC that causes MG2 to send power to the wheels.
   
   
   

   Originally Posted by Dan

   Next question is on regen. If the AUX pack holds the OEM pack at 80% SOC, what happens when I hit my 1 mile regen off the freeway. Will the OEM pack eventually hit MAX_SOC and start ditching regen? What does the OEM pack do when a regen is directed to an overcharged pack?

   The target is around 70-75% SOC, not 80. Seven bars is what you should see. If the OEM pack does get up to 80%, then the normal thing happens, the ICE will start and fight with the MG to drain the excess energy.
   
   

   Originally Posted by Dan

   On to the DC/DC inverter. Does it regulate the bleed off of the AUX pack or is it simply always dumping 10A down towards the OEM pack? Will it stop if it senses the OEM pack is topped off, or will it overfill the glass?

   This is yet to be determined. I will let you know in the next week or so.
   
   

   Originally Posted by Dan

   On to balancing. I understand that the balancers are like bleed off pressure valves. If the SOC of one of the bundles of cells is too high it will just bleed that charge off. So... Why? Why do you need your cells to have like SOC? And what kind of efficiency hit does this constant 0.3 AMP bleed per balancer really mean to the efficiency. If my math is right, on a 4 KWh pack, your bleeding 1.2 AMP (.3*4) or 30Wh in balancing. OK so maybe 0.75% being spent in balancing is OK, but what if my math is wrong. Is it more?

   In a 16 cell string, the highest and lowest cell are your weakest links. The highest cell will raise the pack voltage and the charger will shut off before the other cells are fully charged. Likewise, the lowest cell will cause your balancer to alarm before the others are fully discharged. Ideally, you want all cells to be equal so that they all reach full charge or full discharge simultaneously. That way you get the full capacity of your kit. When I say full charge and discharge, I dont mean 100% and 0%, I mean whatever levels you choose as your target. To answer your efficiency question, Seven cells will be discharged to the level of the lowest (eighth) cell. That might take one minute, or it might take a day. It depends on how out of balance they are.
   
   

   Originally Posted by Dan

   Next question is on I/O. What type of control surface do you have on the Inverter and balancers (or other components). Can the software guy hook up a serial or USB cable to these components to get real time data. Does it already have software with APIs to roll your own AUX pack status monitor? How do you know what the SOC of your AUX pack is while your in the pilot's seat?

   There are two ports. The telephone jack port is wired to the switch. There is also an RJ45 port that is not used. Maybe there is some functionality but you will have to contact Jjack about that.
   
   

   Originally Posted by Dan

   Another question about the Inverters/Balancers. From what I read on the spec of the 3.2V cell, the manufacturer recommends DoD (depth of discharge) of no greater than 66%. Is that configurable in the Inverter to cut off at a SOC of 33% or below? Can the same be done for the charger. Can you set it to stop drawing AC power from the wall once the pack hits 80% SoC?

   The charger is supposedly a smart charger and from the reports I am reading, the charger only raises the voltage to about 3.4. The alarm goes off at 3.75 so there seems to be a safety margin built in. The low alarm goes off at 2.8V which appears to be a very low SOC, maybe 5%. My target will be about 3.0V/cell. The converter will shut off automatically by I believe that it uses the total pack voltage to make that decision. As far as I know, you cant set limits on SOC.
   
   

   Originally Posted by Dan

   Another SOC question. If I set the SoC and DoD to keep the SOC between 80% and 33% on the AUX pack, my math yields a operation range of 1.925 KWh using the 3.2V quote per cell. Using the 48V nominal figure and including the 30Wh balancing load that comes down to 1.774 KWh. Is that operation range too conservative, or is the Enginer documentation too aggressive?

   The 2kwh pack has 16*3.2V*40Ah= 2048Wh. That is where the 2kWh comes from. The balancers only load the system when the cells are out of balance. It shouldn't be a constant load. I doubt that it will add up to much. If you use 47% of your SOC, and assuming that the converter is 90% efficient, that leaves you with 0.866Wh to work with. I don't know where you saw the 66% recommmended DOD, but according to the data sheet, a 70%DOD will give a minimum of 3000 cycles, and 80% DoD will give you at least 2000 cycles. I will be at 80% DoD, which will give me 2-4 years. By then, LiFePO4 will be a dime a dozen.
   
   

   Originally Posted by Dan

   Final question. Will this mess up my super clean OEM EV button install. I don't like thier silly little switch. I think Jay can do WAAAYYY better!
   ?

   Yup, you can keep it.
   
   

   Originally Posted by Dan

   OK... last last question. Does anyone know of a city with a participially health PHEV conversion credit. I thought I heard Marc say that Austin was looking at a 7k credit, but surely that fell through. Any other known state, or city PHEV conversion credits, since 10% IRS credit is tantamount to 0%. I'm grateful I'm not broke, but being not broke, makes most IRS credits I apply for unattainable. State and municipal credits on the other hand have never been a problem.

Can't help you there.

Originally Posted by Dan

As a final thought, I don't share most of the concerns I've seen elsewhere (not here) about what the potential benefit will be. It's just like the question about the EV button. In the right hands on the right commute the EV button alone can boost MPG by 10-20%, and in the wrong hands it can REDUCE mpg by 5-10%. Same goes here. If you can tailor your drive to use the AUX pack correctly I think you can easily get a 70%-80% boost on MPG (not MPGe) given the correct commute, but in the wrong hands and wrong route the difference may indeed be negligible.

Agreed!

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[Dan]

Originally Posted by hobbit

Anyone considering the Enginer kit definitely must must must go
read the ENTIRETY of the long-running Priuschat thread on the
subject, to see the litany of problems people are having getting
this thing going [not the least of which is Jack getting banned
from PC for a while because of some cultural preconceptions on
what sort of interaction with forum members is permissible.

Done! At nearly 500 posts now it's a bit more than light reading. After reading the thread, I'll summarize a bit for the impatient.

• Jack got banned for soliciting customers, the ban was lifted eventually.
• Looks like at least a half dozen people with the kit are posting here or there.
• There are now two battery types used, Thundersky for the 2KW kit and Motocell for the 4KW kit. This was an issue with the thundersky not fitting in the redesigned enclosure.
• MPG is mixed with no real substantial data being reported. We definitely need some one who knows how to Hypermile using the kit.
• From the installs I've read about there are a good number of failures. Keeping in mind that irate customers are more likely to post than happy ones may taint the figures, but I've only read about half of the installs being completely problem free. Most of the problems seem to be bad balancers. A close second is bad DC/DC inverters. I've only heard about one or two bad cells. Last I heard, Enginer.us has been in contact with the customers having issues and is working to send them (or have sent them) replacement parts.
• You will need to be patient. It may take a long time to get the kit and once fully installed you probably need to go through mini-charge, and wait cycles for about a week before the cells will be balanced and ready to use.
• Seems like the installs done at their site or as part of a convention hall install seem to be more problem free. They may pre-test these "live" installs so that you get a bit of quality control that may not be in the drop-shipped orders

As best I can guess, the way to use the kit would be to turn it on till your SOC is around 65-70%, then bleed off some charge and turn the kit back on. Basically the kit would be like a SOC Nitrous. Most people seem to just be leaving it on, and just letting the pack hang out at 70%+ SOC. Since I know fairly well what each regen will net me in SOC a bit of planning could probably give MUCH better performance with the kit. Basically a PHEV hypermiling strategy guide.

On a personal note, I just can't buy the kit. There are many many other things on the list first (like school books for my kids) that need to happen before I could drop 3.5K on anything. Once I finish my Job Hunt though, perhaps I could land in Oregon. They have a 25% tax credit on the kit that looks to be combinable with the 10% fed credit.

Personally, knowing what I do about the failures, I would probably still get the kit if I had the money (which I don't), but I would carve out at least two months before I expected to have a fully functioning system.

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[Dan]

Here's my best attempt at a connection diagram of the kit. Please let me know if there are any errors. I was unclear from the docs which connection should be tapped for the main (+) and main (-) lead into the charger and inverter/converter. By my math the main leads have 4 connections (charger, inverter, balancer, pack-interconnect). Can that get spread around since It sounds like that terminal would get kinda crowded. Also in the pics I'm seeing, it looks like people are leaving some terminals uncapped. Isn't that dangerous? Shouldn't every terminal (once tapped) be capped to prevent some random piece of junk making a connection?



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