Enginer Plan B

A Lexus and the Ford Escape Hybrid are at 350 volts. Is this close enough to make my original thought that some run close to 400 volts?

 

If they are 350 nominal then there's no doubt they hit 400+.

 

Sorry, I thought we were talking about Enginer DC booster, which is made for Prius and goes 48V-240V. You said same model DC booster goes up to 400V and I corrected your statement. Same model of DC booster can't cover such large output voltage range ( 240V-400V ), it has to be designed for specific in/out voltages, for specific application. It is definitely possible to design DC booster to much higher voltage, but it won't be the same model anymore. I'm not aware of Enginer kits for any other car with different DC bus voltage.

 

Yes, the booster can and is used for all these cars. As far as I know, Enginer uses the same exact DC boost converter whether it's for a Prius I, II, III, FEH, or whatever. It's a matter of setting the duty cycle with an internal pot. Like I said, it seems like folly to do so. A 48v to 400v boost converter at 5000 watts seems quite a challenge.

 

Do you have any links or references where Enginer DC booster is used for 400V packs? I find it hard to believe, especially since Enginer is not advertizing its kit for any car other than Prius. I'm not an expert in boost converters, but my understanding is that duty cycle adjustment is not likely to provide such wide output voltage range at such great power level. Even the fact that key components like caps, FETs etc would have to be rated for much larger voltage and hence be more expensive to support wide voltage range, makes me doubt it, Enginer must cut costs everywhere to be at the price its sold. I just don't see how the same box can do 240V and/or 400V at 5kW for the same price.

 

Seriously, it is. I just found a whole series of posts where the main guy at Enginer, Jack Chen, posted the installation procedure for the FEH. Unfortunately, if you aren't registered as a user, you can't see it.

Enginer claims that this kit can be used on any hybrid in production. I've seen installation dialogue among the installers related to just about every hybrid out there from Pii 1-3, FEH, Camry, Highlander, Civic, Insight, etc.

It's the same kit and same DC converter. Again, I share your surprise. It seems like folly to create a DC Converter with this sort of dynamic range.

(Just look at the www.enginer.us front page. The verbiage describes all the vehicles it goes in.)

 

Could it be that the converter first boosts to a higher voltage, and then uses modulation to produce final 240V?

 

Hmm, well, my hat goes off to whoever designed such cheap and universal DC booster with such wide operating range. I doubt we can find off the shelf replacements, especially at the same or similar price tag. I wish I had time to learn and build one myself, maybe someday...

BTW, I think PIS kit for Ford Escape uses 105 LiFePO4 cells, which makes it a 336V nominal pack, which means that OEM pack must be just few volts below 336V even when fully charged.

Anyone cracked Enginer DC booster open and have pics to share? I'd love to see its guts up close, but I don't have one at hand.

 

I'm not an EE, but from what I understand on a switching power supply, the output voltage is a function of the duty cycle. I guess Enginer just made the value variable by putting it on a potentiometer. I assure you from first hand experience, that with one pot, I can adjust the output voltage greatly.

 

This would make a lot of sense in order to output a constant voltage as a constant voltage power supply ought to do

 

Sure, if you want, I can take all the highres shots of the inside. But, let me see if I have anything good enough on my local drive.

 

MiniBMS seems a good (even better) subsitute for the original BMS but does using the miniBMS also mean you can store a lot more capacity by top-balancing compared to the original BMS in your opinion?

 

No not really, you are still limited by the cell with the lowest capacity in the pack. even if they are all at 100%, one of them will drop to 20% before the others, ending discharge. if you had reliable bottom balancing as well as the top balance you could go a little further, since that lowest cell would be getting a little balance charge during discharge, but that's only going to be 1-2amp hours at most - not really worth it i don't think.

 

I see, thanks. Just received my upgraded BMS back, I will leave it in the 'not balancing' position, put it in the car tomorrow and see how it performs.
Overall I'm still happy with the Enginer kit as is, on my current tank 2.6 l/100km over a distance of 1575 kms. The refill alarm started today but I'm hoping to squeeze another 100 km out of this tank.

 

www.pacificEV.com are using their own design BMS which apparently can be bought for $300 ea.

It was designed specifically to replace the BMS16D.

 

It's there. The principle of operation is similar to the VoltBlocher, cell level Batt Control System at an economic price.

 

The website does not Show the BMS but they do install it in their Enginer Kit conversions. If you send a email to them you should get more info.

 

I'm referring to this BMS hardware from your link