Range extender !

JoeS said:

PV1, seems to me this is an extension of the extensive discussions we had prior to your getting your i-MiEV in the first place.
http://myimiev.com/forum/viewtopic.php?p=3435#p3435

Click to expand...

I know! This would've been perfect.

While this could be used as a (marginal) range extender, it's better suited as a portable power source, since the i-MiEV can only deliver a max of 960 watts through the 12 volt system, this can supply 1,500 watts under the current spec. I was planning to take it to events and gatherings as both a power source for booths/music and a discussion post. A friend of mine built a much bigger solar trailer, dubbed the "Pop". It has 12 solar panels on it, 250 watt panels I think. His is purpose built for a mobile power plant.

https://www.dropbox.com/s/d6l7khs4bor2897/20140119_183854.jpg

these would work for us on those once in a while occasion:

http://www.evnut.com/rav_longranger.htm

http://www.tzev.com/2001_rxt-g_.html

though I would prefer a diesel generator, then we can just pour in some veggie oil.

Yay! The site's back up.

Came across this on the Nissan LEAF forum. Anybody have any experience with the Enginer systems?

http://www.mynissanleaf.com/viewtopic.php?f=41&t=16058

Inasmuch as I now have gobs of "48v" Li(NMC) and LIFePO4 packs lying around, some of you may recall that I've been looking for a dc-dc converter to take 48v up to our ~350vdc in order to build a range extender. A few weeks ago I picked up a couple of disassembled Enginer dc-dc converters … a project for this coming winter. If anyone has any Enginer schematics of their dc-dc, I'd sure appreciate them.

PV1 - I have a couple of Enginer system in two Prius: gen1 version with 3000w dc/dc + Mottcells in a 2004 Prius, gen2 version with 5000w + RealForce LIFE in a 2007 Prius, both are working but i had to build my own BMS.

Earlier on, the group was still learning about battery management so my first gen1 system now has a couple of bad cells, so i can only squeeze in (watt-meter) around 1-2 kwh presently. I am plan to replace the cells.

The gen2 in the 07 Prius just recently got a new homebuilt BMS, and seems to be working.

The system does work as advertised, i.e. an assist to the HV pack. The feed is only around 3kw so for a 256v Prius pack, that's a little over 10A. But in low speed around town, the Prius can operate sans ICE for a while.

I think the system could work as a poor-man range extender for the Miev, but would only expect max 3kwhr at best. So with the conservative 250wh/mile rate, it would extend around 12 miles.

The problem is the poor quality, both in components and in assembly. Jack Chen, the original designer, i think he lives in Chicago, was very disappointed with his supply chains.

JoeS: i don't have the schematic, but i do have some photo to ID the various pot adjustment for output voltage, current ... Also, i had to replace a front end relay ($1) on one of my DC/DC.

-Paul

Since it works with the LEAF, which I want to say has a higher voltage pack than the i-MiEV, it would work with the i-MiEV. I could imagine combining this with a cheap ICE generator or my solar trailer idea (which is looking better, I found a lightweight trailer that keeps total weight below 700 lbs with a 4 kWh battery and 1,100 watts of PV) to provide additional energy to the car while moving.

Count me in- I also have an Enginer 4 kWh system that was pulled out of service due to BMS issues, but have not begun the dissection or have any documentation beyond the owner's manual.
Of course, this could be used with a much higher capacity battery pack if desired for range extension. Every application is unique, but if we consider the i-MiEV pack to be one hour/60 highway miles, inputting 3 kW over the course of that hour would extend driving time and range by approx 11 miles/11 minutes. Not a lot, but it could make the difference for some journeys or enable the occasional skipping of a DCFC station on a road trip...

The Aussie forums are always entertaining- here's a bloke who rigged an e-jerry can with just four big Thunder-Sky cells for almost 2 kWh of added charge. (scroll down to the sixth post). I've got all that hardware, but would have to have exactly the right need to invest all that effort in 2 kwh....
http://forums.aeva.asn.au/new-to-the-forum-new-imiev_topic3714_post44469.html#44469

My current priority is installing a couple of photovoltaic arrays. The first is 2200 W of Itek panels on a two-axis tracker in my back yard, and the second is 1530 W of old BP 12V panels that I'll either put atop my 16' enclosed trailer, or on a temporary ground mount... The eventual plan for my car hauling trailer is to have a battery pack for trackside/EVent charging and 120VAC off-grid outlets, while reaping the benefits of Grid-tied PV payback the other 99% of the year.

stumbled across this extender:

http://www.eptender.com/

seem like the idea of renting it would work, as an EV only needs it occasionally.

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By the way, I just learned that the Enginer system for the Leaf charges the Leaf using AC.

http://enginer.us/wiki/tiki-index.php?page=Leaf+Installation+Manual

So it doesn't use a dc-dc converter as in the Prius setup. It probably just uses a DC-AC inverter and hacked the AC charger hook up.

pbui19 said:

=================
By the way, I just learned that the Enginer system for the Leaf charges the Leaf using AC.

http://enginer.us/wiki/tiki-index.php?page=Leaf+Installation+Manual

So it doesn't use a dc-dc converter as in the Prius setup. It probably just uses a DC-AC inverter and hacked the AC charger hook up.

Click to expand...

upon closer inspection, I think I spoke too soon. It looks like the Enginer kit taps into both the HV DC and the AC wirings. So, i don't know how it works.

From what I've heard, it taps into both incoming AC and HVDC. When the car is plugged in, it sips extra current through the J1772 connector to charge the Enginer pack. For example, if the car requests and uses 12 amps, something like 16 amps is actually being used, 4 amps getting used by the Enginer pack charger. When the car is being driven and the pack's activated, it feeds HVDC into the wiring of the car to appear as "regen" on the high-voltage bus.

By tapping incoming AC, you don't have to connect two cords to the car to charge. I see the issue, though, of tripping breakers on 120 volt circuits (would work fine with our 8-amp EVSEs, though).

pbui19 said:

stumbled across this extender:
http://www.eptender.com/
seem like the idea of renting it would work, as an EV only needs it occasionally.

Click to expand...

I've had discussions with the inventor. He's a non-engineer who invested extensive personal funds into professional engineering, and is set upon getting the full blessing of a carmaker and government 'homologation'. The EP Tender communicates with the car to a greater extent than J1772, closer to CHAdeMO. So, if it gets to market, it'll only be for the Renault ZOE at first, and each EV model will require software development and automaker approval. Then, each individual EV will require installation of a custom wiring harness and hitch before it could use the ep tender.

So, I'm continuing work on a pusher trailer that shares no electrons with the towing EV (other than directional lights) and uses a conventional hitch.

Is it just me, or do the LEV50 cells seem to have a rather low energy density? I just spec'd out a custom pack, a little over 10 kWh at 325.6 volts nominal, and it will easily fit in the back of the i-MiEV using LG 18650 cells, yet, our 16 kWh pack takes up more than half of the space under the i-MiEV. The custom pack is 32" long, 18" wide, and 3" high, plus a bit more with a case. This can boost range from 62 miles to just about 100 miles, and since it matches the i-MiEV's voltage characteristics, no converters are needed, just a balancing BMS.

I know, I've been gung-ho on a solar trailer for the longest time, but range-extending hasn't been the strong point of it. Since there are now a couple of solar trailers in my area, I think it'll be better to focus on making the i-MiEV a long ranger, especially with recent additions of quick chargers east of me. I may be traveling to Hershey, PA in a few months, and while the company car gets 35 MPG, I'd like to not use gas. Plus, I've been wanting to do an EV road trip for a while. This booster pack will allow me to span the gap between the quick chargers and really broaden my horizon. With the booster pack, I should be able to do 100 miles, spanning the largest QC gap of 90 miles. Plus, the booster pack gets quick charged with the main pack, allowing a full charge in 1-1.5 hours.

Also, I can use electric heat for 2 hours without diminishing my current range.

PV1, I've been hoping that some more hobbyists would show success with 18650 cells, and now that a Model S has been gutted for the world to see, it seems simpler (just a massive series/parallel array without a cell-level BMS). A 'suitcase pack' or modular range extension battery is very appealing to me, so I hope you'll share all the details.

I, too, am hoping to get a parallel setup going this winter, either using a 48v-->360v dc-dc or maybe even directly sticking in a parallel HV pack. siai47 had a very nice writeup suggesting places to introduce the HV - made more difficult for me as I don't have CHAdeMO.

jray3 said:

... and now that a Model S has been gutted for the world to see, it seems simpler (just a massive series/parallel array without a cell-level BMS)...

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Hmm, that's news to me as I thought their paralleled cell groupings not only had a fusible link for each individual cell but also had top-balancing capability for each paralleled group. That said, I still haven't hooked up my BMS to my EnerDels and, after a year, they are still wonderfully in balance (though, admittedly, I normally run them between 30%SoC and 80% SoC.

PV1, good luck to you and keep us informed and don't forget to wear rubber gloves, take any rings off, and keep one hand in your pocket if possible when working with this stuff.

I was going to do a 48 volt pack with a converter to go up to 355 VDC, but I can't find any converters to do it. I know the Enginer system can do it, but ones that have popped up for sale are already sold. Maybe I'm not looking in the right places. Besides, adding a 48 volt pack won't allow me to quick charge the secondary pack, but I could do a solar add-in, though being able to QC both packs would serve me better on a road trip than a kWh of solar input. I could still put a panel up there to feed the 12 volt system, though .

I can't believe the S doesn't have cell-level BMS.

Thanks, though I'm not looking forward to welding/soldering 1,056 cells together.

Here's the Model S pack dissection.
http://insideevs.com/look-inside-a-tesla-model-s-battery-pac/

http://www.teslamotorsclub.com/showthread.php/34934-Pics-Info-Inside-the-battery-pack

http://www.teslamotorsclub.com/showthread.php/34934-Pics-Info-Inside-the-battery-pack/page27?p=755546&viewfull=1#post755546

Wow! That's a LOT of cells! Thanks for the links.

PV1 said:

Is it just me, or do the LEV50 cells seem to have a rather low energy density? I just spec'd out a custom pack, a little over 10 kWh at 325.6 volts nominal, and it will easily fit in the back of the i-MiEV using LG 18650 cells, yet, our 16 kWh pack takes up more than half of the space under the i-MiEV. The custom pack is 32" long, 18" wide, and 3" high, plus a bit more with a case. This can boost range from 62 miles to just about 100 miles, and since it matches the i-MiEV's voltage characteristics, no converters are needed, just a balancing BMS.

Click to expand...

Energy density of the LEV50 is 3.7Vx50Ah/1.7kg = 109Wh/kg
Energy density of the LG18650 is 3.7Vx2.6Ah/0.048kg = 200Wh/kg

The MiEV's battery pack contains the batteries, battery management system, ventilation system, contractors, bus bars, and connections for both standard and fast charging.

Even though the LG18650 has a higher energy density, the standard LG18650 has a short life of 80% after 300 cycles. The standard LG18650 also does not have a high charge or discharge rate.

jray3 said:

PV1, I've been hoping that some more hobbyists would show success with 18650 cells, and now that a Model S has been gutted for the world to see, it seems simpler (just a massive series/parallel array without a cell-level BMS). A 'suitcase pack' or modular range extension battery is very appealing to me, so I hope you'll share all the details.

Click to expand...

From what I can gather reading the Tesla Forum, the Tesla Model S BMS for the 85kWh battery pack balances cell voltage for the 7,104 individual cells in 96 groups of 74 cells in parallel. The cells are arranged in 16 modules, each module having its own Battery Monitor Board. The 16 BMB's are linked to a main Battery Management System board. Each cell is fused so that an individual cell failure does not result in pack failure. There is a coolant loop that runs through the battery pack.

Here's a post from a member of the Tesla forum:



The cell groups are well balanced and the temperature sensors show that the pack temperature is pretty uniform.

Does anyone know a good way to limit the secondary pack's input/output to 30 amps? I can't seem to find resistors or a PWM current limiter that can handle the voltage, or if they handle the voltage, they don't have the amperage.