48vdc Energy Source Utilization

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JoeS

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Hills above Silicon Valley, California
I have fairly extensive 48vdc power storage capability (combination of AGM, LiFePO4, and Li (NMC) battery packs), with this summer's project (almost finished) being a drive power conversion of my sailing trimaran from a gasoline Yamaha 4-stroke to a Torqeedo electric outboard using LiFePO4 Headway cells, augmented by solar.

One application for these packs is as an energy source to recharge our i-MiEV, either as a backup in case of power failure (using inverter) or as range extenders (either inverter when stationary or dc-dc while underway). I also have a bunch of solar panels lying around and could probably cobble something together and mount everything on a trailer as a transportable power source.

Sure, we could spend a small fortune on a robust power conversion system, but since this is intended as an experimental hobbyist installation and not a 24/7 living requirement then low initial price trumps established reliability. I already have a really inexpensive modified sine-wave inverter which 'worked' at charging the i-MiEV but I only tried it once just to see if it would do it...

OffGridQLD (already seriously into off-grid living with a top-notch installation) is many steps ahead in this area and recently bought a relatively-inexpensive (even with shipping) 50Hz/60Hz 4kW pure sine-wave inverter with integral 60A 48v battery charger:
http://www.ebay.com.au/itm/4000W-48.../141079386084?pt=AU_Solar&hash=item20d8fc97e4
which he discusses on the Australian i-MiEV forum:
http://forums.aeva.asn.au/forums/new-to-the-forum-new-imiev_topic3714_post52659.html#52659

Just passing on this information in case anyone else in interested.

Too many projects, too little time…
 
There's a lot of 48 VDC stuff around as that is the voltage telecoms use (albeit usually positive ground). Also, I have found that there is a lot of solar stuff from Australia around. Many years ago I had a solar system that ran on a 168 VDC nominal voltage. I also had a 48 VDC battery backup system. I found a company called AERL (Australian Energy Research Laboratories) that was in the business of building controllers for solar powered race cars that were popular back in the day. They had come up with a little DC-DC converter with maximum power point tracking for the solar system. These things were one capable of passing one KW of power and you could dial in the input voltage and the output voltage you wanted. So, each one KW bank of my array went in at 168 VDC and came out at a regulated 52 VDC for battery charging. Pretty slick stuff for the early 90's. I don't know if they are still around but their stuff still works.
 
siai47, thank you for your comments. AERL is still in business building high-end stuff.

Just a brief note on a successful experiment this last weekend using '48v' to power a 120vac inexpensive non-sine-wave 2500W inverter to recharge a couple of Corbin Sparrows (using Zivan chargers) and a successful test charging the i-MiEV through a 12A Clipper Creek L1 EVSE. In retrospect, I should have brought a few solar panels and the windgen to the event to add some drama for the spectators.

What I have is -

1) From my trimaran, two '24v' Headway 12Ah LiFePO4 4P8S packaged in narrow wooden cases that I made a couple of years ago. These have wires going to individual cell groups for use with my Revolectrix Cellpro PowerLab8 charger/BMS, as well as internal thermal sensors. Output is through 120A Anderson connectors for the series connection yielding '48v'. Theoretical capacity (fully charged) is 56v x 48Ah = 2688Wh

2) Two banks of EnerDel Lithium(NMC) (Nickel Manganese Cobalt) 16Ahx2 in a 2P14S configuration tied in parallel through a 100A circuit breaker. No BMS (yet), but I mid-range-balanced the individual cells for a week before assembling. Theoretical capacity is 56v x 32Ah x 2 = 3584Wh

Heretically, I parallel the two + one dissimilar banks (through another 100A circuit breaker), voltage levels specifically configured so I can also safely parallel them with any number of FLA, AGM, or Gel '48v' packs. The only thing to note when paralleling is that the bank voltages must EXACTLY match (down to the millivolt level) before closing the circuit breaker.

The output of these banks go through a monitoring shunt and Ah counting by a Bogart Engineering TriMetric TM-2030. Another 120A circuit breaker is in series with the output before it gets to the inverter. I'm still debating whether to get the 240vac inverter that OffGridQLD bought that I mentioned earlier.

Reality is that since I don't have an active BMS for this setup, I limit the upper voltage to about 80% SOC of the EnerDels and ensure the bottom stops at about 20% SOC, thus limiting the total energy available to 60% x (2688 + 3584) = 3763Wh (if you believe the published Ah capacities). In any case, this setup was more than sufficient to recharge the two Corbin Sparrows at this weekend's Guinness world record parade.

Typical current draw was 30A, with current sharing changing from primarily the EnerDels when fully charged to the Headways at the lower end, with 50/50 in the middle, quite similar to what I saw for years when living on a boat and paralleling AGMs with FLAs. When individually measured, all of the cells within the Headways were within 10mv of each other, as, separately, were the ones in the EnerDels!

In order to use this inverter with the Clipper Creek L1 or Mitsu L1 and their ground fault detection circuity, my quick-and-dirty workaround was to use a resistor to tie the 120vac Neutral to Ground. There are extensive writeups on the myNissanLeaf forum on doing this safely.

I was interested in trying this out as this setup is the source for running my trimaran's Torqeedo 4.0R electric outboard as well as a home backup power source should the grid go down. Have a variety of dc-dc converters and solar regulators to be able to feed the 12v bank from the 48v banks and vice versa or to charge either the 12v bank or 48v bank directly off solar or windgen.

Back to the i-MiEV, the battery banks fit very nicely in the footwells behind the front seats of the i-MiEV, leading me to think that someone could easily convert the i-MiEV into a two-seater and a HUGE battery bank (remove the rear seat) to make a long-distance vehicle out of it! My modified Enginer 48vdc-to-360vdc converter setup is a waiting winter project...

Here are some photos including the Headways going into the wooden box when I was building it, but I forgot to take a picture of the Sparrows feeding with the wires coming out of the i-MiEV:

ChargingSystem1.jpg

ChargingSystem2.jpg

HeadwayPack.jpg
 
JoeS said:
Just a brief note on a successful experiment this last weekend using '48v' to power a 120vac inexpensive non-sine-wave 2500W inverter to recharge a couple of Corbin Sparrows (using Zivan chargers) and a successful test charging the i-MiEV through a 12A Clipper Creek L1 EVSE.
.....
In order to use this inverter with the Clipper Creek L1 or Mitsu L1 and their ground fault detection circuity, my quick-and-dirty workaround was to use a resistor to tie the 120vac Neutral to Ground. There are extensive writeups on the myNissanLeaf forum on doing this safely.
.....
Back to the i-MiEV, the battery banks fit very nicely in the footwells behind the front seats of the i-MiEV, leading me to think that someone could easily convert the i-MiEV into a two-seater and a HUGE battery bank (remove the rear seat) to make a long-distance vehicle out of it! My modified Enginer 48vdc-to-360vdc converter setup is a waiting winter project...
....

JoeS - so how to charge the iMiEV while driving ?
 
pbui19 said:
JoeS said:
JoeS - so how to charge the iMiEV while driving ?
You wouldn't be 'charging' the i-MiEV but simply adding capacity to the traction battery pack. Paul, the output of the Enginer 48vdc-->360vdc converter connects to the battery pack which the car 'thinks' is simply power being supplied by the motor as though the car was in regen. My intention is to have a slightly lower voltage (350vdc?) injected through a manually-operated HV contactor and an isolation diode.

siai47 has an excellent discussion of this (I can't put my finger on it at the moment) and it would be easier with your CHAdeMO-equipped i-MiEV. As always, working with high voltage can be LETHAL, so be sure you know exactly what you're doing :shock:

I first need to fix my Enginer dc-dc before tackling anything else...
 
JoeS said:
You wouldn't be 'charging' the i-MiEV but simply adding capacity to the traction battery pack. Paul, the output of the Enginer 48vdc-->360vdc converter connects to the battery pack which the car 'thinks' is simply power being supplied by the motor as though the car was in regen. My intention is to have a slightly lower voltage (350vdc?) injected through a manually-operated HV contactor and an isolation diode.

siai47 has an excellent discussion of this (I can't put my finger on it at the moment) and it would be easier with your CHAdeMO-equipped i-MiEV. As always, working with high voltage can be LETHAL, so be sure you know exactly what you're doing :shock:

I first need to fix my Enginer dc-dc before tackling anything else...

The effect is the same: adding energy to the system, just going through different path. Your test set up converts the extra energy via the 120vac route, to be converted back to ~330vdc by the Miev built-in charger. Obvious the DC path is more efficient with fewer conversion step. I guess add DC power may be easier to fool the Miev computer.

I hear you and appreciate the warning about working with DC power, well worth repeating. Even 48vdc scares me, the current can be so high.
 
Joe, where did you get your Enginer converter? What are the specs on it?

I found high-efficiency flexible solar panels. They are Renogy 100 watt flexible panels. 3 will fit on the roof of the i-MiEV, and a converter can be used to bump it up to 48 volts. I was thinking to add either a 4.8 kWh or 9.6 kWh booster pack somewhere in the i-MiEV, combined with the panels and an Enginer converter if I can find one, and extend the range to 99 miles (extrapolated from 62 mile EPA range over 16 kWh to a new capacity of 25.6 kWh with a 9.6 kWh booster pack). I figure the solar on the roof can add 5-7 miles of charge daily.

With this added capacity (and some way to quickly charge it), I could hop the DC quick chargers across from Pittsburgh to Harrisburg. :cool:

http://www.renogy-store.com/100watts-bendable-panel-p/rng-100db.htm
 
PV1 - I had been looking for some 48v-->360v dc-dc converters for some time. This Enginer unit had been torn apart and it was a fluke that I came across it (word of mouth) - one-of-a-kind source long gone. I need to put it back together to see if it even works. Enginer has been out of business for a couple of years - they had been making add-on packs primarily for Prii.

Coincidentally, I recently bought three of the Renogy solar panels for the trimaran because they conform to the curve of the deck and are very lightweight. For 48v charging, they need to be in series so the voltage is high enough to feed my Morningstar T-45 (non-MPPT) 48v battery charger. Do the math - they're only good for topping up a bank and not for anything serious. For example, I think I'll be lucky to get a total of 1kWh out of these three in a day - certainly sufficient to top up a boat's non-traction battery bank for use overnight, but not to significantly recharge the traction (electric outboard driving) pack. Would have a negligible contribution to an i-MiEV's pack IMO unless you left the car sitting for a week or so.

Adding an already-charged booster pack and dc-dc is a viable proposition for extending the i-MiEV's range, IMO. All it takes is time, some elbow grease, and $$ :geek:
That 27KWh Kia Soul EV with CHAdeMO sure sounds like a viable alternative for someone needing the range (I know, I know, heretical to mention that on this forum). :cry:
 
Each of my Solarworld panels on my house array generates between 1 and 1.5 kWh per day, and they are limited to 225 watts output from the micro-inverters. 3 of the flexible panels equals 300 watts sticker, vs. 265 watts for my house panels. Though not optimally aimed, with MPPT and parking in all-day sun, they should still be able to match what one of my house panels generate, as long as they can generate somewhere near their rated output.

What kind of power are you seeing out of these panels? Should I spring the extra hundred for the Grape Solar variant, or just forget them? I want to do something with mobile solar, and I would like to avoid the range penalty of hauling around a 700 lb. trailer.

My car pretty much lives under sunlight all day, and through the week, could collect enough energy to offset 2 days of commuting. Combine that with the secondary pack, I would only have to plug in once or twice a week instead of every night, though every other night is easily possible for my driving. I could also get 2 extra panels and cover the windshield to collect even more energy and keep the interior cooler in the process.
 
PV1 said:
Each of my Solarworld panels on my house array generates between 1 and 1.5 kWh per day, and they are limited to 225 watts output from the micro-inverters. 3 of the flexible panels equals 300 watts sticker, vs. 265 watts for my house panels. Though not optimally aimed, with MPPT and parking in all-day sun, they should still be able to match what one of my house panels generate, as long as they can generate somewhere near their rated output.
I have some experience using solar panels on boats also. I think you're going to be surprised to see what you don't get when they are flat mounted and not properly aimed for best output. A general rule of thumb for flat mounted panels is you lose about half of what you would get it they were properly aimed. On a car roof which is slightly curved, the losses should be even a bit higher, plus you're going to experience cell heating mounting them on a car roof that you don't experience when mounted in free air

I'm guessing you're going to see something on the order of 40 to 45% when compared to your home solar array. As always, 'real world' numbers trump all calculations though, so it will be interesting to see how this works out when you actually put them on the car

Don
 
I have some rigid 85 watt panels on the porch roof for a small off-grid setup. I see about 50 watts out of each during the day, pointing WNW at 20°.

At home, I park facing due West, and facing southwest at work. The parking lot also slopes towards southwest, pitching the panels in that direction.

I know somebody that has one of these flexible panels. I'll see if I can borrow it for a few days.

Joe, sorry to hijack your thread :oops: .
 
PV1 said:
Joe, sorry to hijack your thread :oops: .
No worries, it's all on-topic. When I got the third solar panel last week I briefly hooked it up to see if it would work at charging the 48v system (it did) but I didn't take any data. I also haven't discussed the onboard 12v battery bank, the 12v-->48v charging dc-dc, the 48v-->12v charging dc-dc, the 120vac-->12v charging, the 120vac-->48v charging, nor the windgen which can put out >20A into a 12v battery.

Pulling out the 48vdc battery bank(s) and some hardware off the boat and using them in the i-MiEV merely increases my ROI for this stuff.

One thing I'd like to make is a portable stand for the windgen - just for giggles, it would have been fun having it (and a few solar panels) setup at that huge eV parade the previous weekend and have wires going to the i-MiEV and Sparrows just to demonstrate the concept … tech savvy folks would realize the practical uselessness of such a small system, but it would have at least demonstrated how off-grid energy independence can be accomplished.

And, PV1, let's not forget your original thread - a few excerpts:
http://myimiev.com/forum/viewtopic.php?p=2955#p2955
http://myimiev.com/forum/viewtopic.php?p=3435#p3435
 
JoeS said:
Some things never change :lol: :mrgreen: . That was well before I had the car.

I'm impressed with the specs on these flexible panels, giving more power and a higher MPP voltage than rigid panels slightly bigger (36 cell rigid vs 32 cell flex.), but I have some doubt to the truth in the figures. What's justifying the specs to me is that the cells have no bus bars on the face, all the connections are on the backs of the cells. The bus bars take up 10-20% of the cell space on standard cells.

For a 15 cell string of LiFePO4, the MPP of 3 panels in series is just below the HVC of the BMS I'm looking at. Open circuit voltage is way above, so 3 panels charging this string would work, in full sun. I'll need to re-measure the roof of the car and see if it's possible to squeeze a 4th panel up there. Then there's no doubt the voltage is high enough.
 
Hmmm, ran across this 48v inverter/charger that is PWM and not MPPT. Same brand/source as OffGridQLD is using.

http://www.ebay.com/itm/161101542882

Here's the MPPT version:

http://www.ebay.com/itm/161243046772

Even though I have MPPT on my grid-tied solar system and have used a small MPPT charger on my 12v boat battery bank, since I'm primarily interested in the 4kW inverter and can live without the MPPT efficiency for charging, this saves about $140 over the MPPT unit, enough to pay for shipping. PWM unit solar upper input voltage limit is 125vdc compared with the MPPT's 145vdc.

Just want to be able to charge my i-MiEV at 240vac off a massive 48vdc bank, that's all. Thought I'd pass this on as I haven't bought yet.
 
I recently picked up a new old stock Outback Power Systems PS1.
http://www.ecovantageenergy.com/catalog/items/item377.htm
This model was produced around 2004-2006, and I think it was just too expensive for the market at $5994 without solar panels or batteries, but they also supplied a good number of these to the US Military, and I'm told that most of the civilian version components are milspec as well. I got it for far less from an Outback retiree who's decided he'll never use it, and Outback still supports it.

It's a 120V 3 kW grid-tie inverter fed by up to a 3.3 kW 48 V nominal solar array and battery pack, with a MPPT charge controller included in the same outdoor-rated enclosure, all prewired for a quick n easy hookup.

So, it should enable off-grid i-MiEV charging at 16a 120V (1.92 kW) through my SPX EVSE. I intend to install it and the array and batteries on my enclosed car hauling trailer. Now that all the parts are assembled, the next challenge is to get a permit to let this trailer connect to the grid via a genset inlet box on my house and get the WA State solar production incentives of $0.54/kWh. That's a bit more 'out of the box' than the 2.2 kW array on a dual axis tracker that I just finished installing in the back yard, so the utility staffer is still scratching his head regarding this project...
 
jray3 said:
It's a 120V 3 kW grid-tie inverter fed by up to a 3.3 kW 48 V nominal solar array and battery pack... So, it should enable off-grid i-MiEV charging at 16a 120V (1.92 kW) through my SPX EVSE...
You bring up an interesting point, as to date I haven't tried charging my i-MiEV on 120vac at anything higher than 12A. Do let us know if the i-MiEV charger can accommodate the SPX EVSE 16A at 120vac setting. Good luck with all those interconnecting and solar approvals.
 
JoeS said:
I haven't tried charging my i-MiEV on 120vac at anything higher than 12A. Do let us know if the i-MiEV charger can accommodate the SPX EVSE 16A at 120vac setting.

Oh yes, the i-MiEV happily pulls 16A at 120V from an SPX (now Bosch Power Express) with no adjustment required to switch between 120V and 240V input, just plug adaptors.
http://www.pluginnow.com/power-xpress

It should do the same on an AVI Turbocord
http://evsolutions.avinc.com/turbocord

I've also charged from an ungrounded inverter on a solar trailer, but just with the Panasonic 8 amp EVSE. Others might show a ground fault- I haven't tried.
 
I've also charged from an ungrounded inverter on a solar trailer, but just with the Panasonic 8 amp EVSE. Others might show a ground fault- I haven't tried.
Hey, so have I! Only it was the EVSEUpgrade version at 120 volts, 12 amps. Now that I know that trailer has an L14-30 on it, that'll be the next adapter I make.

My el-cheapo Black and Decker 750 watt inverter even passed the ground check, though I didn't dare plug the car in...instant overload.
 
PV1 said:
My el-cheapo Black and Decker 750 watt inverter even passed the ground check, though I didn't dare plug the car in...instant overload.
If you have the newer version of the EVSE Upgrade with adjustable current, it just might work if you dial the EVSE back to 6 amps

A 2Kw inverter is only $129 if you catch it on sale at Harbor Freight

Don
 
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