Portable Fuel Cell to extend range

[randvegeta]

Hello all.

I was wondering what the viability of a fuel cell (probably hydrogen) would be as a range extender.

It occurred to me that for highway cruising speeds, 30KW is more than sufficient. 20KW would even be enough to be highway legal, but assuming you want to be travelling at 70mph | 110km/h or more, 30KW is all you need.

I haven't been able to find much in the way of cost of a fuel cell, and yes I am aware that producing hydrogen is quite inefficient compared to charging a battery. But if used only for those occasions where a fast charge is not possible then such a device would be very handy. Portable units that can also mean these devices need not be 'owned' but possibly just rented on an as needed basis.

Any serious pitfalls to this idea?

 

[xyeahtony]

not economically or practically viable. Superchargers are very abundant, and in Europe even more tightly concentrated.

 

[jelloslug]

A unit that size would fill the entire cargo area in a Model S and cost about $40,000.

 

[S'toon]

Superchargers are very abundant, and in Europe even more tightly concentrated.

Maybe in your part of the world. Not mine. No idea about Lithuania.

FC very impractical. A range extending battery trailer has been mused about, even by Musk himself.

 

[Saghost]

I think the main downfall is having to keep 10ksi hydrogen in the car - a simple failure of the high pressure gas system can do massive damage, and it's explosive from 18-60% concentration, with very little spark needed.

If I had to do a fuel cell range extender, it's be a solid oxide type that can react hydrocarbons instead, letting you use safer fuels. Those also don't need the precious metals. The downside is they operate at very high temps (~900C).

 

[scottm]

Get a Chevy Volt. It has a gas range extender built-in..

 

[randvegeta]

Get a Chevy Volt. It has a gas range extender built-in..

I'm sure the Volt is a fine car, but I'm not interested in a typical 'Gas' engine for range extension. There is always the ability to charge if you're out in the sticks... just slowly.

not economically or practically viable. Superchargers are very abundant, and in Europe even more tightly concentrated.

They are are abundant in Western Europe, but not east of Germany. Poland, east of Warsaw, seems to be an EV dead zone with no infrastructure what so ever. And in Lithuania, where I live, there are only a handful of fast chargers. My S 60 at 100% charge has a range of 275km. I normally only charge to 90%, giving me a range of 250km. There is a long stretch between these 2 cities I frequent (220km) that has no fast charging facilities at all, and although the Model S can handle the distance fine, in order to make it to my destination with a reasonable buffer (20km) I need to drive pretty much at 100km/h (faster on the downhills and slow on the up). The speed limit on this road is 130km and everyone drives at 150... Doesn't feel too good driving a big and powerful car slower than the lorries on the same road.

A unit that size would fill the entire cargo area in a Model S and cost about $40,000.

I found this: Fuel cell for the automotive industry - 30 kW - Hydrogenics

It does not look all that big, but I suppose it could be massive, extremely heavy and cost $40k... I haven't found any price info or any kind of weight/size description yet.

Still, even a 10kw generator would actually be extremely useful. So maybe a smaller fuel cell would be more affordable, and still practical.

With 10kw is still plenty for around 60-65km/hr, which isn't enough to go on the highway safely. But if you have it running throughout your journey, supplementing you battery, then you can travel a whole lot further, or a fair bit faster. I reckon an extra 10kw of power would mean I could push my speeds up from 100km/h average to 130-140km/h, which would make a big difference in driving time.

Anyone know how big or how expensive a 10kw fuel cell is?

 

[transpondster]

the only pseudo solution probably would be http://serenergy.com/wp-content/uploads/2016/10/H3-2500-5000-48V_datasheet_v2.0-0916.pdf
they did Fiat 500e conversion I think, there is video on youtube. BUT main problem with fuel cells is when you look at numbers . That thing weights 80 kg add fuel, tank, wiring and you probably at 120 kg minimum, 120 kg means about 25kWh worth of Tesla 's modules, so basically you'd better start with more batteries...

And the easy fix: charge to 100% before trip, there is nothing wrong charging to 100% if you don't keep there.

 

[Alphacrux]

Trade in the S60 for a 100D

 

[randvegeta]

the only pseudo solution probably would be http://serenergy.com/wp-content/uploads/2016/10/H3-2500-5000-48V_datasheet_v2.0-0916.pdf
they did Fiat 500e conversion I think, there is video on youtube. BUT main problem with fuel cells is when you look at numbers . That thing weights 80 kg add fuel, tank, wiring and you probably at 120 kg minimum, 120 kg means about 25kWh worth of Tesla 's modules, so basically you'd better start with more batteries...

And the easy fix: charge to 100% before trip, there is nothing wrong charging to 100% if you don't keep there.

The trip all in all is 380km. Well beyond my 275km max range.

There is a chademo charger 100km from my home on the way to my destination. It charges at 35kw (190km/hr) but rapidly slows down past 90%. Faster to drive slower once reached 90% than to wait for 100% only to drive a little faster.

The next charger is 220km away from the last. I reach that charger normally with less thab 10%. I need to charge another 50-60km to reach my final destination.

The last 60km or so is on a stretch where the speed limit is 50-90km/h, meaning even a 10kw power supplement would possibly be sufficient to eliminate the need for the 2nd chademo charge.

Charging to 100% at home makes nearly no difference vs charging to 90%. At best it saves me 10mins when I reach the 1st charge stop so I rather keep my charge to 90% for my battery sake.

 

[tga]

Discounting weight, size, and cost...

You'd also need to figure out how to vent the exhaust, so the interior doesn't turn into a swamp from all the high temp/high humidity exhaust from the fuel cell.

How are you planning to connect to the car's electrical system? Run a cable outside into the charge port? Hack into the HVDC or AC buses inside the car?

You need to figure out how to control the voltage applied to the HVDC bus. You could try to feed the output of your fuel cell into an inverter, then feed AC into the car's chargers and let the existing charging hardware handle it, but that limits you to 10-20kW (the rating of the internal chargers). Else you need a high voltage DC-DC converter that can communicate with the car's BMS, so that the car can control voltage and amperage delivered by the fuel cell. You'd basically be creating a portable, car mounted, fuel cell powered Chademo/supercharger station. No easy task.

Keep in mind that the car doesn't allow you to drive while charging/connected to external power (or a truck or trailer mounted power source/generator), so you'd need to figure out how to modify the firmware to bypass those restrictions.

All-in-all, it'd probably be cheaper and easier to sell the Tesla and buy a Prius/Volt, etc. Or a 100D, if that has enough range for your needs.

 

[jelloslug]

I found this: Fuel cell for the automotive industry - 30 kW - Hydrogenics

It does not look all that big, but I suppose it could be massive, extremely heavy and cost $40k... I haven't found any price info or any kind of weight/size description yet.

Still, even a 10kw generator would actually be extremely useful. So maybe a smaller fuel cell would be more affordable, and still practical.

With 10kw is still plenty for around 60-65km/hr, which isn't enough to go on the highway safely. But if you have it running throughout your journey, supplementing you battery, then you can travel a whole lot further, or a fair bit faster. I reckon an extra 10kw of power would mean I could push my speeds up from 100km/h average to 130-140km/h, which would make a big difference in driving time.

Anyone know how big or how expensive a 10kw fuel cell is?

The 32kw generator in the BMW i3 is not big enough to keep that car moving at highway speeds. For something as large and heavy, you are going to need something much larger than that.

 

[randvegeta]

The 32kw generator in the BMW i3 is not big enough to keep that car moving at highway speeds. For something as large and heavy, you are going to need something much larger than that.

The i3 should have a 25kw generator but even that should be plenty for 110km/hr.

When I drive my model s, 30kw is enough for 130km/h. Even with 4 people in the car

 

[Max*]

The i3 should have a 25kw generator but even that should be plenty for 110km/hr.

When I drive my model s, 30kw is enough for 130km/h. Even with 4 people in the car

What happens if there's a slight incline?

 

[Rocky_H]

@randvegeta I really don't get the kinds of mental gymnastics you're going through to create this problem for yourself and an overly-complicated non-solution.

You're talking about this wasteland of lack of infrastructure in Lithuania and eastern Europe, so how in the world do you think you would be able to get hydrogen to run your fuel cell generator? That's going to be impossible. So then it goes back to how you dismissed out of hand the idea of using a Volt, which has a gasoline engine. Hydrogen comes from fossil fuels too, so why do you think it's any better? That's the big bait-and-switch lie about hydrogen. People sell it from the idea that it can be totally clean by using wind or solar electricity to split water, but that is horribly inefficient and therefore takes huge amounts of wasted energy. So that is never how hydrogen is actually produced. Any hydrogen station gets it from steam reforming at a natural gas refinery. It's just much cheaper. So you're still using a fossil fuel, just in a much more inefficient way.

 

[jelloslug]

The i3 should have a 25kw generator but even that should be plenty for 110km/hr.

When I drive my model s, 30kw is enough for 130km/h. Even with 4 people in the car

Well, it's not. There are plenty of instances where the REX version of the i3 cannot even keep up with 50 MPH traffic on the most slight incline.

 

[Saghost]

Well, it's not. There are plenty of instances where the REX version of the i3 cannot even keep up with 50 MPH traffic on the most slight incline.

This has more to do with unrealistic programming than the generator itself. The REx has enough power to meet the average load up to about 75 mph.

It doesn't have a lot of surplus power to handle climbing hills at speed, but there's no reason it needs to - you have this giant battery pack sitting right next to it.

If the REx were turned on with 4 or 5 kWh of usable battery left, it could go over any road at 75, using the battery power on the climb and rebuilding it on the descent.

However, BMW negotiated with CARB the BEVx deal, where BMW gets full electric credits for REx i3s - provided they have a shorter gas range than electric and the engine can't come on until the very end.

The EPA rating also gives no credit for the last bit of battery - they measure charge until the engine starts as electric range, and gas range based on tank size, but any electric miles after draining the tank just vanish.

That's actually the main reason the REx i3 is rated so much lower than the BEV i3 - it is a little heavier and has standard the staggered tires that all but base BEV i3s include (pretty sure the EPA rating uses the narrow tired base version for the BEV,) so it likely uses a little more power, but the lion's share of the drop is the small buffer BMW did allow for typical acceleration.

So BMW could solve that problem with a simple firmware update, but if they do two different government organizations will penalize them - so instead they let the consumer suffer and accept the bad reputation.

Meanwhile, some consumers flash the car to European firmware, which allows "hold" mode at up to 70% battery and thus solves half the problem if you pay attention and plan ahead. (The car really needs a bigger tank for road trips too.)

 

[Merrill]

Honestly I do not understand why some of the car manufactures want and have done a fuel cell vehicles. There are about 30 places you can get hydrogen in all of California, it is not as cheap as electricity. You cannot charge at home they are potentially dangerous and heavy. Give technology a few more years and you will have batteries with more range.

 

[jelloslug]

This has more to do with unrealistic programming than the generator itself. The REx has enough power to meet the average load up to about 75 mph.

It doesn't have a lot of surplus power to handle climbing hills at speed, but there's no reason it needs to - you have this giant battery pack sitting right next to it.

If the REx were turned on with 4 or 5 kWh of usable battery left, it could go over any road at 75, using the battery power on the climb and rebuilding it on the descent.

However, BMW negotiated with CARB the BEVx deal, where BMW gets full electric credits for REx i3s - provided they have a shorter gas range than electric and the engine can't come on until the very end.

The EPA rating also gives no credit for the last bit of battery - they measure charge until the engine starts as electric range, and gas range based on tank size, but any electric miles after draining the tank just vanish.

That's actually the main reason the REx i3 is rated so much lower than the BEV i3 - it is a little heavier and has standard the staggered tires that all but base BEV i3s include (pretty sure the EPA rating uses the narrow tired base version for the BEV,) so it likely uses a little more power, but the lion's share of the drop is the small buffer BMW did allow for typical acceleration.

So BMW could solve that problem with a simple firmware update, but if they do two different government organizations will penalize them - so instead they let the consumer suffer and accept the bad reputation.

Meanwhile, some consumers flash the car to European firmware, which allows "hold" mode at up to 70% battery and thus solves half the problem if you pay attention and plan ahead. (The car really needs a bigger tank for road trips too.)

I used to have an i3, I know all about coding the REX to work "properly", CARB credits and all the stupid decision BMW made with the North American version of the car. The fact still remains that 30kw is not enough to acceptably move around the i3, let alone a Model S. Also, the reason the REX version has a lower EV range than the BEV is weight, nothing more.

 

[randvegeta]

@randvegeta I really don't get the kinds of mental gymnastics you're going through to create this problem for yourself and an overly-complicated non-solution.

I'm not actually thinking about doing this myself. It's just a general thought for long distance travel. No matter how large the battery, there is always going to be time wasted on charging. Although the larger the battery, and with access to super chargers, you tend to need a break as much as the car. But that's not the case for me as my range is not so large and charging time is fairly long when I only have access to AT BEST 35kw.

You're talking about this wasteland of lack of infrastructure in Lithuania and eastern Europe, so how in the world do you think you would be able to get hydrogen to run your fuel cell generator? That's going to be impossible.

You can generate your own H at home with an electrolysis machine. Yes I know it is not efficient, but it is still comparable to 'gas' and would only be used on very rare occasions in which case efficiency is hardly part of the equation. Just a time saver. And if you generat electricity from renewable sources, the H can be produced with 0 emissions.

I am not advocating hydrogen fuel cell vehicles. I am aware of the inefficiencies compared to batteries, and the fact they are still sourced from fossil fuels. Hydrogren on it's own makes no sense at all. But as a means of 'refueling' quickly, it can serve as a time saver. It's also an additional means of storing larger amounts of energy more densely.

The fact still remains that 30kw is not enough to acceptably move around the i3, let alone a Model S.

Do you have a Model S? How much power do you require to travel at 110km/h? Unless the gauge is wrong, I simply cannot agree with your conclusion. I rarely need to use more than 30kw of power. Even going uphill, there is existing momentum, and 30kw is sufficient to keep the speed at highway speeds for long enough to hit the apex. Yes it slows down, but that's made up for on the downhill. Even when driving off from a stand still, I can happily accelerate quickly enough to keep up with most traffic without exceeding 30kw. You have to also consider that the battery will always have juice in it. If cruising requires 20 - 25kw and the generator is putting out 30kw, then thats 5-10kw going back into the battery, which in turn will be able to output large amounts of power for short bursts. If coming to a stop, or going down hill, regen can recoup a significant amount of power.

So unless the gauge is wrong, 30kw must be enough. At least for flat and gently sloping terrain. There is no way an i3 cannot keep up with highway speeds if it is being fed 25kw +. It must be getting less power, or drawing more power for other things.