@fizzguts Compressed air holds a similar amount of energy as lead-acid batteries. Presumably, then, the range will be similar to if you took an extremely lightweight car like the Airpod and put a lot of lead-acid batteries and electric motor in it.
@Deddily "Compressed air holds a similar amount of energy as lead-acid batteries." Nope Nothing like as much on a VOLUME basis. Compared to Lithium ion it's so pathetic it's embarrassing. 5 times less efficient than an EV. The air pod is only a 6 hp motor. As an example the so called 98% efficient engineair 5.8hp motor will exhaust two dive tanks in about 3 minutes. MDI won't even post their air consumption to power curves
@fizzguts Sorry but your statement is incorrect. The energy density for lead acid and compressed air is about the same. I wasn't comparing to lithium ion, I was comparing to lead-acid, let's keep this on topic.
If you are comparing a std 12L dive tank (2.0MJ) to car batteries. Volume is equivalent to 2 batteries (ie 5MJ) . The USABLE energy is half that again for air as the engine and pressure regulator wastes more than 50 % of the energy stored vs 90% for battery to electric motor. Oh dear how sad. As no one with a clue uses lead acids anymore a comparison with Lithium ion is correct and air is even more appalling on weight & volume.
So, you're right, compressed air is a around half as efficient in volume. By weight, though, it compares very favorably.
Even assuming you are right and you only get 50% of that capacity, remember that you only have 50% of the lead acids, too (to get a decent amount of charge cycles). MDI claim to have developed a near isothermal efficiency engine - if that is true, then saying 50% is unfair.
@Deddily A car is volume limited so weight is not that relevant. All the EV conversions I've had the misfortune to be associated with run the batteries down to 20% or more to get any sort of range. Yes it stuffs the batteries, you don't burn gas, you burn batteries. Lithium has a much better discharge vs life but it's still not great looking solely at the $. MDI runs a pressure reg to a single stage engine as their three stage unit keep icing up. They tell lies non stop
@fizzguts The Airpod has 200L tanks=40MJ. You say the the usable power is 50%, which is disputable but we'll say 20 MJ. Lead acids can be discharged by 80%, so that's the equivalent of 20*1.2=24 MJ in lead acids. Using your 5 MJ per battery, this is the same as having about 5 batteries. Search for Yugo-greg - his car has 4 batteries, 5hp motor and a range of 21 km in a car that weighs at least 850 kg - that's an inneficient car that is more than 4 times as heavy as the Airpod.
@fizzguts So, four times lighter = four times less energy to move, right? Our 21km range increases to 84km. And that car only has four batteries, so we need 20% more range: 84*1.2= 100.8 km. As for your claim that the three stage engine is not used, please provide a link to prove your point. Otherwise I will assume the engine is working as designed and we can remove the 50% handicap you have imposed upon it, which brings us to 201.6 km, which is not far off MDI's claim of 220 km.
@Deddily "So, four times lighter = four times less energy to move" NOPE. You have confused acceleration with a steady state velocity. Newton's first law of motion. Weight change (and the actual weight of an airpod is more like 450kg) makes a MINOR change to rolling resistance. MDI's struggles with air motors & the current use of a pressure regulator to a single stage motor are explored in aircars dot tk, on the yahoo air car forum & MDI's current website ie "crosses a pressure reducer"
Did the investors ask for their money back?
Topazman12 2 weeks ago
<15km per KLM's testing of the prototype at Schiphol airport.
Charlieutube99 1 year ago
@Charlieutube99 Drom where do you have this information? First time I'm hearing from a REAL range...
etbadaboum 7 months ago
Range 5km?? 10km????
fizzguts 1 year ago
@fizzguts Compressed air holds a similar amount of energy as lead-acid batteries. Presumably, then, the range will be similar to if you took an extremely lightweight car like the Airpod and put a lot of lead-acid batteries and electric motor in it.
Range shouldn't be too bad, then.
Deddily 1 year ago
@Deddily "Compressed air holds a similar amount of energy as lead-acid batteries." Nope Nothing like as much on a VOLUME basis. Compared to Lithium ion it's so pathetic it's embarrassing. 5 times less efficient than an EV. The air pod is only a 6 hp motor. As an example the so called 98% efficient engineair 5.8hp motor will exhaust two dive tanks in about 3 minutes. MDI won't even post their air consumption to power curves
fizzguts 1 year ago
@fizzguts Sorry but your statement is incorrect. The energy density for lead acid and compressed air is about the same. I wasn't comparing to lithium ion, I was comparing to lead-acid, let's keep this on topic.
Deddily 1 year ago
@Deddily
If you are comparing a std 12L dive tank (2.0MJ) to car batteries. Volume is equivalent to 2 batteries (ie 5MJ) . The USABLE energy is half that again for air as the engine and pressure regulator wastes more than 50 % of the energy stored vs 90% for battery to electric motor. Oh dear how sad. As no one with a clue uses lead acids anymore a comparison with Lithium ion is correct and air is even more appalling on weight & volume.
fizzguts 1 year ago
@fizzguts
Lead Acid battery: 0.14 MJ/kg, 0.36 MJ/L
Compressed air at 300 bar: 0.5 MJ/kg, 0.2 MJ/L
So, you're right, compressed air is a around half as efficient in volume. By weight, though, it compares very favorably.
Even assuming you are right and you only get 50% of that capacity, remember that you only have 50% of the lead acids, too (to get a decent amount of charge cycles). MDI claim to have developed a near isothermal efficiency engine - if that is true, then saying 50% is unfair.
Deddily 1 year ago
@Deddily A car is volume limited so weight is not that relevant. All the EV conversions I've had the misfortune to be associated with run the batteries down to 20% or more to get any sort of range. Yes it stuffs the batteries, you don't burn gas, you burn batteries. Lithium has a much better discharge vs life but it's still not great looking solely at the $. MDI runs a pressure reg to a single stage engine as their three stage unit keep icing up. They tell lies non stop
fizzguts 1 year ago
@fizzguts The Airpod has 200L tanks=40MJ. You say the the usable power is 50%, which is disputable but we'll say 20 MJ. Lead acids can be discharged by 80%, so that's the equivalent of 20*1.2=24 MJ in lead acids. Using your 5 MJ per battery, this is the same as having about 5 batteries. Search for Yugo-greg - his car has 4 batteries, 5hp motor and a range of 21 km in a car that weighs at least 850 kg - that's an inneficient car that is more than 4 times as heavy as the Airpod.
Deddily 1 year ago
@fizzguts So, four times lighter = four times less energy to move, right? Our 21km range increases to 84km. And that car only has four batteries, so we need 20% more range: 84*1.2= 100.8 km. As for your claim that the three stage engine is not used, please provide a link to prove your point. Otherwise I will assume the engine is working as designed and we can remove the 50% handicap you have imposed upon it, which brings us to 201.6 km, which is not far off MDI's claim of 220 km.
Deddily 1 year ago
@Deddily "So, four times lighter = four times less energy to move" NOPE. You have confused acceleration with a steady state velocity. Newton's first law of motion. Weight change (and the actual weight of an airpod is more like 450kg) makes a MINOR change to rolling resistance. MDI's struggles with air motors & the current use of a pressure regulator to a single stage motor are explored in aircars dot tk, on the yahoo air car forum & MDI's current website ie "crosses a pressure reducer"
fizzguts 1 year ago
@fizzguts Sorry, the car weighs 744 kg so it's 3.5 times heavier.
Deddily 1 year ago