That last bit would at least be useful for reducing the habitual moisture content of Freelander carpets!
Nodge68
Well-Known Member
I'm being dim Ali.
The output air is what you can use. The input to the pump will be via the servo filter, just above the brake pedal. I wouldn't think the lid needs to overlap that much Ali. I'm thinking biscuit tin type overlap, which I would think is enough. The seal will do most of the work, but there's nothing to stop you putting a wrap of tank tape round the joint too, just to make sure. If you're not wading, then it's much easier to keep water out.
That's interesting. I wonder if VW are simply using the discharge from the cells to warm them up, although they doesn't help when the cells need cooling.
Alibro
Well-Known Member
The eGolf was very much a make shift job to get VW into the EV market. The car was not designed to take batteries so they did the best they could, I guess they decided to maximise the number of cells and have them a bit compromised rather than have fewer but better managed. Don't forget Nissan built a ground up EV with no cooling or heating so I'm not concerned about it for my car.
Nodge68
Well-Known Member
Oh very much so.
The ID3 and ID4 are much more sorted vehicles, and have temperature management for the battery packs.
They did indeed, although battery degeneration is higher on the Leaf than a Tesla for example, its still not horrendous.
I figured the input was where the air got sucked in and the output was where it was blown out.
I guess it depends on whether I try to suck air through the boxes or push it through. If I use a single air pump for both the battery boxes and the brakes I need to bare in mind that the vacuum for the brakes is the no.1 most important thing so
I was thinking of using the exit to blow air through the boxes.
In my (limited!) experience of messing about with electric vacuum pumps, they are barely up to the job of working the brakes. Trying to get them to purge the battery box as well, is likely to burn them out, I think. Many of them have only a 30 or 50% duty cycle, so they will cook themselves if they try to run continuously. Even the engine-driven one on the TD4 needs a vacuum reservoir. A decade or so ago, when we tried converting a few conventional vehicles into electric ones at work, (and this was a "Transit-sized" van), the vacuum pump would generate -0.9 Bar of vacuum in about 20 seconds from having a completely depleted servo (i.e. at atmospheric pressure). It would get down to -0.5 Bar in about 5 seconds. One of the sign-off tests was to be able to sit in the car park, stationary, and stab the brake pedal hard, every 2 seconds. The vacuum pump had to be able to maintain at least -0.6Bar while that was going on.
If it's of any interest (and I'm not for one minute suggesting that it would be practical for your project, this is just for interest!), Here's ECE Reg 100.02, which is the minimum legal requirement for battery packs (they call them "REESS" in the regulation - Rechargeable Electical Energy Storage System", because "battery" would be too simple
), for mainstream cars being newly type approved today. Electronically controlled circuit breakers are preferred because when there's a crash bad enough to cause an airbag to deploy, the battery pack has to split itself into groups of cells with a potential of no more than 50 Volts each. Annex 8 is interesting. They're the tests carried out on the battery pack itself...https://op.europa.eu/en/publication-detail/-/publication/fd8e6b47-d767-11e4-9de8-01aa75ed71a1
Alibro
Well-Known Member
I haven't tested my setup yet with the brake servo but I have a cut out so when the vacuum reaches a certain level the pump will turn off. It is an Audi pump with an Audi sensor so not cheap rubbish but I'm not expecting the setup to be perfect without some tweaking. If I decide to go with the setup we've been discussing it will only be pumping air through the boxes when the brake system needs more vacuum. If it compromises the brakes in any way I'll have to add a second pump.
That is really interesting as a friend of mine was a crash investigator and he was shocked there is no physical disconnect (as in a lever to pull) in the eGolf and no way to reduce the voltage to half.If it's of any interest (and I'm not for one minute suggesting that it would be practical for your project, this is just for interest!), Here's ECE Reg 100.02, which is the minimum legal requirement for battery packs (they call them "REESS" in the regulation - Rechargeable Electical Energy Storage System", because "battery" would be too simple
https://op.europa.eu/en/publication-detail/-/publication/fd8e6b47-d767-11e4-9de8-01aa75ed71a1
As for breaking the battery into groups of 50V that is not catered for in any way with this pack or any other I'm aware of. The pack was connected in series by solid copper wires with no break in the circuit.
These tests are for cars currently being type approved as "new types" today. With the older cars you're working on, the regulatory framework hadn't really caught up with the manufacturers and it was pretty much "the Wild West" out there, with manufacturers each doing whatever they thought was "safe enough"!
Although we no longer dabble with electric vehicle conversions, I'm keeping half an eye on developments here, as the next decade will be tough for us because soon, we won't be able to buy new ICE-engined passenger cars. That means I'm going to have to start looking at converting electric ones, and with the mods we typically do, the battery packs are going to be a real problem!
Did I read that right? As in your work will be pitting internal combustion engines into electric vehicles? Would that be allowed? And why would you need to be doing that?
Ah! No, sorry! We convert new, mainstream vehicles for wheelchair access. Typically medium-to-large MPVs. Basically, cut the floor out from the B pillars backwards, and replace it with a fabricated section that drops the internal floor level (over a width that's just a bit wider than a typical wheelchair) to a level where the wheelchair user has enough headroom and a seated eyeline height similar to those of the other conventionally-seated vehicle occupants. That, of course, involves moving things like fuel tanks, exhaust systems, AdBlue, etc on current cars, but by the time we run out of ICE vehicles to convert, the base vehicles will be coming in with battery packs under them instead. That's going to be a whole new set of challenges! (Not least, the Reg 100 tests described in that other link...).
Alibro
Well-Known Member
So I've finished making the brackets to hold two large modules. I might tweak them a bit but his is the general shape.
And this is how I made the securing screws
And how I plan to bolt them down. When I get the box built I'll drill the holes and weld in studs.
I've made a start on the fuel tank battery box too.
I've decided to build a frame with 3mm angle steel to give it strength and will clad it with 1.6mm sheet. This is the base built but I still have to weld in corners and top but this is enough for today.
And this is how I made the securing screws
And how I plan to bolt them down. When I get the box built I'll drill the holes and weld in studs.
I've made a start on the fuel tank battery box too.
I've decided to build a frame with 3mm angle steel to give it strength and will clad it with 1.6mm sheet. This is the base built but I still have to weld in corners and top but this is enough for today.
That's looking good Ali. I know this is months before you'll be thinking about it, however, if I wait that long to tell you about this idea, I'll have forgotten it by the time you are ready to use it So... I was thinking about your heater on this vehicle, I'm guessing you'll be taking heat from the coolant for the motor/invertor? And possibly using the PTC heater? But have you considered rejigging the AC into an air source heatpump?
So... I was thinking about your heater on this vehicle, I'm guessing you'll be taking heat from the coolant for the motor/invertor? And possibly using the PTC heater? But have you considered rejigging the AC into an air source heatpump?
Alibro
Well-Known Member
That's looking good Ali. I know this is months before you'll be thinking about it, however, if I wait that long to tell you about this idea, I'll have forgotten it by the time you are ready to use it
I'm planning to use the Nissan Leaf heater as the motor and inverter will never provide enough heat to warm the cabin. Its a 5kW HV water heater so it should be fairly easy to plumb into the Freelander matrix.
As for an air source heat pump I wouldn't know where to begin.
I still have the components for the air con tho so interested to hear your idea.
Headsup - this is going to be a "wall of words", but if I've taken the time to write them, I'm hpoing you'll take the time to read them?
How an air source heat pump works is expained in that video I linked, 'yanks often call it reverse air conditioning, and it is exactly that. To put it in context for you, allow me to give you a primer on refidgeration, AC101 if you will, although I have to admit that I'm a little bit rusty on reefer stuff, so I'd want to do my homework before we commit to any purchases, but I know enough to outline the concept for you here...
First off, you know 0° isn't absolute zero, as we can get minus temperatures, well absolute zero is -273.15°c = 0k where K stands for Kelvin. So even at -10°c there is still 263.15°c above absolute zero. This means there is always SOME heat in there, even if it is literally freezing. Another key principle is that the boiling point of fluids is related to atmospheric pressure,the lower the atmospheric pressure, the lower the boiling point. So if you stop for a brew up half way up everest, the water would boil at a lower temperature than if you were making the same brew up at the seaside. These might initially sound irelevant, but they are important facts that come into play later on.
If you think of how aircon works in your car, it's just two heat exchangers, one in the dashboard, one in the engine bay, a pump and a couple of valves, all piped together. To cool the cabin, liquid refrigerant is pumped into an expansion valve, which is just a flow restrictor, in front of the the heat exchanger in the cabin, called the AC evaporator. When the refridgerant goes through the flow restriction of the expansion valve, and into the evaporator (heat exchanger) it experiences a reduction in volume, before encountering more room to expand, resulting in a pressure drop. But to expand to fill that larger volume, the refridgerant needs to absorb heat to boil it into it's gaseous state, which it does by taking heat from radiator like element of the evaporator, which in turn takes heat from the surrounding air which is on its way to the vents, and boom - the air gets colder.
So now we have gaseous refridgerant coming out of the evaborator going back to the pump (compressor), which then compresses the gas back into a liquid state by pumping it in to a smaller volume, increasing the pressure of it. However, the gas that's just been turned to liquid still has all the heat it absorbed from the evaporator and used to expand, so as it's volume decreases, its temperature increases, pascals law applies here, so to dump that heat, rather than melt the pump with the roasty hot temperature it would increase to, the gas goes through the heat exchanger in the engine bay, known as the "condensor" or "AC radiator", which allows the gas to reduce it's temperature in muhc the same way as an intercooler works. The gas cools, and gets forced against another flow restriction to increase it's pressure and help it liquify, and then the compressor pumps the gaseous/liquid refrigerant back into a pressurised liquid and back to the evaporator in the cabin and so the cycle begins again.
TLDR - through clever manipulation of the pressure, liquid refrigerant is tricked into boiling in the evaporator in the cabin to rob heat from the air heading for the vents, it then transports that heat to the Condensor / AC radiator at the front of the vehicle and radiates the heat out there.
For the airsource heatpump idea, you'd want to effectively reverse the function of the two heat exchangers, so the refridgerant is expanded by heat from the outside world, puts it into the refridgerant, and dumps that heat into the air going into the cabin's air duct. So essentially you'd want to pump the gaseous refridgerant into the AC element in the heater blower/matrix/AC box, then force it to condense in there, dumping it's heat, into the heat exchanger and thus into the air going to the vents, then the liquid refrigerant would head back to the AC radiator in the engine bay, where it would absorb more heat, turning it back into a gas, which gets pumped to the cabin again, where it dumps more heat.
It's a bit convoluted, but it would consume less electrical power for the same amount of heat in the cabin than just using the electric resistive heater would consume. Which in an EV such as this would help maximist battery charge to range conversion. It also has the advantage that with a bit of clever thinking, we could set this up as a reversable system, where you could retain AC for the "hot" days (if NI's climate's like NE Scotland's hot is a relative term, say double digits) and able to use it as a more efficient heater in the more typical days we get in out locales.
How an air source heat pump works is expained in that video I linked, 'yanks often call it reverse air conditioning, and it is exactly that. To put it in context for you, allow me to give you a primer on refidgeration, AC101 if you will, although I have to admit that I'm a little bit rusty on reefer stuff, so I'd want to do my homework before we commit to any purchases, but I know enough to outline the concept for you here...
First off, you know 0° isn't absolute zero, as we can get minus temperatures, well absolute zero is -273.15°c = 0k where K stands for Kelvin. So even at -10°c there is still 263.15°c above absolute zero. This means there is always SOME heat in there, even if it is literally freezing. Another key principle is that the boiling point of fluids is related to atmospheric pressure,the lower the atmospheric pressure, the lower the boiling point. So if you stop for a brew up half way up everest, the water would boil at a lower temperature than if you were making the same brew up at the seaside. These might initially sound irelevant, but they are important facts that come into play later on.
If you think of how aircon works in your car, it's just two heat exchangers, one in the dashboard, one in the engine bay, a pump and a couple of valves, all piped together. To cool the cabin, liquid refrigerant is pumped into an expansion valve, which is just a flow restrictor, in front of the the heat exchanger in the cabin, called the AC evaporator. When the refridgerant goes through the flow restriction of the expansion valve, and into the evaporator (heat exchanger) it experiences a reduction in volume, before encountering more room to expand, resulting in a pressure drop. But to expand to fill that larger volume, the refridgerant needs to absorb heat to boil it into it's gaseous state, which it does by taking heat from radiator like element of the evaporator, which in turn takes heat from the surrounding air which is on its way to the vents, and boom - the air gets colder.
So now we have gaseous refridgerant coming out of the evaborator going back to the pump (compressor), which then compresses the gas back into a liquid state by pumping it in to a smaller volume, increasing the pressure of it. However, the gas that's just been turned to liquid still has all the heat it absorbed from the evaporator and used to expand, so as it's volume decreases, its temperature increases, pascals law applies here, so to dump that heat, rather than melt the pump with the roasty hot temperature it would increase to, the gas goes through the heat exchanger in the engine bay, known as the "condensor" or "AC radiator", which allows the gas to reduce it's temperature in muhc the same way as an intercooler works. The gas cools, and gets forced against another flow restriction to increase it's pressure and help it liquify, and then the compressor pumps the gaseous/liquid refrigerant back into a pressurised liquid and back to the evaporator in the cabin and so the cycle begins again.
TLDR - through clever manipulation of the pressure, liquid refrigerant is tricked into boiling in the evaporator in the cabin to rob heat from the air heading for the vents, it then transports that heat to the Condensor / AC radiator at the front of the vehicle and radiates the heat out there.
For the airsource heatpump idea, you'd want to effectively reverse the function of the two heat exchangers, so the refridgerant is expanded by heat from the outside world, puts it into the refridgerant, and dumps that heat into the air going into the cabin's air duct. So essentially you'd want to pump the gaseous refridgerant into the AC element in the heater blower/matrix/AC box, then force it to condense in there, dumping it's heat, into the heat exchanger and thus into the air going to the vents, then the liquid refrigerant would head back to the AC radiator in the engine bay, where it would absorb more heat, turning it back into a gas, which gets pumped to the cabin again, where it dumps more heat.
It's a bit convoluted, but it would consume less electrical power for the same amount of heat in the cabin than just using the electric resistive heater would consume. Which in an EV such as this would help maximist battery charge to range conversion. It also has the advantage that with a bit of clever thinking, we could set this up as a reversable system, where you could retain AC for the "hot" days (if NI's climate's like NE Scotland's hot is a relative term, say double digits) and able to use it as a more efficient heater in the more typical days we get in out locales.
Alibro
Well-Known Member
Phew. I can promise that I read it but can't promise I understood it all.
So are you saying to take the heat that would have gone to the air con radiator and instead put it in the heater matrix?
But if it is that simple why didn't Nissan do it?
Nodge68
Well-Known Member
Lol!!
I understood it, but luckily I have reasonable understanding of AC and heat pump operation.
Not the heater matrix, but the AC cooler (evaporator) matrix.
They do now and so do many other EV manufacturers. They're called heat pump heaters, but are normally an option.
You're almost right, I'm suggesting you repurpose Aircon componentry to take heat from outside and put it in to the Aircon components in the heater box. It's good for us that as John points out that nissan now offer this as an option, because that means it's an accepted EV technology, rather than a crackpot idea, so there's a chance that others in the EV conversion community are already playing with it, so there could be examples of other projects we can learn from
Tesla have done it for a while - especially on their upmarket cars. I think the main reason Nissan didn't do it on the Leaf, is cost. The 5kW heating element is peanuts compared to the cost of all the parts for (as Jayridium has explained) an aircon system. The science works though. You get about a 4 or 5 -to-1 advantage (so instead of using 5 kW your heater would use 1 kW or maybe a bit more. The disadvantage is that the colder it gets, the harder the heat pump has to work, to "harvest" heat from the colder surroundings. Houses with ground source heat pumps, for example, need an area of ground about the size of a tennis court to keep the house at a reasonable temperature in a British Winter. Likewise air source heat pumps need a big volume of air (which gets bigger as it gets colder) to do the same job.
However, doesn't your old Freelander that you're converting, still have its original fuel burning heater? I realise it probably won't be the completely green alternative and may not get you that many brownie points from Greta, but could you carry (say) a gallon of diesel and burn that in the fuel burning heater to help? (It probably won't be enough to keep the cabin sufficiently warm, but it would help offset energy consumption from the battery a bit!
However, doesn't your old Freelander that you're converting, still have its original fuel burning heater? I realise it probably won't be the completely green alternative and may not get you that many brownie points from Greta, but could you carry (say) a gallon of diesel and burn that in the fuel burning heater to help? (It probably won't be enough to keep the cabin sufficiently warm, but it would help offset energy consumption from the battery a bit!
Alibro
Well-Known Member
I'm aware that several companies have heat pumps in their cars now but didn't a few years ago. I thought perhaps it was a tad complicated or just very expensive so
it seems odd that Nissan Leaf's had air con but not heat pumps in their early cars, especially given how small the battery packs were.
The Freelander I'm using for a test mule is an S model so doesn't have a fuel burning heater. Having said that even if it had one I wouldn't keep it as it would be totally defeating the purpose of the conversion. There is no way I would have my converted car complete with Electric badges pulling up to the diesel pumps for a gallon of Dino juice for the heater.
I'm afraid that heat pumps will have to wait for EV conversion V2.0 or even V3.0. V1.0 is already proving to be complicated enough.
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Nodge68
Well-Known Member
Although effective, using and FBH isn't in keeping with an electric conversion.
So yes, the Leaf electric heater will need to be used.
That's the way I'd go Ali. Keep this one simple, as it's complicated enough already.
What's wrong with a log burning stove with a wacky-racers style chimney? That would work!
May not please Ms Thunberg though...