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hi all,

I was browsing the forum earlier, and noted a lot of i3 owners loving their Rex, so it got me pondering an idea, can a Rex genny be fitted as a retrofit, either as a permanent fixture or remove able unit, and integrated into the leaf of env200 models.

I then research the i3 battery.

Ok, the i3 battery uses the same lithium manganese type lion chemistry, with a nom voltage of 3.7v, same as the Nissan, also, they have the same number of cells, the bmw has 96 cells voltage 360vdc, the Nissan, the same 96 cells (albeit in a 48 x 2 configuration, but target voltage is the same.

So, it could be done as the batteries are nigh on compatible, both want 360vdc, and clearly the Rex unit is capable of doing this.

If a Rex became available in a breakers yard for reasonable money, could this be done.

I used to have a Toyota Prius with a plug in hybrid conversion on it, plus some electronics that intercepted some fault codes sent across the can network as it didn't know where the extra energy was coming from, so would want to throw a code, but the electronics would intercept and cancel that particular error code.

For sure the leaf or env200 wouldn't like the extra energy arriving from somewhere, so would also want to throw a code, but as long as we know what codes they were these could also be intercepted.

If the unit wasn't too heavy and the space could be found under the frloor to mount the Rex, why couldn't this b done.

What you think?
 

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The rex adds 120kgs to the i3 curb weight. That's a lot to secure safely. You'd need to mount it "through the floor" of the Leaf boot, as it looks to big to go under and you really don't want it just sat in the boot. You need to put the tank somewhere safe, and the filler somewhere safe, too. I am sure the Rex will be "paired" to the i3 it came from, so tricky to persuade to run, although anecdotally the Leaf won't actually mind about the extra power coming in so you don't have that headache. You'd need to build your own controller for it to, I guess reading the Leaf SOC and sending appropriate messages for what power output you want (and maybe some feedback to you so you know how much petrol is left?)

I think, all told, the cost, including obtaining the rex, the Leaf, any other bits you need, the help you might need with welding etc, and if you value your time at anything more than zero, would very quickly get to be more than the cost of a second hand i3 rex.
 

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I think that the problem will be designing, building and writing software for a control system to run the REX engine. I very, very much doubt that you can just fit a BMW REX controller in a Leaf and have it do the right thing.
 

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Save yourself the hassle and trouble, if you need more range buy a diesel Van. You would be unlikely to ever get a REX to talk Japanese sufficiently to make it work. BMW signalling protocols are completely different to Nissan, Nissan use CAN, other than providing the required CAN interface very few BMW subsystems communicate with each other using CAN.
 

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I think that the problem will be designing, building and writing software for a control system to run the REX engine. I very, very much doubt that you can just fit a BMW REX controller in a Leaf and have it do the right thing.
The engine probably has it's own controller, and I suspect the main vehicle controller just tells the REX how much power to deliver. So yes you'd have to create something with pretended to be the i3 main controller telling the REX controller what to do, taking hundreds of hours of watching can traffic on a functioning system, reverse engineering and testing testing testing.
 

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Save yourself the hassle and trouble, if you need more range buy a diesel Van. You would be unlikely to ever get a REX to talk Japanese sufficiently to make it work. BMW signalling protocols are completely different to Nissan, Nissan use CAN, other than providing the required CAN interface very few BMW subsystems communicate with each other using CAN.
Oh that surprises me, what do they use?
 

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On top of all that, you need to provide cooling and a fuel tank. I suppose the fuel system could come from a scrapped i3.

The engine cooling on the i3 Rex is complex and is integrated into the i3's cooling system.
 

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On top of all that, you need to provide cooling and a fuel tank. I suppose the fuel system could come from a scrapped i3.

The engine cooling on the i3 Rex is complex and is integrated into the i3's cooling system.
Hmm, that's tricky. I doubt the Leaf cooling system could cope at motorway speeds if the rex were plumbed into it.
 

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Hmm, that's tricky. I doubt the Leaf cooling system could cope at motorway speeds if the rex were plumbed into it.
And the battery needs cooling too, air cooling of the NV200 probably wont cut it, the spec for the i3's coolant system can evacuate 1kW of heat from the battery alone.
 

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i3Cooling copy.jpg


i3 cooling system schematic The part in the dashed line is the only on the Range Extender.

1 - Radiator
2 - Electric coolant pump
6 - REME - Range Extender Electrical Machine Electronics
7 - REx electrical machine (motor - generator)
8 - coolant pump
9 - Electric fan
11 - combustion engine
12 - coolant temp sensor
13 - expansion tank
14 - thermostat
15 - coolant to coolant heat exchanger
18 Electric fan
 

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Fan number 9 keeps the engine compartment air temp from getting to hot.
And it does get quite warm, it vents in the offside wheel arch. Uses wheel spin to keep it fed with fresh air, clever.
 

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Discussion Starter #14
Ok thanks for those replies

Very interesting to see the level of cooling bms have installed, is that due the fact that they have to cover all markets whether their climates are cool like ours or hot like Arizona, I can't tell you the last time I heard the cooling fan running on my Peugeot expert actually, don't think I've ever heard it running and I've had the van for 4 years.

It does make you wonder though with the applause the Rex gets why Nissan hasn't tried to emulate something similar and even offer it as an additional retrofit extra.

Like I read earlier, BMw are offering all their i3 customers ( in certain countries) an upgrade from the 60 ah to the new 90 ah battery packs, OK the price isn't yet known but at least they are thinking that way.
 

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Ok thanks for those replies

Very interesting to see the level of cooling bms have installed, is that due the fact that they have to cover all markets whether their climates are cool like ours or hot like Arizona, I can't tell you the last time I heard the cooling fan running on my Peugeot expert actually, don't think I've ever heard it running and I've had the van for 4 years.

It does make you wonder though with the applause the Rex gets why Nissan hasn't tried to emulate something similar and even offer it as an additional retrofit extra.

Like I read earlier, BMw are offering all their i3 customers ( in certain countries) an upgrade from the 60 ah to the new 90 ah battery packs, OK the price isn't yet known but at least they are thinking that way.
Well at peak output the Rex makes 30kw of electrical energy, that's probably ~33kw of mechanical energy going into the MG, so 3kw of heat there. The engine itself is making about 66kw of heat, good news is 44kw of that goes out the exhaust but 22kw goes into the coolant loop, so 25kw. If the car is using all that 30kw (we're tanking along at 85mph) then it too is dumping about 5kw of heat (from the inverter and the traction motor) into the loop, so at least 30kw of heat going in there all together. If you are overtaking someone then temporarily you might be pulling an extra 70kw from the battery, so you'll get battery heat and extra heat from the motor/inverter too.
 

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Discussion Starter #16
Any idea on how efficient the leaf or env200 is at dissipating the heat they actually generate in real world driving applications, I know the env tries to air cool but it's hardly an effective solution like water coolers heat sinks etc..... What in real terms does 5kw of heat mean, what cooling would be required or effective to cool 5kw of heat? And is that 5kw of heat per min, sec, hr, not being a heating engineer trying to get my mind into what may be a requirement

Thanks.
 

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The Leaf does no battery cooling, the ENV200 does battery enclosure cooling (and drops this heat into the AC loop). So on Leaf, with 80kw rated power, there is perhaps 10kw of heat being created (from the motor and inverter, and a smaller load the air conditioner) at maximum output, but Leaf cannot output maximum power for very long at all, firstly because of the speed limiter (100mph indicated is about 40kw on the level) but also because the battery, even on the 30kwh model, would run out in 45 minutes if you were travelling at the speed limiter. The cooling of the motor/inverter/AC is done by radiators at the front of the car, fed by the air intake in the nose. When you look at it, it's comparable to the radiator you'd expect to see on a similar sized car. I don't think it could cope with all of it's own heat if you were able to run the car for 2 hours continuously because of the extra power from the REX, PLUS the heat from the REX, it would just be too much.

To give you an idea, the boiler for my good sized 4 bedroom detached house is 24kw.
 

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And is that 5kw of heat per min, sec, hr,
It is 5kW for however long you run the system :) If you run it for an hour it would be 5kWh of heat.


Edd's approximation is you are adding 25kW of heat for as long as the REx motor is running. I doubt the radiator in the eNV-200 would be large enough to handle the extra heat. It is sized for what is already there.
 

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I think there is some man maths or something going on here. Lets take the NV200 dci - 108hp so 80kW ish. That's only got to deal with around 25kW into the cooling system at peak so the idea of a 34hp genny throwing more out seems a bit off. Infact I make it more like 8kW.
 
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