EV *NiMH* cells. Lithium cells are an entirely different kettle of electrolyte.
(although most of those are prismatic too - Tesla started with laptop form-factor cells and built out from there because the machinery was available, but most other EV manufacturers use larger prismatic cells. Remains to be seen whether Tesla's advantage in battery longevity is due to better cell cooling due to the gaps between the cylinders, or whether that can be achieved with prismatic. I would imagine it probably could)
Some electric vehicles have pre-conditioning cycles you can do while plugged in.
Plugging in, does two things.
1) Charging opportunity.
2) With charging stopped, you can heat cabin interior to comfortable temperature, using mains power and the onboard heatpump. Or, you can heat the battery pack to 25C, while the exterior temperature is -10C. Heat pump based conditioning only works, if there is heat to pump. If the exterior temperature is low enough, resistive heating assist (running off mains power from the charging cable), helps finish the job. The idea is, mains power is being used to beat the vehicle into shape for the trip. Some cars, you leave them plugged in, and they heat the cabin interior to room temp at 8:00AM, you unplug cable and drive off, warm and toasty. Scheduled pre-heat.
While some cars make extravagant claims about cold weather losses, the small print is, you need a preconditioning cycle to help the performance. This will give you a bit more range.
If you drive to the cottage, and the cottage has no mains power, then your return trip has less range than the outgoing trip from home. This is something you have to be aware of, during trip planning. The vehicle has some foggy notion of range. It has a sensor for exterior temperature. It can do the arithmetic. But it's still only an approximation, and the prediction should not be stretched to the max as it were.
Insulating a converted vehicle, will reduce the amount of battery needed to continuously heat the cabin.
Even on an experimental hybrid transit bus, the specs are not overwhelming.
6.0 L, 210 hp diesel engine Enova Systems hybrid system with: Plug-in capability Post-transmission parallel drive 80 kW electric motor 35 kWh Li-ion phosphate battery pack
If you look at enough of these vehicles, you see a theme emerging. and that theme is, for a hybrid, they're just not giving you a giant battery pack. This means the plugin-only range, is limited.
There are serial hybrids, where you have a battery and a kind of "emergency petrol recharger" which work to give you highway capability, but the range without stopping for petrol, is not large. The petrol device in that case, is not an automotive engine. It's a device that runs at a constant speed and runs a genny. I think in one car, it might have been a motorcycle engine. some of these genny-things, use the Atkinson cycle.
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The petrol engine never drives the wheels. There is no transmission, combining the output of the petrol part and the electric (like on some hybrids).
The only reason for even mentioning this idea, is just maybe, you get a larger battery pack with the scheme :-) On a pre-built vehicle.
The “power density” and weight are two reasons. For a given capacity ( A/hr) Li batteries are smaller and lighter.
To give a guide, I have two 110 Ahr Lead acid leisure batteries in my motorhome. I could replace them with one, using have the volume, and probably gain a bit on capacity. Plus, at a guess for a quarter of the weight.
Plus, unlike Lead batteries, which you shouldn’t discharge more than 50% ideally, the useable capacity of Li batteries is at least 80%.
True, Li batteries are expensive, 5x to 10x the cost of a Lead one.
Plus, Lead has other problems. It has its own environmental / health issues. Like Lead, Li can be recycled.
My Outlander’s claimed number is 30 miles or so but they acknowledge it varies. Driving conditions / style make a huge difference. I can manage 33
but on a bad day, cold, traffic, etc it could drop to 10 -15.
We find it ideal for our needs. Most local trips are all electric - we have the option of the larger car if needed or my wife’s small one for local trips- and the hybrid is comfortable for long trips but we don’t need to worry about finding charge points.
We considered an all electric (a Tesla 4x4) but the range and charging issue were show stoppers. We don’t do many long trips in the car ( most are in our motorhome) but we don’t need the hassle of finding chargers etc.
I don't know of anybody using NiMH for a plugin hybrid. A regular hybrid is just using the battery as a buffer for different parts of the driving cycle: acceleration takes power out of the battery, braking puts it back in; and to allow the ICE to turn off (eg in stop/go traffic). There isn't much benefit in having a larger buffer battery for that, because eventually there is no more excess energy to capture. These kind of packs also get a lot of cycles, and NiMH was/is more robust at handling that, especially before modern EV batteries were developed. The way to manage the wear is to only to use the battery between about 30-70% SoC, which meant the usable capacity is about 40% of the nameplate capacity. So your 2kWh NiMH battery is only giving 800Wh of usable capacity, which is about 8 laptops or drill batteries worth.
Once you start going to PHEV you need a lot bigger battery (tens of kWh) and lithium wins for that. It is also a lot less stressful on the battery to do stop/go, because they're now a much tinier part of the overall battery capacity.
One downside with those is it becomes a non-zero-emissions vehicle, so the regulatory position is worse (eg there might be certain areas you aren't allowed to drive a vehicle with an ICE, even if switched off), and you'll be taxed as a PHEV, not a BEV.
In the Toyota system the engine starts 7 seconds after powering up from cold, to make sure the cat is warm for emissions-control purposes. It runs for about a minute then shuts off. If you don't want that you can press the EV button, but there's not a lot of point since it'll run sooner or later anyway.
In a Prius the reverse is pure electric, so it doesn't need the ICE for that.
No, it's a full series-parallel hybrid, just not a PHEV.
The battery is indeed used mostly to 'torque-fill', for regen and for stop/go electric-only use, since ultimately the only source of energy is petrol.
(a mild hybrid typically just has a fancier lead acid battery and a beefed up starter/alternator for a bit of regen and electric assist, but no separate high voltage traction battery)
I get the impression the Outlander is a bit of a lardbutt when it comes to efficiency? How many miles / kWh do you get? What's the petrol-only MPG like?
Yes, mine describes itself as a mild hybrid, though it doesn't do any electric assist, just stop/start and recuperating to the beefier battery during deceleration.
It doesn't earn it any form of "pass" against LEZ charges, other than by being Euro6, it generally gets better fuel economy that the previous car (subject to my right foot) but that could be explained just as much by the 4WD being part-time, rather than permanent.
I mean I was in the electrical and electronics business then, and what we had was lead acid and dry primary cells and that was it. I believe the school had a voltage reference cell of special chemistry.
Nicads, in the shape of DEACs were a novel curiosity. And expensive.
Nickel Iron is of course very old tech, but very few companies made them.
The advantages of lead acid, whereby a milk float had a bank of heavy duty truck batteries (under the seat IIRC) is obvious - any motor factor could supply them
I can see the issue in a factory fork lift - lead acid makes hydrogen if left on charge, and hydrogen inside builds up and can go bang.
The purpose of that sort of hybrid is to maximise fuel efficiency by regenerative braking, having a smaller engine for cruising and having the electrics develop the peak power.
My friend has some form of hybrid and gets 60-70mpg with a decent performance
Well it will do if the NiMH battery is flattish. Normally, mine is EV at low speeds (up to 15-20 mph or so) and petrol after that. If I force it into EV mode around town, then AISB, it will do something over a mile and then drop out and start the engine.
The EV battery improves mileage around town. But, having said that, a 2-hour journey across country usually gives me up to 60mpg. Long term average (over 6 years) has been 55.
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