Electric cars

Martyn1981

Herzlos wrote: »

Presumably you could configure it such that the leisure battery can't drain below x miles or percent of charge, to avoid running it to empty. It just doesn't make sense to physically split the batteries, as the leisure battery could hold a few extra miles of range, or the drive battery could provide a few hours* extra leisure.


*I've honestly no idea how much extra leisure. Standard leisure batteries are essentially 2x 12V car batteries?

Possibly the issue here is that charging the batts from the engine is incredibly inefficient. It's not just the efficiency rating of the engine, but then the losses in the power take off, and the efficiency of the charging equipment such as the alternator. Most likely vastly more efficient to charge from the mains.

I chat with lots of guys who 'play' with batteries, or are off-grid with batteries, and they are starting to come round to Li-ion, though a 'decent' set of ex fork trucks batts is still high on the choice list. But with the Li-ion able to discharge further without harm to the cycle lives, say 80% DoD v's 30-50% DoD for the LA's, plus the size of them, and the weight, Li-ion in campers etc does make a lot of sense, as we move forward, especially as prices keep falling and supply increases (but so does demand).

Only a quick google, so my findings may be questionable, but it seems a LA car batt is around 1kWh and 20kg, so at 50% DoD, two batts give you 1kWh at around 40kg, whereas 2.4kWh Li-ion packs come in at about 1.9kWh (80% DoD) and 25kg, so about 1/3rd the weight (kg/kWh). The Li-ion will also last about 3x the cycles, and suffer far less vampire drain.

AdrianC

Martyn1981 wrote: »

Only a quick google, so my findings may be questionable, but it seems a LA car batt is around 1kWh and 20kg

Bit more than that - a typical leisure battery would be at least 100Ah @ 12v, so 1.2kWh.

so at 50% DoD, two batts give you 1kWh at around 40kg, whereas 2.4kWh Li-ion packs come in at about 1.9kWh (80% DoD) and 25kg, so about 1/3rd the weight (kg/kWh). The Li-ion will also last about 3x the cycles, and suffer far less vampire drain.

But at what cost?

110Ah lead acid for £70
https://www.batterymegastore.co.uk/batteries-by-application/leisure-batteries/caravan-batteries/hankook-xv110.html


100Ah LiIon for... £700

https://www.amazon.co.uk/LiFePO4-LITHIUM-BATTERY-Leisure-Off-grid/dp/B01BDP4T0C

Yes, there's a weight saving - 14kg instead of 23kg, so about 40%.

NBLondon

AdrianC wrote: »

You mean like the one Nissan Spain were waving around this summer, based on the e-NV200?

https://www.youtube.com/watch?v=q1MtYU1ELg4
(The story was that it is/was orderable through dealers, but there's nothing on nissan.es)


Or the ones that various converters have been building on the same base for three years or so?
https://www.hillsideleisure.co.uk/blog/the-dalbury-e-electric-campervan-review/

I was thinking motor home rather than camper van but I'll bow to your actual experience. Bigger roof area means more cells but of course a trade-off with the extra weight and possibly extra gadgets. Cailfornia might be a marketplace for an eWinnebago?

AdrianC

Problem with coachbuilt motorhomes, rather than van conversions, is going to be the base vehicle. The base vehicle that gets ordered is very often what's called a "back-to-back"...


Onto that, a specialist rear chassis is then bolted.

Add water tanks and the like under the floor, and there's less space than you'd expect.


Sure, Al-Ko and the other suppliers of rear chassis can easily start to build chassis that'll take traction battery packs, perhaps by raising the floor height, but you're getting away from the economies of scale from taking a straight, driveable base vehicle. Yes, those back-to-backs are driveable...

Martyn1981

AdrianC wrote: »

Yes, there's a weight saving - 14kg instead of 23kg, so about 40%.

As always, you get it wrong. You've forgotten to take DoD into account.

Regarding cost, I was also looking at batts at around £700, but 2.4kWh, so half the price, and 6,000 cycles v's 1,000-2,000 for the LA's.

So you'd need 3 of those LA's at 50% DoD, to match the Li-ion at 80%, and have to replace them 3 to 6 times, so:

£70 x 3batts (92kg)x 3replacements = £630 or
£70 x 3batts (92kg) x 6replacements = £1,260 v's £700 and 25kg.

But I'm sure you'll explain how this is all wrong, as usual.

[Edit - apologies, I see the link you gave for the LA batts provided a life cycle figure, so I should have used that, not the 1,000-2,000 cycles I assumed for a 50% - 30% DoD.

So using the figures you provided, that's 6,000 cycles divided by 250 cycles = 24 replacements, so the cost comparison becomes:

£70 x 3batts x 24 replacements = £5,040 v's £700.

Sorry again for the poor assumption I made. M.]

Martyn1981

NBLondon wrote: »

Cailfornia might be a marketplace for an eWinnebago?

Short range, but already out there.

Winnebago launches an all-electric RV platform

Martyn1981

Coincidence, but I was watching Transport Evolved yesterday and they mentioned a solar powered EV.

The team behind it have previously (in University) won the annual cross Australia solar powered car competition.

The car being built is however a luxury car and expensive, but ..... PV on the roof!

Their site estimates that for me (Cardiff) at 12,000km pa, we'd get 150 days usage from the solar. Nice.

Lightyear

There's also the Acar and the Sono Sion, that I've mentioned in the past, but these would get much less generation.

zeupater

AnotherJoe wrote: »

Note, all my comments were / are in respect of panels on cars not trailer roofs.


My comment is in respect of, if I had (say)£2k should I spend them on solar on a car, solar on a roof, or just buying electricity. I think that on a car is nearly always the worst option.



With refeence to, on a car, that's fairly obvious I'd have thought. Even best case, some panels are always in the shade, and the whole car may be and no panels will be at optimum angle.

Hi

... Yet there have been PHEV cars with PV assistance for a number of years - Mrs Z had the option on her's but at the time we saw it as being too expensive for the additional benefits ...

As it could possibly double the daily EV range in the right conditions (from approx 15 to 30 miles) and increase efficiency whenever the sky is bright, if/when the price is right it effectively becomes a 'no brainer' so expect to see them as standard fit on many EVs in the future

HTH
Z

AdrianC

Martyn1981 wrote: »

Regarding cost, I was also looking at batts at around £700, but 2.4kWh, so half the price

Link?
The LiIons were the first that came up, so - yes - they may very well not be the most competitive.


Oh, and one of the charging points in town was in use this morning.

By one of these...
https://www.commercialfleet.org/vans/review/first-drive-ford-transit-connect-electric/39931/

zeupater

AdrianC wrote: »

Link?
The LiIons were the first that came up, so - yes - they may very well not be the most competitive.


Oh, and one of the charging points in town was in use this morning.

By one of these...
https://www.commercialfleet.org/vans/review/first-drive-ford-transit-connect-electric/39931/

Hi

Considering the margin of error that would need to be bridged, would you really want to open up yet another can of worms which could only lead to even more argument which you would have little possibility of maintaining, let alone standing a chance of winning? ...

The logic employed by Mart is basically sound so the exact costs are effectively irrelevant!

HTH
Z