V2H recommendations

but at what cost ?

Theres some evidence to suggest that the decay in E.V. battery capacity is not entirely matched by a reduction in charge power requirements - in other words, the efficiency of the battery is reduced as well as the capacity.

So, just for one example ... If you were buying an ICE opowered car and the dealer told you that is does 35 mpg then that might be "acceptable" - but if he went on to tell you that within 5 years of normal use and regular servicing it would be doing 25 mpg then you probably wouldnt go anywhere near it

That is the thing. The whole industry seems to be quite unpredictable. It really needs something like the FIT scheme - some sort of framework for 20 years.

In other news I see my battery/inverter people (Givenergy) are going through the early throes of liquidation, and cheering everyone up by suggesting a subscription for using their software. It doesn't matter especially to me - I can tap into open source alternatives. But for many on lower incomes and not willing/able to faff about it does add a lot of uncertainty.

Elderly Leafs and a few battery-owned Zoes can be had for about a grand. eg a listing for 875:

Any losses have to go somewhere as heat, so that would presumably be noticeable? We've not seen elderly batteries slowing their charge speed to reduce battery heating, AFAIK.

Theo

If the charge speed is not reduced, then whats happening with the charge current ?

Some more details:

Seems like the MG4 has good support, and the cheapest on Autotrader is £8k.

Theo

If your technology is crap, get the taxpayer to pay for it instead?

Most 'new energy' companies are headed that way.

Are you seriously asking that question?

yes, seriously - if the charge speed is not reduced and the charge current is also not reduced over time, then the battery degradation amounts to a reduction in "mpg"

I guess you wont be answering that one then

My point was the level of ignorance displayed by asking the question

WTF is 'charge speed' if not 'charge current'?

To hammer home the point, let's look at the energy balance.

A battery has a certain capacity, let's say it's 50kWh.

Degradation means the usable capacity becomes less, say 45kWh on a modern EV or 25kWh in a knackered Nissan. That is normal.

You were talking about efficiency. Suppose the roundtrip efficiency is

Then let's suppose your battery is old and the roundtrip efficiency becomes

Running a 25kW heater while standing still is something you would notice - it's like a hot engine with the fan blasting.

Maybe then that, to reduce the fan heater effect, the charger holds back the current. Now your rapid charge takes an hour instead of half an hour (and the fan heater is only 12.5kW).

Both of those are things you would notice. You would also notice that your range has reduced because now only 50% of the charge you put into the battery is usable energy. The rest is turned into heat.

The energy has to *go somewhere*. You can't just make many-kWh disappear without noticeable effects.

Theo

what I mean by "charge speed" is the amount of time before the battery (regardless of it "efficiency") says that its fully charged.

A degraded battery might do this on a lower current, unless its creating a load of heat

If you dont know the difference between speed and current then your snotty patronising approach to this seems a little misplaced - but it does retain a rustic amusement factor

"level of ignorance" :-\

Did old cars have V2H capability anyway, or is Roland proposing to undertake some pretty major engineering?

In what way is the tech 'crap'? And why should the tax payer pay for it?

Writing was on the wall IMHO. Market seems to be too crowded to support any company with a long term strategy. And the warranties (10yrs+) too extravagant to be real. I suppose I have some support from the installer should anything go wrong - if they're still in business of course.

In message <10r8o9r$gs54$ snipped-for-privacy@dont-email.me, at 18:40:11 on Thu, 9 Apr

That's one half of my question.

I'm prepared to do some wiring, but not any electrical engineering design.

The idea is to get some solar panels, a fairly old EV, and a cheap way to charge the car from the grid on days there's no sun.

Then to have a way to power the house's base-load primarily from the solar using the car's battery as storage. Occasionally actually use the car to go shopping locally (or whatever).

I have plenty of off-street parking, and somewhere to put five or six square metres of solar panels, possibly the new "balcony" ones, if they do start to become available.

In message <10r7ma2$5pnf$ snipped-for-privacy@dont-email.me, at 09:00:03 on Thu, 9 Apr

The depends on whether I use it for more than base-load. According to my smart-meter weekly consumption for all uses (fridge/freezer, daily dishwasher, maybe twice a week laundry) is 70kHh per week. Heating is gas.

The Fogstar battery claims 8000 cycles, or circa 20 years, so the saving over that time (20 minus 12 years, at £630) will be just enough to pay for the replacement of the battery, leading to the question as to whether the exercise is really worth all the faff.

It’s a technical possibility, but is it really a viable one given all the circumstances?

Probably not, but also to note that you don't need to buy a battery to cover all of your consumption on the coldest day of the year. With a say 20kWh battery you might cover all of your baseload and heating in autumn and spring, with only winter needing you to go to the grid during time of use.

Much spreadsheeting required, which will also depend on how much solar you are able to generate. Also how much life you might get out of it beyond the rated cycle life (batteries don't just suddenly fail, they just gradually lose capacity).

Theo