EV Battery State of Health
Discussion
I guess knowing the state of health of the EV battery tells helps with buying and selling your car like when you buy second hand smart phone. Thinking about it, you don't want to be buying an EV that is heavily degraded. Yeah I have seen online that Kwik Fit have the facility at selected centres and thought if anyone had the test done and is it something people are generally considering? Unsure if I should consider checking my battery - I guess no harm.
stevemcs said:
Seems odd that people what battery checks on ev s but would never dare ask for a compression test on a petrol/diesel
As for Kwik Fit doing it they sometimes struggle fitting tyres correctly
Engines don’t degrade over time if looked after properly. Batteries just do albeit the degradation on EV’s is way overblown these days. Early ones sure but current ones seem fine. As for Kwik Fit doing it they sometimes struggle fitting tyres correctly
I did one of the Aviloo tests a few months back. Cost about £100 I think. It was South London / Surrey area of that s any use. The report was a piece of paper that really didn’t tell me much more than I could tell off some simple maths on what’s shown on the screen when I start the car.
I had to do it for the car to be accepted on a ship for export.
I had to do it for the car to be accepted on a ship for export.
p1stonhead said:
stevemcs said:
Seems odd that people what battery checks on ev s but would never dare ask for a compression test on a petrol/diesel
As for Kwik Fit doing it they sometimes struggle fitting tyres correctly
Engines don t degrade over time if looked after properly. Batteries just do albeit the degradation on EV s is way overblown these days. Early ones sure but current ones seem fine. As for Kwik Fit doing it they sometimes struggle fitting tyres correctly
Its a bit like getting a bore test before buying a Porsche.
stevemcs said:
Seems odd that people what battery checks on ev s but would never dare ask for a compression test on a petrol/diesel
As for Kwik Fit doing it they sometimes struggle fitting tyres correctly
They managed to fit directional tyres on a company car the wrong way round a few years ago. The fitter and the checker both missed it…As for Kwik Fit doing it they sometimes struggle fitting tyres correctly
They seem pointless to me as they re distorted by a number of factors such as cell balancing and BMS calibration. I know some examine actual battery cell voltages but that s only half the story. Tesla have the ability (albeit through a hidden service menu) to check the battery and it requires about 24 hours and a discharge and slow charge of the battery. Your average quick test doesn t do that and so 96% health v 92% could be the other way around after changing charging and journey habits
The second reason I wouldn t bother is because degradation is not a great measure of potential failure. Sure a battery that one day shows 95% then next 70% could be about to implode, but anecdotally failure is pretty rapid. It s like measuring the compression in an engine only for the big end or timing chain to fail
A third reason, depending on make, there are withheld buffers of capacity which the car releases to maintain a useable level of capacity. I think BMW started this with the i3 which generally appears to hold on very well to its capacity. Measure battery health on such a car and I think it s hard, if not impossible, to tell how much of the buffer capacity has been used. It s akin to a report saying over x% .
My hunch is the battery health industry came about to address a fear and in doing so make cash for themselves. Education seemed less important.
I m more than happy to be educated but I don t believe the figures I read, so may as well not bother asking.
The second reason I wouldn t bother is because degradation is not a great measure of potential failure. Sure a battery that one day shows 95% then next 70% could be about to implode, but anecdotally failure is pretty rapid. It s like measuring the compression in an engine only for the big end or timing chain to fail
A third reason, depending on make, there are withheld buffers of capacity which the car releases to maintain a useable level of capacity. I think BMW started this with the i3 which generally appears to hold on very well to its capacity. Measure battery health on such a car and I think it s hard, if not impossible, to tell how much of the buffer capacity has been used. It s akin to a report saying over x% .
My hunch is the battery health industry came about to address a fear and in doing so make cash for themselves. Education seemed less important.
I m more than happy to be educated but I don t believe the figures I read, so may as well not bother asking.
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