Would you buy a year old EV with only 1500 miles?
Discussion
Been looking at getting a Citigo EV or one of its cousins and a very low mileage year old example has become available. My worry is how can you tell how the battery has been charged in the last year…has it sat empty etc with the degradation that apparently brings. I know more sophisticated EVs have ways of being ‘questioned’ but I assume that’s not the case with more basic models?
Buy it. The battery will be perfect.......
There, next question ;-)
If the battery has been left "flat" when new and has eventually self-discharged below the min operating voltage, all that will happen will be that the BMS will prevent the car powering on, and it will require a specific recovery sequence/charge before it will work again. In reality, the car would have to have been at pretty much zero percent SoC and left for many many months for this to have occured because the self discharge rate of a modern lithium cell is really very very low indeed
There, next question ;-)
If the battery has been left "flat" when new and has eventually self-discharged below the min operating voltage, all that will happen will be that the BMS will prevent the car powering on, and it will require a specific recovery sequence/charge before it will work again. In reality, the car would have to have been at pretty much zero percent SoC and left for many many months for this to have occured because the self discharge rate of a modern lithium cell is really very very low indeed
Bobtherallyfan said:
Been looking at getting a Citigo EV or one of its cousins and a very low mileage year old example has become available. My worry is how can you tell how the battery has been charged in the last year…has it sat empty etc with the degradation that apparently brings. I know more sophisticated EVs have ways of being ‘questioned’ but I assume that’s not the case with more basic models?
It's equally as damaging to the battery to leave it at 100% charged for long periods, but still a good buy if the price is right.kambites said:
I'd imagine all EVs have a means to query cell health. Leafs certainly do and you don't get much simpler than that.
My first gen leaf has a fairly easy way of monitoring the battery state. I’m almost certain the VAG product will have similar. Unknown how easy it is, but I’m sure the Internet knows. Bobtherallyfan said:
I know more sophisticated EVs have ways of being ‘questioned’ but I assume that’s not the case with more basic models?
How long do you plan to keep the car for? And what is the minimal acceptable range in 5 years time for you?Some EVs suffer horrific longterm battery degredation, how the owner of an EV treats the battery has an impact on long term battery health.
A badly treated EV battery pack will have significantly(20%) degredation even after just 50k miles.
https://youtu.be/jA2PWiRfBOg
Edited by gangzoom on Thursday 26th May 06:39
kambites said:
I'd imagine all EVs have a means to query cell health. Leafs certainly do and you don't get much simpler than that.
Why don't you ask at a Skoda garage if they have a means to do a healthcheck?
Leafspy can be 'tricked', I suspect all BMS systems can be 'reset' after all if you delete all historical data and not charge the car how would the BMS know anything about the health of the battery cells? The BMS will than have to just use 'default' values.Why don't you ask at a Skoda garage if they have a means to do a healthcheck?
Am surprised so many people are not worried about the state of the traction battery on EVs!
Combustion engines have built in safety limits with rev counters and limp modes etc. No one here would want to buy a combustion car that's been driven to the rev limiter from a cold start every day by its previous owner.
Loads of DC rapid charging, leaving battery packs empty or full, there are now lots of real world examples of used EVs having much much higher degredation than the 10% at 100k+ miles after 10 years we are told to expect.
Personally I would be very weary of buying an used EV without knowing its charging history. Even brand new no manufacturer will cover degredation unless its more than 30% after 3-4 years, pretty worthless if the OP wants to keep the car for longer.
gangzoom said:
Leafspy can be 'tricked', I suspect all BMS systems can be 'reset' after all if you delete all historical data and not charge the car how would the BMS know anything about the health of the battery cells? The BMS will than have to just use 'default' values.
Am surprised so many people are not worried about the state of the traction battery on EVs!
Combustion engines have built in safety limits with rev counters and limp modes etc. No one here would want to buy a combustion car that's been driven to the rev limiter from a cold start every day by its previous owner.
Loads of DC rapid charging, leaving battery packs empty or full, there are now lots of real world examples of used EVs having much much higher degredation than the 10% at 100k+ miles after 10 years we are told to expect.
Personally I would be very weary of buying an used EV without knowing its charging history. Even brand new no manufacturer will cover degredation unless its more than 30% after 3-4 years, pretty worthless if the OP wants to keep the car for longer.
This is why I have TeslaMate logging all charging sessions. When I come to sell my M3P I can hopefully placate any qualms a potential buyer has with “full charging history”.Am surprised so many people are not worried about the state of the traction battery on EVs!
Combustion engines have built in safety limits with rev counters and limp modes etc. No one here would want to buy a combustion car that's been driven to the rev limiter from a cold start every day by its previous owner.
Loads of DC rapid charging, leaving battery packs empty or full, there are now lots of real world examples of used EVs having much much higher degredation than the 10% at 100k+ miles after 10 years we are told to expect.
Personally I would be very weary of buying an used EV without knowing its charging history. Even brand new no manufacturer will cover degredation unless its more than 30% after 3-4 years, pretty worthless if the OP wants to keep the car for longer.
As it stands, my battery has never been charged beyond 90%, usually 80%, has only been rapid charged twice, and only been under 20% once (to 19%).
Just had a great demonstration of how utterly useless it is to rely on BMS figures to calculate battery health (even on a Tesla).
Our EV has a 72.5kWh usable pack new, its now coming up to 5 years old and 50k miles. It's charged to 60-70% most of the time, and get DC rapid charged once a month. I can count on one hand the number of times I've let the SOC drop below 10% in 5 years and only once below 5%.
The last 6 months or so the BMS was reporting a usable energy status of as low 62kWh, which would translate to a massive 14-15% degredation.
Off to France today, so charge up to 100% from 50%, the car is now balancing the cells, but 34kWh added to the battery for 50% SOC would represent 6% degredation which is expected for a 5 year old Tesla.
To take any single 'battery health' reading from any BMS from any EV without understanding the history/context is pretty much worthless. It's like a used car dealer telling you the car has had 'careful owners'.
.
Our EV has a 72.5kWh usable pack new, its now coming up to 5 years old and 50k miles. It's charged to 60-70% most of the time, and get DC rapid charged once a month. I can count on one hand the number of times I've let the SOC drop below 10% in 5 years and only once below 5%.
The last 6 months or so the BMS was reporting a usable energy status of as low 62kWh, which would translate to a massive 14-15% degredation.
Off to France today, so charge up to 100% from 50%, the car is now balancing the cells, but 34kWh added to the battery for 50% SOC would represent 6% degredation which is expected for a 5 year old Tesla.
To take any single 'battery health' reading from any BMS from any EV without understanding the history/context is pretty much worthless. It's like a used car dealer telling you the car has had 'careful owners'.
.Or you just do like me and don’t give a toss. I appreciate that Tesla uses less margin than most and pushes the problem to the owner to get impressive looking numbers on their web site but all or nearly all other manufacturers have ample margin to avoid stressing the battery when “full” or “empty”. As much as I’m concerned about anything in relation to this, I would be more concerned about very fast charging.
I do think some concern on a very low miles EV is warranted, though. If the battery does discharge below the minimum then that is very bad as we all know. This would actually worry me the most of all potential worries. It’s absolutely not a problem now but maybe when things return to normal, a dusty EV that’s sitting at the back of the used car lot with rusty discs is probably best avoided.
Those battery health readings from the car itself is total fiction in my experience. I think they mostly tell you what the ambient temp is tbh.
I do think some concern on a very low miles EV is warranted, though. If the battery does discharge below the minimum then that is very bad as we all know. This would actually worry me the most of all potential worries. It’s absolutely not a problem now but maybe when things return to normal, a dusty EV that’s sitting at the back of the used car lot with rusty discs is probably best avoided.
Those battery health readings from the car itself is total fiction in my experience. I think they mostly tell you what the ambient temp is tbh.
BertBert said:
Just curious and off topic sorry, how do people charge their EVs up to a certain percentage that's below full? Do you watch it and unplug it at the vital moment?
Like this (Tesla app):
Or this (Ohme app):
Edited by paradigital on Saturday 28th May 11:13
Edited by paradigital on Saturday 28th May 18:01
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