Mo1820
Posts: 18
Joined: Tue Nov 10, 2020 12:22 am

Re: Battery Health Check procedure - correct method?

Thu Jan 21, 2021 8:59 pm

Thanks very much everyone - it’s quite reassuring to see that I shouldn’t get too hung up on the battery range reading / guessometer!

Littlescrote - your term paralysis by analysis is a great bang on description!
I really hope the battery isn’t going to need replacing after 8 years though as I’d like to keep the car for longer than another 3 (it’s reg is March ‘16).
I thought the battery warranty was 8 years or 100k miles - so I’m hoping that as the car has done 41k miles it might be ok beyond the 8 years - we’re only occasional users in Zone 2 London with the odd long trip so estimated annual use is only about 3k miles.

Yes ThudnBlundr I read an older thread posted ‘somewhere’ on this forum about SOH readings but frustratingly I can’t seem to relocate it - it also mentioned the reluctance of dealers to test on request.
I recall it mentioned certain good or bad figures/amps? If anyone knows the thread I mean please feel free to direct me?

As I said in my original question, one dealer mentioned the BMU reading should be above 25.6 amp to be considered ‘good’. Out of interest I’d like to know if this is correct info?
It’d be nice to be able to rely on at least one thing a dealer has said. (Sigh!)

He said that he would check that amp figure ‘before’ he sent it to Mitsubushi HQ and before he drained and refilled the battery, sending them the ‘after’ figures for comparison. He said he wouldn’t do the whole battery draining overnight diagnostic if the reading was above 25.6 amp as it would already be deemed healthy(?)

Mitsubishi HQ also said they’d need to be sent the figures for a diagnostic check to be valid.

A couple of dealers did tell me they’d only ever done one or two 12+ hour diagnostic checks ‘on request’ which rarely showed to be bad batteries. They seem to have more likely done overnight health checks for something specifically wrong.

Subject to availability I will also consider the Surrey car - especially if the MMCS glitch/heating timer (separate post) on the Cheshire one can’t be rectified!

greendwarf
Posts: 2242
Joined: Tue Aug 05, 2014 1:32 pm

Re: Battery Health Check procedure - correct method?

Fri Jan 22, 2021 12:45 am

I'm afraid all these either/or warranties are - whichever comes first. So you've only got until next March for a 2016 car, irrespective of the mileage.

My 2014 car with a similar mileage to the ones you are looking at only had a 5 year battery warranty but I am still getting about 22 miles actual range. Like you, I am in Zone 2 with only occasional out of London trips (plus annual holiday to France) - hence about 7k per year. We are the ideal users for a plug-in hybrid.

One thing you should know, is that lithium batteries have a fixed life based on the number of full discharge/recharge cycles - around 2000. This is presumably where the warranty comes from i.e. 250 per year, about 1 a day. If you have less than this - say 2/3 times a week, they will last much longer, twice a day of more e,g. as a taxi and battery life will be much shorter. With a second hand car, you won't know how many cycles have been used so far - unless this is stored in MMC, which I don't have in my Gx3h (OTHER READERS PLEASE ADVISE) - but a high mileage would suggest fewer charges, due to longer journeys.

However, capacity will tail off over time - so less mileage. What Mitsu have done is introduce a buffer of 20% when new which can't be used under normal circumstances. It appears the software is designed to eat into this over time to "disguise" the decline in capacity. I suppose a full battery check readout would show how much of this reserve is left but you would probably need technical knowledge to understand the figures.

A couple of other points - the current Congestion Charge exemption (£10 per year fee to renew) is due to be removed in October this year, and currently for Westminster Council area only parking on street is almost free . You have to pay for the first 10 mins (so they know when you parked) to get up to 4 hours free parking. NB. In practice you can renew by text remotely and pay for another 10 mins to extend for another 4 hours extra time (i.e. less than £2 per day :P )

ThudnBlundr
Posts: 736
Joined: Mon Mar 12, 2018 2:18 am
Location: Yorkshire end of M1, UK

Re: Battery Health Check procedure - correct method?

Sat Jan 23, 2021 5:48 am

The warranty for the battery and EV components for a 2016 car (and indeed a late 2015 car) is 8 years, so you have until 2024 to claim for battery degradation. The mechanical warranty is 5 years for those cars.

I've not seen any definitive reference to this extra 20% which the car then uses. Please could you list your source. It seems strange that degradation appears to be fairly linear despite this extra buffer. Are you saying that the BMU still degrades the battery in a linear fashion, but less than it would otherwise as it's eating into this extra 20%?
2015 GX4hs since 03/18
2015 Renault Zoe R240 owner since 11/17

You may have speed, but I have momentum...Image

Mo1820
Posts: 18
Joined: Tue Nov 10, 2020 12:22 am

Re: Battery Health Check procedure - correct method?

Sat Jan 23, 2021 7:21 pm

greendwarf wrote:
Fri Jan 22, 2021 12:45 am
I'm afraid all these either/or warranties are - whichever comes first. So you've only got until next March for a 2016 car, irrespective of the mileage.

My 2014 car with a similar mileage to the ones you are looking at only had a 5 year battery warranty but I am still getting about 22 miles actual range. Like you, I am in Zone 2 with only occasional out of London trips (plus annual holiday to France) - hence about 7k per year. We are the ideal users for a plug-in hybrid.

One thing you should know, is that lithium batteries have a fixed life based on the number of full discharge/recharge cycles - around 2000. This is presumably where the warranty comes from i.e. 250 per year, about 1 a day. If you have less than this - say 2/3 times a week, they will last much longer, twice a day of more e,g. as a taxi and battery life will be much shorter. With a second hand car, you won't know how many cycles have been used so far - unless this is stored in MMC, which I don't have in my Gx3h (OTHER READERS PLEASE ADVISE) - but a high mileage would suggest fewer charges, due to longer journeys.

However, capacity will tail off over time - so less mileage. What Mitsu have done is introduce a buffer of 20% when new which can't be used under normal circumstances. It appears the software is designed to eat into this over time to "disguise" the decline in capacity. I suppose a full battery check readout would show how much of this reserve is left but you would probably need technical knowledge to understand the figures.

A couple of other points - the current Congestion Charge exemption (£10 per year fee to renew) is due to be removed in October this year, and currently for Westminster Council area only parking on street is almost free . You have to pay for the first 10 mins (so they know when you parked) to get up to 4 hours free parking. NB. In practice you can renew by text remotely and pay for another 10 mins to extend for another 4 hours extra time (i.e. less than £2 per day :P )
GD I’ve heard different definitions about the 5yr/8yr warranties. Where I thought you had 5 years for the car and 8 years for the battery a Mitsubishi HQ customer service advisor (called Ariel) recently told me that only the ‘capacity’ of the battery warranty was claimable for 8 years if it dropped below 70% within that time. Which he said meant that if the car was outside of its 5 year warranty then the rest of the battery wasn’t claimable for the remaining 3 years - just the ‘capacity’ holding part?

If he is correct it sounds like it’d still be expensive to rectify if the capacity dropped lower than 70%, despite having an ‘8 year warranty’?

Good to know that if I charge the battery less often it should last longer. Unfortunately I don’t know whether the previous owner/s ‘rapid’ charged it a lot - from what I’ve read this degrades the battery - so I hope they didn’t. Yes it’d be great if the computer actually displays this info?

Will the battery also hold it’s charge/mileage range if the car is not used for a week or so? (Due to lockdown etc.) Will it also maintain its capacity or will this drop without regular use?

I knew about the congestion charge no longer being free to EV/PHEV users from Oct this year but I didn’t know about the almost free parking in Westminster, thanks GD. I’m obviously wanting a PHEV due to the ULEZ anyway.

ThudnBlundr
Posts: 736
Joined: Mon Mar 12, 2018 2:18 am
Location: Yorkshire end of M1, UK

Re: Battery Health Check procedure - correct method?

Sun Jan 24, 2021 5:24 am

Lithium batteries degrade with use due to charging/discharging. They degrade over time regardless of use. They will happily hold their charge for weeks, though storing a battery with high or low charge also degrades the battery. For long-term storage, it should be around 50% full as this is close to the equilibrium point for the internal chemical reaction.

There is no proof that rapid charging degrades the battery, merely unproven conjecture. And don't forget that in normal driving the car charges the battery way more than 50% of the time once it shows empty (or you press Charge or Save).

Basically using the car degrades the battery; not using it degrades the battery. :roll:
2015 GX4hs since 03/18
2015 Renault Zoe R240 owner since 11/17

You may have speed, but I have momentum...Image

greendwarf
Posts: 2242
Joined: Tue Aug 05, 2014 1:32 pm

Re: Battery Health Check procedure - correct method?

Sun Jan 24, 2021 8:45 am

I don't disagree with ThudnBlundr but we went into the battery technology in great detail in the early years of this forum (not sure if threads are still available) so I am relying my amateur understanding and what aged memory can recall. :roll:

As I remember, whilst it may be lithium batteries do degrade over time anyway, it was shown that the ultimate limiting factor is charging cycles, as I described. No doubt individual usage, including too frequent rapid charging, may have some effect on this, but it would appear to be only marginal.

In the last 7 years there have only be a handful of suspected battery failures and only a couple of warranty replacements, in the early days, that I remember - i.e. manufacturing faults, which would have already surfaced in a second hand car and dealt with.

No, I haven't seen any "proof" about the BMU using the buffer with age but this was suggested as a reason why Mitsu have the buffer at all, rather than offer a longer range when new. One of our departed Aussie contributors did experiments with trying to run the batteries flat by deliberately running out of petrol. As I recall even though showing "No Charge" the car went back into EV mode once the ICE died but he still didn't get to exhaust the batteries - he only got a few miles in Turtle mode down to about 10% capacity.

So unless there is some technical reason that has not been explained here why there is a buffer other than as a reserve to maintain a useable range, why is it there? Of course, very few drivers who measure capacity would have needed it yet (given their relative newness) - so most of us may be using the buffer but don't realise. :idea:

ThudnBlundr
Posts: 736
Joined: Mon Mar 12, 2018 2:18 am
Location: Yorkshire end of M1, UK

Re: Battery Health Check procedure - correct method?

Mon Jan 25, 2021 10:01 am

Batteries degrade more as they near their theoretical capacity, so I wonder if having a buffer at the "top end" would reduce degradation. Most EV manufacturers appear to do this, though it appears that Tesla do not. That would mean that the buffer would remain as the battery degrades, which appears to be borne out in practice. Obviously I don't know either, but this explanation seems to fit the typical degradation pattern.

Not sure if there's anything "at the bottom" as the PHEV tries to maintain significant charge even when showing empty
2015 GX4hs since 03/18
2015 Renault Zoe R240 owner since 11/17

You may have speed, but I have momentum...Image

oscarmax
Posts: 123
Joined: Sat Oct 27, 2018 3:47 am

Re: Battery Health Check procedure - correct method?

Sat Jan 30, 2021 4:34 am

Due to the milder weather yesterday 11 degree C this morning my PodPoint APP recording 9.9kWh for a full charge, normally this time of year due to the colder weather we normally see 9.6kWh.
Mitsubishi Outlander 2.4 PHEV Design 2020 Towing a Swift Conqueror 480 2016 1500kg

Please be patient I suffered a brain injury several years ago and get confused at times

hughwi
Posts: 1
Joined: Fri Feb 05, 2021 11:06 am

Re: Battery Health Check procedure - correct method?

Fri Feb 05, 2021 11:19 am

I am in a very similar situation to the OP having just purchased a September 2017 4hs from a car supermarket and I have been getting really variable range readings (from 9 to 30 miles) after a full charge off a 13a home socket.

I bought an OBD2 dongle and with the free version of the phev watchdog app can see that the battery has a SOC of 77% and 31.2aH - I'm slightly surprised that it's so low and the car has only done 32k miles.

I was considering taking it into my local dealer and seeing what they could do under the warranty (I have read several reports of people managing to get their local dealers to do the battery cell smoothing procedure under warranty) but am sure I will just be fobbed off.

greendwarf
Posts: 2242
Joined: Tue Aug 05, 2014 1:32 pm

Re: Battery Health Check procedure - correct method?

Sat Feb 06, 2021 2:31 am

Battery degradation is not linked to mileage but the number of recharges, with a lifetime limit of around 2000 full cycles. So a car only used in EV for most of its life will show a greater decline than one used for mainly lengthy journeys powered by the ICE.

However, I would not judge battery effectiveness by what the guessometer shows - especially when it gives the wide variety you report. This is more likely to be a function of the different types of journeys you have undertaken e.g. lengthy downhill stretches under EV power (i.e. coasting) can produce ridiculously high range forecasts, if done just before charging - similarly, living at the top of a hill will demand a lot of energy to lift 2 tonnes in altitude whilst only travelling a short distance horizontally. :idea:

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