Volkswagen ID.3 Forum

Hey all,

Just a quick one. Is yo-yo charging the battery bad or harmful. So say I regularly take the battery down to 50%-60% and then charge it back up to 80%. Will that have a negative effect on the battery, am I instead best to always try and hit 10% before charging or? Do we have any advice ?

Many thanks.

VW provide advice here:
https://www.volkswagen.co.uk/en/electri ... ranty.html
They wouldn't advise dropping to 10% unless you need to on a long trip. I think it used to also say that you shouldn't top up unnecessarily every night if you are just using a small amount, but it doesn't seem to say that now. Broadly speaking, for day to day use if you don't need much range, just keep it between 40 and 80%. This aligns conveniently with the available EV tariffs in the UK (Octopus Go) because the most you can charge overnight at a cheap rate is about 45%.
Yo-yoing is usually used to describe something else: alternate fast acceleration and regen to heat the battery up when approaching a rapid charger in cold climates. Whether this also damages the battery if done often I don't know - I expect it could if you overdid it and made the battery very hot but this is a very extreme case as yo-yoing in itself is a niche thing, and the battery cooling system should kick in anyway.

sidehaas wrote: ↑Wed Jun 22, 2022 10:32 am VW provide advice here:
https://www.volkswagen.co.uk/en/electri ... ranty.html
They wouldn't advise dropping to 10% unless you need to on a long trip. I think it used to also say that you shouldn't top up unnecessarily every night if you are just using a small amount, but it doesn't seem to say that now.
Yo-yoing is usually used to describe something else: alternate fast acceleration and regen to heat the battery up when approaching a rapid charger in cold climates. Whether this also damages the battery if done often I don't know - I expect it could if you overdid it and made the battery very hot but this is a very extreme case as yo-yoing in itself is a niche thing anyway.

I will take a read thank you.

For us, lately we are using it so little we can top up once / twice a week at a Tesco's meaning our charge drops to around 55% on avg and then we charge back to 80%. Helps cut costs on our electricity bill because every little helps right .

But I am wondering whether this will cause harm tot he battery if we sustain this for say 1, 2 or even 3 years or whether this is generally alright.

I think that sounds completely fine based on the guidance available

Well, we officially hit the 1st day of Summer yesterday, is anyone now letting battery drop to 20% before charging?

Weather has been scorching recently.

I think do whatever is cheapest whilst keeping it between 20 and 80% is the most logical advice.
I mean how much can you baby the battery …

TheMack wrote: ↑Wed Jun 22, 2022 10:18 am Hey all,

Just a quick one. Is yo-yo charging the battery bad or harmful. So say I regularly take the battery down to 50%-60% and then charge it back up to 80%. Will that have a negative effect on the battery, am I instead best to always try and hit 10% before charging or? Do we have any advice ?

Many thanks.

This is a very good point and a question I have too. In the summer I am reducing the charging rate (to 2 Kw/h) in order to utilise the solar panels. This means I regularly use the the car (on short journeys) before it has charged up to 80% and reconnect on return. Thus the battery is cycling up-and-down more often albeit through a very small percentage range.

Don't know if this is detrimental but figure that it can't be too bad, or at least the benefit of the free electricity outweighs the downside. Would be interested to hear views from any battery experts.....

It's fine, partial charging is the better practice. There's lots of information at Battery University e.g.

https://batteryuniversity.com/article/b ... -to-charge

It depends on how much time you have and how in depth you want to understand batteries I guess, the below is relevant

https://batteryuniversity.com/article/b ... t-chargers

As for charging rates. Best practice is charging at no more than 1C where C is capacity of the battery. So this translates to something like no more than 62kW for an hour or 120kW for 30minutes etc. A 7kw charger is doing little more than trickle charging in reality.

G43FAN wrote: ↑Wed Jun 22, 2022 2:21 pm As for charging rates. Best practice is charging at no more than 1C where C is capacity of the battery. So this translates to something like no more than 62kW for an hour or 120kW for 30minutes etc. A 7kw charger is doing little more than trickle charging in reality.

Actually C rate is not that simple, and does not correlate with time (it is possible to calculate the charging time based on C rate but you cannot increase power and maintain C Rate). Charging at 1C means that you cannot pass a certain amount of Amps into the battery. For a 32Ah battery charging at 1C -> 32A is the max current you can send into your pack. As for the battery, 62kWh is the capacity but depends on the voltage of the pack to know in reality how many Ah (battery capacity) it actually has.
Assuming a pack of 300V, 62kWh battery is actually ~206Ah capacity

javasp wrote: ↑Wed Jun 22, 2022 5:20 pm

G43FAN wrote: ↑Wed Jun 22, 2022 2:21 pm As for charging rates. Best practice is charging at no more than 1C where C is capacity of the battery. So this translates to something like no more than 62kW for an hour or 120kW for 30minutes etc. A 7kw charger is doing little more than trickle charging in reality.

Actually C rate is not that simple, and does not correlate with time (it is possible to calculate the charging time based on C rate but you cannot increase power and maintain C Rate). Charging at 1C means that you cannot pass a certain amount of Amps into the battery. For a 32Ah battery charging at 1C -> 32A is the max current you can send into your pack. As for the battery, 62kWh is the capacity but depends on the voltage of the pack to know in reality how many Ah (battery capacity) it actually has.
Assuming a pack of 300V, 62kWh battery is actually ~206Ah capacity

No it's not simple, but yes it does correlate with time you can't remove the h(our) from the basic principles and leave it making sense? As per your explanation of how to calculate the relationship between V and A it still per hour?
In my very general 'something like' statement I just stated a charging rate of 1C translated to 62kWh or as per your figures 61.8kWh.

If people want to spend a lot more time on it then check the links or some of the other available literature on battery charging. I don't think the average forum member is that interested, they just want a quick answer to questions about yo-yo charging, to which the simple answer is 'No, it isn't more detrimental to battery health'.