MassDeduction
Posts: 51
Joined: Tue Feb 25, 2020 3:24 pm

What's better, immediately putting a low battery on charge or leaving it 90 minutes before putting it on charge?

Sun Sep 06, 2020 9:53 am

It's easy to get lists of battery best practices, things such as wait 90 minutes before putting it on charge, not charging it above 80%, storing it near 50%, etc. But they rarely address the fact that some suggestions can be mutually exclusive. For example, if you finish a trip at 25% charge, you're well below the ideal charge to store the car at, but if you immediately put it on charge then you're not giving the battery any time to cool down beforehand.

My normal inclination is to wait 90 minutes, then charge the battery up to only 50%, then set a timer to get it up to 80% right before the next trip. But different battery chemistries benefit more, or less, from the "cool down" period before going on charge. And temperature makes a different too, so I suppose it can depend.

Thoughts on whether someone living in a mild climate with a 2016 Kia Soul EV would benefit more from a 90 minute cool down before any charging, or would benefit more from immediately charging back up to 50%?

JejuSoul
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Location: Jeju
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Re: What's better, immediately putting a low battery on charge or leaving it 90 minutes before putting it on charge?

Sun Sep 06, 2020 11:49 am

-
My practice, if I arrive home at 6pm with 30% and don't need the car again that evening would be :
Plug in and set the timer to start at 11pm when rates are cheapest. Charge to 80%.
This lets the battery cool down first and charges when it is cooler.

I have a 32A charger. If you were charging at 6A you would probably have to start earlier.
The codes for using Torque Pro can be found by clicking the link in the website icon under my user name on the left.

tinsley207
Posts: 6
Joined: Thu Sep 03, 2020 9:36 am

Re: What's better, immediately putting a low battery on charge or leaving it 90 minutes before putting it on charge?

Mon Sep 14, 2020 4:00 pm

I'm interested in this too. I'm new to the form BTW and I'm a proud new owner of a 2016 Soul with 15k miles on it! Today I ran it down pretty far, 14% left. I parked it and set the timer for 80% to start at 4am. That was about 3 hours ago. Should I give it a little "boost" right now to 50%? Or is it ok to sit for several hours at 14% until 4am? Thanks.

PS: I have a 32 amp charger.

MassDeduction
Posts: 51
Joined: Tue Feb 25, 2020 3:24 pm

Re: What's better, immediately putting a low battery on charge or leaving it 90 minutes before putting it on charge?

Fri Oct 02, 2020 2:20 pm

tinsley207 wrote:I'm interested in this too. I'm new to the form BTW and I'm a proud new owner of a 2016 Soul with 15k miles on it! Today I ran it down pretty far, 14% left. I parked it and set the timer for 80% to start at 4am. That was about 3 hours ago. Should I give it a little "boost" right now to 50%? Or is it ok to sit for several hours at 14% until 4am? Thanks.

PS: I have a 32 amp charger.

My current inclination is to think that 14% is too low, and that it would be best to immediately top it up to about 40-50%, then set the timer to later complete the charge to 80%. It's just as undesirable (if not more so) to have it sit below 20% than it is to have it sit above 80%.

I would never let the car sit more than 90 minutes before starting topping it up to at least 50%. And if it was 35% or lower I might put it on charge immediately. You're trading off the value of letting it sit fallow before being charged, vs. the detriment of it sitting at a low charge level longer than it needs to.

It can change from one battery to the next, as different chemistries are more/less tolerant of certain kinds of abuse, but in general I tend to wait 90 minutes, then top up to 50%, then set it for timed charging to whatever I want it at for its next use. The exception is if it's really low, then I put it immediately on charge to get it up to 50%. What's really low is subjective, I suppose. :)

IanL
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Location: Jersey, English Channel Islands

Re: What's better, immediately putting a low battery on charge or leaving it 90 minutes before putting it on charge?

Fri Oct 02, 2020 11:34 pm

I wonder how valid the "letting it cool down" is in temperate climates? To my mind, the battery will charge best if it is at "normal operating temperature", and if the ambient temperature is (say) less than 30C, it should be fine to charge straight away. I have not tested this, but I expect the cooling fan in the trunk will function during charging if required - I believe it takes in air from the cabin which I assume is replaced from outside.

A lot of assumptions there, so I'd welcome other views.

ksoul2084
Posts: 122
Joined: Thu May 16, 2019 10:48 am

Re: What's better, immediately putting a low battery on charge or leaving it 90 minutes before putting it on charge?

Sat Oct 03, 2020 7:58 am

IanL wrote:I wonder how valid the "letting it cool down" is in temperate climates? To my mind, the battery will charge best if it is at "normal operating temperature", and if the ambient temperature is (say) less than 30C, it should be fine to charge straight away. I have not tested this, but I expect the cooling fan in the trunk will function during charging if required - I believe it takes in air from the cabin which I assume is replaced from outside.

A lot of assumptions there, so I'd welcome other views.


I agree with your assessment. To my knowledge it is more efficient/better to charge a battery that is already warm as it lowers resistance in the pack. Unless you are talking about a climate where it's >35c outside I'd charge as soon as I parked.

I believe with the latest firmware updates the car will engage the AC and the battery fan to control temp. if necessary. Living in Canada, and usually charging using Level 1 it's not something I've experienced. :)

MassDeduction
Posts: 51
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Re: What's better, immediately putting a low battery on charge or leaving it 90 minutes before putting it on charge?

Sat Oct 03, 2020 11:18 am

ksoul2084 wrote:
IanL wrote:I wonder how valid the "letting it cool down" is in temperate climates? To my mind, the battery will charge best if it is at "normal operating temperature", and if the ambient temperature is (say) less than 30C, it should be fine to charge straight away. I have not tested this, but I expect the cooling fan in the trunk will function during charging if required - I believe it takes in air from the cabin which I assume is replaced from outside.

A lot of assumptions there, so I'd welcome other views.


I agree with your assessment. To my knowledge it is more efficient/better to charge a battery that is already warm as it lowers resistance in the pack. Unless you are talking about a climate where it's >35c outside I'd charge as soon as I parked.

I believe with the latest firmware updates the car will engage the AC and the battery fan to control temp. if necessary. Living in Canada, and usually charging using Level 1 it's not something I've experienced. :)

To be clear, I meant letting it cool down metaphorically rather than literally. It's frequently stated that the battery coming to rest first can be beneficial before re-charging it, with times in the 30-90 minute range frequently cited.

Higher temperatures are more efficient for battery charging and operation, but charging at cooler temperatures is better for long-term battery life. A battery will charge and operate more efficiently in Phoenix, but it will have a longer service life in Vancouver. :)

None of this explicitly confirms whether it's best to immediately start re-charging a very low battery, or to let it sit a bit beforehand. The evidence I've seen, however, suggests that a low charge level damages a battery a lot and putting it immediately on charge after use damages it only a little, so my current thinking is to put a very low battery immediately on charge. The trick is what is "very low"? I'm leaning to 35% as the dividing line, below that put it on charge immediately, above that wait 30-90 minutes before charging it back up to at least 50%.

IanL
Posts: 84
Joined: Tue Feb 18, 2020 12:57 pm
Location: Jersey, English Channel Islands

Re: What's better, immediately putting a low battery on charge or leaving it 90 minutes before putting it on charge?

Sun Oct 04, 2020 4:58 am

Well, it rarely, if ever, gets to 30C here, so my practice of running down to 20-30% and then charging immediately seems ok to me. My car seems to agree:

(149 miles = 238 km)
(long-term efficiency is 5.3 miles/kWh)

Image

ksoul2084
Posts: 122
Joined: Thu May 16, 2019 10:48 am

Re: What's better, immediately putting a low battery on charge or leaving it 90 minutes before putting it on charge?

Sun Oct 04, 2020 5:39 am

MassDeduction wrote: It's frequently stated that the battery coming to rest first can be beneficial before re-charging it, with times in the 30-90 minute range frequently cited.


Interesting, this is not something I'd heard of. Could you post a reference for followup?

If you think about the normal operation of the car it's continually switching between discharge and charge when driving about town due to the regenerative braking.

JejuSoul
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Re: What's better, immediately putting a low battery on charge or leaving it 90 minutes before putting it on charge?

Sun Oct 04, 2020 6:00 am

ksoul2084 wrote:...To my knowledge it is more efficient/better to charge a battery that is already warm as it lowers resistance in the pack...

This is an argument I have had with TeslaBjorn.
It is true that the battery will charge quicker and more efficiently when it is warm.
It also charges faster at the lower end of the SOC curve
His recommendation for long distance drives is to drive fast to a low SOC - then charge faster.

I think this is bad advice. Charging while the battery is hot degrades the battery faster, especially at the very low and very high ends of the SOC curve.
The air pump is not effective enough to counteract the heat build-up in the battery. Even if you have the air-con on full in the cabin.

I argue that it is better for the battery to drive a bit slower, and then charge a bit slower.
It takes a bit longer but it is much better for the long term health of the battery.

MassDeduction - I doubt that 35% SOC is very low. I would guess 15%.

IanL - 238 km at 8.5 km / kWh is great. The best I have got is 211 km at 7.5 km / kWh.
Either a) You have 100 cells - so your car has a higher voltage and hence is more efficient. or b) You have a softer foot than me. or c) your island's roads are much slower than mine. or d) a combination of all 3.
The codes for using Torque Pro can be found by clicking the link in the website icon under my user name on the left.

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