Precondition batteries without charging

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Kristian

Active member
Joined
Apr 23, 2018
Messages
32
Location
Wiltshire, England
Hi,

Only had my i3 a few months and trying to work out how best to charge it.
Can I warm the batteries without charging them?
My Office is offering free charging so if I can charge for free at work and then the next day I want to be able to warm my batteries and cabin, but not charge the batteries before setting off for work (28 miles)

I'm looking to keep the car a long time and will be doing around 15,000 miles so want to treat my batteries well.

Thanks
 
The cabin can be preheated without being plugged into an EVSE. But I don't think that the battery pack can be heated (preconditioned) without being plugged into an EVSE. You could plug in the 120 V Occasional Use Cable (OUC) that is included with your i3 when you precondition your battery pack. Preconditioning can use more power that the OUC can provide, so the battery pack's charge level would usually be lower after heating depending on the pack's temperature. So you could minimize your home electricity usage in this way.
 
Thanks for the reply.
I don't mind using the OUC to warm the batteries but couldn't find an option to do it.
Currently I only charge the car using the OUC as it can fully charge the battery overnight, but then the UK version is rated at 2.4kw.

And now with the office providing charging I won't bother getting a fast charger installed at home.
 
The electric battery heater element is 1Kw. The cabin conditioning can be more than that, depending on conditions. The 120v OUC can't keep up most of the time. The 240v unit sold elsewhere might be able to, but maybe not on the REx, again, depending on conditions.
 
Kristian said:
I don't mind using the OUC to warm the batteries but couldn't find an option to do it.
Currently I only charge the car using the OUC as it can fully charge the battery overnight, but then the UK version is rated at 2.4kw.
We live in the tropics, and our i3 doesn't have the heated seats and battery pack heater option, so I have no experience with preconditioning the battery pack. A departure time must be set before preconditioning is possible, so maybe this has to be done before the preconditioning option is displayed.
 
The battery heating is only necessary for longer ranges and faster DC charging.
The liftime won‘t decrease if you drive with a cold battery.
 
DeJay58 said:
The battery heating is only necessary for longer ranges and faster DC charging.
The liftime won‘t decrease if you drive with a cold battery.
By having a warm battery then in the long term the battery will have gone through less charge/discharge cycles. If you only do low annual mileage then maybe not worth it. I do 20,000 miles a year so am looking to get the best out of the battery over the long term.
 
The rate at which the battery can charge will be somewhat dependent on its temperature, but don't think it really affects its life. IF the battery is too cold or hot, the conditioning will occur maybe even prior to much charging occurs.

The OUC supplied in the UK might be enough to warm the battery pack and precondition the cabin without drawing down the battery, but it's likely going to take more power than the OUC can provide. While hooked to my 32A, 240vac EVSE, I've seen it drawing over 20A during this phase even after the battery was fully charged earlier.

There will be no battery conditioning done unless it is hooked to an EVSE, but you do have the option of conditioning the cabin.

My guess is that the batteries will warm up if you set a departure time while on the OUC, but you may not end up with a full battery if you also ask it to precondition the cabin as the combined load may exceed what the OUC can provide. I think it's limited to about 10A, and, as I said, I've seen my vehicle drawing over 20A at the same input voltage during that process.

It doesn't make a lot of sense to use battery capacity to warm itself, at least not with the current tech. There are some battery packs with internal heaters that might work, but they aren't used in the i3.

The actual act of charging the batteries will warm them somewhat, so you might get more benefit from telling it to use a low-cost charging window the is near your anticipated departure time. So, in the process of charging them, they'll warm somewhat. That also requires setting a departure time. IF the starting charge is low, that window may be ignored so that it can achieve full charge.
 
https://www.youtube.com/watch?v=KNC2LgMB1no
Watch this video @ 19:50

The video clearly states that "the i3 is equipped with intelligent heating and cooling system that is engineered to keep the battery in the ideal temp range, thus ensuring the range is not negatively impacted". So, one would have to assume that the battery management is always on?

I personally have noticed that I am losing range by parking over night in cold temperatures without the vehicle plugged in. I have also noticed that the range is negatively affected in cold temperatures in "comfort" mode and "eco pro" modes. But the range is NOT negatively affected under "eco pro plus" mode.
 
samomc said:
https://www.youtube.com/watch?v=KNC2LgMB1no
Watch this video @ 19:50

The video clearly states that "the i3 is equipped with intelligent heating and cooling system that is engineered to keep the battery in the ideal temp range, thus ensuring the range is not negatively impacted". So, one would have to assume that the battery management is always on?

I personally have noticed that I am losing range by parking over night in cold temperatures without the vehicle plugged in. I have also noticed that the range is negatively affected in cold temperatures in "comfort" mode and "eco pro" modes. But the range is NOT negatively affected under "eco pro plus" mode.

The optimum temperature for the battery is around 30°C (David Bricknell book on i3).
My highest range I've seen on the GOM was 178 miles (eco pro plus) - The temperature that day was 28°C last summer.
 
I'd be surprised if the battery temperature system wasn't the same on every i3 to include both heating and cooling. In places like HI, the dealers may never decide to spec a vehicle with the heated seats.

I've seen my range estimate drop by moving it from a 60-degree garage and sitting overnight in 30-degree weather by as much as 20% or so. The thing only having been driven about 100' for less than a minute to reposition it. Temperature does matter.preconditioning does help recover some of that, but depending on how cold it is outside, probably not all of it.

Given the OUC sold in the USA is 10 or 12A depending on the MY, at 10A, that's only 1200W, or only slightly more than the battery heater's 1Kw drain. If you'd asked it to precondition the cabin, that way exceeds the power available. IT will still try to do it, but will be drawing down the battery some in the process. You'll be comfortable when getting in, but not have the maximum range. If you're going to run the heat anyway, it probably doesn't make all that much difference from an efficiency viewpoint, but does in the comfort aspect.
 
jadnashuanh said:
In places like HI, the dealers may never decide to spec a vehicle with the heated seats.
You'd think so, but you'd be wrong. I think the heated seat and battery pack option is now standard. However, it wasn't in 2014. Living in Honolulu, I didn't want to pay for this option but finding BEV's without this option was difficult. When I questioned a BMW of Honolulu salesperson about why they ordered so many i3's with this option, he told me that drivers with bad backs really loved heated seats :shock: Of course, the real reason is to increase the dealer's profit margin. I found a BEV without this option but had to settle for the ugliest color, Arravani Gray.
 
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