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Battery Design and Info
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Battery Design and Info
updated 1 month, 1 week ago 67 Members · 121 Replies
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What about the folks that drive less often. Vehicle sits for three weeks at a time (vacation etc.)?
Would keeping the battery cooler than normal lighten it’s life span?
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@John Shenton Lithium batteries can sit partially-charged for a very, very long time: What you don’t want to do is to fully charge or fully discharge them and then leave them sitting… They seem to be most comfortable in mid-70°F temps – so too cold or too hot make them equally uncomfortable. Think “Goldilocks” and you’ll understand the “care and feeding” of lithium batteries.
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Battery life expectancy is dependent on many factors, the most important is the battery management system (BMS) built into the vehicle and how much control it actually has of temp, charging and discharging. Assuming that the BMS can control all of the factors at all times, the battery should last at least 10 years (while retaining at least 80% capacity), regardless of the number of cycles one will actually do. Actually the battery the battery should remain useful down to 60% or less capacity, so maybe 20 years. The cycle life calculations are done under ideal conditions and even the best practical BMS can not guaranty this. Temp., time, charging and discharge control are the major factors in actual use.
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Here’s some real-world data about the battery degradation of my TM3LR.
We got the car on 8/16/21 and yesterday (5/16/22) it turned 9 months “old”.
During that time we’ve driven the car 30,229 miles with a total of 304 regular AC charges adding 8,090 kWh and 20 times using a supercharger adding 436 kWh.
Compared to the “fleet” (Teslafi using other TM3 with similar odometer reading) at 30,229 miles our TM3 has a now a “rated range” of 341.97 miles while the fleet average is 330.34 miles.
This also proves that driving a lot is certainly NOT a death sentence for a battery as many anti-EV folks wrongly claim – unfortunately such non-sense gets stuck in the heads of the uninformed.My starting range was 345.77 – resulting in a range loss of 3.8 miles or 1.1 %
Good “charging habits” seem to make a huge difference and have a huge and quick impact on battery life. My spouse was in charge of charging while I was gone for 2 weeks starting around 27k miles. The range of our car dropped below the fleet average during that time.
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(Fast charge happens between 20% and 80% battery capacity. Generally charge to 80% and try not to discharge below 20% battery capacity.)
Looking from a battery longevity perspective, does it basically say that you have effectively 60% of your battery to use without potentially causing any negative change in the battery state of health? Or, Maybe only limit a DC fast charge to 80% ? This would totally change my thoughts on which battery to purchase on my Aptera.
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Correct. In real world practice a full range of 250 miles on most EVs produces a highway range of about 150 miles which is plenty for interstate travel in the US. It doesn’t sound like a lot but it’s a good amount. You can DC fast charge to 100% too if needed but it’s not super common. It’s just slower.
More than that would be nice for special circumstances or for skipping areas of poor infrastructure easier. But realistically, modern DC fast charging is to the point (in the US) where you don’t need a lot more than that. 400 would be great and 600 would be just dreamy for long desert trips to non-ev saturated areas and places like Alaska.
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Does anyone know what the projected Aptera battery life is? When it comes time to replace the battery, how much will it cost and who will do it?
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As a rule of thumb a battery should last for at least 500 cycles and as much as 1500 cycles depending on how you treat it. A cycle is defined as 0-100%, so the 400 mile version should last at least 200,000 miles. I haven’t seen anything that mentions the effects of age. They haven’t said what their warranty period will be but the warranty on Tesla’s batteries is 8 years and 120,000 miles (for the LR battery) and 8 years and 100,000 miles for the SR battery. That tells you that Tesla thinks batteries will last for more than 8 years.
Thermal management is very important to battery life. Aptera is using liquid cooling so that should be OK. Nissan used air cooling in the Leaf and it was a disaster, the early Leafs saw very fast degradation in hot climates. Nissan changed the battery chemistry which improved things a bit. Nissan has switched to liquid cooling it the Ariya.
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Battery and battery management technology is getting much better, but for what it is worth my 2015 BMW i3 (with liquid cooling) has 53K miles on it and the battery capacity is down ~15% and most of that was before I owned it at 29K miles in 2018, so the rate of loss slows down over time.
My charging is commonly level 2 from 20% to 100% and with the small battery (22Kwh) in the i3 I expect it has been charged close to 1000 times now. Probably about 5% of charging is rapid charging to 90% on long journeys.
Note. A ‘100%’ charge in the i3 is not actually 100% as BMW limits it (18.2Kwh) protect the battery.
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This reply was modified 1 year, 10 months ago by Graham Smith.
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This reply was modified 1 year, 10 months ago by Graham Smith.
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This reply was modified 1 year, 10 months ago by
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All this can now be rehashed since we know they’ll use the EVE Energy 2170 50E cells.
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Here is a spec sheet on the cells. They seem very similar to the samsung 50g or 50e cells. Most likely this vendor is cheaper which is important because the cells are a huge part of the cost of the vehicle. I could not find any public pricing and don’t know how large EVE is compared to other major chinese cell manufacturers. The search for pricing is not aided by the fact they use the same model number inr21700/50e as samsung.
https://www.evebatteryusa.com/_files/ugd/abe55e_0360b6a842444cefb74d5daf435e2104.pdf
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Will pack voltage change with battery size?
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The battery will consist of multiple battery packs in parallel. Each pack will operate at the same voltage, some where in the neighborhood of 400V. The maximum current will be dependent on the number of packs.
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Do the NMC batteries self ignite as often as Li batteries? Easier or harder to extinguish?
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NMCs are a Lithium battery and yes they can self ignite but it’s a very low probability event, it’s nothing to worry about. EV fires are much much less likely than gas fires, its rare enough that they make national or even international news. Gas fires are so common that they don’t even make the local newspaper, a gas car caught fire in my town last year, the only mention of it was in the Patch.
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We all know the 2170 batteries have a limited amount of cycles before it’ll need replacing,
Depending on the chemistry, it has been stated the best range to charge/discharge the battery is between 20%-30% low to 80%-90% high. If the solar cells continuously charge or peak them out how will this effect the batteries lifespan?
Will there be limits in the software to adjust the lows and highs like other EV’s?
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A good resource for this question can be found at Battery University; if you haven’t seen it.
https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries
Not all charge cycles affect lifespan the same way. As stated in the article above, low charging deltas shouldn’t impact battery life very much, however there is an impact. I would point out the 65-75% charge curve. I think we should be fine. However, I too hope the company builds into vehicle software charge limits. Once the limit is reached, the extra solar could be used to cool/heat cabin or monitor weather/traffic while waiting 😀 There is also energy needed to keep the vehicle even in sleep-mode so probably looks of uses for spare energy. -
I’ve been curious about this too. I’m planning to use my Aptera as a daily driver to and from work almost exclusively. It’s 32 miles one-way. Figuring 35 mile solar charge daily (a little conservative to be slightly more realistic for my location), I shouldn’t have to plug it in. Maybe once every 3-4 months if really needed.
I won’t really be draining the battery and the solar panels will keep it fully charged over a full week. This is what I would consider “normal” use for this vehicle. It makes me wonder how the batteries will hold up long term without more depletion on a regular basis.
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I thought this was a nice video reviewing the chemistry and advantages of Aptera’s battery choice.
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There have been different battery pack configurations suggested by the Aptera Motors graphics department. One suggested multiple flat packs supported on each end, making it look like the different range was determined by the number of these packs. There was also one which had multiple of these packs, but with “humps” in the middle that protruded vertically into the vehicles center tunnel. The latest was a video with Luke in the foreground referencing a more traditional looking pack in the background. ( Art people ! ! ! )
The “Luke” configuration appeared to be multiple cells in a cell module, with multiple modules in a battery pack. This appears to be a convenient and clever arrangement. Sandy Monro videos have shown battery packs with multiple layers of cells.
These modules do not cross the center of the pack. They are butted together in the center. This makes it possible for support “bolts” to pass through the battery pack in the middle, going upward into the vehicle’s tunnel. Thus the weight of the pack can be partially supported by the tunnel. The tunnel would not only give structural rigidity to the vehicle, but it would also help support the weight of the pack. If this configuration is used, about 50% of the weight would be supported by the tunnel and 25% would be supported at each edge. This would help explain the tunnel’s size.
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I am not an expert by any means on this subject- looking for insight? From everything I am seeing in data for these two batteries the NMC battery is superior to the LFePO4 – so I suspect that the reason for creating two different battery sources is more business oriented than engineering?
The new tax credit requirements for the $7500 new EV have slipped into new territory- where any of the RMI (Responsible Mineral Initiative) EMRT/CMRT tracked minerals will be required to be either mined within US, or processed within US to receive 3750 of that credit? Am I correct in this being an issue? Therefore, It seems that the LFePO4 batteries- as they do not include Cobalt (EMRT RMI-tracked mineral) would allow this issue to be moot.
Another area of interest is that the EVE battery sounds as if the would product the battery on US soil – which would allow that aspect of the credit to be eligible? All of these are in question if the 3-4 tire option for what is considered an EV vehicle is not addressed, as well — correct?In any case, this looks to me as if these options are approaches to protect supply chain and assure production in either eventuality, and I believe there are percentage of production goals that must be met to be eligible for credits as well- perhaps there will be a production blend? Different models to use different battery types? I would love to hear other opinions! Cheers.
https://www.responsiblemineralsinitiative.org/reporting-templates/emrt/
https://electrek.co/2022/08/07/senate-improves-ev-tax-credit-in-largest-climate-bill-ever/-
Arguments about longevity and number of charges are really moot. Consider that if you get a 40kwh Aptera and drive it 16000 miles a year, you’ll only need charge it a couple of times a month. Between solar charging in the parking lot and trickle charging overnight, a full charge will hardly ever be necessary. A few hundred charges over the life of the car, maybe 20-30 charges a year. Charging speed at DCFC stations is more important than battery chemistry. Calendar aging is going to be the biggest problem.
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Curious how long we can expect the battery to last if we live somewhere extremely hot half the year like in the Phoenix area. Interior car temps can get to around 160+ if you leave your car unshaded.
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The car will have active battery temperature management. Assuming they do the right thing the thermal management will run when the battery temperature reaches it’s upper and lower bounds.
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Should I expect the battery to drain managing temperature?
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No, because it will be charging from the solar cells.
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According to CA, the 66kWh & 99kWh packs, will utilize “fatter and taller” cells.
Does that mean, one of the Aptera suppliers (and recently tapped by BMW, according to an Electrek article link below) EVE Energy would supply the 4680s “Tesla” cells for these bigger 2nd & 4rth production pack releases?
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@James Gatan To add to what @Curtis Cibinel mentioned, there’s a 2665 cell currently in manufacture: Where 2170 cells have capacities between 4000 and 5000 mAh, 2665 cells have capacities up to 10,000 mAh. The only fly in this suppositional ointment is that Chris said “fatter and taller”: 2665 cells are taller, but more slender than 2170 cells…
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Tesla is using Lithium Iron Phosphate. Are we, and / or should we?
