Battery Capacity and Charging

[ChasingCoral]

Yes, for a single cell, the healthiest SOC is 50%. But, when there are many cells involved which are arranged in arrays, it's not realistic to expect the same charge to be on every single cell equally after many cycles that hover around 50% SOC. When you drive, some cells will tend to loose more energy than others. And apparently, charging won't recover them equally if you stop charging too early. Therefore, you'll need to force a full charge (>=90%) occasionally in order to equalize all of the cells. That is why I think Ford recommends charging to 90%. It is a compromise between topping it off and keeping it under 100% to increase longevity.

There is a video from a Tesla tuber talking about this concept:

After watching that video I wonder if 90% might be better for the battery than 80%?

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[machefan]

After watching that video I wonder if 90% might be better for the battery than 80%?

That video is targeted for Tesla, maybe next phone with engineering ask them.

I’m sticking with 90%.

 

[JSW]

I suspect Ford (engineers, lawyers, etc) discussed/debated what % to put in the manual. Ford selected 90%. I’ll charge to 90% unless I really need more for a trip.

FWIW, this debate raged on the Bolt forum for years. (Don’t park/charge in the sun/heat, don’t charge in the cold, don’t charge above 90 %, use “hilltop reserve,” etc.). I ignored all of it for 3 solid years, and my Bolt’s batteries seemed to possess the same usable capacity as the 80% ‘ers.

So why did I ignore the conservative Bolt advice? Because I know me. I knew in 4 years some new technology would come out and I’d want it. Bad. And here I am, 4 years later with a sweet First Edition.

So why am I now following the 90% advice? Well, at least for now I’m unsure whether Ford built in the same extra/unusable capacity and other safe-guards as did GM. Plus, the MMe was more $ than the Bolt, so I feel compelled to enjoy it for perhaps as many as 5 or 6 years.

 

[SJ_Okay]

Reviving this thread now that we have a bit more hands on experience with our cars.

I’ve noticed that when you set a Max Charge Level, the car will condition and balance cells when it hits said charge level. I’ve not tried this at a charge level set lower than 60%, but at 60% it conditions and balances… it also, understandably, takes longer to balance and condition at 70, 80, 90 etc.

Like others, I’m having some issues with charging schedules, departures and max charge levels. Seems the car is prioritising max charge level over everything else and chargers outside windows etc. This has me wondering if it could be prioritising the max charge level because it wants to balance cells? Is this a plausible explanation? It then makes me wonder if I should be setting and hitting a max charge level before each departure for optimum performance and health? If the answer to this is Yes, then I have another conundrum…

Like @Kamuelaflyer, I do very low daily miles and also live on an island. I trickle charge at a speed of 1.4kW between 8am - 4pm in the summer to utilise my excess solar. In this instance, and over the course of a regular driving week, I’ll be able to add around 15% battery, which means I’m normally always hovering around 65- 80% SoC… that means I only ever get a balanced and conditioned battery once or twice a week, since the charge is too slow to hit a rounded off battery percentage AND utilise my solar.

So my conundrum… I would like to continue receiving the free miles I get in the day with my trickle charge, but if I’m not hitting one of the cars 10% set charge levels, I don’t get cell balancing and conditioning. it also means I can’t use scheduled charge times, because I have a max charge level set and the slow trickle is not enough to reach it, so the car charges outside of schedule every time. Very annoying.

Does anyone one on here think this is going to be an issue… not hitting an SoC that triggers cell balancing? If it only happens once or twice a week, will that be okay? The only performance issue I notice is that the car has no lag off the line when the cells are balanced. If not, I often get that short delay between flooring the accelerator and moving off the line… or a slower first few feet before the car kicks in.

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