Charging opinions

[hgmichna]

I am sure these questions will have been covered somewhere, but I am going from about 65% to about 80% (I don’t think it shows exact% anywhere) daily and charge at 32amps. Lately I have lowered the charge rate to 20 amps. Any thoughts on that. Lower rate should mean inside battery lower heat. Also, my full battery mileage has been creeping downward over the last 6 months from about 219 to 202 Is this a real loss or a brick thing?

If you are sure that you need only 15% a day, you might consider going from 45% to 60% instead and charge higher only if you need it.

Lower current is, of course, always a bit better, but not because of heat, but because of the charging voltage. Li-ion cells begin to suffer when charged above 3.92 V, which is about 60% state of charge. But the degradation is gradual and not catastrophic. Elon Musk once mentioned that repeated charging to 80% is OK.

If you charge overnight, you can calculate how much current you actually need and don't use a higher current that you don't need.

All these measures will pay off only slowly, because the batteries are quite resilient. If you reckon you often need 80% or 90% charge, by all means charge up. If you drive a lot, a new battery after 6 years doesn't seem too expensive.

As to the mileage going from 219 to 202, that's a loss of about 8%. From what I read, that's a bit on the high side, but not outrageously so. Some people report a loss of 6% in the first year, then 2% per year. It depends on how much you actually drive and charge and how often you use fast charging.

But these figures are created by the software and are not entirely reliable. Theoretically they could change with a software update. It is better to watch the actual energy going into the battery.

 

[dmurphy]

Kind of implied based on the words and tone of your post.

Thread title: "Charging opinions"

Opinions are like buttholes... everyone's got one, and they usually stink. (Mine included - opinion, anyway... LOL)

 

[camalaio]

... Elon Musk once mentioned that repeated charging to 80% is OK. ...

I think this is the greatest part.

Regarding needing range: "Charge to 90% to 95% & you’ll be fine" [link]​

When asked best range for 50% usage, for health: "80% to 30%" [link]​

There's apparently some other quote from him regarding long-term storage where he recommended a lower SoC, but I can't find it.

Point is, ideal charge amount is very situational. Need all the range, but still care? 90-95%. Use 50% every day but want best health? Charge to 80% only. Need to store it? Don't charge it quite that high. Everyone note that he didn't say 80% vs. 90% didn't matter - there is clearly a difference. Likewise, he said 95% is "fine" given those circumstances, not ideal (and note he's not recommending 100%, but only because of lack of regen?).

The man we keep quoting hands out different recommendations depending on the case, just like we do here.

So basically, if you don't want to think about it, don't. But if you do, then it varies. I really can't blame people for thinking this is complicated

I am sure these questions will have been covered somewhere, but I am going from about 65% to about 80% (I don’t think it shows exact% anywhere) daily and charge at 32amps. Lately I have lowered the charge rate to 20 amps. Any thoughts on that. Lower rate should mean inside battery lower heat. Also, my full battery mileage has been creeping downward over the last 6 months from about 219 to 202 Is this a real loss or a brick thing?

I charge at 24A simply because the cable gets less warm, and I don't like warm cables. But it's actually more efficient to charge at higher rates if you can (due to overheads like running the computers and pumps).

For a 15% charge you aren't really adding noticeable heat to the battery at 32A. I only noticed an increase after adding something like 70% at 32A in an enclosed garage, and I want to say it was maybe 5 degrees C added? (that would be 9F added). So not a lot. I'd just use 32A if I was in your situation.