Reduced total charge after rebalancing?

[SSGP90X]

Hi,

I have a 2016 p90x, with current 100% charge is 233 miles (purchased used, this is what was on it originally). I normally charge to 80-90% for regular driving, 100% if long weekend trip planned.

I was taking a trip with very marginal arrival to my next supercharger (5% estimate charge on evtripplanner and Tesla gpa navigation) and no alternative charging locations along the trip. I did a deep battery rebalancing from 1% to 100% night before in an attempt to see if any other miles or energy existed that wasn’t being captured by the BMS. On my following morning charge prior to trip it went up to 95% and stopped charging and said ‘charge complete’. On my home charger all energy stops prior to that. I then went to supercharger to see if it would go to 100 and functionally it stopped at 95% (doesn’t say ‘charge complete’ but is charging at 1kw and energy percent doesn’t change after half hour there). Thankfully I made the marginal first supercharger leg of the trip (186 miles, 28 degrees F, mountain environment) with 5% battery left with conservative driving maneuvers. Talk about range anxiety!

Does anyone have any advice on what is going on with my battery? (Yes I have attempted to replug charger in multiple times - no change). Did I damage my battery with this rebalancing attempt? Is there something else I should attempt to do to correct this? I thought battery balancing at worse was unnecessary, didn’t anticipate attempting it would backfire.

 

[gaswalla]

You need to let the charging actually complete - yes, it will charge at 1kw or less at the end of a full charge. The longer it charges at this trickle slow rate, the more it is rebalancing.

 

[ajdelange]

Heavily charging the battery pack damages it. This does not, of course, mean that you can't charge fully on occasion (as for a trip) but you should not fully charge as a matter of course. I believe the BMS keeps track of your charging and if it detects excessive heavy charging it will limit the level to which you can charge in the future in order to prevent further damage.

 

[SSGP90X]

Gas,

At 1KW or less energy transfer is there any reason my home charger would not be capable of ‘rebalancing’. Seemed excessive to spend an hour at a supercharger to try to go from 95 to 100%. Any way to accomplish this without supercharger?

 

[SCW-Greg]

Heavily charging the battery pack damages it. This does not, of course, mean that you can't charge fully on occasion (as for a trip) but you should not fully charge as a matter of course. I believe the BMS keeps track of your charging and if it detects excessive heavy charging it will limit the level to which you can charge in the future in order to prevent further damage.

Please note, from many discussions here on TMC about this topic - siting Tesla’s own JB and other Li battery experts - Tesla protects the top end of the batteries, so even when you charge to 100%, there’s still room on top that they are protecting. And similarly, even when you discharge to 0%, they are still protecting the true bottom end of the battery. By doing this, the extend the life of the battery by 100’s of thousands of miles in use.

Here’s a great discussion Kim had directly with Elon about this topic. Charts included. Hint, she knows what she’s talking about...

So recalibration of your BMC by topping off the battery to 100% is sometimes needed.

 

[gaswalla]

Correct, you should do this at home. Charging up to 100 percent all the way at a supercharger qualifies one as an EVhole

 

[SSGP90X]

I understand but my issue is at home currently at 95% charge it will say ‘charge completed’ and at that point no additional energy is beinf transferred to battery. Is there anything to do (reset etc) to change this?

 

[ajdelange]

I'd like to know more about this 'ballancing'. Clearly only passive balancing is possible within a brick but the BMS could do active balancing between bricks. ?

 

[Doutt]

According to my SA, you need to do the drain and charge twice:

"However the algorithm can be rework and make sure the car will give you the actual mileage of the battery. Here is how to proceed.

Drive the car down to 20 miles (if needed drive in the neighborhood to get down to the mileage with to risk to get to 0 ) Then fully charge the battery to 100% of its capacity then repeat this cycle one more time without recharging in between. This will help the car computer to see the real value of the battery charge."

I have not done it yet.

 

[DCGOO]

According to my SA, you need to do the drain and charge twice:

"However the algorithm can be rework and make sure the car will give you the actual mileage of the battery. Here is how to proceed.

Drive the car down to 20 miles (if needed drive in the neighborhood to get down to the mileage with to risk to get to 0 ) Then fully charge the battery to 100% of its capacity then repeat this cycle one more time without recharging in between. This will help the car computer to see the real value of the battery charge."

I have not done it yet.

It is way more exciting to take it to zero

 

[SCW-Greg]

According to my SA, you need to do the drain and charge twice:

With stubborn packs, other owners have indicated it can take as many as 3 to 5 charge efforts to achieve full rebalancing.