Decline in regen braking

I have a 2012 SL with 19,000 miles and have noticed a big decline in the amount of regen from braking or release of accelerator. When going downhill I usually only see the dot in the center, and when I brake maybe 1 dot to two dots towards regen tops for a full stop. Going uphill when I release the accelerator it only gives me 1 dot. A typical trip downhill for 10 miles I usually get 10-15 miles back......now I am getting 2-3 tops. Warranty just ended in early December. Anyone have this or know what is involved to fix?

It's a classic result of battery degradation... Short of battery replacement, there is nothing that can be done about it. Cold weather only makes it worse...

Tpsfoto said:

I have a 2012 SL with 19,000 miles and have noticed a big decline in the amount of regen from braking or release of accelerator.

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Where are you located, and how many battery capacity bars do you have left? I have 3 bars missing, almost ready to lose the 4th bar, and my regen seems almost nonexistant at times. Cold weather will also make it worse, as the car limits the regen when the battery is cold.

It's "normal" for the '11-12 LEAF to lose quite a bit of regen as it ages, especially once you've lost a capacity bar and only gets worse from there.

The car also significantly reduces the amount of available regen at higher speeds - the faster you are driving, the less regen is available and it's proportional to the max regen achievable for a particular SOC/temperature.

I very rarely achieve 30 kW regen now. Takes a combination of a hot battery and SOC down near LBW or lower. Typically most of my driving only sees 10-15 kW regen max. At 55mph, 50% SOC and pack in the low-mid 60F range, I have less than 10 kW available.

The loss of regen at higher speeds really hurts because you know that it will allow substantially more regen at lower speeds and cell voltages aren't any where near a level which isn't safe.

There are a few other threads which talk about this in depth, try searching for "Where's my regen?" as an example.

Thanks all for your responses......I have lost two bars it has 19k miles and live in Las Vegas.....this was a California car that I purchased in July.

This may be a stupid question, but why does battery capacity affect the amount of regen?

I believe internal resistance increases as battery deteriorates and BMS limits regeneration current (and hence power) to keep cell voltages from exceeding their maximum safe level. Since internal resistance is lower when temperature is higher, reduced regeneration is more noticeable in cold weather.

Gerry

Yesterday we drove our 2011 LEAF down the mountain we live on, from ~6000 ft. elevation down to ~1200 ft., for the first time in months. Prior to the descent, the battery had been warmed up to maybe the low 50s F or so by another drive, and there were four bars of charge remaining. We had hoped that the lower SOC and warmer battery would result in enough regen to comfortably descend the mountain, but my wife ended up having to stop a couple of times to let the friction brakes cool, so the regen was still pretty lousy, significantly worse than in prior years. (I think it started off okay on yesterday's descent, but the BMS really limits continuous regen unless you're able to drive ~20 mph.)

Thankfully, with a "full" charge to 204 gids ("72.6%" in gids) down in north Redlands at the new Mountain Gate ChargePoint EVSEs and a battery temperature of 62 F, I was able to drive the ~20 miles back up the mountain at ~45 mph (a respectable speed on CA-330) and arrive home with about "14%" in gids (a couple of miles after the "low battery" warning).

Given the poor regen, our LEAF will continue to spend the great majority of its life on the mountain, shuttling between the small towns up here where the elevation changes are more limited. While I'd like to buy a used Tesla at some point, the Prius is for now our "go to" car for trips down the mountain, unfortunately. I didn't think that loss of regen would turn out to be such a limiting factor, more so than the actual battery capacity, but here we are.