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Engine Braking with Full Battery?
- Thread starter zecar
- Start date
AMPd
Well-Known Member
I’m assuming they’ll trust drivers are not going to charge the batteries fully when engine braking is going to be required right away.
Most places require a secondary braking system on heavy trucks. It's absolutely necessary in mountainous areas. I doubt that relying on the driver to evaluate SOC before descending meets that requirement. But perhaps a software warning/management system is acceptable.
A company is unlikely to put a semi charging station at the top of a mountain.
A company is unlikely to put a semi charging station at the top of a mountain.
scottf200
Well-Known Member
Blending (physical pad+regen) brakes like has been announced with the S3XY cars? If you just climbed a hill you are likely not >95% SOC. Regain ~80% on decent with regen won't "overfill" you.
The amount of power required to get the vehicle moving fast enough to require "engine braking" will likely be more than enough to create space in the battery for regenerative braking.
Also, I suspect most of the time these trucks will only be charged to 90-95 % capacity. Same as cars.
Also, I suspect most of the time these trucks will only be charged to 90-95 % capacity. Same as cars.
AMPd
Well-Known Member
They have to support air brakes so they can hook up to a standard trailer... On the truck itself I'm sure they are using standard truck drum brakes, at least on the rear.
AMPd
Well-Known Member
I’m not sure what you mean, our Volvo trucks are spec’d with disc brakes all around. Drum brakes are outdated
Operator64
Member
Operator64
Member
I’ve never had a secondary braking system on any class 8 truck and do plenty of mountain driving here in the USA so you may be referring to another country?
Olle
Active Member
If engine braking is truly required as a secondary braking system at all times, they may need a resistor. Cold battery is another condition that limits charging power.
Only other alternative I see is hard coded stop at max x% SOC and never leave truck unplugged under y% SOC in cold wether more than z hours. Else not legal to drive and it would have to be towed to a charger.
Only other alternative I see is hard coded stop at max x% SOC and never leave truck unplugged under y% SOC in cold wether more than z hours. Else not legal to drive and it would have to be towed to a charger.
Last edited:
AMPd
Well-Known Member
I’m not sure such a thing is required. Modern truck engine brakes don’t work when engine is cold. At least the the trucks we run in our fleet.
Never trust all people. If it’s possible but dumb to do, someone out there will do it. Toyota had issues with the first plug in Prius. Someone lived on top of a mountain and charged it full before leaving each day. Toyota had to lower the available capacity of the battery to account for it. I guess that must have been easier than just limiting regen when the battery is full.
scottf200
Well-Known Member
Aside: The Chev Bolt even named their charging option "Hilltop Reserve mode (for 2017-2018 model years) or Target Charge Level (for 2019-2022 model years) mode."
Operator64
Member
NewbyMaybe
Newby1Kenowby
Fail-safes are always good but truckers won't charge all the way up if they know it's a waste of time.
SmartElectric
Active Member
FYI regarding Tesla's strategy for regenerative braking at 100% state of charge (SOC = reported on dash).
Our 2013 Model S had zero/no regenerative braking when charged full UNTIL a firmware update in 2021 lowered the maximum range, ie, reduced available kWh of capacity at 100% reported SOC. This reserved more kWh at the top of the pack which cannot be filled using L2/L3 charging, but CAN be filled using regenerative braking.
Thus, Tesla changed the way the battery was used to provide regenerative braking at full charge, while providing lower ultimate charging capability. This does not affect us in any way, on road trips we rarely charge above 80% unless we're taking a long food break.
Our 2013 Model S had zero/no regenerative braking when charged full UNTIL a firmware update in 2021 lowered the maximum range, ie, reduced available kWh of capacity at 100% reported SOC. This reserved more kWh at the top of the pack which cannot be filled using L2/L3 charging, but CAN be filled using regenerative braking.
Thus, Tesla changed the way the battery was used to provide regenerative braking at full charge, while providing lower ultimate charging capability. This does not affect us in any way, on road trips we rarely charge above 80% unless we're taking a long food break.
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