Prius Prime Battery Life Cycles

While I agree that a BEV stresses the battery more than a PHEV does, I attribute that to range anxiety; The manufacturer is trying to show the greatest range. In a PHEV, you just add gas.

 

I'm willing to wager this is going to be a huge YMMV. The Toyota Prime and Tesla BEV will do fine; the LEAF BeV and Hyundai PHeV will do poorly. And within those two broad categories driver habits and local conditions will lead to overlap.

 

A 200 mile range BEV getting used 25 miles a day is experiencing a much smaller depth-of-discharge cycle than a 25 mile PHEV getting used 25 miles a day. The BEV will experience fewer deep DOD cycles over its lifetime unless it's getting driven 200 miles a day, which few people do.

 

You are presuming too much about how people will charge a BeV

 

Doesn't matter.

If they charge it every day, it's the same number of much smaller cycles.

If they wait to charge it until they need to charge it, it's a much smaller number of the same DOD cycles.

Anything in between is a mix of smaller cycles and a smaller number of cycles.

 

Hogwash. Your car's ample reserve at the top and bottom should clue you in.

 

If BEV manufacturers are dumb enough to charge to 4.2V and discharge to 0%, that's another story. But it doesn't look like they are. Maybe the first Leaf, but no others. Tesla, Bolt and the new Leaf certainly don't.

 

BEVs have 'psychological lower buffer' resulting from owners' range anxiety.
If you have a 40 miles planned trip, would you charge when 60 miles left? 70 miles?
Maybe BEVs manuf. are taking the psychological factor into account when lowering more and more the actual lower buffer to show better range rating?

 

140 miles in good weather, 190 miles in bad weather for me.

 

Exactly.

 

I'm refering to the buffer capacity and battery management the manufacturer puts in place. There is a federally mandated warranty on car emission systems of eight years or 100k miles that hybrid batteries, plug or not, have to perform for. So while the hybrid battery might see more cycles and at greater depth than a BEV will in practice, the manufacturer is going to put their best effort into ensuring that the use won't lead to them having to replace the battery under a warranty forced on them.

There is no such minimum warranty in place for BEVs, and thus they could charge and discharge their batteries to whatever limits they desire.

Why do you say the Hyundai PHEV will do poorly?

 

UK spec is to charge in just over 2 hours. So that's about 3kw per hour or 12A.

Is there any benefit for me to set the change rate down to 8A max?

Does the inclusion of this option on the car imply that 8A it's better? Otherwise what's it's purpose?

(Most of the time I will be charging overnight so a slower rate won't matter.)

Posted via the PriusChat mobile app.

 

The in car charger is a 16A charger, and that is the default rate. An EVSE can command the rate to be anything it wants up to the maximum. The car can be set to 8A maximum for the reason stated in the manual - in case you are popping your charge breaker because you are overloading the circuit.

 

The portable EVSE (charge mode 2 from household outlets) supplied in Europe is rated at 12A so can supply up to 240V*12A/1000=2.88kW (is the single phase voltage in the UK 240V?).
This is really slow charge rate and IMO there is no need to go to 8A for extra protection of the battery. You may find out that although you usually charge at night, there will be times you will supplement-charge during day and the quicker rate helps.
The option of 8A can be useful when you have an opportunity to charge out of home from a household outlet which may be old or suspicious or is triggering the line overload protection (if there is one at all).
Note that the portable EVSE you have has an extra safety feature (not supplied with the PiP) of detecting plug/outlet overheating by a thermistor located inside the plug. Over temp. (I think above 60 deg. C) will cause reduced charging rate in a controllable manner.

 

Keeping in mind that the standard household voltage in the U.K. is 230 volts vs. the 120 volts in the U.S.
Type G plug used in the U.K., 240 volts, 13 amps.

 

From what I read on another forum regarding Li-ion batteries a slower charge rate is better for longer battery life. I think for marketing reasons of stating charge in 5.5 hours with the faster charge at home in the US that 12A is used as the default charge mode. In Japan homes owning Primes the default charge is set even lower taking longer time than 8 hours.
However, the majority on this forum do not agree that 8A charging is needed to prolong battery life. Since I have the time to charge overnight for 8 hours at 8A thats what I will do. At least unless I find out later by someone who can take data, that 8A charging is not better for the chemistry of the Prime's Li-ion battery.

 

Charging Lithium-Ion Batteries – Battery University

The advised charge rate of an Energy Cell is between 0.5C and 1C; the complete charge time is about 2–3 hours. Manufacturers of these cells recommend charging at 0.8C or less to prolong battery life; however, most Power Cells can take a higher charge C-rate with little stress. Charge efficiency is about 99 percent and the cell remains cool during charge.

.5C is a 2 hour charge, 1C is a 1 hour charge. There's no appreciable difference between a 1.25 hour charge and an 8 hour charge when it comes to longevity. The charge rate in CHG mode is about 1C. The charge rate in B mode on a big hill is likely much faster. The Prime's batteries are likely more optimized for power than energy indicating they can take charge rates faster than 1C with little stress.

 

I think the information presented in most forums gets a lot of people to confuse DC and AC charging. Most manufacturers do not recommend charging via DCFC (or DC Fast Charge) all the time. People have a tendency to extrapolate that to AC charging as well in which even L2 rate is a really low stress rate. Therefore it's rather easy to misinterpret the intention of what is a "good" charge rate for the battery.

Two reasons why manufacturers do not recommend DCFC all the time: temperature and HV stress. Battery life cycle is extremely aligned with temperature. Actually most electronics are as well. But the point I'm trying to make is that charging does make the internal temperature of the battery go up. DCFC will produce a much higher internal temperature rise over a much shorter period of time. I can tell you even with my L2 EVSE, the highest temperature rise I've ever seen is about 2 F in the summer over an hour and 20 minutes via OBD II data.

However, this all pales in comparison to discharging. Discharging a battery has the effect of raising internal temperatures about an order of magnitude over a similar time period. So running your Prime at 80 mph on just battery power has FAR more effect on battery longevity than charging.


Unsupervised!

 

Depending on how effective is the battery temp management system in taking that heat away . . .

Anyone know whether the Euro version has battery cooling as well as heating? Toyota uk said in a blog that there is a heater. Do they actually mean that it had a battery temp conditioner linked to the car's HVAC that can both heat AND cool? I'm assuming so.

P.s. I have a 7kw Charger on a 32A 230v dedicated circuit. If the car's charger can charge at 16A, by my reckoning I should get a full charge in 1hour 50 minutes, assuming a 6.6kw charge. I guess the other 10 minutes to take it to the 2hrs that Toyota quote is due to charger efficiency losses.

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