Recharge efficiency

[Jerican]

How efficient is the Outlander at recharging? What, for instance, would this ratio be: (Recharge going downhill)/(Discharge going uphill) for a given hill X?

 

[Tai626]

I really don’t know how to measure it (reverse round trip efficiency?)

https://www.upsbatterycenter.com/blog/round-trip-efficiency-batteries/

Here is a fact: sometimes I need to go B0 (no regen) just to maintain the speed (~85mph or 135km/h) in a 5% downhill. Our PHEV is not very aerodynamic...

On the other hand, it is fun to see my wife’s amusement when she notices the total range actually increases (B5 regen) when I go downhill slowly (45mph or 70km/h)

Tai

 

[MH8173]

How efficient is the Outlander at recharging? What, for instance, would this ratio be: (Recharge going downhill)/(Discharge going uphill) for a given hill X?

The converter has an energy efficiency of about 85% (AC <---> DC).

The motors (which act as generators) are generally pretty efficient (90-99%). We have no exact data from Mitsubishi as far as I know.

Charging and discharging the battery is more efficient with lower currents, i.e. B1 regenerative breaking is more efficient than B5 and driving 40km/h is more efficient than driving 80km/h. Battery temperature, state-of-charge (SOC), and state-of-health (SOH) also affect charge/discharge energy efficiency. I'd say 70-95%, and again, we have no Mitsubishi data as far as I know.

Now let's try two scenarios:
1. 0.85*0.98*0.75= 62%
2. 0.85*0.98*0.90 = 75%

That's wheels -> battery, now battery -> back to wheels:
1. 0.62*0.62 = 38%
2. 0.75*0.75 = 56%

Any breaking is a loss and it's always going to be. My guess is, in reality, you get 30-60% back on the wheels with regenerative breaking. But sometimes you have to brake and regular brakes gives right about 0% back!

Gary Reed did a test on B0 vs B2: https://www.youtube.com/watch?v=v6dZiAeb5w0

Cheers

 

[Craigy]

I have no data to back this up but saying lower currents are more efficient for charging doesn’t sound right, there must be an optimum current to charge at. You also have to factor in the losses in circuits which need to be used while charging is taking place the battery monitor etc.
I would wager the most efficient way of charging the PHEV without any special equipment would be with a 16A 240V EVSE.

 

[Craigy]

I have no data to back this up but saying lower currents are more efficient for charging doesn’t sound right, there must be an optimum current to charge at. You also have to factor in the losses in circuits which need to be used while charging is taking place the battery monitor etc.
I would wager the most efficient way of charging the PHEV without any special equipment would be with a 16A 240V EVSE.

 

[MH8173]

I have no data to back this up but saying lower currents are more efficient for charging doesn’t sound right, there must be an optimum current to charge at. You also have to factor in the losses in circuits which need to be used while charging is taking place the battery monitor etc.
I would wager the most efficient way of charging the PHEV without any special equipment would be with a 16A 240V EVSE.

- Yes of course there's a lower limit here as well, that would not increase efficiency further and an even lower limit that would just keep the battery at it's current SOC (due to self-discharge). Higher currents does make charging less efficient.

- Of course there are other losses to account for but I've covered the major ones. The point here was to give TS a general idea, not to write an academical article.

How efficient is the Outlander at recharging? What, for instance, would this ratio be: (Recharge going downhill)/(Discharge going uphill) for a given hill X?

- I think TS meant regen breaking, not regular charging

From Battery University: "While the coulombic efficiency of lithium-ion is normally better than 99 percent, the energy efficiency of the same battery has a lower number and relates to the charge and discharge C-rate. With a 20-hour charge rate of 0.05C, the energy efficiency is a high 99 percent. This drops to about 97 percent at 0.5C and decreases further at 1C. In the real world, the Tesla Roadster is said to have an energy efficiency of 86 percent. Ultra-fast charging on newer EVs will have a negative effect on energy efficiency, as well as the battery life." https://batteryuniversity.com/learn/article/bu_808c_coulombic_and_energy_efficiency_with_the_battery

MY2019 in Europe have a 13,8kWh battery, regen breaking for example 40kW would mean a C-rate of about 2.9.