EVPlus - Frequently Asked Questions
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Electric Vehicle - EV
Q. What is an EV ?
A. An EV is a vehicle that is
powered by onboard batteries and driven by one or more electric
motors.
The batteries are recharged from the power grid either from a
home power outlet or a commercial charge point.
There is no gasoline (petrol) engine in this vehicle.
Q. What is an EV Conversion ?
A. To make an EV from a standard
vehicle you must firstly remove the gasoline engine and all
parts associated with this engine eg. the gas tank, fuel
lines, fuel pump, exhaust system, radiator etc. etc.
Then an electric motor is usually attached to the
gearbox/transaxle using a newly made adapter plate and a
coupler attaches the motor drive shaft to the original gearbox
input shaft.
Other major components required are a motor controller,
batteries, battery charger, battery box/frame. There are a few
other minor components required as well.
Q. Do all EV's have regenerative braking ?
A. EV's driven with AC
(Alternating Current) motors will have regenerative braking
and usually have regeneration on deceleration as well.
Most commercial EVs are driven by AC motors.
Some low voltage DC (72V and below) conversions have regen.
These are usually known as SEPEX systems and have a special matched
motor/controller combination.
In general, DC conversions do not have regenerative braking.
Q. What determines the
range of an EV ?
A. The range of an EV depends on
many factors. The main considerations are the total weight of
the car, the size of the battery pack (KWh) and the efficiency
of the motor/controller combination. The air and rolling
resistance play a part in this as well.
Extended Range Electric Vehicle - EREV,
E-REV, R-EEV
Q. Can you please give
some examples of an Extended Range Electric Vehicle?
Q. How does an EREV
differ from a Plug-in Hybrid ?
A. With the EREV, the auxiliary
gasoline engine is only used to charge the batteries when the
voltage reaches the minimum level. This engine does not drive
the wheels* at any stage, the electric motor drives the wheels
at all times. *Please note, that in the
case of the Volt and the Outlander PHEV, it has been shown
that in some circumstances the petrol engine does in-fact
drive the wheels.
In the Plug-in Hybrid the electric motor and the gasoline
(petrol) engine both drive the wheels at various times.
Q. Isn't the EREV just another hybrid ?
A. Yes, technically any vehicle
that utilizes two or more different fuel sources is a hybrid.
To be totally correct the EREV is also known as a Plug-In
Series Hybrid.
Hybrid/Electric Vehicle - HEV
Q. What is the advantage of a Hybrid over a conventional car ?
A. The hybrid vehicle utilizes
the efficiency of an electric motor/generator system to
improve the fuel economy of the vehicle. An electric motor has
an overall efficiency of greater than 90% whereas an Internal
Combustion Engine (ICE) has an efficiency of less than 20%. By
combining the two with very clever control systems the vehicle
can be designed to present very good fuel economy figures,
improving on the standard car by greater that 50%.
All this is achieved without being able to plug the vehicle
in.
A typical Toyota Prius in its standard form will give fuel
economy figures up to 60MPG.
Q. If I buy a hybrid car, can I plug it in to charge it ?
A. No, there is no provision for
plugging in a standard hybrid vehicle. eg Toyota Prius, Honda
Insight. Toyota have promised to produce a Plug-in Prius and this may
be available world wide in 2013.
Q. I have heard of the Toyoto Prius, what other Hybrids are around ?
Plug-in Supply Kit
Q.
How does the original Toyota battery pack
work with the add-on pack?
A. The original pack is
1.4kWh - NiMH
The add-on pack is 9.7kWh - LiFePO4 (40Ah cells)
The different capacities and chemistries are not a concern, as
when in parallel mode, they will follow each other and act as
one large 11.1kWh battery.
The "76 cells" of the add-on pack was chosen by Plug-in Supply
for best match to the original pack for
many reasons including the top voltage from
regenerative braking and deceleration.
The regen will then be shared by both battery packs. This
allow much greater gain from regen compared to the very
limited amount gained prior to "conversion".
This works out at around 260 Volts DC. ... at 3.42V per cell
for the add-on pack so the add-on pack will never be
overcharged during normal driving.
When the add-on pack is being charged from
an outlet, the original
pack is not connected. On charge the individual cells charge
to a max of 3.65V per cell.
This maximum is controlled by the maximum voltage of the
charger, assuming all the cells are balanced. There is safety
built in to this as well (BMS), so that if any of the cells reach
around 4V during charge the charger is disabled.
When the add-on pack is connected to the original pack (under
the control of the Plug-in Supply system), while driving,
there will be a slight difference in voltage between the two
battery packs.
I have questioned Plug-in Supply about this and he said that
it not a problem and is well with in the capabilities of the
contactor, and certainly not detrimental to the original pack.
The original cells will still be exercised as normal because
of the direct parallel connection and particularly when the
car is driven in "EV Only" mode.
The system will be setup (my idea) so that the Plug-in Supply
system switches off and disconnects from the original hybrid
system when the add-on cell reach a preset minimum Ah level,
eg 10Ah; 25% of total Ah. There is an additional safety
feature built in as well (via the BMS), so that if,
for any reason, on discharge, an
individual cell reaches a low voltage of 2.5V, this
switches the
add-on system off as well.
Once this switches off, the car runs in normal factory hybrid
mode.
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