Electronics International VA-1A, VA-1A-XX, RSVA-3 Operating And Installation Instructions
Volts / AmpsVolts / Amps
Volts / Amps
Volts / AmpsVolts / Amps
(Primary Instruments)(Primary Instruments)
(Primary Instruments)
(Primary Instruments)(Primary Instruments)
(VA-1A, VA-1A-XX & RSVA-3)(VA-1A, VA-1A-XX & RSVA-3)
(VA-1A, VA-1A-XX & RSVA-3)
(VA-1A, VA-1A-XX & RSVA-3)(VA-1A, VA-1A-XX & RSVA-3)
Operating and Installation InstructionsOperating and Installation Instructions
Operating and Installation Instructions
Operating and Installation InstructionsOperating and Installation Instructions
S0224921
OI 041032 and II 040934
S/N: ~74000 and up.
4/9/83
Rev. C: 2/24/92 ***
You must read this manual before installing or operating the instrument. This
manual contains warranty and other information that may affect your decision
to install this product and/or the safety of your aircraft.
Model:Model:
Model:
Model:Model:
S/N:S/N:
S/N:
S/N:S/N:
Electronics International Inc. Electronics International Inc.
Electronics International Inc.
Electronics International Inc. Electronics International Inc.
63296 Powell Butte Hwy • Bend, OR 97701 • (541) 318-6060 • Buy-EI.com 63296 Powell Butte Hwy • Bend, OR 97701 • (541) 318-6060 • Buy-EI.com
63296 Powell Butte Hwy • Bend, OR 97701 • (541) 318-6060 • Buy-EI.com
63296 Powell Butte Hwy • Bend, OR 97701 • (541) 318-6060 • Buy-EI.com 63296 Powell Butte Hwy • Bend, OR 97701 • (541) 318-6060 • Buy-EI.com
®®
®
®®
Important NoticeImportant Notice
Important Notice
Important NoticeImportant Notice
***** MUST READ ********** MUST READ *****
***** MUST READ *****
***** MUST READ ********** MUST READ *****
If you think it is not important to read this manual, you're wrong!If you think it is not important to read this manual, you're wrong!
If you think it is not important to read this manual, you're wrong!
If you think it is not important to read this manual, you're wrong!If you think it is not important to read this manual, you're wrong!
contains important installation information that may affect the safety of your air-contains important installation information that may affect the safety of your air-
contains important installation information that may affect the safety of your air-
contains important installation information that may affect the safety of your air-contains important installation information that may affect the safety of your aircraft, delay your installation or affect the operation of your instrument. You craft, delay your installation or affect the operation of your instrument. You
craft, delay your installation or affect the operation of your instrument. You
craft, delay your installation or affect the operation of your instrument. You craft, delay your installation or affect the operation of your instrument. You
read this manual prior to installing your instrument. read this manual prior to installing your instrument.
read this manual prior to installing your instrument.
read this manual prior to installing your instrument. read this manual prior to installing your instrument.
installation instructions is the sole responsibility of the installer/pilot and mayinstallation instructions is the sole responsibility of the installer/pilot and may
installation instructions is the sole responsibility of the installer/pilot and may
installation instructions is the sole responsibility of the installer/pilot and mayinstallation instructions is the sole responsibility of the installer/pilot and may
render the STC invalid.render the STC invalid.
render the STC invalid.
render the STC invalid.render the STC invalid.
Read the Warranty / AgreementRead the Warranty / Agreement
Read the Warranty / Agreement. There is information in the Warranty / Agreement that may alter
Read the Warranty / AgreementRead the Warranty / Agreement
your decision to install this product.
install this productinstall this product
install this product. This product may be returned for a refund. Contact Electronics International inc. for
install this productinstall this product
details.
Check that the instrument make and model marked on the side of the instrument and on the invoice are
correct before starting the installation. The VA-1A is an internal shunt unit and the VA-1A-XX is an
external shunt unit (“XX” = your aircraft shunt value in amps).
It is possible for any instrument to fail thereby displaying inaccurate high, low or jumpy readings.
Therefore, you must be able to recognize an instrument failure and you must be proficient in operating your
aircraft safely in spite of an instrument failure. If you do not have this knowledge, contact the FAA or a
local flight instructor for training.
If you do not accept the terms of the Warranty / Agreement, do notIf you do not accept the terms of the Warranty / Agreement, do not
If you do not accept the terms of the Warranty / Agreement, do not
If you do not accept the terms of the Warranty / Agreement, do notIf you do not accept the terms of the Warranty / Agreement, do not
Any deviation from theseAny deviation from these
Any deviation from these
Any deviation from theseAny deviation from these
This manual This manual
This manual
This manual This manual
MustMust
Must
MustMust
The ability for this product to detect a problem is directly related to the pilots interpretation and observation
skills.
The pilot
to operate the aircraft that does not know the operation of this product. Keep the Operating Manual in the
aircraft at all times.
must must
must understand the operation of this product before flying the aircraft. Do not allow anyone
must must
ContentsContents
Contents
ContentsContents
WARRANTY ................................................................................................................... 2
VA-1A, VA-1A-XX Operating Instructions................................................................. 3
Features ......................................................................................................................................................... 3
VA-1A Installed in the Battery Lead ........................................................................................................ 4
VA-1A Installed in the Alternator Lead ................................................................................................... 6
VA-1A, VA-1A-XX Installation Instructions............................................................... 8
General Information.................................................................................................................................... 8
Installation .................................................................................................................................................... 9
1. Important Information and Initial Check Out ............................................................................... 9
2. Instrument Set Up ............................................................................................................................... 9
3. Determine how the VA Unit will be installed in your aircraft's electrical system .................... 9
4. Install the External Shunt (External Shunt Unit Only, VA-1A-XX) ......................................... 1 2
5. Route the Circular Connectors....................................................................................................... 12
6. Route the Power and Ground Wires.............................................................................................. 12
7. Route the Backlight Wires ............................................................................................................... 12
8. Route the Shunt Wires (External Shunt Unit Only, VA-1A-XX) ............................................... 1 3
9. Connect the Large Shunt Wires (Internal Shunt Unit Only, VA-1A) ....................................... 1 3
10. Install the Instrument in the Panel ................................................................................................. 13
11. Connect the Circular Connector to the Instrument ................................................................... 1 3
12. Ground Tes: ...................................................................................................................................... 13
Troubleshooting.............................................................................................................14
VA-1A (Internal Shunt Unit) Wiring Diagram ......................................................... 1 6
VA-1A-XX (External Shunt Unit) Wiring Diagram ................................................. 1 7
VA-1A and VA-1A-XX Circular Connector..............................................................18
RSVA-3 Installation Instructions................................................................................. 19
1. Install the External Shunt .................................................................................................................... 19
2. Install the VA-1A-XX Instrument ...................................................................................................... 19
3. Route the Shunt Wires ......................................................................................................................... 19
4. Route the Instrument Wires to the RSVA-3 ..................................................................................... 19
5. Install the RSVA-3 in the Panel.......................................................................................................... 20
6. Ground Test ........................................................................................................................................... 20
RSVA-3 Wiring Diagram .............................................................................................21
RSVA-3 Circular Connector ........................................................................................22
Specifications and Operating Features .......................................................................23
STC Information ..................................................................................... See Back Pages
1
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Electronics International Inc. warrants this instrument and system components to be free from defects
in materials and workmanship for a period of one year from the user invoice date. Electronics International Inc. will repair or replace any item under the terms of this Warranty provided the item is
returned to the factory prepaid.
1. This Warranty shall not apply to any product that has been repaired or altered by any person other
than Electronics International Inc., or that has been subjected to misuse, accident, incorrect wiring,
negligence, improper or unprofessional assembly or improper installation by any person.
ranty does not cover any reimbursement for any person’s time for installation, removal,ranty does not cover any reimbursement for any person’s time for installation, removal,
ranty does not cover any reimbursement for any person’s time for installation, removal,
ranty does not cover any reimbursement for any person’s time for installation, removal,ranty does not cover any reimbursement for any person’s time for installation, removal,
assembly or repair.assembly or repair.
assembly or repair. Electronics International retains the right to determine the reason or cause for
assembly or repair.assembly or repair.
warranty repair.
2. This warranty does not extend to any machine, vehicle, boat, aircraft or any other device to which
the Electronics International Inc. product may be connected, attached, interconnected or used in
conjunction with in any way.
3. The obligation assumed by Electronics International Inc. under this warranty is limited to repair,
replacement or refund of the product, at the sole discretion of Electronics International Inc.
4. Electronics International Inc. is not liable for expenses incurred by the customer or installer due to
factory updates, modifications, improvements, upgrades, changes, or any other alterations to the
product that may affect the form, fit, function or operation of the product.
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This war-This war-
This war-
This war-This war-
5. Personal injury or property damage do to misinterpretation or lack of understanding this product is
must must
solely the pilots responsibility. The pilot
the aircraft. Do not allow anyone to operate the aircraft that does not know the operation of this
product. Keep the Operating Manual in the aircraft at all times.
6. E. I. Inc. is not responsible for shipping charges or damages incurred under this Warranty.
7. No representative is authorized to assume any other liability for Electronics International Inc. in
connection with the sale of Electronics International Inc. products.
If you do not agree to and accept the terms of this warranty, you may return theIf you do not agree to and accept the terms of this warranty, you may return the
If you do not agree to and accept the terms of this warranty, you may return the
8.
If you do not agree to and accept the terms of this warranty, you may return theIf you do not agree to and accept the terms of this warranty, you may return the
product for a refund.product for a refund.
product for a refund.
product for a refund.product for a refund.
This Warranty is made only to the original user.
OTHER WARRANTIES OR OBLIGATIONS: EXPRESS OR IMPLIED. MANUFAC-OTHER WARRANTIES OR OBLIGATIONS: EXPRESS OR IMPLIED. MANUFAC-
OTHER WARRANTIES OR OBLIGATIONS: EXPRESS OR IMPLIED. MANUFAC-
OTHER WARRANTIES OR OBLIGATIONS: EXPRESS OR IMPLIED. MANUFAC-OTHER WARRANTIES OR OBLIGATIONS: EXPRESS OR IMPLIED. MANUFACTURER EXPRESSLY DISCLAIMS ALL IMPLIED WARRANTIES OF MERCHANT-TURER EXPRESSLY DISCLAIMS ALL IMPLIED WARRANTIES OF MERCHANT-
TURER EXPRESSLY DISCLAIMS ALL IMPLIED WARRANTIES OF MERCHANT-
TURER EXPRESSLY DISCLAIMS ALL IMPLIED WARRANTIES OF MERCHANT-TURER EXPRESSLY DISCLAIMS ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. PURCHASER AGREESABILITY OR FITNESS FOR A PARTICULAR PURPOSE. PURCHASER AGREES
ABILITY OR FITNESS FOR A PARTICULAR PURPOSE. PURCHASER AGREES
ABILITY OR FITNESS FOR A PARTICULAR PURPOSE. PURCHASER AGREESABILITY OR FITNESS FOR A PARTICULAR PURPOSE. PURCHASER AGREES
THAT IN NO EVENT SHALL MANUFACTURER BE LIABLE FOR SPECIAL, INCI-THAT IN NO EVENT SHALL MANUFACTURER BE LIABLE FOR SPECIAL, INCI-
THAT IN NO EVENT SHALL MANUFACTURER BE LIABLE FOR SPECIAL, INCI-
THAT IN NO EVENT SHALL MANUFACTURER BE LIABLE FOR SPECIAL, INCI-THAT IN NO EVENT SHALL MANUFACTURER BE LIABLE FOR SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS OR LOSSDENTAL OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS OR LOSS
DENTAL OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS OR LOSS
DENTAL OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS OR LOSSDENTAL OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS OR LOSS
OF USE OR OTHER ECONOMIC LOSS. EXCEPT AS EXPRESSLY PROVIDEDOF USE OR OTHER ECONOMIC LOSS. EXCEPT AS EXPRESSLY PROVIDED
OF USE OR OTHER ECONOMIC LOSS. EXCEPT AS EXPRESSLY PROVIDED
OF USE OR OTHER ECONOMIC LOSS. EXCEPT AS EXPRESSLY PROVIDEDOF USE OR OTHER ECONOMIC LOSS. EXCEPT AS EXPRESSLY PROVIDED
HEREIN, MANUFACTURER DISCLAIMS ALL OTHER LIABILITY TO PURCHASERHEREIN, MANUFACTURER DISCLAIMS ALL OTHER LIABILITY TO PURCHASER
HEREIN, MANUFACTURER DISCLAIMS ALL OTHER LIABILITY TO PURCHASER
HEREIN, MANUFACTURER DISCLAIMS ALL OTHER LIABILITY TO PURCHASERHEREIN, MANUFACTURER DISCLAIMS ALL OTHER LIABILITY TO PURCHASER
OR ANY OTHER PERSON IN CONNECTION WITH THE USE OR PERFORMANCE OFOR ANY OTHER PERSON IN CONNECTION WITH THE USE OR PERFORMANCE OF
OR ANY OTHER PERSON IN CONNECTION WITH THE USE OR PERFORMANCE OF
OR ANY OTHER PERSON IN CONNECTION WITH THE USE OR PERFORMANCE OFOR ANY OTHER PERSON IN CONNECTION WITH THE USE OR PERFORMANCE OF
MANUFACTURER’S PRODUCTS, INCLUDING SPECIFICALLY LIABILITY IN TORT.MANUFACTURER’S PRODUCTS, INCLUDING SPECIFICALLY LIABILITY IN TORT.
MANUFACTURER’S PRODUCTS, INCLUDING SPECIFICALLY LIABILITY IN TORT.
MANUFACTURER’S PRODUCTS, INCLUDING SPECIFICALLY LIABILITY IN TORT.MANUFACTURER’S PRODUCTS, INCLUDING SPECIFICALLY LIABILITY IN TORT.
must understand the operation of this product before flying
must must
THIS WARRANTY IS IN LIEU OF ALLTHIS WARRANTY IS IN LIEU OF ALL
THIS WARRANTY IS IN LIEU OF ALL
THIS WARRANTY IS IN LIEU OF ALLTHIS WARRANTY IS IN LIEU OF ALL
2
VV
A-1A,A-1A,
V
A-1A,
VV
A-1A,A-1A,
Operating InstructionsOperating Instructions
Operating Instructions
Operating InstructionsOperating Instructions
VV
A-1A-XXA-1A-XX
V
A-1A-XX
VV
A-1A-XXA-1A-XX
OI 041032
Features
1. 12/24 Volt Select Switch
On the back of the VA-1A is a select switch to set the “High Volts” and “Discharge” warning
features for a 12 or 24 volt system (see Installation Instructions).
2. “High Volts” Warning Light
If the bus voltage rises to 15.3 volts (30.6 volts for a 24-volt system) or higher, a bright red “High
Volts” warning light will alert you of this condition. The high volts feature is sensed off the red
power lead and will function regardless of installation variations or what position the mode switch
is in. If this light is on, an External Warning Line will be pulled low which can be used to activate
an External Warning Light.
0219922
3. “Discharge” Warning Light
If the bus voltage drops below 12.6 volts, (25.2 volts for a 24-volt system) a bright yellow “Discharge” warning light will alert you of this condition. The discharge warning feature is sensed off
the red power lead and will function regardless of installation variations or what position the mode
switch is in. If this light is on, an External Warning Line will be pulled low which can be used to
activate an External Warning Light.
Discharge Warning LightHigh Volts Warning Light
12/24 Volt Select
Switch (on back)
12.312.3
12.3
12.312.3
vv
v
vv
Digital Display
Mode Switch
3
Operating Instructions Features
4. Digital Display
The VA-1A comes with 12 and 24 volt digital display back light control lines. The digital display
should be backlit all the time. This will allow it to be viewed easily in dim light. The digital display
is best viewed in high ambient light or direct sunlight.
Voltage will be displayed in 0.1 volt increments and a “V” annunciator will show in the display.
Amperage will be displayed in 0.1 amp increments for the VA-1A and any external shunted unit 60
amps and below (i.e., VA-1A-60 and below). For any external shunted unit above 60 amps (VA1A-70 and above) amperage will be displayed in 1 amp increments. Any time the Mode Switch is
in the “Amps” position, an “A” annunciator will show in the display.
Note: When the VA-1A (-XX) is mounted in the alternator lead and the engine is off, the VA-1A
(-XX) may display up to +/- 0.3 amps. This is due to any leakage current in the alternator and any
offset in the VA-1A (-XX).
5. Mode Switch
The Mode Switch sets the display between “Volts” and “Amps.” The setting of this switch will not
affect the operation of the “High Volts” or “Discharge” warning lights.
VA-1A Installed in the Battery Lead
The two common methods of installing the VA-1A or VA-1A-XX in the electrical system of your
aircraft are in the battery lead and in the alternator lead. Following are the operating characteristics
of the VA-1A installed in the battery lead.
1. Master On, Engine Off
The following describes the operating characteristics of the VA-1A installed in the battery lead
with the master switch on and the engine off.
With the Mode Switch in the “Amps” position, the VA-1A will display the electrical system load on
the aircraft. Since the engine is off, all of the current is being supplied by the battery. The VA-1A
will show a discharging condition (the “Discharge” light will be on) and display an accurate reading of the total current drain from the battery. With all your electrical equipment off, this will be
around 2 to 6 amps. In this mode of operation any piece of electrical equipment can be checked
for proper operation by performing the following steps:
A. Note the amps reading on the VA unit.
B. Turn on the piece of electrical equipment you wish to check.
4
Operating Instructions VA-1A Installed in the Battery Lead
C. If this piece of electrical equipment is working properly, you will see an increase in load
current that corresponds to the current that piece of equipment requires. Compare this
current with the current you measured for that same piece of equipment at an earlier date.
Using this method with the digital display of the VA-1A, many important aircraft functions
(strobes, retracts, radios, transponder, ADFs, DMEs, pitot heat, etc.) can be checked from the
pilot’s seat. It would be worthwhile to write down the load current for the entire system and for
each piece of equipment. This would give you something to compare to when you wish to check for
proper operation at a later date. You may also check the entire electrical system with one check
by turning all the electrical equipment on and comparing the amps reading with your normal
reading taken at an earlier date. If an improper reading is noted, the VA-1A may then be used to
diagnose which piece of equipment has malfunctioned by checking each piece of equipment separately.
With the mode select switch in the “Volts” position, the VA-1A will display the bus voltage to 0.1
volts. With all electrical equipment off and a fully charged battery the bus voltage will be around
12.1 to 12.5 volts (double these levels for a 24-volt system). Each battery has its own operating
voltage when charged. As the battery gets near the end of its life, this voltage will start to drop. A
discharged battery will also run at a lower voltage. Don’t confuse a good discharged battery with
an old battery.
2. Master On, Engine On
The following describes the operating characteristics of the VA-1A installed in the battery lead
with the master switch on and the engine on.
With the Mode Switch in the “Amps” position, the VA-1A will display the charging current to the
battery. When the engine is first started, the current will jump up to 20 amps or more and will
quickly decrease as the battery takes a charge. Within a few minutes, the charging current will
have dropped to 6 amps or lower and will continue to drop for the next hour until it settles to 1.0
amps or lower.
With the VA-1A installed in the battery lead, load current cannot be monitored during flight. The
Alternator (or generator) is supplying all of the electrical load and charging the battery. Only the
battery charging current can be monitored for this installation.
With the mode selector switch in the “Volts” position the VA-1A will display the bus voltage to 0.1
volts. With the engine running the alternator is capable of raising the bus voltage to a dangerously high level. It is the voltage regulator's job to limit the bus voltage between 13.5 and 14.8
volts (double these levels for a 24-volt system). Look for this level on the VA-1A. A low voltage
reading will cause the battery to charge very slowly. A high reading can damage the battery and
most of your electrical equipment. If the aircraft bus voltage goes to a dangerously high level
(15.3 volts or higher) a bright red “High Volts” light on the VA-1A will warn you of this condition.
If this happens turn the field to the alternator off to eliminate the over voltage condition.
5
Operating Instructions VA-1A Installed in the Battery Lead
Another common electrical problem is a discharging condition. If this condition goes unnoticed
(which it normally does) you will end up with a dead battery in flight rendering all of your electrical equipment useless. To help you avoid this situation the VA-1A has a “Discharge” Warning
Light which acts as an early warning, alerting you as soon as the battery goes into a discharging
condition. The amount of discharging current can be displayed in the “Amps” position. Discharging current will be displayed as a minus number. If this situation occurs, turn off any unnecessary
electrical equipment. The lower you can get the discharging current, the longer the battery will
last.
The VA-1A will display trend information when your battery is in a discharging condition. As you
watch the battery discharging 0.1 volts at a time, it becomes relatively easy to judge the remaining
time you have before the battery reaches a seriously low condition. As the battery voltage approaches 11 volts (22 volts for a 24 volt system), the aircraft’s electrical equipment will start to
malfunction. The exact voltage at which each piece of equipment will start to malfunction depends
on the design of that equipment. The VA-1A will work accurately from 40 to 7 volts--far below
where most electrical equipment starts to fail.
VA-1A Installed in the Alternator Lead
Two common methods of installing the VA-1A or VA-1A-XX in the electrical system of your aircraft
are in the battery lead and in the alternator lead. Following are the operating characteristics of the
VA-1A installed in the alternator lead.
1. Master On, Engine Off
The following describes the operating characteristics of the VA-1A installed in the alternator lead
with the master switch on and the engine off.
With the Mode Switch in the “Amps” position the VA-1A will display 000 (+/- a few counts). Since
the battery is supplying all of the electrical load and the alternator is off (not turning), there is no
current being supplied from the alternator and the “Discharge” warning light will be on.
With the mode select switch in the “Volts” position, the VA-1A will display the bus voltage to 0.1
volts. With all electrical equipment off and a fully charged battery the bus voltage will be around
12.1 to 12.5 volts (double these levels for a 24-volt system). Each battery has its own operating
voltage when charged. As the battery gets near the end of its life, this voltage will start to drop. A
discharged battery will also run at a lower voltage. Don’t confuse a good discharged battery with
an old battery.
2. Master On, Engine On
The following describes the operating characteristics of the VA-1A installed in the alternator lead
with the master switch on and the engine on.
6
Operating Instructions VA-1A Installed in the Alternator Lead
With the Mode Switch in the “Amps” position the VA-1A will display the electrical system load on
the aircraft plus the battery charging current. Since the engine is on, all of the current is being
supplied by the alternator. The VA-1A will show a charging condition (the “Discharge” light will
be off) and display an accurate reading of the total current drain from the alternator. In this
mode of operation any piece of electrical equipment can be checked for proper operation during
flight by performing the following steps:
A. Note the amps reading on the VA unit.
B. Turn off the piece of electrical equipment you wish to check.
C. If this piece of electrical equipment is working properly, you will see a decrease in load
current that corresponds to the current that piece of equipment requires. Compare this
current with the current you measured for that same piece of equipment at an earlier date.
Using this method with the digital display of the VA-1A, many important aircraft functions
(strobes, retracts, radios, transponder, ADFs, DMEs, pitot heat, etc.) can be checked from the
pilot’s seat. It would be worthwhile to write down the load current for the entire system and for
each piece of equipment. This would give you something to compare to when you wish to check for
proper operation at a later date. You may also check the entire electrical system with one check
by turning all the electrical equipment on and comparing this reading with your normal reading
taken at an earlier date. If an improper reading is noted, the VA-1A may then be used to diagnose
which piece of equipment has malfunctioned by checking each piece of equipment separately.
With the mode selector switch in the “Volts” position the VA-1A will display the bus voltage to .1 volts.
With the engine running the alternator is capable of raising the bus voltage to a dangerously high level. It is
the voltage regulator's job to limit the bus voltage between 13.5 and 14.8 volts (double these levels for a
24-volt system). Look for this level on the VA-1A. A low voltage reading will cause the battery to
charge very slowly. A high reading can damage the battery and most of your electrical equipment. If the aircraft bus voltage goes to a dangerously high level (15.3 volts or higher) a bright
red “High Volts” light on the VA-1A will warn you of this condition. If this happens turn the field
to the alternator off to eliminate the over voltage condition.
Another common electrical problem is a discharging condition. If this condition goes unnoticed
(which it normally does) you will end up with a dead battery in flight rendering all of your electrical equipment useless. To help you avoid this situation the VA-1A has a “Discharge” Warning
Light which acts as an early warning to alert you as soon as the battery goes into a discharging
condition. If this situation occurs, turn off any unnecessary electrical equipment. The lower you
can get the discharging current, the longer the battery will last. With the VA-1A installed in the
alternator lead, discharging current cannot be monitored.
The VA-1A will display trend information when your battery is in a discharging condition. As you
watch the battery discharging .1 volts at a time, it becomes relatively easy to judge the remaining
time you have before the battery reaches a seriously low condition. As the battery voltage approaches 11 volts (22 volts for a 24-volt system), the aircraft’s electrical equipment will start to
malfunction. The exact voltage at which each piece of equipment will start to malfunction depends
on the design of that equipment. The VA-1A will work accurately from 40 to 7 volts--far below
where most electrical equipment starts to fail.
7
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