12V Battery Bank
www.wagan.com
9
Elite 1500W—Pure Sine Inverter
by Wagan Tech
©2010 Wagan Corporation
All Rights Reserved
Wagan and wagan.com are trademarks used by Wagan Corporation
10
User’s Manual—Read before using this equipment
will need 50 amps at 12 volts DC. Using the 500 watts (or 50 amps) for 10
hours example as above, then 50 amps is needed for 10 hours. This provides
us with the basic amp-hours (AH) of battery that is required. Ten hours at 50
amps equals 500 amp-hours (AH). There are additional factors that determine
actual run time. These include:
• AC appliance load and time in use (basic AH).
• Cable gauge and length (cable losses).
• Charge level of the batteries (between use, chargers have to be able
to fully charge the batteries).
• Temperature of the batteries (colder batteries provide fewer amps).
• Age and condition of the batteries (older batteries lose AH capacity).
• Compliance with turning off unnecessary AC loads.
• Use of DC appliances and compliance with turning off unnecessary
DC loads.
Derating the Battery Bank
Most lead-acid batteries have a rating expressed in amp-hours (AH). The most
common rating of AH is “at the 20 hour rate”.
NOTE: Despite several internet explanations, there is no relationship between
cold cranking amps (CCA) and ampere-hours (AH).
For example, if a 20 AH battery is discharged at a 1 amp rate, is will take 20
hours to discharge that battery. The terms “charged” and “discharged” relate
to actual battery voltage. This means that the output voltage of a nominal
12 volt battery starts at 13.4 volts (fully charged) then drops to 10.5 volts
(discharged). If the load on the battery causes the battery to discharge faster
than the 20 hour rate, the capacity (AH) of the battery is measurably reduced
(derated). In heavy battery discharge applications, double the estimated Amp
Hour rating and configure batteries to support this capacity. If the batteries are
frequently charged by an alternator, the Amp Hour rating of the battery may
be reduced.
Configuring the battery bank
Batteries that are used indoors or inside a vehicle or vessel, should be deep-
cycle, sealed lead acid batteries.
NOTE: It is important that for any inverter installation to battery protection
fuses. Battery fuses are added to the positive (+) battery cable as close as
possible to the battery bank’s positive terminal. The fuse amperage rating
must be sized to allow simultaneous operation of all the AC appliances
to be powered, plus 20 percent safety factor. Fuses are very important to
protect equipment, batteries and personnel. The fuses protect against battery
explosion if the cables that connect to the inverter accidentally short.
Battery Bank Diagram
The diagram below shows inverter connections to a battery bank with
recommended fuse protection.
Fuse
WARNING—Exploding Batteries!!
e
xploding
baTTeries
can
spray
molTen
lead
,
hoT
sulfuric
acid
,
and
oTher
meTal
and
plasTic
fragmenTs
. b
aTTeries
ThaT
are
charging
or
under
high
discharge
raTes
produce
explosive
hydrogen
gas
inTo
The
surrounding
area
. b
e
safe
–
fuse
The
baTTery
bank
and
make
sure
The
baTTeries
are
properly
venTilaTed
.
