Product Manual

Proline 5000

™

Inverter by Wagan Tech

www.wagan.com

• 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)

• Use of DC appliances

• Compliance with turning off unnecessary AC and 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 13.2 volts (fully charged) then drops

to 10.6 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). Derating is

a major run time factor. The following curve can help to determine what the battery bank can

deliver under load. The results are used to estimate how much additional battery capacity is

needed to achieve the desired run time.

The left vertical numbers of the curve represents percentage of the battery capacity at the 20

hour rate. In this example, the user needs a one hour run time. If the example battery is 220 Ah

(20 hour rate), and the load is 220 amps that is 100% (horizontal number) of the Ah (20 hour

rate), starting at the 100% horizontal point and looking up to the curve the results are that only

56% of the battery capacity is available. This means that a higher battery capacity is required to

get the desired run time: one hour. The curve also shows that a load of 200% of the 20 hour rate

yields only 31% of the battery capacity. The installer must carefully plan the capacity of battery

bank or the run time may be seriously affected. To the inexperienced installer, several trial

battery capacities may be required to make sure a large enough battery capacity is available to

achieve the desired run time.

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