Samlexpower PST-60S-48E, Руководство пользователя

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- The resistances of the interconnecting cables will be balanced.
- All the individual batteries / battery strings will see the same series resistance.
- All the individual batteries will charge / discharge at the same charging
current and thus, will be charged to the same state at the same time.
- None of the batteries will see an overcharge condition.
7.16 SIZING THE INVERTER BATTERY BANK
One of the most frequently asked questions is, "how long will the batteries last?" This
question cannot be answered without knowing the size of the battery system and the
load on the inverter. Usually this question is turned around to ask “How long do you
want your load to run?”, and then specific calculation can be done to determine the
proper battery bank size.
There are a few basic formulae and estimation rules that are used:
1. Active Power in Watts (W) = Voltage in Volts (V) x Current in Amperes (A)
x Power Factor.
2. For an inverter running from a 48V battery system, the approximate DC current
required from the 48V batteries is the AC power delivered by the inverter to the
load in Watts (W) divided by 40.
3. Energy required from the battery = DC current to be delivered (A) x Time in Hours (H).
The first step is to estimate the total AC Watts (W) of load(s) and for how long the
load(s) will operate in hours (H). The AC Watts are normally indicated in the electrical
nameplate for each appliance or equipment. In case AC Watts (W) are not indicated,
Formula 1 given above may be used to calculate the AC Watts. The next step is to
estimate the DC current in Amperes (A) from the AC Watts as per Formula 2 above. An
example of this calculation for a 48V inverter is given below:
Let us say that the total AC Watts delivered by the inverter = 1000W.
Then, using Formula 2 above, the approximate DC current to be delivered by the 48V
batteries = 1000W ÷ 40 = 25 Amperes.
Next, the energy required by the load in Ampere Hours (Ah) is determined.
For example, if the load is to operate for 3 hours then as per Formula 3 above, the energy
to be delivered by the 48V batteries = 25 Amperes × 3 Hours = 75 Ampere Hours (Ah).
Now, the capacity of the batteries is determined based on the run time and the
usable capacity.
From Table 7.3 “Battery Capacity versus Rate of Discharge”, the usable capacity at
3 Hour discharge rate is 60%. Hence, the actual capacity of the 48V batteries to
deliver 75 Ah will be equal to: 75 Ah ÷ 0.6 = 125 Ah.
SECTION 7 | General Information on Lead Acid
Batteries