Xantrex Technology 815-2524-02 Charger Settings in a Dual Freedom SW Configuration, Calculations

Stacking Features

Charger Settings in a Dual Freedom SW Configuration

The Freedom SW 3524-230 includes a maximum 90A charger. When using two stacked Freedom SW 3524-230 inverter/chargers connected to the same battery bank, a total of 180A (90A × 2) of bulk charging is possible into that single common battery bank. For small battery banks and/or certain battery types this bulk mode current may be too high, therefore Freedom SW 230V models include a battery bank capacity (Batt Capacity) setting and a maximum charge rate (%) (Max Chg Rate) setting.

The battery bank capacity (C) is the bank’s total Amp-hour capacity, which is best determined by a qualified RV electrical technician.

The Max Chg Rate depends on the battery manufacturer's maximum charge rate for the specific battery model being used to construct the bank. This total bank maximum charge rate is best determined by a qualified RV electrical technician. Suitable battery types include Flooded, GEL and AGM. Do not mix different battery types within the same battery bank.

For a Flooded type battery bank, the preferred charge rate (in Amps) is usually 10-15% of C where C = battery bank’s total Amp-hour capacity. However, the industry-accepted maximum charge rate is 25% of C. Some AGM or Gel battery models may have a maximum charge rate as high as 50% of C and in rare cases, up to 100% of C.

Do not exceed the battery manufacturer’s recommended maximum charge specifications because the resulting battery temperature rise shortens battery life.

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Calculations

Once installed and configured, each Freedom SW 230V charger in
the dual configuration should be set to its own bulk charge current
limit as follows:	only.
Industry accepted maximum charge rate (%)
× battery bank’s total Amp-hour capacity (C)	personnel
= Maximum charger #1 output current (in Amps)
× 1/ (for one of the chargers)
2
allowed in bulk mode (also limited to the charger’s	qualified
To calculate the system total bulk output for the stacked pair,
maximum capacity)
Charger #1 output current (in Amps)	by
	use
+ Charger #2 Actual output current (in Amps)
= System Total BULK output current (in Amps)	for
The System Total BULK output current flows into the battery	guide
bank. As such, this total bulk current is split/distributed within the	This
bank through each individual parallel and/or series connected

battery. Therefore, the current each battery “sees” must not exceed each individual battery’s maximum allowed charge current as specified by the battery manufacturer. Since most battery banks are comprised of the same battery type, model and length of interconnecting cables, current sharing is roughly equal through

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