Charger
See the Morningstar SunSaver Duo SSD-25 connection points and wiring example. Open the diagram in Crimp to add your equipment and plan the cables between them.
Open this example as a new project. Use your own parts and cable lengths to make the plan yours.
Use the diagram as a starting point for your installation. Replace the example equipment and cable lengths with your own, and check the connections against your exact model's instructions.
3.3 ft one way
12 V system
Sized against ABYC E-11. The design current is the unit's rated output. The length is one way; voltage drop includes an equal-length return.
The editable example uses 3.048 m (10 ft) runs unless a shorter run is stated. Metric overviews round these to 3 m. Adapt the parts and lengths to your installation before choosing cable and protection.
Single-bank example uses the shared 25 A rating. Manual specifies 30 A battery fuse per connected bank; 5 mm² at 25 A permits 4.3 m one-way, rounded up to 6 mm² here. Another battery needs its own fuse and shares the same 25 A total. PWM lead-acid only, cold PV Voc <=30 V. Manufacturer installation manual
Wiring diagram
Open this example in Crimp to use your own parts and cable lengths. Review the assumptions and installation notes as you adapt the circuit.
Single-bank example uses the shared 25 A rating. Manual specifies 30 A battery fuse per connected bank; 5 mm² at 25 A permits 4.3 m one-way, rounded up to 6 mm² here. Another battery needs its own fuse and shares the same 25 A total. PWM lead-acid only, cold PV Voc <=30 V. Manufacturer installation manual
Edit this wiring exampleInstallation notes
Guidance for this model, with sources linked beside the relevant advice.
Verified against the manufacturer's documentation (rev. MS-001164 v2.1, 2016), checked 2026-10-01. Manufacturer documentation →
SSD-25 is a PWM, 12 V, lead-acid controller. Its two outputs share 25 A total; two attached banks do not create a 50 A charger. Select sealed or flooded charging separately for each bank. The priority switch allocates 90/10 or 50/50 while both need charging, and unused capacity can pass to the other bank. These profiles do not establish LiFePO4 compatibility. See configuration, PDF p. 8.
Connect the PV pair and the two battery pairs to their marked positive and negative screws. The negative terminals are electrically common. The optional remote temperature sensor and meter use dedicated connections; they carry no battery charging current. Keep cold-weather PV open-circuit voltage below the published 30 V maximum, which rules out many higher-voltage residential modules.
Fit a 30 A fuse in each battery-positive lead. The installation drawing places battery fuses within 305 mm; a stricter applicable installation rule takes precedence. At 25 A the cable table allows 5 mm² conductors over 4.3 m one way; rounding up to 6 mm² for a short run is a practical metric choice. Terminals accept up to 10 mm² and are tightened to 4 Nm. Leave 75 mm above and below for cooling and avoid a sealed flooded-battery compartment. See wiring sequence, PDF p. 12 and terminal specifications, PDF p. 27.
Set the DIP switches before charging, connect and verify both bank polarities, then introduce solar. Check that each bank sees its selected charging voltage. Observe the allocation while both banks need charge and again when one is full; instantaneous current can move between outputs. A wiring example with one bank uses the whole shared limit but does not illustrate the second bank's required fuse. The detailed cable-distance table is on wire sizing, PDF p. 28.
Build it out
Add SSD-25 to your diagram, then connect your batteries, chargers and loads. Crimp calculates cable sizes and checks the connections as you draw.
Every cable you draw there is sized against ABYC E-11, from the same tables as the reference on this page.
Technical reference
Check the model, ratings and connection points against your own unit before choosing installation hardware.
Check stud sizes, fuse type, run length and how warm the space gets against the gear you actually have before you order.
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
PV +
pv-pos
positive · input
PV −
pv-neg
negative · input
BANK 1 +
out-pos
positive · output
BANK 1 −
out-neg
negative · output
BANK 2 +
bank2-pos
positive · output
BANK 2 −
bank2-neg
negative · output
REMOTE TEMP
rts
signal · bidi
REMOTE METER
meter
signal · bidi
A dash means a current rating is not specified here.
Method & provenance
Manufacturer specifications describe the equipment. Crimp calculates cable results from the circuit and assumptions you enter.
From the maker
Manufacturer, model, ratings and which terminal does what come from the catalog. A newer revision, or the nameplate on the unit in your hand, can say something different — when it does, the nameplate wins.
ABYC E-11
Sized against ABYC E-11 — the US reference, and what Transport Canada accepts as an alternative to TP 1332 for pleasure craft under 24 m. The run length and the current above are what drive the result. Crimp doesn't know how warm your space gets; draw the cable inside an engine-bay zone on the canvas and it sizes for the heat.
Next step
Open this example as a new project. Add your equipment and cable lengths, then review the sizing and checks for your setup.