Battery
Lifeline GPL-31T 105Ah AGM wiring diagram
12 V, 105 Ah (C20) Group 31 AGM deep-cycle battery. Copper-alloy marine terminals use M10 positive and M8 negative studs, both tightened to 7.9 Nm; requires temperature-compensated AGM charging.
- Nominal voltage
- 12 V
- Capacity
- 105 Ah
- Maximum discharge
- 105 A
Wiring diagram
How the GPL-31T 105Ah AGM is wired.
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Cable sizing for this example
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Installation notes
Before you install.
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Verified against the manufacturer's documentation (rev. 6-0101 G — 2019-11-26), checked 2026-09-30. Manufacturer documentation →
Which Lifeline battery is represented here?
The GPL-31T is a 12 V, 105 Ah AGM deep-cycle battery, with capacity rated over 20 hours at 25°C. Its model drawing specifies 195 minutes at a 25 A discharge. Those capacity ratings depend on discharge rate; they do not define a 105 A continuous-current ceiling. The similar names GPL-31XT and GPL-31T-2V identify different batteries. See Lifeline's GPL-31T page and its model drawing, revision A.
What do the positive and negative terminals require?
Crimp's + maps to the M10 positive marine terminal and − to the M8 negative terminal. Both use 70 in-lb (7.9 Nm) tightening torque, despite the different stud sizes. Select correctly sized cable lugs and protect the terminals against accidental shorts. The canvas does not represent terminal hardware, enclosure ventilation or a battery disconnect. See terminal table, manual page 13.
Install upright, with terminals facing upward, and leave at least 0.25 inch between adjacent batteries for airflow. AGM means electrolyte is absorbed and no water is added; it does not make an airtight enclosure suitable. Lifeline requires ventilation because gas can still be released. The installation instructions, page 14, also specify matched batteries in multi-battery banks and cables sized for the system load.
Which charging settings should be used?
At a battery temperature of 25°C, use 14.3 ± 0.1 V absorption and 13.3 ± 0.1 V float. Apply Lifeline's temperature compensation when the battery is hotter or colder. Full charge is reached when absorption current falls below 0.5% of rated Ah, approximately 0.53 A for one 105 Ah battery. See charging instructions and temperature table, page 19.
For repeated cycles deeper than 50% discharge, Lifeline recommends charger output of at least 0.2C, or 21 A for this battery, to preserve cycle life. This is a minimum charger recommendation for that use, not a maximum charge-current rating. The catalog's 26 A charging allowance should not be read as a manufacturer-imposed limit. See page 20.
How should storage and discharge be planned?
Lifeline recommends sizing a bank around 50% average depth of discharge for longer life. Return it to full charge after use. During storage, the manual calls for a boost charge every 90 days, or when resting voltage falls to 12.5 V, following its storage procedure. See pages 14 and 18.
Technical reference
Specifications and terminal map.
Check the model, ratings and connection points against your own unit before choosing installation hardware.
Catalog specification
12 V, 105 Ah (C20) Group 31 AGM deep-cycle battery. Copper-alloy marine terminals use M10 positive and M8 negative studs, both tightened to 7.9 Nm; requires temperature-compensated AGM charging.
- Nominal voltage
- 12 V
- Capacity
- 105 Ah
- Maximum discharge
- 105 A
Terminal map
Catalog connection points, current direction and planning limits. Check the manufacturer's pinout and connector ratings before installation.
+
positive · bidi
−
negative · bidi
Sources and sizing method
Equipment specifications. Model details, ratings and terminal roles come from the catalog. Check your unit’s label and current manufacturer documentation for its exact revision.
Example sizing. Wire sizes and fuse ratings apply to the connected example, not a fixed cable size for this component. Set your actual equipment, current, lengths and installation conditions in Crimp before choosing hardware.
Read how the sizing worksNext step
Plan your installation with GPL-31T 105Ah AGM.
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