Battery Inputs Explained

The battery section tells GridGap what one battery unit looks like, how much of it can be used, and how cautiously the app should treat that stored energy. These inputs have a direct effect on the battery result, but they also affect inverter sizing, charging, and the warnings you may see later.

What the battery section does

If your appliance list and scenario hours describe the load, the battery section describes the energy source that must carry that load when solar or grid support is not available. GridGap uses these inputs to work out how much total stored energy is needed, how much of that energy is actually usable, and what battery arrangement is likely to make sense with the rest of the system.

In Simple mode, this section stays focused on the essentials. In Technical mode, extra fields appear so you can control battery behaviour more directly. Those extra controls are useful when you already understand the battery you are working with. They are not there to be filled in for the sake of it.

Battery size, Capacity mode, and Voltage

The first field is the battery size itself. That value means different things depending on the Capacity mode you choose.

If Capacity mode is set to kWh, you are entering the energy content of one battery unit directly. This is common with many modern lithium products that are sold and compared in energy terms.

If Capacity mode is set to Ah, you are entering charge capacity instead. In that case, Voltage becomes critical, because amp-hours only become useful energy once voltage is part of the picture.

Voltage is the nominal voltage of one battery unit, such as 12 V, 24 V, or 48 V. This is not the final bank voltage. It is the building block voltage that GridGap uses later when checking whether the battery arrangement can match the chosen Inverter / system voltage.

This is why battery voltage should never be chosen in isolation. A perfectly reasonable battery unit can still be a poor fit if it does not combine cleanly into the system voltage expected by the inverter.

Chemistry and DoD

Chemistry is more than a label. In the app, it changes the sizing assumptions tied to the battery profile. Battery type affects usable depth of discharge and wider sizing assumptions, so if you change chemistry, it is sensible to review battery voltage and depth of discharge at the same time.

This matters because different battery types are not used in the same way. A setup based on lead-acid behaviour should not be treated like a lithium system, and a lithium system should not automatically inherit the conservative limits of a much older chemistry.

DoD (%) is the allowed depth of discharge. This is one of the most important fields in the entire scenario editor. It tells GridGap how much of the battery's nominal capacity you are prepared to use in practice.

A lower DoD means you are protecting the battery more conservatively, but it also means the app must recommend more total battery capacity to deliver the same usable energy. A higher DoD can make the required bank look smaller, but only because you are allowing more of each battery to be used.

If you do not yet know the exact battery specification, rough guide values can help you avoid unrealistic assumptions early on. They are a starting point, not a replacement for manufacturer data once a real battery has been chosen.

Technical battery controls

In Technical mode, GridGap exposes more of the battery model. Temperature oversizing factor lets you increase required battery storage for colder conditions. Batteries stored in lower average minimum temperatures may need extra sizing margin, which is why this field is expressed as a multiplier rather than a simple yes-or-no option.

Enable Peukert correction is mainly there for lead-acid style batteries where higher discharge rates can reduce usable capacity. It is usually not needed for lithium systems.

If Peukert correction is enabled, two more fields matter: Peukert exponent and Rated hour capacity. The exponent describes how strongly usable capacity falls at higher discharge current. Rated hour capacity tells the app the discharge rating behind the advertised Ah figure, such as a C20 rating.

Discharge current mode lets you choose between Calculated and Manual. In most cases, Calculated is the sensible choice. It allows GridGap to estimate discharge current from the scenario itself. Manual is there for situations where you already know the current you want the battery model to use.

If you switch to manual mode, the page shows Manual discharge current (A). This is an override field, not a normal starting point. It is best used when you have a good reason to depart from the calculated current rather than when you are still exploring a scenario.

Battery Current Limits

The Battery Current Limits section appears in Technical mode. It begins with Use Default Battery Current Limits. If this stays on, GridGap uses the charge and discharge limits tied to the chosen chemistry profile.

If you turn that option off, the form shows Max Charge Current (A) and Max Discharge Current (A). These are manual overrides for the battery profile defaults.

These limits matter because total energy capacity is only part of the story. A battery can look large enough in kWh terms and still be a weak fit if it cannot safely charge or discharge at the currents the scenario demands.

This is especially relevant when you are comparing batteries that look similar on paper but have very different current capabilities. In that situation, current limits can change the quality of the final recommendation even if the headline battery size stays close.

Installation and planning fields

If you enable Installation & Protection, the battery part of the form expands beyond core sizing and into planning inputs. These fields cover practical installation context such as cable runs, cable material, cable type, voltage-drop allowance, installation environment, protection preferences, and isolation details.

They are useful when you want a more complete planning view, but they do not turn GridGap into a final engineering design tool. The app remains a preliminary sizing and planning tool, so these fields should be read as advisory installation context, not as a substitute for final design checks.

A good working approach is to size the battery sensibly first, then use the installation layer to understand whether that battery choice still looks practical once routing, protection, and environment are taken into account.