TinyHouseGrid planning tool

Tiny House Battery Bank Calculator

Add your appliances and we’ll size a battery bank that can carry your tiny house, cabin, or rig through cloudy days—with honest math and every assumption on the table.

This is a planning tool, not a final electrical design. Calculations and raw appliance entries stay in this browser. When site analytics is enabled, this tool may send coarse usage events without appliance names or free text.

This calculator needs JavaScript. Calculations and raw appliance entries run locally in your browser; optional site analytics may receive coarse usage events when JavaScript is enabled.

Step 1

Your appliances

Use measured running watts when possible. Presets are provisional planning estimates and always editable.

Field help:

Appliance	Running watts	Hours/day	Qty	Power	Runs at same time?	Remove

0 Wh/day AC 0 Wh/day DC

Daily energy is calculated from each appliance’s watts and hours per day. Check appliances that may operate simultaneously—even if their schedules overlap for only part of the day. Their combined wattage is used for peak-current and equipment screening. If none are checked, the calculator still uses the largest individual load as a conservative minimum.

Step 2

Your system

These choices determine usable capacity, rated voltage and cold-weather behavior.

Installation Battery chemistry System voltage Days of backup (autonomy) Coldest temperature where batteries live Pick the published anchor at or below your battery room’s expected minimum.

Fine-tune and manufacturer checks Optional, but useful before buying

Capacity assumptions

Depth of discharge (%) Size for 80% end-of-life capacity Search-mode power (W) Search-mode hours/day Other DC conversion losses (Wh/day) Battery is heated or manufacturer allows charging at the selected temperature Manufacturer minimum charge temperature (°C) M

Inverter and startup checks

Manufacturer ratings must use matching units and durations. A result that passes here is still a screening check, not equipment approval.

Largest startup load (W or conservative VA) M Startup duration (seconds) M Inverter continuous rating (W) M Inverter surge rating (W or VA) M Inverter surge duration (seconds) M Minimum battery voltage under load (V) M Use the inverter/manual cutoff basis, not charging voltage.

Battery module and BMS limits

Module nominal voltage (V) M Module capacity (Ah) M Max continuous discharge/module (A) M Recommended discharge/module (A) M Surge current/module (A) M Battery surge duration (seconds) M Max charge current/module (A) M Maximum modules in series M Maximum parallel strings M

Charging sources and conductor estimate

Charger DC output (A) M Alternator rating (A, mobile) M One-way battery cable length (m) Copper conductor size (AWG) Conductor-only 25 °C estimate. Not a wire-size or fuse recommendation.

Your estimate

Battery-bank results

Add an appliance or two, choose the coldest battery temperature, and your battery-bank size will appear here.

Planning inputs and recharge summary

Can solar refill this bank? Optional average-day check

Tiny House Battery Bank Calculator

Your appliances

Your system

Your inverter

Capacity assumptions

Inverter and startup checks

Battery module and BMS limits

Charging sources and conductor estimate

Lead-acid Peukert advisory

Battery-bank results

Power-delivery screening check

Assumptions in this result

Planning inputs and recharge summary

Start over?