# Battery runtime worksheet

A free worksheet for listing daily loads, choosing a reserve target, estimating usable amp-hours, and checking how many 100Ah batteries the plan really implies.

- **Source:** OffGridRVHub
- **Resource page:** https://www.offgridrvhub.com/email-planners/battery-runtime-worksheet
- **Download URL:** https://www.offgridrvhub.com/email-planners/battery-runtime-worksheet/download
- **Format:** Markdown worksheet

## Use this when

- You know the appliances you run but not how long the battery bank will last.
- You are comparing AGM and lithium usable capacity.
- You need to explain why one more battery may not solve a charging bottleneck.

## This is not for

- Brand-specific battery recommendations without current spec checks.
- A replacement for battery manuals, BMS limits, or installer review.
- A one-click answer when loads, reserve days, and recharge windows are still unknown.

## Recommended workflow

1. **List the daily loads:** Start with watts, hours, and duty cycle for the appliances that actually run when you are off-grid.
2. **Choose the reserve target:** Decide whether the bank needs to cover one night, a cloudy day, or multiple days before recharge.
3. **Check recovery before buying batteries:** If charging cannot refill the bank, adding capacity only delays the same problem.

## Daily load table

| Appliance or load | Watts | Hours/day | Duty cycle | Daily Wh | Notes |
| --- | ---: | ---: | ---: | ---: | --- |
| Refrigerator |  |  |  |  |  |
| Furnace fan |  |  |  |  |  |
| Laptop or work gear |  |  |  |  |  |
| Lights and small devices |  |  |  |  |  |
| Water pump or controls |  |  |  |  |  |
| Other |  |  |  |  |  |
| **Daily total** |  |  |  |  |  |

## Capacity worksheet

| Step | Formula | Your value |
| --- | --- | --- |
| Daily energy need | Sum of daily Wh |  |
| Reserve target | Daily Wh x reserve days |  |
| Inverter and system loss | Add 10-20% where AC loads matter |  |
| Usable battery Wh needed | Reserve target + losses |  |
| Nominal battery Wh | Usable Wh / usable percentage |  |
| Nominal Ah at 12V | Nominal Wh / 12.8 |  |
| 100Ah batteries | Nominal Ah / 100, rounded up |  |

## Charging reality check

- Solar, alternator, shore, or generator charging can replace a normal day's use in the expected window.
- Charger output does not exceed battery BMS or manufacturer limits.
- Wire, fuse, breaker, and disconnect choices match the expected current.
- A battery monitor or shunt is included if state of charge matters for trip decisions.
- Parallel battery rules, cable lengths, and balancing guidance are checked before expanding the bank.
- Low-temperature charging protection is covered if lithium batteries may see freezing conditions.

## Related links

- **Open the battery calculator:** https://www.offgridrvhub.com/tools/battery-calculator
- **Preview the battery-bank worksheet:** https://www.offgridrvhub.com/implementation-assets/battery-bank-worksheet
- **How to size an RV battery bank:** https://www.offgridrvhub.com/batteries/how-to-size-rv-battery-bank
- **Lithium vs AGM for RVs:** https://www.offgridrvhub.com/batteries/lithium-vs-agm
- **Battery not charging checklist:** https://www.offgridrvhub.com/batteries/rv-battery-not-charging-troubleshooting

## Final check

- Re-run the matching calculator after changing any major assumption.
- Verify all component specs against current manufacturer manuals before buying.
- Treat this worksheet as planning support, not an engineered installation plan.