Fondsites Diagnostics
Energy & Tiny Homes
Home Backup Load Diagnostic
Choose essential loads for an outage plan before estimating runtime or buying a larger battery.
Backup power planning starts with loads, not battery marketing. A refrigerator, router, light, laptop, and medical device have different priority and measurement needs.
This diagnostic is educational. Verify electrical work, transfer switches, medical-device power, generator use, and local rules with qualified sources.
Interactive Diagnostic
Home Backup Load Diagnostic
Select the closest symptom and context. The output is a cautious first test, not a certain diagnosis.
Diagnostic output
Choose the closest symptom to see likely causes and a first reversible test.
Symptom, Cause, Action Table
| Symptom | Possible cause | First action |
|---|---|---|
| Router and phone only | Low-watt communication priority. | Measure watts and plan USB/DC options. |
| Refrigerator included | Cycling load with startup surge. | Measure running watts and allow surge margin. |
| Medical-device load | Safety-critical power need. | Use official guidance and redundant backup. |
| Multi-day plan | Energy budget plus recharge problem. | Estimate daily watt-hours and recharge path. |
Fast checks
- List loads before choosing battery size.
- Measure watts instead of trusting nameplate guesses where possible.
- Leave reserve margin for inverter losses, surge, temperature, and battery limits.
- Use professional guidance for transfer switches, permanent wiring, and medical devices.
What not to change yet
- Do not connect a battery or generator to home wiring without approved equipment and qualified guidance.
- Do not size from advertised capacity alone; usable watt-hours are lower.
- Do not assume a refrigerator runs at nameplate watts continuously.
Assumptions and limitations
Runtime estimates are approximate and depend on measured loads, inverter efficiency, cycling, temperature, and battery reserve settings.
This page cannot guarantee electrical safety, code compliance, or medical-device suitability.