← Energy H61-03 · Module 3 of 7 · Pages: 21 · Worksheets: 7

Batteries and inverters

Choose the battery, charge controller and inverter to match your use, work out cables and fuses, and keep the system safe from fire

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Batteries and inverters

In short

  • Work out capacity in Wh, not just Ah: Wh = Ah × voltage. Only 50 % of a lead-acid and 80–90 % of a LiFePO4 battery is usable.
  • LiFePO4 lasts roughly 3,000–6,000 cycles, a solar lead-acid battery 1,200–2,500. Per cycle, lithium is now usually cheaper.
  • Above roughly 1,500 W go to 24 V, above 3,000 W to 48 V: less current, thinner cables, smaller losses.
  • The inverter must be pure sine wave, with continuous power 25 % above your load and surge power for the biggest motor.
  • A fuse right next to the battery positive is a must. A battery short circuit melts tools and sets cables alight.

What's inside

Chapters

  1. What a battery does and how it is measured
  2. Lead-acid or LiFePO4
  3. How much battery you need
  4. System voltage: 12, 24 or 48 V
  5. Charge controller: PWM and MPPT
  6. The inverter
  7. Cables, fuses and switches
  8. Where the battery goes: safety
  9. Charging, maintenance and life
  10. Common mistakes
  11. Printable checklist

Worksheets

  • Battery capacity
  • Inverter size
  • Cables and fuses
  • System diagram
  • Battery log and maintenance
  • Labels for the battery and isolator
  • Battery calendar

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