Why long runs lose voltage, and how to size the cable for the drop, not the current.
Calculating voltage drop
Drop rises with length and current; size for a few percent, not for the ampacity table.
Practical cable and fuse choices
Fuse at the battery, size the cable for the run, and never let the connector be the weakest link.
- What Does Battery Group Size Mean and Why Is It Important
- How Do You Calculate the Appropriate Inverter Size for a 48V Battery System
- What Size Inverter Do I Need for a 12V 100Ah Battery
- Are All 12V Batteries the Same Size
- What is the Capacity of a 24 Battery and How Does It Compare to Other Sizes
- How Do You Use a Battery Group Size Chart Correctly
- BCI Battery Group Size Chart BCI Battery Knowledge
Voltage & sizing questions
Short answers to the ones that come up most.
How do I choose a battery voltage?
It is set by the equipment: 12V for small loads, 24V for light traction, 48V for storage and most traction, higher for industrial systems.
How do I work out runtime?
Multiply amp-hours by nominal voltage for watt-hours, then divide by the real load — and discount 10–15% for conversion losses.
Why is a 12V lithium battery labelled 12.8V?
LiFePO4 cells are 3.2V nominal, so four in series give 12.8V, which 12V equipment accepts.
What does C-rate mean?
Current relative to capacity: 1C on a 100Ah battery is 100A.
Can I series-connect different batteries?
No — same model, capacity and age, or the strings unbalance.
