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opinion:solar:sizing.walkthrough [2022/04/20 14:26] frater_secessus [minimum charging current] |
opinion:solar:sizing.walkthrough [2022/04/20 14:51] frater_secessus [minimum charging current] |
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4,168Wh / 12.0v nominal voltage = **347Ah** of lead-chemistry required. | 4,168Wh / 12.0v nominal voltage = **347Ah** of lead-chemistry required. | ||
+ | Also see the [[opinion: | ||
==== lithium ==== | ==== lithium ==== | ||
Line 152: | Line 152: | ||
MPPT controllers are more expensive so they often sized to the average solar harvest wattage rather than rated panel wattage. | MPPT controllers are more expensive so they often sized to the average solar harvest wattage rather than rated panel wattage. | ||
- | Example: | + | Example: |
==== minimum charging current ==== | ==== minimum charging current ==== | ||
+ | |||
+ | Note: if your offgrid system will use lead-chemistry batteries and needs to last for years then read this section. | ||
Lead-chemistry batteries have minimum and maximum charging current specifications. | Lead-chemistry batteries have minimum and maximum charging current specifications. | ||
- | Lead acid typically require a minimum of [[electrical: | + | Lead acid battteries |
- | * increase our panel and controller to cover it. 34.7A x 12v nominal / 0.85 system efficiency = 490w and a 40A controller.((this is //only// about charging current, not the panel required to charge the batteries fully)) or, | + | * increase our panel and controller to cover it. 34.7A x 12v nominal / 0.85 system efficiency = 490w and a 40A controller.((this is //only// about charging current, not the panel required to charge the batteries fully over time)) A pleasant side effect is the system would make more power (+16%) than we strictly need for charging, so we might be a little looser with power use. Or might do a little better under adverse solar conditions. and/or, |
- | * add alternator charging or other high-current source (see below) and let that system | + | * add alternator charging or other high-current source (see below) and let that system |
Lithium batteries do not have a minimum charging current spec in the normal sense. | Lithium batteries do not have a minimum charging current spec in the normal sense. |