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What’s a Deep Cycle Battery?
Deep cycle batteries may look a lot like car batteries, but they’re quite different.
Deep cycle means that the batteries have the ability to be fully charged and discharged. A deep cycle battery is very useful for situations where you need a continuous source of electricity to power things like lights, computers, and household appliances.
Are Deep Cycle Batteries Good for Solar?
Deep cycle batteries are great for solar charging because you can discharge and recharge them much more than a standard vehicle battery.
When learning how to build your own off-grid solar system, you’ll often hear of two types of deep cycle batteries:
- lead-acid batteries
- lithium batteries
Lead-Acid Deep Cycle Batteries
Compared to lithium batteries, lead-acid batteries have a lower upfront cost but they typically don’t last as long.
You’ll usually come across 2 types of lead-acid batteries when shopping for solar batteries, flooded and sealed.
Flooded Lead-Acid Batteries
Flooded lead-acid batteries require routine maintenance of electrolytes, must always be upright in orientation to prevent electrolyte leakage and needs a ventilated environment to diffuse gases created during cycling. But they do the trick and they don’t cost much compared to other solar batteries.
Sealed Lead-Acid Batteries
Although they’re more expensive, I prefer sealed lead-acid batteries because they’re maintenance-free and typically last longer than flooded lead-acid batteries. That alone is worth the extra money.
Just look for AGM deep cycle batteries. These sealed lead-acid batteries are clean, safe, and you don’t have to worry about maintenance or keeping them upright.
Another reason why AGM deep cycle batteries are great is that they tend to handle cold, freezing weather better than other types of batteries. (Weather can affect battery performance, especially when it comes to winters.)
Lithium Deep Cycle Batteries
Compared to lead-acid batteries, lithium batteries are typically more expensive initially but they have a longer lifespan and more power. So they’re cheaper in the long run.
You can expect lithium batteries to have roughly 10 times more lifespan than lead-acid batteries.
Also, you can discharge a lithium battery 100%. But with a lead-acid battery, you really should only discharge it to 50% before you start negatively affecting the battery’s lifespan (although some can handle up to 80% discharge).
Lithium batteries are also much more efficient with electricity than lead-acid batteries.
When you put electricity inside a new sealed lead-acid battery and then you take it out, you lose about 10 to 15% of that electricity. That means you only get 85-95% of that electricity back. But when you put electricity in a lithium battery and then you take it out, you’re getting 99% of that electricity back.
The most powerful, efficient, and long-lasting battery for solar power systems is Lithium Iron Phosphate (LiFePO4).
If you want to learn more about the two most recommended solar system deep-cycle batteries, check my post: AGM vs Lithium Batteries for Solar