Deep Cycle Battery Reserve Minutes Calculator

But take away all the marketing hype and what’s left? A number. In this case, the amp-hour rating on the label. This doesn’t tell you anything about actualy performance in the real world. Reserve capacity give you a better sense of how much reserve a battery has; it indicates the ability to hold a charge for a given amount of time under certain loads.

When customers buy batteries, most considers either the peak surge current or group size. While those specs will tell you what it takes to crank an engine, neither tells you much about performance under prolonged, consistent load. Batteries that can sustains a continuous drain over time are rated as deep cycle batteries. Reserve capacity is standardized way of rating these batteries in terms of how long they can handle a 25 amp drain until the voltage collapses. It provides a definitive measurement instead of a blanket “it should of last a long time” claim.

How to Check Your Battery Performance

After entering both your battery type and a description of what you’ll be charging, the calculator will process the information. The most important thing here is that you have to enter your depth of discharge; most calculations don’t consider what part of your battery are usable. For example, if you frequently take a flooded lead acid battery down more than half way, it won’t last long. Just because it has power doesn’t mean you should treat all of it as usable.

With lithium iron phosphate batteries, however, you can go down to 90 percent and not hurt its longevity. That’s twice as much juice as you’d get with the same amount of lead-acid battery. Chemical reactions within the battery slow down as temperature drops. When you camp in the wintertime, temperatures can drop as low as forty degrees Fahrenheit. These lower temperatures reduces a lead-acid bank’s effective capacity. Cold also results in higher internal resistance: Your batteries will generate more heat then they do electricity to power your gadgets. The calculator corrects for this reduced performance in winter but you should plan for it ahead of time.

Many people don’t even think about this when they buy their units, only to find themselves disappointed by poor performance. The final hidden cost to your DC battery drain is the efficiency of the inverter. When running AC devices through an inverter, more DC power will be pulled from the battery than what the appliance wattage label says it is using. An 85% efficient inverter means that when a microwave with a rating of a thousand watts runs, the battery is actualy supplying about eleven hundred watts. Our calculator takes AC draw and shows the actual DC use so you can understand how much it is really doing to your battery bank. You will have no more unexpected voltage drops while you’re making dinner.

Sulphation builds up over time, reducing surface area available for chemical exchange. As batteries get older, they decreases their ability to hold a charge. Over time, flooded batteries will lose some of their surface area for chemical reactions and become less able to hold their charge. A 5-year-old flooded battery won’t hold a charge like it did when new. If you plan with old specs without adjusting for battery age, your runtimes will not account for that age. You will end up estimating wrong. Account for battery age so you’re estimating based off today’s performance instead of yesterday’s. Being underpowered is better than being left out in the dark.

These factors don’t affect LiFePO4 batteries as much due to low internal resistance at cold temperatures. These batteries has very little Peukert effect (they produce close to rated capacity at all discharge rates). And with high load requirements, lead acid batteries are greatly compromised while lithium holds steady and consistent. Going lithium isn’t just about reducing weight, it’s about having confidence while off-the-grid.

The page has reference tables that let you compare various battery groups against typical camper loads. Then, you can see how a Group 31 works out for a quiet night of LED lighting versus a weekend trip with a bunch of inverter use. Raw numbers become practical decisions based on context. The point is to learn how to effectively manage your power. This way, you can go to bed at night and sleep soundly knowing your phone batteries won’t drain at the same time as your RV batteries.