![]() ![]() ![]() ![]() I continued discharging down to 11.5V because most people using an inverter or lights will go that far. Because this was pushing that battery to its limit the voltage settled to 12.34V and stayed close to that voltage for most of the cycle. I used a 6.5 amp load and reached 12.0V in 45 minutes on the nose. Here's a test I did using the reBel 6AH LiFePO4 battery to prove this. unlike Led-Acid batteries when a LiFePO4 battery is fully discharged while the capacity doesn't recover to any real usable amount the resting voltage does recover enough to appear the battery still has some capacity left when a high current load is removed near the end of its cycle and will still recover some voltage when a light load is removed near the end of its cycle. So, why can't you just go by the resting voltage if you know a certain voltage is reached at a certain percentage of charge?īecause there isn't enough difference to get an accurate measurement. It's getting its measurement from knowing how many amp hours have been used and how many are left. The reBel batteries also show state of charge but it's not going by the voltage. By knowing how many amp hours are left you will know how charged your battery is. This is one of the areas the bluetooth feature reBel batteries have really shines because their bluetooth batteries have an amp hour meter. Knowing how many amp hours or watt hours are left is better than just seeing a percentage. So if you have a 100AH battery and the meter shows you have 70 amp hours left it's a no brainer, you know your battery is seventy percent charged. An amp hour meter measures the amount of amp hours used. The only accurate way is with an AH meter. So how can you know the state of charge of a LiFePO4 battery? They can be almost fully discharged and still have a resting voltage of close to 13V. Lithium Iron Phosphate batteries not only have a flat discharge curve, they also have great resting voltage recovery. But it also means we can no longer use the old school method of knowing the battery's state of charge. This is good because it means with a LiFePO4 battery you get to use almost all of the capacity you pay for above 12V. Back in the "old days" with Lead-Acid batteries, it was pretty easy to calculate the state of charge by the resting voltage.īut, because of the flat discharge curve of LiFePO4 batteries you can't go by the resting voltage to get the state of charge other than knowing if the voltage is 13.3V or higher the battery is full or close to it and if the voltage is 12.5V the battery is fully discharged or real close to it, which I will demonstrate in a minute. ![]()
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