I think it is important to note that when using lead acid batteries and a multi-stage converter or battery charger, typically lead-acid batteries are first bulk charged to 80-percent, around 14.4 volts. The last 20-percent stage of charging a lead-acid battery to 100-percent is the absorption phase that can take as long and often longer than the bulk charging time since it occurs at a lower voltage of around 13.6 volts to avoid excessive battery heat and water loss from the electrolyte. I know that when we are dry camping, and we are not full-timers, we cycle our lead-batteries between however low they go in one- or two-days’ time and 80-percent. It is unlikely we ever get down to 20-percent given the high drain items we run from time-to-time such that we are cycling our batteries between something greater than zero and 80-percent charge as I shutdown the generator shortly after the bulk charging phase or 80-percent of capacity. It makes little sense to run a generator, even at idle, only pushing a few amps to get a battery to-100-percent unless the generator is being run to do more than recharge batteries. The batteries can later be fully recharged when we plug into shore power at an RV park or at home. In the real world, using a lead-acid battery between 50- and 100-percent is somewhat of a fallacy, just as using a lithium battery between zero and 100-percent. Our batteries are there to care and comfort us, more than we are there to nurse them.
Makes perfect sense James to not waste the time to charge a lead acid battery to 100% with a gene. And though discharging to less than 50% will reduce the number of cycles you get from if, if your not a full timer and don’t use it too much, you will still probably get a lot of cycles (or camping seasons) out of your battery. That said, if you switch to Lithium next time you need a battery, you might not need your generator! But if you do, the charging time is so much shorter with lithium batteries. You can easily charge at 40A or more which can recharge a 50% discharged battery in an hour or so.
I wonder how many of the folks who don’t understand electricity well enough to have a grasp for Watts and Watt-hours will have the interest / attention span to read through an intermediate level article like this? I love the article and bank account analogy. It’s brilliant! But I think there is another concept that would really help. Mike, you’re written before (multiple times I think) about the difference between the amount of energy stored per unit weight and volume between a lead-acid and an LFP Battery and propane. A 20 lb tank of propane holds ~120 kW hours of energy compared to a measly 1kW-hr in a standard 12V lead-acid or LFP battery. So, a tank of propane will heat your RV for days rather than minutes! That should get someone’s attention real quick! It’s also head turning to realize that a bank of LFP batteries is good for ~3 times more energy than a bank of lead acid batteries of the same weight. And, even more importantly, for the same amount of stored energy, a bank of LFP batteries wil occupy less than 1/3 the volume of a bank of lead-acid batteries. In bank account terms, these days, a good AGM battery capable of supplying 100A-hr costs about $200 -$300 and a mid-grade 100 A-hr LFP battery costs $300-$500. Even at the California high price of $5/ gallon, a 20 lb tank of propane costs about $20-$25 to refill. So, the cost of 10 - 20 tanks of propane is equivalent to the cost of a lead-acid or a LFP battery, respectively. Even with their lower energy storage density, if you go on a lot of camping trips, lead acid and LFP batteries are cheaper by a lot over the long run to use to heat your RV than propane (inconvenience aside)! We are willing to pay a lot for the ability to heat our RV for days rather than minutes!
I think it is important to note that when using lead acid batteries and a multi-stage converter or battery charger, typically lead-acid batteries are first bulk charged to 80-percent, around 14.4 volts. The last 20-percent stage of charging a lead-acid battery to 100-percent is the absorption phase that can take as long and often longer than the bulk charging time since it occurs at a lower voltage of around 13.6 volts to avoid excessive battery heat and water loss from the electrolyte. I know that when we are dry camping, and we are not full-timers, we cycle our lead-batteries between however low they go in one- or two-days’ time and 80-percent. It is unlikely we ever get down to 20-percent given the high drain items we run from time-to-time such that we are cycling our batteries between something greater than zero and 80-percent charge as I shutdown the generator shortly after the bulk charging phase or 80-percent of capacity. It makes little sense to run a generator, even at idle, only pushing a few amps to get a battery to-100-percent unless the generator is being run to do more than recharge batteries. The batteries can later be fully recharged when we plug into shore power at an RV park or at home. In the real world, using a lead-acid battery between 50- and 100-percent is somewhat of a fallacy, just as using a lithium battery between zero and 100-percent. Our batteries are there to care and comfort us, more than we are there to nurse them.
Makes perfect sense James to not waste the time to charge a lead acid battery to 100% with a gene. And though discharging to less than 50% will reduce the number of cycles you get from if, if your not a full timer and don’t use it too much, you will still probably get a lot of cycles (or camping seasons) out of your battery. That said, if you switch to Lithium next time you need a battery, you might not need your generator! But if you do, the charging time is so much shorter with lithium batteries. You can easily charge at 40A or more which can recharge a 50% discharged battery in an hour or so.
I wonder how many of the folks who don’t understand electricity well enough to have a grasp for Watts and Watt-hours will have the interest / attention span to read through an intermediate level article like this? I love the article and bank account analogy. It’s brilliant! But I think there is another concept that would really help. Mike, you’re written before (multiple times I think) about the difference between the amount of energy stored per unit weight and volume between a lead-acid and an LFP Battery and propane. A 20 lb tank of propane holds ~120 kW hours of energy compared to a measly 1kW-hr in a standard 12V lead-acid or LFP battery. So, a tank of propane will heat your RV for days rather than minutes! That should get someone’s attention real quick! It’s also head turning to realize that a bank of LFP batteries is good for ~3 times more energy than a bank of lead acid batteries of the same weight. And, even more importantly, for the same amount of stored energy, a bank of LFP batteries wil occupy less than 1/3 the volume of a bank of lead-acid batteries. In bank account terms, these days, a good AGM battery capable of supplying 100A-hr costs about $200 -$300 and a mid-grade 100 A-hr LFP battery costs $300-$500. Even at the California high price of $5/ gallon, a 20 lb tank of propane costs about $20-$25 to refill. So, the cost of 10 - 20 tanks of propane is equivalent to the cost of a lead-acid or a LFP battery, respectively. Even with their lower energy storage density, if you go on a lot of camping trips, lead acid and LFP batteries are cheaper by a lot over the long run to use to heat your RV than propane (inconvenience aside)! We are willing to pay a lot for the ability to heat our RV for days rather than minutes!