Clyde
H.M.F.I.C.
Tired of lugging around lead acid batteries? Check out this Lithium Iron Phosphate (LiFiPO4) battery from Bioenno.
A couple of corrections Texas:If you get that 12v 100a-hr AGM lead-acid battery, you're probably spending $100-150. And it has a usable 50 amp-hour capacity (50% drainage).
There is no doubt when you look at the longer life of the lithium it becomes closer pricewise, but to get a 200AH lithium battery is an initial outlay of a lot more than a comparably AGM battery. I just checked Amazon and the range for 200AH lithium was 1550 to 3100 dollars, so Let’s say 2300. average. I got the 200AH AGM batteries for about three hundred twenty out the door. Even with the longer life and better discharge depth (as in more usable power without damaging the batteries), it’s hard to justify that initial expense. Don’t get me wrong here, when you factor in all this and the weight reduction, I think lithium is a much better battery. Just not in my budget to experiment on my campers solar system. There are other factors too. There is usually a substantial shipping charge for batteries, along with core charges and taxes. The quoted price is not the final cost.Li ion batteries actually aren't more expensive than lead/acid or AGM. Consider...
Let's say you have a deep cycle lead acid battery for $150. It might be 12 volt, 150 amp-hour. And a reasonable life would be 100 cycles at 50% discharge. One way to look at it is what is the total charge/discharge capacity? 100 cycles x 50% x 150 amp-hour = 7500 cycle-amp-hours. And price per unit, it's $150/7500 = 2 cents/c-a-hr
Now compare this to a lithium ion battery. I can buy 12v Li-Ion 20 amp-hour batteries for $60 all day long. You can deep cycle it 80% for 500 cycles. So capacity: 500 cycles x 80% x 20 amp-hour = 8000 cycle-amp-hours. And price per unit, it's $60/8000 = 0.75 cents / c-a-hr.
So in this comparison, the lithium-ion battery is only 40% the cost over the life of the battery.
The more expensive factor with Li-ion batteries is immediate capacity. If you get that 12v 100a-hr AGM lead-acid battery, you're probably spending $100-150. And it has a usable 50 amp-hour capacity (50% drainage). That smaller Li-Ion battery is 12v 20amp-hour rated, of which 16 a-hr can be cycled. I'll need about 3 of these to get to the 50 amp-hour rating of the AGM, which means $180.
Another factor is weight. The example above, the AGM battery is probably 50+ pounds. The Li-ion batteries are 4 lbs each, so 3 of them are 12 pounds. It's also maybe 1/2 the volume.
A couple of corrections Texas:
AGM batteries have a depth of discharge of 80%. It is flooded cell batteries that have a depth of discharge of 50%
Capacity is usable capacity, not total capacity. Deep cycle batteries have a 20 hour rating. A 100 Amp Hour deep cycle battery will deliver 5 amps for 20 hours. After that point it can no longer deliver a 5 amp current. Starting batteries have a 10 hour rating. So a 100 amp starting battery can deliver 10 amps for 10 hours.
Any higher current and you get fewer amp hours. Any lower current and you get more amp hours.
There is no doubt when you look at the longer life of the lithium it becomes closer pricewise, but to get a 200AH lithium battery is an initial outlay of a lot more than a comparably AGM battery. I just checked Amazon and the range for 200AH lithium was 1550 to 3100 dollars, so Let’s say 2300. average. I got the 200AH AGM batteries for about three hundred twenty out the door. Even with the longer life and better discharge depth (as in more usable power without damaging the batteries), it’s hard to justify that initial expense. Don’t get me wrong here, when you factor in all this and the weight reduction, I think lithium is a much better battery. Just not in my budget to experiment on my campers solar system. There are other factors too. There is usually a substantial shipping charge for batteries, along with core charges and taxes. The quoted price is not the final cost.
The most common measure of battery capacity is Ah, defined as the number of hours for which a battery can provide a current equal to the discharge rate at the nominal voltage of the battery.
I figured on a 125 amp resettable circuit breaker switch. As long as the inverter isn’t under a load when switching there shouldn’t be an arc when switching. This is mainly for shutting it off during the day or all night to help stop the small drains on the batteries.A couple of notes.
Doc, first, I think we're not seeing eye-to-eye on how batteries are rated. Let's say you have a 12v 150 amp-hour battery (doesn't matter if flooded/AGM/Li-ion). That 150a-hr is the full capacity, no reserve. So if it's 80%, then you have 120 a-hrs. If it's 50%, you have 75 a-hrs of usable power. Nobody rates a battery at the downgraded rating but rather at the full "dead battery" rating.
Brent, I hope you put a monster switch in there. Whatever the watt rating of the inverter, divide that by 12 (assuming 12v system) and that's how many amps the switch should be rated at. So if you have a 2000 watt inverter, that switch needs to be rated at 170 amps. And you are going to get a monster arc when you flip on the inverter. It charges a big bank of capacitors and that's quite a surge. Something to consider.
That sucks to hear of the efficiency dropping that low on minimal output. I will test mine out with my actual use and see how I can modify my usage to make it as efficient as I reasonably can.Texas, do you have any sources for that? I have not seen anywhere that the amp hour rating is amp hours to a dead battery. I've given you a source that says the opposite. I can give you many more.
Brent, I tested four of my inverters today with a DC current tester. The no-load DC draw was between 3-10 watts, with the no-load draw going up roughly proportional with capacity. All had a maximum of between 85-88% efficiency at around 40% capacity. At less than 10% capacity efficiency fell off rapidly, usually down to 60 something. The voltage under a 200 watt load was all over the board: from 110 v to 120 v.
I tested at 25 watts, 35 watts, 90 watts, 200 watts, and 600 watts.
Texas, do you have any sources for that? I have not seen anywhere that the amp hour rating is amp hours to a dead battery. I've given you a source that says the opposite. I can give you many more.
Again, they reference the cutoff voltage, and here note it is 10.0v for a 12v lead-acid battery. I can assure you 10.0v does not have 20 nor 50% capacity left over.
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