AJI wrote: ↑
Sat Apr 28, 2018 5:53 am
18650 all the way, but $300 for 20kWh sounds a bit unrealistic. If it's true I got ripped off!
I guess if they're making them out of old stock, maybe..?
Either way, if you can get 20kWh for $300 jump on it. Even if they only last a couple of years you're way ahead of me!
less actually, 300 bucks was including a hundred dollar glass cover for the wooden construction that also cost money to mount the battery pack in, simulating a tesla wall.
though i didn't see actualy proof of spending, i take the story as being honest.
the note that must be said, is that those batteries are not new but second hand. he managed to get his hands on a lot - and i do mean a lot - of discarded / 'dead' laptop batteries, which he then disassembled to take out the 18650 batteries inside (9 in every battery pack). then took the effort to measure which batteries were fine and which not (time consuming obviously) and discarded the bad ones and saved the good ones.
mentioned that the laptop battery protective chip is built to recognise power fluctuations between batteries, so from the 9 batteries in each pack, if 1 is faulty, or the chip itself, the batteries decides to quit and gets replaced under warranty normally and that leaves a 'discarded' (scrap) battery which in many cases actually is far from worthless.
he had 600 well usable 18650 batteries for his system.
if i had to calculate that 300 bucks minus 100 bucks for the glass cover, i forgot the wood paneling (plywood), let's say 20 bucks, so 180 bucks for the batteries. each pack has 9 batteries, so 600 batteries divided by 9 equals about 66 to 67 laptop battery packs atleast. that means me might only have paid 3 bucks for each discarded laptop battery. after all, 3 bucks x 67 batteries equals about 200 bucks so if he's being honest........that's a amazing deal.
so the biggest game here would be to get ones' hands on enough laptop battery packs. let's say half of the cells in the battery packs in itself actually can't be used, so then let's say 130 laptop batteries would be required for the 'system'.
now where and how to get me hands on a grand total of 130 laptop batteries that are 'dead' ? i might know some ways though. question is, how much is that going to set me back. if 3 bucks are anything to go by, then i'd calculate i'd need to spend 400 bucks for 130 laptop batteries. that would be a directive.
laptop batteries are the preferred direction as there are many crappy 18650 batteries from china that don't even produce a tenth of promised output, so the advise is sony, lg, etc. etc. a-brand batteries over 'unknown' brands.
i've seen offers that go as low as 0,65 euros for a single 18650 cell but repetitively, those exist of non a-brand cells, so quite frankly, completely useless.
but again, indeed, as mentioned,
i've seen lead acid batteries that have 100 amps or more for about 150 euro's, as another poster mentioned above.
so i'm in between on what would be the right decision then.
it's said those 18650 batteries need to operate between 40% lowest and 68 to 70% tops in charging and depletion to get most life out of those cells. likewise, leadacid batteries don't really enjoy being depleted either, so i'd say fair treatment would hold the same number.
thus again - taking in concideration the standard average figures for wear and lifespan, energy loss, and combining that with investment, not the least mentioning 'practicability' of replacing a cell/unit, and also taking in concideration the specific battery's 'danger' (leadacid is dangerous in different ways than lithium-ion batteries, but then there are also 'traction batteries' and 'gel' batteries (still lead acid if i'm correct, but without the need to refill), which claim are actually fully 'safe'.
i've already seen computer server rack housings as little as for completely free up to 30 bucks for a 180cmx80x80 cm including cooling fan array on top, made out of metal and covered in weatherproof paint which can theoretically sit outside but i'd go and set it in the garage anyway. another option would be second hand electricity rack housings in similar or smaller sizes for similar prices, but are factory-made to be mounted outdoors.
as a safety measurement, outside of a complete kill switch (which should also be controlled through sensors), i want to look into 'extinguishing' measurements. water obviously isn't the smartest move i'd say so i'm going to need to look into other extinguishing measurements in the case of short-circuiting, (small) fires, or potential leaking of either lead-acid or lithium-ion leakage. safety over taking a potential risk any time.
btw i'm not at all in the position to assume or think you 'might' have been ripped off, as in all reality, i'm gathering theoretics, not personal experience or touchable evidence. I only have accounts of multiple youtube testimonials which are supported by evidence (though not 100% waterproof), and own googling through ebay, online stores, and traders. which does however paint a picture of what is reasonable to expect. still, a lot of routes to go.
for example, i head out repetitively to the dominican republic, and due to the countries well-known power outages, a good amount of homes run on backup power through 12v or 24v lead-acid batteries, which power only the absolute neccesites like the refridgerator, 1 or 2 fans, and some 12v appliances. more than 1 opt for diesel generators, but that's something i'm rather trying to avoid. offcourse safety measurements over there are vastly different (minimal, if any
) over there, and same goes for the energy bill
the lead-acid batteries offcourse then are a proven concept, BUT demand there is vastly different too. let's call it different way of life. solar panels over there then again are costly and a costly investment, especially concidering the amount of theft and....cough....cough....law enforcement
still, any reliable info i can base my calculations on are worth noting, so thanks guys for sharing this vast wealth of information.
who knows it may lead to something we can all benefit from