crazy power bank - Page 1
Forum section: electronics / general

author: jmelson
author_rank: Super Contributor
timestamp: October 04, 2018, 08:36:43 pm
content: OK, today I got a spam for a 50 A-Hr solar power bank. They didn't give a reference for size, but I'm guessing the thing MIGHT be the size of a cell phone. It had a hole at one end and a carabiner hooked on the hole. But, carabiners come in all sizes. it had a soler panel that covered most of one side of the thing.Well, how many batteries do you need to put in the thing to get 50 A-Hr capacity? Sounds like a lot, even if just 3.7 V terminal voltage. How long does it take a 3 x 5" solar cell to charge a 50 A-Hr battery? I'd guess about a WEEK!OK, here's one that's 600 A-Hr!<https://www.walmart.com/ip/Waterproof-600000mAh-Dual-USB-Portable-Solar-Charger-Solar-Power-Bank-For-Phone-Red/361608483?wmlspartner=wlpa&selectedSellerId=5705&adid=22222222227246824345&wl0=&wl1=g&wl2=c&wl3=290728191968&wl4=pla-495014917113&wl5=9060158&wl6=&wl7=&wl8=&wl9=pla&wl10=114441947&wl11=online&wl12=361608483&wl13=&veh=sem&gclid=EAIaIQobChMI3ea9v9Ht3QIV1bbACh0l3gC0EAQYAyABEgJ9uPD_BwE>Sorry about the stupid long link.Jon

author: Ice-Tea
author_rank: Super Contributor
timestamp: October 04, 2018, 09:17:06 pm
content: Seen a load of those on Wish and others.The only thing those turds have plenty of is BS.

author: tsman
author_rank: Frequent Contributor
timestamp: October 04, 2018, 09:26:58 pm
content: Look down a bit at the notes from the sellerOutright scamming going on there with this as their fail attempt at covering their ass.Quote

author: amyk
author_rank: Super Contributor
timestamp: October 05, 2018, 01:42:43 am
content: A real 600Ah battery:https://www.solaronline.com.au/raylite-600ah-6v-deep-cycle-battery.htmlNote the size, weight, and more importantly price.

author: digsys
author_rank: Unknown
timestamp: October 05, 2018, 03:36:28 am
content: Agreed, but I'd add a few comments ...These sorts of figures are common in these types of devices .. To be fair, I'd guess they meant 6,000Ah peak current for 1 sec? so 200-300C?I didn't believe those emergency car start packs could start a dead flat car, until I saw them in action. They were only the size of 1-2 cig packs.150-180Ah is possibly 15-20C, which is doable for some chemistries. Shorter life, but doable. I'd assume that no-one would actually need to use it at thatrate, and if so, not for any length of time, so they're fine with that imo. "We" should be used to filtering headline claims :-)The real problem I have with it is - NO charge profile / termination !!!! ... It seems. That would be an immediate NOPE for me.Once you get past the headlines, the "Note:"s are not that unreasonable.Quote from: Walmart

author: Cyberdragon
author_rank: Super Contributor
timestamp: October 05, 2018, 04:56:47 am
content: Why would you need the charge curve? Who's looking at that kind of stuff for a USB charger?Most of these are one weak battery and the rest literal dirt inside (seach for youtube teardowns). The solar panel could even be paper (like in fake solar calculators). Occationally you get lucky and get a real one with decent (but way overmarked) capacity.

author: Ice-Tea
author_rank: Super Contributor
timestamp: October 05, 2018, 07:15:14 am
content: Quote from: digsys on October 05, 2018, 03:36:28 amThat's not howAhworks. Aside from the fact that for a peak current of 600Ayou'd have to have total system resistance of less than 0,006or a lot less if you want to end up with a meaninfull terminal voltage. Even if they're talking about the uS or nS discharge of ceramic caps it's unlikely.

author: station240
author_rank: Unknown
timestamp: October 14, 2018, 11:37:26 am
content: Quote from: digsys on October 05, 2018, 03:36:28 amAh is stored capacity in the battery, A (no h) is current.600Ah = 600A over 1 hourOR = 1A over 600 hoursOR = 2,160,000 over 1 secondOf course in reality, internal resistance etc means the battery could never supply more than a few amps or tens of amps at a time.Even if they did mean A and not Ah, 600A from a powerbank sized battery is still questionable. Some Lithium car jump starters may manage it, but with dramatically short lifespans.

author: CCitizenTO
author_rank: Contributor
timestamp: October 17, 2018, 04:48:39 pm
content: The batteries that run my pallet jack at work are I think somewhere between 80-120AH using conventional lead-acid batteries and they're pretty freaking huge and weigh enough that to change them you need a crane or something that's rated to lift 2 tons.