Anker makes some very good portable charges ( they are expensive),
Will charge an iphone 10 times.
Will last you all weekend. Will charge phone 6-7 times from dead
Anker PowerCore 26800 Portable Charger, 26800mAh External Battery with Dual Input Port and Double-Speed Recharging, 3 USB Ports for iPhone, iPad, Samsung Galaxy, Android and Other Smart Devices https://www.amazon.com/dp/B01JIWQPMW/ref=cm_sw_r_em_apa_i_REPsEb3EDGFR9
I've had this Anker PowerCore 26800mAh battery since early 2017 and love it. That's enough power to recharge a Pro Max iPhone seven times.
Lower capacity means I cant leave stuff running forever but the i3 is uniqueish in that its dc-dc converter is always running except cabin lights before startup, connecting the HV, and the 10-15 min of cabin lights til it falls asleep. When the car is charging, it also runs dc-dc to charge the 12v battery, so there is really no need for any longtime running capacity at all.
In a gas car of today, the engine turns off in traffic, stops lights, etc. and the battery has to run the ac system, restart the engine multilpe times, etc. and you need that capacity.
Plus, if I end up being wrong, I just need to pop the hood.
Battery size wise, to give you a comparison, this is 99Wh, and the battery I installed is 128Wh. The OEM Battery is 240Wh. Typically though, you never want to discharge a lead acid below 50% capacity so BMW would've sized the 12v for ~120Wh of usage or less, and a lifepo4 is lithium, which should handle deep discharges better (if needed).
For comparison purposes, here is a well reviewed Power Bank with 26,800mah, for $60. I haven't been able to find a battery with that much capacity for that cheap, and what I did find was much larger in size. I'm assuming they must be using lower discharge, higher supply cells, like 18650's maybe? Not sure.
Edit: I just realized that the common usb charger boards can take as low as 3 volts in, meaning I don't need a 12v supply battery at all, if I custom make the outputs rather than buying car chargers. This means I can run a bunch of single lithium cells in parallel - getting me bigger mah for less money and size. Then there are also charger boards available with build in overcharge protection, for charging this custom pack.
Edit Again: For anyone interested, I priced the whole thing out. To match(or beat) that linked power bank, I'd need 8 Sanyo NCR18650s (10amp cells, $6 each). Add in 3 2 amp charger output boards (again, to match) and a couple input charge boards from amazon, and you are at almost exactly the same price as the premade item. Kinda sucks, I was thinking I could get way more for my money - I guess the prices are reasonable.
Task light https://www.amazon.com/gp/product/B01I1V9V6S/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
I don’t recommend using the lamp without the charger. Even from full charge, it doesn’t take long for it to start dimming.
Anker 26800 mAh Power Core Charger https://www.amazon.com/gp/product/B01JIWQPMW/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
The Anker is the better of the two chargers, so I’m only listing that one.
I use multiple power banks so there's always something available. The MaxOak was purchased in 2016 so there may be a newer model available. It has been really good for a laptop though. The 26800 might work for your purposes. The small Ankers charge quickly and pack a surprisingly good punch.
MAXOAK Laptop Power Bank 185Wh/50000mAh Portable Laptop Charger External Battery Pack
https://www.amazon.com/gp/product/B00YP823NA/ref=oh_aui_search_asin_title?ie=UTF8&psc=1
Also use one of these:
Anker PowerCore 26800 Portable Charger, 26800mAh External Battery with Dual Input Port and Double-Speed Recharging
https://www.amazon.com/gp/product/B01JIWQPMW/ref=oh_aui_search_asin_title?ie=UTF8&psc=1
Have three of these for on the go:
Anker PowerCore 10000 Portable Charger, One of The Smallest and Lightest 10000mAh External Battery
https://www.amazon.com/gp/product/B0194WDVHI/ref=oh_aui_search_asin_title?ie=UTF8&psc=1
Just purchased one of these but it takes FOREVER to charge so it may end up living somewhere else:
https://www.amazon.com/gp/product/B07776PVH5/ref=oh_aui_search_asin_title?ie=UTF8&psc=1
I have the Anker 26800. I bought it specifically for taking to music festivals and have loved it. At full charge, I think I charged 5-7 phones fully before the battery went out.
https://www.amazon.com/gp/product/B01JIWQPMW/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
if thats too much that I would say any other Anker battery would work too. I'm satisfied with mine!
Not sure how much this would charge a laptop but this is the biggest anker battery they make and only weighs a pound. You would need some sort of USB adapter as well I assume. They make even bigger batteries for jumping cars but they are really heavy.
I use these 2 together. When I am not charging anything else both USB can charge the powerbank. I have used these on backpacking trips.
