Hello, I will be off the grid climbing Kilimanjaro for 8 days in February. I am a photographer and will need to be able to charge my GoPro, cell phone (S7 Edge), and potentially my camera batteries once during this time.
I’ve estimated that I will need roughly 20,000mAh in total over the course of 8 days of use.
Where it get’s tricky is that I will be carrying all of my gear on my back, so weight and size are critical. The powerbank will also likely be subject to extreme conditions, including rain and harsh cold temperatures.
Does anyone have any recommendations for an Anker product that will meet these needs?
8 days is long enough to consider Solar.
To answer your question, if you went with 1 powerbank of 20Ah then what if it were to fail? Would you not be a bit more resilient to have 2 10Ah powerbanks so if one fails you got the other?
Also 2 allows you to have one recharging in solar panel and one safely tucked deep in your clothing roll inside dry bag in your pack, to survive a fall.
I recommend the Powercore 10000 as it is dense power, comparable to the density of 20000 and 268000 packs.
I loosely maintain a spreadsheet of mah/weight and mah/volume and it points to the Powercore 10000. Others come very similar in density but they are then have the “what if it fails?”. Anker changes its product lines so much I’m probably out of date in some cases, but shows the method you can use to make your own choice.
This is on a daily deal in USA. This is the densest product currently from Anker in terms of energy per unit volume and weight.
The 2nd best density is the Powercore 10000 which is on the weekend’s offer, of which you’d buy 1 for say 3 days, 2 for say 6 days. Above 6 days I’d consider adding solar.
Buy some slim power banks, they tend to be easier to slide in a backpack anywhere. Anker has a 5000 mah one but not larger than that. KMASHI and other companies do have 20000mah slim power banks. I own one of those and have no complaints.
No DONT buy slim ones as they bend more and if squished in hard against items like water bottle, tent poles, stove, they risk bending and doing something nasty. Go with something shaped like the Powercore 5000 or Powercore 10000.
Slim is for lower pressure situations like in a laptop bag, or trouser pocket.
Know your shear force and torsion!
Oh come on, Nigel. How much force is going to be applied in a backpack? I’d say it will fit nicely and since the slim ones are wider the force of being squished can be distributed across the surface of the power bank.
I’d tend to agree with @nigelhealy. The OP is climbing Kilimanjaro, not going on a day/weekend hike. Therefore dependability and durability are more important in those extreme environments.
Glad you don’t design anything where people can get hurt.
The force in a backpack is proportional to the surface area. It is not a constant force. As such the bigger the surface area, the bigger the force. This is because the force is transmitting through the pack and any item inside presents a surface, where that item isn’t the contents pass to the side and present the force somewhere else. Imagine say 3 people pushing against a wall. Imagine you put 1 battery under the hand of 1 of the persons pushing. That 1 battery would feel the same force if that 1 person pushes or all 3 people push because its not able to experience the force of 3.
The strongest shapes are circular like spheres or tubes because they contain the most strength material per unit area.
You have torsion effects also. So take say a tube and try to twist it. Take say an oblong and try to twist it. The oblong has more distance between the forces so the moment is higher, this leads to more force at the center of the rotation.
The most circular like of the batteries with high mah/weight and mah/volume are the Minicore 5000, then the Minicore 10000.
You then have the effect of if the item is dropped. Here the force of impact is proportional to mass, so heavier items hit on a corner with a force more for heavier items. Heavier batteries will hit with a greater force. The thickness of the materials need to proportional to mass for the item to have the same strength per unit weight, but they tend to not, its similar thickness material making larger batteries more likely to damage when dropped. Inside a backpack its not the weight of the battery but of the backpack, then see my 1st point above.
Then you have that the force is not constant through a backpack, the item which is facing down at impact has the force of weight of all the items above if, the item at the top (opposite of impact) has only its own weight pressing in. Hence you’d be better putting 2 or 3 batteries at different sides (left/right say) of the pack so a fall is unlikely to damage both batteries.
So you want 2 or 3 smaller tube like or less-wide spread around your pack more than 1 big flat battery.
Your point is valid in other contexts, but not this one. Say in the 3 people pushing example, if they pushed a plate which was placed over the battery then all 3 people can push on the battery. That would be for example under a foot where a tube would experience the same force as a flat battery.
Ankur has a 30,000 mah battery pack. That’s plenty enough to power all your needs for your whole trip
That’s not the point, if that 26800 battery were to fail then what?
If you are budget limited, larger batteries tend to be more value per mah, but if you’re expecting to rely on it… then multiple smaller spread around would be more likely to survive.
Lol Nigel, I understand the scientific reason why the thicker one may be better in the most extreme of conditions. But come on, it’s not like a backpack is applying thousands of pounds of force on any of its contents. Slim powerbanks aren’t necessarily weak, you can get them in aluminum and other rugged housings. You make it seem like a slim powerbank is a sure way to death.
The battery being damaged is very unlikely to cause death.
No, the issue is if you are carrying the battery on the assumption of expecting to use it. You want it then to work. A common example is you slip and fall, then your body mass lands on the pack. If you had one large flat battery it is more likely the battery is damaged, or more likely the battery damages other items. If the casing splits then there may be damage to other contents in the pack.
A few smaller batteries is less likely to damage any of them, if any are damaged then it’s less likely all are damaged.
The only downside I see is in general it costs more.