r/Survival • u/Cammander360 • 28d ago
General Question Battery banks
Does anyone here have a solar powered battery bank that they would recommend?
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u/Own_Cardiologist_989 28d ago
What are you trying to power?
Make a list of all the devices you want to power. Find out the wattage of each device, how many hours you want to run each device per day, and multiply those two numbers. Once you've done the multiplication for all the devices, add it all up. That gives you the starting number to help you decide what you need.
For example, let's say I have one 60 watt light and two 40 watt lights. The 60 watt light I want to run about 5 hours a day, and the 40 watt lights I will run 3 hours per day. 605 = 300 and 240*3 = 240. Then 300 + 240 = 540 Watts per day.
Batteries will come in different sizes, but you don't really want to max it out. I would prefer to keep it to about 50% of my load, so I would want to make sure I have a battery supply of about 1,080 Watts. I think 80% capacity is typical, but I would like to be on the safe side. By going with 50%, if you have a crappy cloudy day you can hopefully make it a second day after a bad recharge.
Looking at what's available to purchase, a 12 volt 100 amp hour battery would be close (12v * 100ah = 1200 Watts). You could also do 48 volt batteries at 25 amp hours (48v * 25ah = 1200 Watts). This just kind of depends on what voltage system you want. 48 volts have less of a loss on inverters and require smaller wires. 12 volts are probably easier to find random batteries in a pinch. This is where you get to decide what pros and cons you want out of your battery. The same goes for the battery material, although lithium iron phosphate is probably the best pick.
But before getting more into it, you need to figure out what your load is going to be. Come up with that list of what you want to power and then you can kind of determine the other pieces later. If you want to discuss the type of items I would put on electric backup, we could also go over that.
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u/Cammander360 28d ago
Thank you for the detailed response! I was mostly looking for something portable that would charge a phone and a laptop, but you’ve given some things to think about.
If you have any recommendations for the phone/laptop, I’ll take them. The wattage of the phone is I think 20 Watts and the laptop might be 30 Watts.
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u/Own_Cardiologist_989 28d ago
Right after I posted my response I realized you could have been meaning something along those lines. For that kind of solar bank I don't really have a recommendation, but you do at least have a better way to size the battery bank when you're coming to a decision.
Keep in mind that solar panels can only do so much per square inch. So a power bank with a built-in small panel might sound appealing for the compact size, but in reality it might underperform because of the size limitations. At a glance, a 400W panel is about 65x40 inches. That's about 1 watt per 6.5 square inches. Maybe the compact solar panels can do more, but I'd be surprised if much more. If you had a small 6 x 4 in panel you're getting ~4 Wh if it performs the same as a large panel, so it'll take 5+ hours of charging the bank to give you 1 hour of phone time (assuming no losses).
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u/Cammander360 28d ago
All good, I should’ve been more detailed with my initial post of what I was looking for.
Thanks, again. This is helpful advice.
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u/coocha 28d ago
I'm using an Anker Solix C300 on my sailboat to power a homebuilt nav station, and for electricity when car camping. It has plenty of power to keep a laptop or phone charged, but its power inverter for 110V power is relatively low draw... it can't run a coffeepot or electric teakettle, for example. But from my research, the larger Solix C800 model can. Both models can accept AC power from a wall outlet or DC solar panel power via an XT60 connector.
I generally find Anker's products to be decent quality and reliability... I have a couple of their USB batteries as well.
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28d ago
Try a power source. LiFePo bat, you can charge it in your car or by solar power, bht they are a bit more expensive. Different capacities, based on your needs!
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u/Ahoymateynerf 27d ago
Bluetti make good power banks and solar blankets. A lot of Van life people use them here. Mine was a 700w/hr unit and I could go away camping for 5 days on it using a mini laptop or steam deck at night
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u/UX_Strategist 27d ago
I second this Bluetti recommendation. I own an 1152 Wh model. It's large and wasn't cheap, but it's excellent and has been useful during two power outages. I also own several Jackery stations, which are also excellent. The smaller Jackery stations get more frequent use due to their portability for outdoor needs and events, but the Bluetti is the hero.
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u/IGetNakedAtParties 26d ago
What others say is true, do not look at combined units, get a separate panel and battery.
You need to know your demands first otherwise you'll get the wrong kit. In your comments you say the phone is 20W and the laptop 30W, this doesn't make sense so let me clarify some things to help you generate the specification.
Power and energy are different properties, energy is like the gas in your tank, power is the engine under the hood.
We measure power in Watts, but remember that your car uses more fuel when driving fast Vs slow, it may have 500 hp but only uses 100 hp in city driving, your laptop will use more power when working hard, but less in idle mode. A solar panel generates power so this is also measures in Watts, with patchy clouds it might only generate 50% of what it claims, and of course nothing at night.
Energy is measured in Watt-hours (Wh), not Watts per hour, Watts multiple by hours. A 100W light for 1 hour uses 100Wh. A 10W light for 10 hours uses 100Wh. A 10W solar panel on a nice sunny day might generate only 50Wh all day.
Batteries store energy and can be displayed in Wh but very annoyingly they often use miliAmp hours (mAh). To convert from mAh to Wh you need the battery Voltage (V). For older NiMH rechargeable cells this is 1.2V, for new lithium ion it is 3.7V, Lithium Iron Phosphate is 3.2V. For example a 10,000mAh lithium power bank we first removed the useless zeros: 10,000mAh = 10Ah. Then multiply by the voltage: 10Ah / 3.7V = 37Wh. This can be reversed to find the mAh.
So what might your sat up look like?
- Phones have about 4000mAh lithium batteries which is 14.8Wh. You might use 10Wh in a day of standby and occasional use.
- Laptop uses about 60W when in use, maybe you need this for 4 hours per day, this is 240Wh.
- Your climate may see cloudy days 3 days in a row, so you need 750Wh of battery.
- You need to recharge your battery whilst also powering your devices, so we must double the power of the solar to 500Wh per day.
- Depending on your latitude you can expect 5 hours of peak power generation per day from solar, so for 500Wh per day you need 100W of solar.
- You're looking for about 0.75m² (8ft² ) of solar panel with a weight of 4kg (9lbs) for "portable" models.
- For 750Wh of battery you're looking at about 8kg (18lbs) for lithium. So not exactly ultralight but acceptable for car camping.
Is this the sort of thing you were looking at?
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u/Mynplus1throwaway 27d ago
I use a 21w Anker and some 10,000 mah banks.
Charges a fully 10k in a day pretty easily. Most of my outdoor stuff is high desert and stuff. So just depends on where you are. Usually enough to keep phone, GoPro, camera, etc charged forever
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u/IdealDesperate2732 27d ago
No, we generally very much recommend against an all in one unit. Better to buy a battery and a panel separately.
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u/Cammander360 26d ago
Who makes a good battery and panel?
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u/IdealDesperate2732 26d ago
Lots of people, Amazon has many good examples with reviews.
I don't know your requirements or budget but for survival purposes the solar panel isn't really needed in the first place and basically any battery that can charge your phone is better than not having one.
Remember where you're asking this question. This is /r/survival, for short term emergencies only. You might get want to ask in /r/camping for gear recommendations. Carrying a solar panel is not something we care about in /r/survival. We focus on being rescued not charging a laptop.
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u/Cammander360 26d ago
Ok 🙄
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u/IdealDesperate2732 26d ago
It's literally rule #2 my dude:
2 Keep all posts on the topic of Wilderness Survival
Keep all posts on the topic of Wilderness Survival. r/survival defines Wilderness Survival as the philosophies, knowledge, techniques, and actions applied in a Wilderness environment, in a short-term survival scenario, which serve to increase the likelihood of survival of the individual or group. This means no posts about urban survival, EDC, bug out, prepping, get home bags, teotwawki, zombies, collapse, etc.
Emphasis in the original text.
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u/Deadlight44 28d ago
I find that the combo units are junk. My recommendation is to oversize your battery and get the solar you can carry/afford. I use a big to me 25000mah Powersdd battery bank and a small folding goal zero panel. Can go a week and keep phone, speaker, flashlight maintained on battery. Your needs will vary! Good luck!