I am a believer of car batteries as a power source to charge the many small electronics we have today. In the last post, Boris recommended a solar charger and that is perfectly fine, but I don’t trust the suckers, call me old fart.

Here is my idea that I am finally getting together. It come out to under $85 and it will last you a long time.

One cheap car battery.  Walmart is selling one for under $50, with 650 amps of cold cranking. If it is fully charged, you’d probably charge every phone in your particular Zip Code.

Top Post Battery Terminals, because you will be needing where to connect cables for the next thing.

A Battery Box. Always nice to keep your battery in one, specially if you need to mount an important accessory later.


And here is the accessory: Automotive DC Power Outlet Extension: How many 12 V USB chargers do you have around in drawers? Or if you don’t (weirdo) they are cheap as heck.

Next is to make the appropriate holes to thread the wires inside. Attach the outlet to the top of the box and make the necessary connections.

What’s left is the election of DC-USB charger and that is up you whatever you want to use. My only tip is do not use the “flush to the dashboard” types because they are a pain to remove. Make sure the ones you use are compatible with your phone. I think the new phones require something called USB 3… anybody knows better, drop a line in the comments so I can update here. There are some that display voltage which is good if you use the battery also for other  more energy-sucking devices.

If you have a generator that is somewhat modern, there should be a 12 DC port to recharge. If not, you can use the  battery charger you should have already. And if not, you can use your vehicle to charge the battery while taking a drive around the neighborhood and enjoying a few minutes of air conditioning.

Anyway, that is my idea. You can improve and adapt at your convenience.

UPDATE: I want to apologize to you readers because I could not understand why was everybody going with cutesy Li Ion battery stuff and not POWER (insert grunts here) till I re-read the post and realized I had left at least one paragraph of explanations.

I have used the battery before and with success. But it was not only for recharging phones and iPods, but also ran a portable TV/Radio (easily 6 hours  day) and rigged car lights for perimeter illumination.  Last year after Hurricane Michael I even ran a table fan using an inverter so mom could sleep in somewhat comfort. But I had everything running on clamps or the wire wrapped around the poles which is not safe or presentable.  The battery will be used and a lot by different items drawing different loads, but I spectacularly failed to mention so.

To Ratus: I understand the selection of a Deep Cycle battery. In fact, the battery  that we initially had was a good quality deep cycle marine which went to waste because it did not get used in 5 years. The “problem” is that if you are very lucky, you don’t get hit by a hurricane and lose power for many years. A Deep Cycle battery is wasting money IMHO.

I have one just like this.

Back to everybody: We don’t have a whole house generator, but a small portable Coleman and it is an exercise of proper usage. Priority of generator power goes to the fridge and the freezer. I have not tried yet, but probably I could run the water heater which would forgive many sins with the missus.  I don’t have to point out the silliness of running the generator for watching TV or play with a gaming console or any unnecessary crap.  If the generator is running, the battery charger is plugged and the battery gets a recharge if needed.

Again, my apologies. I was not clear and the message was lost.

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By Miguel.GFZ

Semi-retired like Vito Corleone before the heart attack. Consiglieri to J.Kb and AWA. I lived in a Gun Control Paradise: It sucked and got people killed. I do believe that Freedom scares the political elites.

18 thoughts on “Power source to charge small electronics. (Update with Mea Culpa)”
  1. Not to be too persnickity, but let’s disambiguate what we’re talking about here.

    Sorry for the long post, by the way.

    Specifically, let’s differentiate between energy sources, energy storage, and energy transformations.

    What Miguel and Joe are posting about, are energy storage. Basically, batteries; regardless of capacity, voltage, self-discharge rate, etc., what they’re doing is storing energy you’re getting from somewhere else. This is also true of using a truck battery to run a power tool, as J.Kb pointed out. The battery will eventually run out, though, so you need an energy source to recharge it.

    An energy source could be a solar panel, a car or truck engine, or (for our purposes) a wall outlet. It can provide electrical energy so long as the sun is shining, vehicle has fuel, or the mains are up, respectively. You need something like this to recharge your energy storage. Variables here are the amount of power the device can supply, and in what form (e.g. max. power output, voltage, AC or DC, etc.)

    Finally, for transformation, this is the stuff that lets you use an energy source or storage with one type of output, with a device designed for a different type of input. For instance, there’s the inverter in J.Kb’s truck that takes the 12VDC (*) the battery supplies and converts it to 115VAC; that lets you plug in things like drills, refrigerators, etc., that are normally designed to run off a wall outlet. Also included are things like USB car adapters (12VDC to 5VDC), or car battery chargers (120VAC to 12VDC).

    To use your battery, you might need a way to get its output to the right voltage. That’s a gizmo like a USB car adapter (ala Miguel’s post). In the case of a USB storage battery, though, it’s just a cable. (**) You may need a completely separate set of gizmos to recharge the battery .. or you may not.

    So what?

    Mainly, my suggestion is: know what you will want or need to do, and then go for the simplest system that will let you do it. That means minimizing, if possible, the number of transformer-type devices that are required; each represents power loss, and also an additional point-of-failure. The reason I recommended a small solar panel with a USB battery brick is it’s very simple to use; quiet to use; and requires the minimal number of cables to get something useful out of it. For that matter, there’s no need to go through the battery part if you just want to charge your cell phone / AAA with a USB port / radio / whatever; it can plug right into the solar panel.

    Will it let me run a power tool? No, unless we’re talking a silly USB fan or something. But then, its purpose – for me – is to simply keep basic electronics and lights charged up. If I want to run a power tool I’ll plug into my truck … but if I’m not doing so, why run the truck engine or drain its battery?

    (*) Yes, some vehicle busses are 24V or higher these days….
    (**) Yes, the “battery” likely has some rather sophisticated electronics to do this for you internally, and to regulate the output voltage and current, etc.; for our purposes, this is part of the battery itself because we don’t have to carry a separate item. Same for the solar panel-type USB chargers.

  2. Don’t forget the small USB Battery/ cell phone chargers. They are small, and will keep your phone charged up for those long days, like when you are sitting in the ER with your parent or child. Or stuck in the middle of nowhere… My sister stole my first one while we were at the ER; because her phone would die before she got home on some days like that one.

    $5 at Five Below. Maybe even cheaper/better at a Blck Friday sale.

    Charge them up as part of a weekly routine. Mine is visiting Mother, which is a hundred mile round trip two- three times a week. It is topped off in a few minutes.

  3. This reminds me of an article about the car battery business in Africa where they are a popular power source for small appliances and lights in places without power grids. There are battery charging services who have generators or mains connections and either charge their customer’s batteries or exchange them like propane tanks.
    Which sparks the idea of getting a marine or RV fridge that runs on propane or kerosene in addition to electricity. Also if you have a truck, you could set up a split charge system for your “house” battery, just like an RV. The only problem is that car alternators need 20-30 miles of driving to charge a battery.

  4. On the subject of usb flavors, they should all be the same voltage (or they wouldn’t be compatible with one another). The difference is in the data transfer rates, which isn’t relevant if all you’re using them for is charging batteries.

    On a related note, IMO, it’s reasonable to be suspicious of usb outlets in public places. It’s possible that they’re connected to your data lines as well as the power supply (charging) lines, which means it’s possible that someone has set one up to hack your data. You can buy usb cables that are for charging only (data lines aren’t connected), or you can use only usb cables connected through wall worts–it’s either quite difficult or not possible to hack your data lines through the mains power.

    YMMV, of course…

  5. Great idea, but the wrong way to implement it.

    First, you have chosen the wrong type of lead-acid battery. It should be a “Deep Cycle” not a “Starting/cranking”. Just Google “deep cycle vs starting battery” to find out why the you chose with need to be replaced sooner if you discharge it only a few times.

    The other thing is that you are wasting power when converting down to around 5v from the 12v of the battery. Those cheap and some not so cheap 12v USB chargers turn the excess voltage to heat.

    Most of the USB power banks boost the voltage up to the 5v from the 4.2v-3.7v of a li-ion battery.

    A better way is spending the same amount on li-ion rechargable batteries, either 18650 or the more recent 21700 size, that you can use directly in a light or power bank.

    There’s several “power banks” that allow you to swap batteries to charge a phone.

    Also the 18650 is the most common size of li-ion rechargable battery available with an energy density of around five AA batteries for the weight of about one and half to two.

    If anyone is interested I’ll post some links or you can just have a look at r/flashlight for them.

  6. As people pointed out, you don’t want to use 12VDC to convert to 110VAC to convert to 5VDC. It is just a waste of money. Even the best inverters lose power in the transformation.

    Get yourself some 12Volt pig tails and wire them in. These are what the 12V power outlets in your car look like. You only need an inverter if you need 110VAC.

    But what I would also recommend is: https://www.amazon.com/gp/product/B07FPB1WJR/

    This is a battery with built in solar charger. Most small electronics eat power at a rate you don’t want to think about. This device is charge off a standard USB charger (mains, 12V to USB) when you have “real power” available. It then can use its power to charge a cell phone or something small like that. There is a lose in this process.

    If you don’t have a source of power, you can unfold the solar panels. Let the sun shine on it for a few hours. This will recharge the battery. It takes a long time but it does work.

    We use one of these to tend 4 or 5 cell phones when we are at Ren Faires without power. During the day it is kept in the sun and collecting power. Members of the camp can plug in and charge a phone in 30 to 40 minutes.

  7. I just re-read my post and realized I left out a whole paragraph. which it now makes me understand why the confusion. Read the update in a few.

    1. Ahhhh… Ok, I see where you are coming from.

      I don’t have a portable TV that isn’t a CRT, so I don’t plan on using it or any TV for information.

      I just picked up some 18650 powered fans, so I’ve got that covered.

      Most new-ish smartphones have an FM radio in them, so I’m covered on the broadcast information. (I also still have a few battery powered radios around.)

      As for “perimeter illumination” I don’t think that is a good idea. No need to advertise that you have any type of power.

      Most of the time we haven’t used our generator when we have lost power.

      A decent cooler or two filled with frozen water bottles lasts for a few days. I’ve always treated it a chance to clean out the fridge.

      1. “As for “perimeter illumination” I don’t think that is a good idea. No need to advertise that you have any type of power.”
        Not advertising but for identification purposes. I have two car halogen headlights with extension attached: One for the front of the house and one for the back. I hear something I don’t like and suddenly it is a movie about a prison break… I do need the siren though 🙂
        PS: Use the boxes it came with rather than try to figure a mounting system.
        Besides, if you are not sleeping, there will be some sort of light inside the house and it will be seen from far.

        PS: TV, there are small LCDs the (12 inches) that run on 12 volts. We have one of those and to catch the local stations are just perfect.
        Prices start about $70

  8. Great discussion here on this blog, Miguel.

    You’ll be much more versed as you enter the amateur radio sphere.and its just as wicked as the normie peeps. Blue skies and 73.

  9. Ahhhh… “Bump in the night” lights.

    I think I have that sorted. 😀

    “Besides, if you are not sleeping, there will be some sort of light inside the house and it will be seen from far.”

    Not really, I use a good headlamp with a bunch of nice low modes. (I was using the “older” one. 😀 )

    When I lost power during “Irma” I mainly used only the lowest modes 0.4 lm, 2.6lm, with the occasional use of the slightly higher ones 7.5lm and 47lm.

    (Of course with it being a good light the runtime was between 100+ days at the lowest mode to about 30+ hours.at the highest that I used it at. The runtime at its brightest, 1200lm, is only about an hour. )

    But even then it was pointed directly at what I was looking/working on, so not lighting up the room for no real reason.

    On the portable LCD TVs, I did an Amazon search for them after you mentioned them. I’m just not that interested in broadcast TV to get one.

    I have a nice 8″ Lenovo Yoga Tab 3, that works just fine for watching whatever video that I wanted to watch.

    I also had several podcasts, ebooks and regular books available to amuse myself.

    1. We have now headlamps in the inventory, love them. Bt 87 year old mom refuses to use that. We have a Streamlight Siege lantern which I recommend a lot. More light than a kerosene or gas lamp without the annoying heat In south Florida is a big ass plus. .

      And something I have all over the house are COAST HP1 190 Lumen flashlights. They are one AA battery size, aluminum and under $10 now (I paid $7.45 back then) Having a small light in your pocket that is barely felt is great and not having to go find a flashlight, but just get the one in a room (every day use) is too convenient.

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