Hi, to start off I would like to point out that I know the basics of electricity, and understand the principles that power converters work on. I'm trying to plan out the setup for a DIY laptop power bank using a lead acid battery and an inverter. Specifically this battery, or one like it at a similar price point, and this inverter, or one like it at a similar price point. The battery I linked to is not a car battery but instead one for a small scooter or for other smaller appliances. Will a standard inverter like the one I provided a link for work the same with this kind of battery? And if not, which inverter would work? If there is a better battery option at a similar size, weight, and price I would be greatful if someone could link me to it. My idea is that the whole setup will weigh 10 pounds or less and can be thrown in my backpack to charge my laptop and other accessories. Fuses will be added where needed and I'm also planning to add a voltage meter to see when the battery is getting low on power. Speaking of which, how do you charge a lead acid battery safely and cost effectively? Any help at all is appreciated and even a link to someone else's project using a battery like mine would also be appreciated.
While I'm trying to picture a situation that necessitates this kind of setup I'll throw out a couple things.
A regular lead-acid battery isn't ideal for constant draining and recharging - look for a marine or other "Deep Cycle" battery.
You probably don't need a 400W inverter. Add up what you'll be using at the same time and round up to what's available, should save you some money.
Aaannd I just found this article (looks like it covers what you're looking to do):
An inverter will work regardless of the type of the battery, all lead acid batteries are the same - some are bigger some are smaller.
A scooter battery just won't give you much because of its relatively bad capacity. Then there's power losses to take into consideration both when the inverter changes the DC to AC plus at the laptop charger that changes the AC yet back to DC...
If the laptop charging voltage would be for example 20V I'd take 2 batteries, connect them in series and attach a small voltage regulator to drop 24V down to 20V. That would give both more capacity and less power loss.
Laptop batteries should have the protection circuits built-in (should. Don't quote me on that, find out how yours is), which regulate the charging current - Li-Ion cells can't be charged with a maximum current, they need a 'soft' charge to stay alive.
And charging a lead-acid battery, any 12V car battery charger. But there will be gases emitting from the battery when it's charging so not really safe to charge it in your bedroom.
But to be pragmatic: buy extra laptop batteries and swap them when one runs out.
This ^ plus hand cranked charger.
Thanks for the help, I'll definitely take your advice. One more question, do these inverters draw power as needed or all the time while running. So for instance if Im only drawing 200 watts of power with the devices I'm charging, will the inverter's draw from the battery differ from a 300 watt or 400 watt inverter?
oh and btw its a Macbook I got for free, so buying an extra set of batteries would probably end up more expensive a purchase and would be inconvenient to replace as you have to remove the entire backplate and a plastic guard to get to it. Also AC is required as the macbook uses magsafe 2 and will not charge without the OEM charger (which is a pain in the ass and one of the many reasons I refuse to shell out my own money on their stuff).
Forget the large and clunky power inverter, and just buy a portable battery bank which can charge laptops. I currently own this one (http://www.romoss.com/proview.php?ID=4), and although it's not the best, it can fully charge my 45WH laptop battery (19V charging voltage), and still have a bit of power left over to charge my cell phones.
There are other power banks on the market which can charge laptops, varying significantly in prices, but they all basically do the same thing; have 4S lithium ion batteries, and buck/boost the power to the required voltage. You can even find some on EBay for less than $100 (but beware, some of the EBay ones do not include cells).
Just read that. My method probably won't work, since you use an Apple product. Shame.
Im refusing to spend more than $50 on this project hence why Im using lead acid, or as of now deep cycle batteries and the one you linked me is about 300% more than I want to spend. Also its a 2011 Macbook that will only charge with an Apple Magsafe... Just going to leave this here as you just edited your comment
I got the Macbook for free as my cousin who bought it second hand was locked out by the original owner. I reflashed the EFI chip bypassed my cousin's password and installed Manjaro which I use for most tasks, I only boot into OSX when necessary, this is just what I use when Im on the go as well. I'm typing this reply on my desktop.
ok would a power wheels battery work? If you don't know what they are they are those toy cars that kids can ride around in like small pimps. I found one advertised to work in them for less than $20
You REALLY don't want to carry around a lead/acid battery. This is a serious safety concern. First they can and do leak ... which won't be very pleasant for you, or anything else with which the acid comes into contact. Secondly, they can gas and this vapor is EXTREMELY EXPLOSIVE!!!
Also, lead/acid batteries like to be charged 100% all the time. Not keeping them topped up will dramatically reduce their lifetime. This is why folks are recommending a deep cycle type battery. which is much more tolerant of being drained and charged intermittently.
An AGM (Absorbed Glass Mat) type of automotive battery would be safer, since they do not contain acid in a liquid form, but it is still hard to recommend if the intention is for it to be lugged around on a daily basis.
Thanks for the advice but I am way ahead of you https://raywoodcockslatest.wordpress.com/2012/12/30/car-battery-to-charge-a-laptop/ after reading this I've just given up on the deep cycle and am now looking for ways to fool the magsafe connecter to think that its connected to an Apple charger when its really connected to a battery bank made of Lipos from another dead laptop
I don't want to rain on your parade, but there is most likely some sort of serial data handshake and conversation happening between the laptop, the laptop battery and the laptop charger.
I am well aware of that, which is why I said Im going to see if there is a way to trick it into believing it is connected to a legitimate adapter, some 3rd party companies made magsafe adapters early on but were quickly sued by apple. They had to have the data for the charger to convince that laptop that it is legitimate, so im going to spend my night trying to find out if anyone has a way of implementing a microcontroller to handle communications between a 12v power supply and a Macbook. I'm in highschool, I have all the time in the world but I dont have a lot of money after paying for insurance and gas. Which is why I'm going for the DIY approach.
actually after looking on Amazon there are a lot of cables that have no electronic converters and are just bare wire to a magsafe head. There's a lot of good reviews that say they work and they don't sound foreign or like a bot (5 STARS- GREAT PRODUCT AS DESCRIBED) but actually seem like comprehensive reviews by average people. for $10 it might be worth a try, and if it doesn't work I can always use the magsafe head as a replacement for the original power supply as the cable is starting to fray. The middle pin on the magsafe connector is used for communications between the macbook and charger, but maybe that communication isn't required ¯_(ツ)_/¯
Alright another edit, fuck it, I have a variable power supply and probes small enough to fit on the magsafe pins. I'll just crank it to 12 volts and an amp or so to see if it even registers a charge. Worse case scenario I destroy the magsafe circuit. But its separated from the logic board and you can get replacement magsafe circuits for $5, wish me luck.
I first used an inverter during the 486 days in my truck to power a desktop.
For a backpack setup I would go with a second and even third charged laptop battery and charge the phone off the laptop of just get an extra phone battery.
I had to bump up the idle allot to game on in. Also later when I used a smaller inverter if I shut the truck off the inverter would shut off when volts dropped below 12 or so which can happen quick on smaller lead acid batteries
I don't even own a phone but thanks anyway
turns out the sensor pin does all of its communication inside of the magsafe head and the cheap ones have a bootleg chip that interacts with the mac. For some reason mine charges without a middle pin connection but after further inspection it is not stable and I may have damaged my Magsafe board.
I use solar power exclusively to charge my laptop, phone, and a few other devices including a small computer. I don't use any alternating current for any of my devices. Stepping up and inverting voltage, just to step back down and convert to DC wastes quite a bit of power. My system is stationary so I can imagine it being even more problematic for a portable system where size and weight are a factor.
My laptop is a Dell and they do not provide any car chargers for my device. I did some searches of people trying to reverse engineer the 'sense' pin or whatever proprietary nonsense Dell uses. This is way too complicated for what I figured out to be a simple solution.
These power bricks with special connectors and circuits run off of DC power. I bought a car charger on Amazon that had proper voltage and sufficient amperage to charge my laptop. I then took the AC power brick and added an XT-60 connector in between the power brick and the proprietary plug (DC side). I cut off the car charger plug and added the other half of the XT-60 connector so I can plug in my 19V coming from the car charger.
This both charges my laptop AND backfeeds the circuit inside the power brick. It tricks the laptop into thinking it is being powered by a Dell charger when in fact it is a chinese knock-off being powered by the sun. You would have to look into exactly how it works for your setup, as I haven't touched anything from Apple since the 1990's. On rare occasion I get an error when booting up saying it is the wrong charger. I just make certain to unplug before booting and then plug it in.
Also, I have no idea if plugging into the wall at the same time would damage either or both of the power supplies. I can still use the wall charger, but I make certain to unplug the car charger first. I've been using solar power this way almost exclusively to power my laptop and have never had an issue. If you have some skills and patients to test voltages, cut wires, and solder connectors then I would strongly advise doing this vs using an inverter.
I also use a Pico-PSU to run a motherboard directly from solar. I've had it maybe 8 years now without any problems. My HTPC also uses a Pico-PSU with a power brick and I draw around 30 watts at idle vs 40 watts with an ATX PSU. Straight DC power delivery is the future of computers. I can't wait for more USB-PD devices to flood the market!
I've just ordered a broken Macbook adapter off ebay, im going to take on the cable with the magsafe end and attach a 16.5 volt, 5 amp power supply. The sense pin on the magsafe adapter is in end of the connector, not the powerbrick so as long as I feed in the right amount of power it will be happy. If I can get the right charging board off Aliexpress or some other cheapo website I can hook up some lipo batteries and power the computer that way.