Making DIY external battery for laptop, need help

[OX-49]

Hi, I'm pretty much beginner in electronics, but I have determination to make external battery for my laptop (lenovo Y50-70) because it doesn't last long (approx. 1h 40 min and 2h 30min max).


When I bought it (brand new year ago) battery lasted approx for 2h 40min and max 3h 20min.
The big change happend when I change HDD to SSD.

Now I'm thinking about making 6-12 18650 cell battery.

Things I need help with:
Charging batteries from 220V;
Creating required need of output power (20V DC 6,75 A);
Cell's that will be good for it;
Making it safe to use.

Optional:
Making it possible for universal use;
(5V 2,1A) USB port for smart phone.

Why I need this:
I travel a lot;
Hard to get to the power outlet in public places;
Work requires mobility;

Big thanks in advance

 

[13thmonkey]

To be honest if you have to ask those questions, you shouldn't be doing it, if you were electrically competent enough to do it, you'd be asking just 1 of those questions and not all 6.

And the reason that this is important, without literally standing over you and seeing what you see, we're not going to be able to tell you how to make it safe, we're not going to be able to tell you what to watch for, we might forget that capacitors only work one way around, we could miss something, because you haven't made it 100% explicit, and that something could kill your laptop.

Something like this: https://www.amazon.co.uk/dp/B01M9IZHA3/ref=asc_df_B01M9IZHA346425141?smid=A296JJ7EW4ORVE&tag=hawk-future-21&linkCode=df0&creative=22242&creativeASIN=B01M9IZHA3&ascsubtag=trd-60547816-21 might be better a battery pack with a 3 pin 240V output.

 

[Alabalcho]

Your spec of "20VDC, 6.75A": If your laptop needs 130VA to operate, you are looking at car-battery capacity if you want to get more than an hour of runtime.

 

[mjslakeridge]

You: "I want to carry this car battery sized homemade device through airport security and on to a plane".

TSA Agent: "Go right ahead, nothing suspicious here".

 

[USAFRet]

One of the main tenets of DIY is knowing when you are out of your depth. This is you.

What you are attempting to build will be A) More expensive, B) More expensive than a retail battery for your laptop, and C) More explosive.

If you need more runtime, your have basically 2 choices:
1. Buy a bigger battery for your current laptop

2. Buy a laptop that consumes less power (less performance)

 

[OX-49]

One of the main tenets of DIY is knowing when you are out of your depth. This is you.

What you are attempting to build will be A) More expensive, B) More expensive than a retail battery for your laptop, and C) More explosive.

If you need more runtime, your have basically 2 choices:
1. Buy a bigger battery for your current laptop

2. Buy a laptop that consumes less power (less performance)

It seems so, but the thing is I couldn't find other battery bigger than 54 Wh which I have now and 3d modeling requires good performance (not the best choice, I know ). The alternative would be to get a new laptop, but I'm not willing to buy one in next one or two years.

And yes. DIY external battery is going to be expensive although it will be interesting to try something new for myself.

 

[OX-49]

Your spec of "20VDC, 6.75A": If your laptop needs 130VA to operate, you are looking at car-battery capacity if you want to get more than an hour of runtime.

I wrote laptop adapter output. Then how 7.4V 7400mAh 54Wh manages to work for +1h?

 

[13thmonkey]

https://www.amazon.co.uk/dp/B01M9IZHA3/ref=asc_df_B01M9IZHA346425141?smid=A296JJ7EW4ORVE&tag=hawk-future-21&linkCode=df0&creative=22242&creativeASIN=B01M9IZHA3&ascsubtag=trd-60547816-21

 

[OX-49]

You: "I want to carry this car battery sized homemade device through airport security and on to a plane".

TSA Agent: "Go right ahead, nothing suspicious here".

Good one

Yeah, I've been thinking about carrying car battery size DIY device with 50/50 chances of exploding because I may didn't done stuff right

 

[13thmonkey]

You: "I want to carry this car battery sized homemade device through airport security and on to a plane".

TSA Agent: "Go right ahead, nothing suspicious here".

Good one

Yeah, I've been thinking about carrying car battery size DIY device with 50/50 chances of exploding because I may didn't done stuff right

There's probably many of us here that could help, BUT without actually seeing what you are seeing, and feeling what you feel when you touch, shake and try and bend things we have no idea whether it is safe. That's what you have to get experienced enough to tell for yourself.

 

[OX-49]

https://www.amazon.co.uk/dp/B01M9IZHA3/ref=asc_df_B01M9IZHA346425141?smid=A296JJ7EW4ORVE&tag=hawk-future-21&linkCode=df0&creative=22242&creativeASIN=B01M9IZHA3&ascsubtag=trd-60547816-21

Good suggestion, but not this particular one (doesn't ship to my country and not 220V). You see I'm interested into learning something new and because I need such thing I get a motivation to do it.

 

[13thmonkey]

https://www.amazon.co.uk/dp/B01M9IZHA3/ref=asc_df_B01M9IZHA346425141?smid=A296JJ7EW4ORVE&tag=hawk-future-21&linkCode=df0&creative=22242&creativeASIN=B01M9IZHA3&ascsubtag=trd-60547816-21

Good suggestion, but not this particular one (doesn't ship to my country and not 220V). You see I'm interested into learning something new and because I need such thing I get a motivation to do it.

220V and 204V are nominally the same according to the specs. There are others that are similar. Go to an electronics night class for 12 months then you can start, as then you'll have the basics.

 

[OX-49]

https://imgur.com/JuSKuPc

Well this is what I was thinking about so far. Couldn't remember high school physics and electronics. I guess this is how it works.

To laptop (no ideas so far)
I know that charging isn't efective

PCB
http://www.ebay.com/itm/6S-15A-PCB-BMS-Protection-Board-For-6-Packs-18650-Li-ion-Lithium-Battery-Cell/263088090312?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2648

USB
http://www.ebay.com/itm/5V-2A-USB-Charger-Board-DC-DC-Buck-Converter-Step-down-Voltage-Regulator-Module-/122090642804?epid=1880741308&hash=item1c6d2b5d74:g:1~UAAOSw9NdXtbxc

I've been looking for 18650 cells, but I couldn't manage to find specific ones that would fit
Also by doing the math I found that it will cost way uo +100 euro and I did found something similar to 13thmonkey suggestion for 140 euro. So...math to be done.