6hour battery Mod for 770X made of old crap. *PICS*
Posted: Mon Jun 04, 2007 5:40 pm
Once I discovered to my astonishment that that old dude 770 has a 1280x1024 screen, i decided to fix it and make it usable laptop. I put max a total 320mb ram, tried two sticks of 256, but it would complain. Cd-rom was broken, but I don’t need cd-rom anyways – so I removed it. Now about the battery. Battery was completely dead and impossible to revive, I tried and didn’t succeed, despite that I have some experience with li-ion batteries. So I just took some old li-ion cells from various dead laptops, and assembled a 770 battery.
Battery holds for 15mins, and 50mins , If I disable all battery warnings and shutdown.
Old batteries don’t hold very long NOT because they have lost most of their capacity, but rather because they have increased internal resistance. As a result, battery indicator reaches 0% very quickly, sometimes after 10-15 mins. But at this moment battery isn’t even half empty. You may disable all warning, and you may discover that this battery can sometimes run the laptop for another hour or more after 0%.
In these cases it helps to connect batteries in parallel. I will give you an example, Say you have battery A and B both hold only 15 minutes. Now If I connect them in parallel, you may think that this double battery would hold for 30min, but no, It will probably work 1-2 hours easy. The load on each cell is twice smaller, thus voltage is much higher given the increased internal resistance in old cells.
Now I have another old laptop. Really old. More than 10 years old. It also has li-ion battery (5.4Ah), which uses very large rare cells. In 95% of laptop batteries there are standard 18650 cells (from right). And those huge cells (from left) are 2.6Ah - or at least they were 2.6Ah 10 years ago. Now they are also half dead.
These cells are too big to put them in place of cd-rom. I had to cut out the aluminium cover over the cd-rom. This is how it looks in it’ original condition:
After cutting out the aluminium:
I soldered 4 wired to the original battery to connect to auxiliary battery:
Now I put the auxiliary batteries in the made free space. I also had to cut out a small area over the original battery to pass the wires.:
BTW, If I had to put there regular li-ion cells, I would probably be able to stuff there some 10-15 cells easy. Since there is lot of free space.
Everything is soldered together and taped with isolation tape:
Final View:
Testing conditions: medium brightness, disable lcd and hdd auto shut off, disable all battery warnings, disable stand-by and hibernate. I also put a Xvid movie for never-ending loop. So it would play video non-stop. This requires approximately 50% of cpu usage.
After full charge battery lasted for full 6 hours. .By the way, in the first 2.5 hours percentage went down from 100% to 0%. Rest 3.5 hours it was constant 0%.
Nice, don’t you say? If all those batteries were 100% brand new instead of old dead crap, this would give me 10.8Ah total.
I measured the consumption current ant it's slightly over 1A (for this specific test condition of course). So I assume this battery could give 10hours easy (and some 15 hours with low brightness/office use)
Moderator edit: Please include "PIC" in subject line when posting inline images
Battery holds for 15mins, and 50mins , If I disable all battery warnings and shutdown.
Old batteries don’t hold very long NOT because they have lost most of their capacity, but rather because they have increased internal resistance. As a result, battery indicator reaches 0% very quickly, sometimes after 10-15 mins. But at this moment battery isn’t even half empty. You may disable all warning, and you may discover that this battery can sometimes run the laptop for another hour or more after 0%.
In these cases it helps to connect batteries in parallel. I will give you an example, Say you have battery A and B both hold only 15 minutes. Now If I connect them in parallel, you may think that this double battery would hold for 30min, but no, It will probably work 1-2 hours easy. The load on each cell is twice smaller, thus voltage is much higher given the increased internal resistance in old cells.
Now I have another old laptop. Really old. More than 10 years old. It also has li-ion battery (5.4Ah), which uses very large rare cells. In 95% of laptop batteries there are standard 18650 cells (from right). And those huge cells (from left) are 2.6Ah - or at least they were 2.6Ah 10 years ago. Now they are also half dead.
These cells are too big to put them in place of cd-rom. I had to cut out the aluminium cover over the cd-rom. This is how it looks in it’ original condition:
After cutting out the aluminium:
I soldered 4 wired to the original battery to connect to auxiliary battery:
Now I put the auxiliary batteries in the made free space. I also had to cut out a small area over the original battery to pass the wires.:
BTW, If I had to put there regular li-ion cells, I would probably be able to stuff there some 10-15 cells easy. Since there is lot of free space.
Everything is soldered together and taped with isolation tape:
Final View:
Testing conditions: medium brightness, disable lcd and hdd auto shut off, disable all battery warnings, disable stand-by and hibernate. I also put a Xvid movie for never-ending loop. So it would play video non-stop. This requires approximately 50% of cpu usage.
After full charge battery lasted for full 6 hours. .By the way, in the first 2.5 hours percentage went down from 100% to 0%. Rest 3.5 hours it was constant 0%.
Nice, don’t you say? If all those batteries were 100% brand new instead of old dead crap, this would give me 10.8Ah total.
I measured the consumption current ant it's slightly over 1A (for this specific test condition of course). So I assume this battery could give 10hours easy (and some 15 hours with low brightness/office use)
Moderator edit: Please include "PIC" in subject line when posting inline images
what a mod!
. This is despite that I know there are T2x ibm's with 1280 screen. 
