Laptop running on a sealed lead acid battery


[Viktor's] laptop needed a new battery; he had the trade off between carrying around a cheap but heavy sealed lead acid (SLA) battery, or buying an expensive but light Li-Ion battery. Figuring his old laptop was pretty heavy already, and having an unused SLA available, re-purposing it for his laptop wouldn’t be too much of a hassle. Using a boost converter he built out of a custom dip MAX668, he is able to output the necessary 5 amps required. An MC 34161 voltage monitor chip is planned for future revisions, but he’s currently running it just fine. Check out some of his other cool hacks on Karosium.

Related: MSI Wind extended battery


  1. taco says:

    Who would voluntarily lug around an SLA?

  2. babble says:

    how long does the battery last

  3. JDP says:

    Yeah. See the Mac Portable and the Powerbook 100…

  4. barry99705 says:

    His site says 30 minutes.

  5. booger says:

    Doesn’t seem that portable… but, then, msybe the doesn’t need it to be that portable. Regardless, it’s always cool to see what kind of ingenious solutions people come up with using spare parts and spare time. Needs more arduinos, though.

  6. PHP. says:

    I did the exact same thing back in 2000… except that i didnt know what i was really doing. and the only thing i did was a conection straight to power jack and the 2 leads from the battery. worked pretty good. xD

  7. Bill Hates says:

    All that just to run my Windows 95 ? I am flattered !

  8. ascendant says:

    @Bill Hates
    The laptop’s running Linux
    Keep hatin’

  9. Haku says:

    I have a laptop running off a SLA using a car adaptor – the Asus Eee 701 can be picked up & held easily with just two fingers, but the 24kg 70Ah SLA needs two hands to pick it up. No they don’t go travelling anywhere :)
    I estimate I’ll get up to 48 hours runtime but haven’t tried running it flat yet.

  10. jsngrimm says:

    those sla batteries are heavy – my ups takes one and when you remove the battery it gets about 7 pounds lighter

  11. jsngrimm says:

    also expensive ups ones r about $30 each

  12. Mukle says:

    IDK, about lugging it around anywhere. but there’s a few folks who live off the power grid that are interested in this kind of thing. Use a couple of solar panels and or a wind mill along with a charger and your all set. Don’t need the laptop to waste cpu time to do power monitoring. desktop pc use way more power then the laptops which is another reason why off griders use laptops.

  13. Hirudinea says:

    Build the converter so if fits into the battery space and it would be even better.

  14. TBJR6 says:

    i had a similar situation and i handled it in a similar way

    only i used a 12v to 115ac adapter and generic laptop power adapter

  15. Steven says:

    hmm I always wanted to make something similar for when im traveling. But Lead in a box is not an elegant way.

    Nowadays 60 to 70 Watt LiPo pack are about 50 dollar/euro.

  16. eric says:

    Am I the only one who noticed the strange wording in the description? It says he used a boost converter to get the 5 amps necessary. He used it to get the _voltage_ necessary at that current.. I know that’s what was meant, but the wording made it sound like he built a current-regulated supply.

    It is of course possible to have a current-regulated switching converter, but that’s not what is happening here :)

    Sorry for the nitpick!

  17. aztraph says:

    I wonder if he tried the Battery reconditioning technique in the laptop resurrection and upgrade article back in 2005?

  18. mikula says:

    I did this a couple of years ago got like 10 hours worth of charge

  19. CampGareth says:

    Just want to point out I’m doing a similar thing with my PSP atm. Scrounged an old SLA from a wheelchair and I have a luggage bag to carry it around in, best thing is I can also use a beagleboard with it if want.

  20. silversurfa64 says:

    how lame is this website…

  21. j9 says:

    When I did something similar, I used 6 Cyclon D batteries (,%202.5AH~ic~2V2.5T1JBU.htm). Seemed like a good idea at the time, since I had originally pulled them out of some portable piece of HP equipment I found.

  22. Power says:

    Why do batteries gradually lose their ability to hold a charge?

  23. Otto Suns says:

    gotta get me a new laptop at some stage

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