Are laptop batteries universal?

[j1979]

sounds like a stupid question, but what i mean is, apart from the voltage 14.8v and 11.1v, the mAh, and the physical connector are the circuits the same?

If i were to get a 11.1v battery for a different model laptop, apart from the obvious physical differences would the battery be recognised in windows if i connected it correctly.

The question relates to this thread, where no one has been able to answer my question.

http://forums.hexus.net/chassis-syst...lp-needed.html

[j1979]

ohh and ignore my spelling

[peterb]

Well I missed the first thread - brilliant piece of work! (Do you still want it moved to small form factors?)

On the topic - Laptop batteries seem to be a bit of a black art - especially the high end ones. As you have seen, some have charging controllers built into them, and if windows is monitoring that, then there must be a driver for that particular controller.

That said, I suspect (but don't know) that the cells are probably all made a handful of mfrs (like memory) and it is then assembled to form a specific battery pack for a specific requirement, so in theory any battery pack with an embedded charger and control cct should work OK as I would expect the common drivers to be built into Windows.

The comment about embedded charger is important because using the wrong charging regime with the wrong cell chemistry could be dangerous, but if you get an old battery pack and are confident that you can replace the cells with the same capacity and cell chemistry, then you should be OK. You would be fine for brief testing to see if windows recognises the controller, and putting the ammeter in series with the battery pack would alert you to an excessive charging current.

Some controllers use cell temperature as an input and contain temperature sensors, so that might be something to consider in the design of a battery pack.

I'm sorry I can't be more specific - but the design of battery packs and so on is a pretty specialised subject - especially with high energy denity batteries.

[j1979]

(Do you still want it moved to small form factors?)

no need to move it now.. i was convinced it was in the right section. but if possible you could change the title of this thread from "batties" to "batteries"

Thanks, you pretty much said there what i had suspected, i guess i should just try it out and see what happens.

[Funkstar]

I think peter is right, inside the case you will likely find a row (or rows) of standard batteries, or cells, with the appropriate connectors, charging circuit, temperature sensors, current sensors etc.

I think the more connectors the battery has, the more complex the interface between laptop and battery is (in general). But I would bet the actual cells are virtually the same.

An issue might be, if you changed the cells, then the charging controller gets all out of whack and doesn't like that the available power is higher than it expects or stops charging before the cells are full.

[caliston]

There will usually be a charging chip on the motherboard to which the BIOS and Windows ACPI talk via a bus like SMBus. That means the battery will be wired however that charging chip expects. The battery doesn't typically include its own charging circuit: you don't just give it power and data. So I think connecting a battery to a board that uses a different charging chip is likely to cause trouble.

You might want to read the Smart Battery Data spec:
http://sbs-forum.org/specs/sbdat110.pdf

[peterb]

Done !

[j1979]

Done !

thanks! i do make these stupid misstakes all the time

[Sputnik]

I found this guide which says they removed the circuit boards from the individual batteries first - Not sure if it helps at all.

http://www.electronics-lab.com/artic...n_reconstruct/

[j1979]

I found this guide which says they removed the circuit boards from the individual batteries first - Not sure if it helps at all.

http://www.electronics-lab.com/artic...n_reconstruct/

thanks for you efforts! i only seen the reply today, and my 99p almost dead battery came from the wonderful postman today via ebay.

i took it apart and ripped out the new/old circuit board, it is similar but took some guess work and testing but now its all pretty much working. My battery is charging