# will my battery charge faster if....?



## junglemike (Jul 3, 2005)

Hi everyone. I'm new here.
I have a very old ultra slim laptop. It is Toshiba 3110ct (Pentum II-300mhz/128mb ram). Since I use it at the university all day long. I needed it to work non-stop for 6-8 hours. So i modified it's battery, putting largest available today Lithium Ion cells (LG 18650- size 2400mAh Each). I put 3 of them in parallel instead of default 2 (and 3 in series, to reach 11.1v.)
So my battery is 7.2Ah instead of 2.6Ah stock battery. It works vell,and delivers 8 hours work time as required, but i have a problem though:
Charging this battry take _EXTREMELY_ long time. Since this is ultra slim type - it has very small and not powerful adapter - 15v and only 2A. Followig the specs, it says that it charges it's _stock_ battery in 6 hours (when lap is off) and 12 hours (when lap is ON). I didnt' do any precise measurements, but one thing for sure - It can recharge my modded 7.2Ah battery overnight for only about 50%. And this is problem to me - since i need it full at the morning.
So my question is:
Will replacing adapter for more powerful one (say, 15v/5A instead of 15v/2A) improve the situation?
Or laptop electronics is simply not designed to charge with higher current, and therefore there will be no change?
TIA.


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## Terrister (Apr 18, 2005)

I think you would have to replace the charging circuit in the laptop to do this. Would be easier to make an external charger.


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## ebackhus (Apr 21, 2005)

Sounds like a "Hmm, I dunno" kind of thing. I do know that some electrnics will get mad (fire, explosions, scarring) when too much juice is applied. Other still will rejoice when you give 'em more. Have you been able to find an external charger for the battery? It'd be easier and safer to mod than the laptop's electrical system.


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## Volt-Schwibe (Jan 12, 2003)

i have to also agree.

an external charger is the best way to go, since the laptop itself has a charging circut in it, and even if you supply more amprage to it, it's still going to trickle charge the battery at about 1 amp.

keep in mind, a slow 1 amp charge will actually force more juice into the battery than a 2 amp charge.

but, you could occaisionally rapid charge it at as high as about 2 or 3 amps, and get a much faster charge.

so, an external charger would be best, i'd make it about 2 or 3 amps at most.

also, an external charger will need to be 11.1 volts, and not the 15 volts the laptop needs.


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## junglemike (Jul 3, 2005)

Thanks for the replies guys.
I think g00nter is right. I've made a little experiment. I tried to overload the adapter a little bit. I connected large 6 ohm resistor to the adapter, and measured 2.41A, which means that adapter is capable of providing above 2 ampers at least for short time (it got protection anyway). Then i measured current during charging (lap is off), and it was only 0.63A. Even if laptop was using full 2 Amps to charge the pack - it would take only 4-5 hours. So i guess charging circuit designed for specific current, and larger adapter will not help.

As for the external charger - I thought about this idea. Practically it's very simple to make by myself (i've built simple charger schemes for li-poly cells), but there is a catch. The catch is that every laptop uses 3 or 4 cells packs in series (11.1v-14.8), and each cell pack 3.7v is controlled separately for over-charge/overdischarge/and most important over voltage. 
When multiple series cell lithium packs are charged (for ariplanes for example) - equel current flows through all cells (ohm's law) but one cell can get little waker and the others, and this may result in voltage over 4.2, which may get unstable and explode. You can read many such stories at electric airplane forums, where people using 2s and 3s lithium packs. 
So if I want security (and i do) - i need to make all inter-connections, and add protection circuit for every cell pack (since i cannot access lap's protection circuit). This is too complicated for me.
Seems that i will have to accept long charge times. 

This is default battery (very old)









This is modded battery:









I know it's bigger (for ultra-slim laptop) and looks pretty scary (battery is w/o casing ) but I hope I can lieve with that


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