cell replacement on laptop battery.

[KA5PIU]

Hello.

I like to play with batteries and flashlights and radios, and pretty much everything else.
My ibook battery took a nosedive so I pulled it apart, 18650A cells, oh goody!
This is a 3 cell series and 2 parallel configuration, 6 cells total.
I found some poly cells that almost the exact size of the inside of the pack but greater capacity.
So I wired that up and tested it, works great.
Of course I use protected cells and am now using RC power connectors inside, everything for safety.
After one weeks use I can now say it is a success!
The total cost of the rebuild was under $50, and I have over twice the runtime.

[n2ize]

What type of cells are you using ? If you are using LiPo cells (such as those used for RC stuff) be careful. They are very volatile and if they are not charged properly the results are not pretty. In any event to charge LiPo's you need a cell balancing charger. Don't use a standard NiMH, Nicad, or Lithium-ion charger.

[KA5PIU]

What type of cells are you using ? If you are using LiPo cells (such as those used for RC stuff) be careful. They are very volatile and if they are not charged properly the results are not pretty. In any event to charge LiPo's you need a cell balancing charger. Don't use a standard NiMH, Nicad, or Lithium-ion charger.

Hello.

Yes, LiPo, the laptop charges the cells as a set of 3 cells and the protection circuit takes care of discharge.
http://www.candlepowerforums.com/vb/...d.php?t=204823

[N2CHX]

Pretty soon there will be a Youtube video of Rudy putting out his iBook with a sleeping bag and kool aid.

[KA5PIU]

Pretty soon there will be a Youtube video of Rudy putting out his iBook with a sleeping bag and kool aid.

Hello.

I am using protected cells as well as the original ibook control circuit, and have added pico fuses and connectors.
The thermistor and sense resistors are still in place.
I was debating building the circuit to intrinsic safe standards, I have the boards out of some bad Motorola batteries, but felt this to be overkill.
As it stands now, any sort of abnormal operation will cause a shutdown, and there are 2 complete safety circuits per cell as well as the thermal and current fuses.

[n2ize]

Was the original ibook control/charge circuit designed for LiPo's. If not, be careful !! Even with proper circuit and thermal protection you need to use a charger that is designed for LiPo batteries. Particularly critical is to make sure the cells are charged at or below the maximum rate for the particular cell. The charger also needs to have a balancing circuit, to make sure that each cell's voltage remains within close tolerances of each other. Also, be careful discharging them. Lipo's are easily damaged if they are discharged at a rate above their recommended capacity and, they are also damaged if they are overly discharged. At no time should a LiPo battery be discharged to below 3V per cell. Many commercial LiPo chargers won't even charge a pack if the cell voltage is below 2.5 - 3.0 volts. Be very careful that they are not overcharged. Overcharging (or charging at too high a rate) will usually cause the cells to puff, overheat and, burst into flames quite dramatically. Lipo's also easily burst into flames if they are shorted (even for brief periods) or if their cases (which are usually soft foil cases) are punctured.

In the Rc hobby we have a general rule for LiPo's. We never charge them unattended... House fires have been known to occur when persons put the batteries on charge and walk away.

It is also a good idea to check them for puffing. If you see the cases are bulging and puffed that is generally not a good sign.

Last but not least, here is an example of what a LiPo fire looks like. Not something you'd want to have happen indoors.

[kb2crk]

Hello.

I like to play with batteries and flashlights and radios, and pretty much everything else.
My ibook battery took a nosedive so I pulled it apart, 18650A cells, oh goody!
This is a 3 cell series and 2 parallel configuration, 6 cells total.
I found some poly cells that almost the exact size of the inside of the pack but greater capacity.
So I wired that up and tested it, works great.
Of course I use protected cells and am now using RC power connectors inside, everything for safety.
After one weeks use I can now say it is a success!
The total cost of the rebuild was under $50, and I have over twice the runtime.

i have bought more than a few brand new laptop batteries for under 50 bucks. i can usually get two for under 50 and no time lost putting them together.

[KA5PIU]

Hello.

No, the original charge circuit of the iBook was not designed for this type of cell, that is why I use protected cells and a safety/charge circuit.
The safety circuit I use limits the charge current to 800ma.
Each cell is monitored an.d charged as one cell, the original iBook design.
But above all, I designed this to exceed ICAO standards for a computer in the cockpit of an aircraft, any aircraft.
In order for a battery to explode or catch fire it must heat to a given point, usually well above the boiling point of water.
Fuses will open long before that time.
Or excess current, again, fuses everywhere.
But the thermistors are set for anything over 150 degree.
Again, I had debated to build this to intrinsic safety standards but decided not to.
From full dead to full charge is 11 hours as each cell must match the other 2 and so the slowest charging cell sets the pace.
I also have another battery pack that I can play with, perhaps IS is the way to go with this one, who knows?

[kb2crk]

now there is a scary thought. rudy typing on a laptop as he is flying the helicopter.....lol

[KA5PIU]

i have bought more than a few brand new laptop batteries for under 50 bucks. i can usually get two for under 50 and no time lost putting them together.

Hello.

I have found that the iBook batteries are harder to find.
If you have any pointers I would love to hear them.