justDIY
Active Member
what sort of thing do I have to worry about or watch out for, building a lithium-ion battery pack?
The basis of my idea revolves around a design similar to this:
**broken link removed**
Her design calls for two nimh batteries, but I'm thinking adding an additional chip, which supports charging a Li-ion battery using USB ... basically adding a built-in recharge capability. I would like to use two lithium cells in parallel for a higher density... this way, I can connect the device to a usb host to recharge the device from the hose, or connect a usb gadget to the device to rechage the gadget from the device ... not sure how to handle the switching between charge and discharge modes
The chips I'm looking at (MAX1555 or MAX1811) will charge and maintain a single lithium ion or lithium polymer cell ... but it makes no mention of cells in parallel ... my thinking is, two cells in parallel should just look like one higher capacity cell, I mean, if I might have a single cell that is rated at 1000 mAh, but I could also use a single cell rated at 2000 mAh ... the datasheet doesn't mention any limits as to the capacity of the cell, so, to the chip, it'll look like I just have a big 'ol cell connected if I take two 2000 mAh cells and parallel them. of course, it would take longer to recharge all that capacity, especially with current limited to only 100mA (or 500ma for the 1811)
does this make any sense?
The basis of my idea revolves around a design similar to this:
**broken link removed**
Her design calls for two nimh batteries, but I'm thinking adding an additional chip, which supports charging a Li-ion battery using USB ... basically adding a built-in recharge capability. I would like to use two lithium cells in parallel for a higher density... this way, I can connect the device to a usb host to recharge the device from the hose, or connect a usb gadget to the device to rechage the gadget from the device ... not sure how to handle the switching between charge and discharge modes
The chips I'm looking at (MAX1555 or MAX1811) will charge and maintain a single lithium ion or lithium polymer cell ... but it makes no mention of cells in parallel ... my thinking is, two cells in parallel should just look like one higher capacity cell, I mean, if I might have a single cell that is rated at 1000 mAh, but I could also use a single cell rated at 2000 mAh ... the datasheet doesn't mention any limits as to the capacity of the cell, so, to the chip, it'll look like I just have a big 'ol cell connected if I take two 2000 mAh cells and parallel them. of course, it would take longer to recharge all that capacity, especially with current limited to only 100mA (or 500ma for the 1811)
does this make any sense?