beachycove
Well-known member
I thought I would put this here rather than in the Newton forum, as it is VERY slow going there.
eMate batteries (which are just 4x1.2v NiMh cells like those found in many old laptop battery packs) have a glass encapsulated thermistor on leads located near the plug that is easily relocated on a replacement battery pack; it literally tapes onto the cells, and you join up the wires a couple of inches from the cells. The original battery pack also has a strap-type safety fuse at the other end, however, as a second line of defence against overcharging. I think this latter is something called a "polymeric positive temperature coefficient (PTC) device." If I have it right, this kicks in if the thermistor fails.
Packs of 4xNiMh cells are readily available without the fuse, but finding ready-made packs with a fuse seems next to impossible. This should not be so much of a problem, you might say, since the fuse can be reclaimed and reused from the old pack. The problem is that it would have to be soldered to the battery terminals, and my experience of soldered batteries suggests that they are severely damaged by heat, so I don't want to have to go there. Waste of time and money, in my opinion, as they just do not last. Reusing the original thermistor, on the other hand, is not a problem.
Thus my question: Will a battery pack without a PTC safety fuse, but with the thermistor re-installed, work safely in an eMate? Has the battery technology advanced so that these secondary fuses are no longer needed?
Anyone here with enough technical background to comment?
eMate batteries (which are just 4x1.2v NiMh cells like those found in many old laptop battery packs) have a glass encapsulated thermistor on leads located near the plug that is easily relocated on a replacement battery pack; it literally tapes onto the cells, and you join up the wires a couple of inches from the cells. The original battery pack also has a strap-type safety fuse at the other end, however, as a second line of defence against overcharging. I think this latter is something called a "polymeric positive temperature coefficient (PTC) device." If I have it right, this kicks in if the thermistor fails.
Packs of 4xNiMh cells are readily available without the fuse, but finding ready-made packs with a fuse seems next to impossible. This should not be so much of a problem, you might say, since the fuse can be reclaimed and reused from the old pack. The problem is that it would have to be soldered to the battery terminals, and my experience of soldered batteries suggests that they are severely damaged by heat, so I don't want to have to go there. Waste of time and money, in my opinion, as they just do not last. Reusing the original thermistor, on the other hand, is not a problem.
Thus my question: Will a battery pack without a PTC safety fuse, but with the thermistor re-installed, work safely in an eMate? Has the battery technology advanced so that these secondary fuses are no longer needed?
Anyone here with enough technical background to comment?