I'd like to open this discussion because with my experiments and observations, I'm now convinced that soldering is ok. I'm willing to be proven wrong, but take my following observation:
The heat under a weld is so hot, it melts solder. I can take heavily tinned wire, place a nickel strip on top of the tinned wire, apply 1 or 2 weld pulses on the nickel strip and it will melt the solder in the wire underneath. I use the strip because otherwise the heat is so quick and violent that it can make the solder blob explode! I want to emphasize this again - the heat of a spot weld is hot enough to instantly melt a substantial blob of solder. That means the total energy of a spot weld can be equal to soldering, and possibly greater, again depending on the wattage, temperature and duration of the applied iron.
That energy of the spot weld (at least equivalent to the energy of soldering), by the laws of physics we hold dear, has to dissipate into the cell. It doesn't just disappear into thin air. It goes into the cell, the gaskets, protection rings, chemistry, everything. And the notion that because a spot weld is quick (on the order of tens or hundreds of milliseconds), that somehow its less damaging is itself a ridiculous notion. In fact, the faster the energy is applied, the more wattage has occurred. For example, if I apply 100 joules of energy in 1ms, that is far more wattage than if I applied that 100 joules in 1s - 100,000 watts vs 100 watts. It is equivalent to taking a magnifying glass to concentrate sunlight. That concentrated sunlight is far more damaging, because it has more watts, but it still has the same joules of energy as regular unconcentrated sunlight of the same area of the magnifying glass. So if I shine magnified sunlight light into 1g of water for say, 1 minute, the temperature of the water will be equivalent to applying regular sunlight that has the same area as the magnifying glass, for the same amount of time. This is one way to measure joules - take a measured amount of liquid that of a known specific heat, apply energy and then measure the temperature increase.
This same concept applies to melting a given mass of metal, and then temperature of the resulting liquified metal. While knowing the exact joules is harder to extract by melting metal, if two applications of energy on similar masses of metal both melt those masses of metal, then their energy is going to be similar to each other. There will be differences, of course, depending on the temperature of the liquid metal, but the majority of the energy was spent in melting.
Now, I think the assumption has been that the heat energy of a spot weld is less joules than soldering, so perhaps the wattage of spot welding and soldering is the same. If a spot weld occurs 1/100 of the time as a soldering iron, but if it has 1/100th of the energy of the iron, then they will have same wattage. If this were actually the case, then I think the argument can be made that spot welding is less damaging. However we know they have similar energy because they both melt a similar mass of solder. That means that regardless of the exact measurement of joules, the wattage inflicted on the battery is far greater than the wattage applied from soldering.
Now, we can actually measure the heat energy of the spot weld and compare it to soldering. One joule is equivalent to increasing the temp of 1g of water 0.24C. I can spot weld nickel strips in a specific volume of water and measure the temperature increase to measure the joules generated by the spot weld. I then repeat, using a soldering iron placed straight into the water, measuring the temp increase, and calculating the joules. At some point the soldering iron will generate more joules by simply holding it in the water too long.
The question now becomes how many seconds of soldering heat applied, at what temperature, and wattage will it become more damaging than spot welding. But at some point, before that critical time point, soldering is at worst, equal to spot welding, and at best, better.
The heat under a weld is so hot, it melts solder. I can take heavily tinned wire, place a nickel strip on top of the tinned wire, apply 1 or 2 weld pulses on the nickel strip and it will melt the solder in the wire underneath. I use the strip because otherwise the heat is so quick and violent that it can make the solder blob explode! I want to emphasize this again - the heat of a spot weld is hot enough to instantly melt a substantial blob of solder. That means the total energy of a spot weld can be equal to soldering, and possibly greater, again depending on the wattage, temperature and duration of the applied iron.
That energy of the spot weld (at least equivalent to the energy of soldering), by the laws of physics we hold dear, has to dissipate into the cell. It doesn't just disappear into thin air. It goes into the cell, the gaskets, protection rings, chemistry, everything. And the notion that because a spot weld is quick (on the order of tens or hundreds of milliseconds), that somehow its less damaging is itself a ridiculous notion. In fact, the faster the energy is applied, the more wattage has occurred. For example, if I apply 100 joules of energy in 1ms, that is far more wattage than if I applied that 100 joules in 1s - 100,000 watts vs 100 watts. It is equivalent to taking a magnifying glass to concentrate sunlight. That concentrated sunlight is far more damaging, because it has more watts, but it still has the same joules of energy as regular unconcentrated sunlight of the same area of the magnifying glass. So if I shine magnified sunlight light into 1g of water for say, 1 minute, the temperature of the water will be equivalent to applying regular sunlight that has the same area as the magnifying glass, for the same amount of time. This is one way to measure joules - take a measured amount of liquid that of a known specific heat, apply energy and then measure the temperature increase.
This same concept applies to melting a given mass of metal, and then temperature of the resulting liquified metal. While knowing the exact joules is harder to extract by melting metal, if two applications of energy on similar masses of metal both melt those masses of metal, then their energy is going to be similar to each other. There will be differences, of course, depending on the temperature of the liquid metal, but the majority of the energy was spent in melting.
Now, I think the assumption has been that the heat energy of a spot weld is less joules than soldering, so perhaps the wattage of spot welding and soldering is the same. If a spot weld occurs 1/100 of the time as a soldering iron, but if it has 1/100th of the energy of the iron, then they will have same wattage. If this were actually the case, then I think the argument can be made that spot welding is less damaging. However we know they have similar energy because they both melt a similar mass of solder. That means that regardless of the exact measurement of joules, the wattage inflicted on the battery is far greater than the wattage applied from soldering.
Now, we can actually measure the heat energy of the spot weld and compare it to soldering. One joule is equivalent to increasing the temp of 1g of water 0.24C. I can spot weld nickel strips in a specific volume of water and measure the temperature increase to measure the joules generated by the spot weld. I then repeat, using a soldering iron placed straight into the water, measuring the temp increase, and calculating the joules. At some point the soldering iron will generate more joules by simply holding it in the water too long.
The question now becomes how many seconds of soldering heat applied, at what temperature, and wattage will it become more damaging than spot welding. But at some point, before that critical time point, soldering is at worst, equal to spot welding, and at best, better.