They make them....

no,just solderd them like previous packs ive had,never had this problem before:( you raise an intresting point though:wtf: because when you read the writing on cells it says no direct soldering on cells:confused: so i thought,how do they expect them to be put together:confused: so i then had a read of my (the buggy book ,by bill burkinshaw)from a bit back and he states soldering direct on cells should never be considered.back then when you wanted to knock up your own saddle packs,you bought a stick pack and cut the spot welded tags in half joing the cell ends together,and it was these tags that you soldered together again to rejoin cells in saddle pack formation.my point here is this avoided direct soldering on cell ends,so why dont the loose cells we buy now have pre spot welded tags on to help prevent cell's been damaged. thought it was worth raising the point.

i would have thought spot welding would do them more damage than soldering anyway? surely welding requires far more heat than soldering, they don't weld together by magic :o

All commercial battery packs have their cells welded together using either nickel plated steel or nickel straps. The process is resistive welding and incloves very high currents for very short periods of time. The reason hobby people solder cells together is that we dont have access to welding equipment. The soldering process can damage the cells internally.

The problem with buying pre-tagged cells is that making the connection between the two would be rather tricky as you woudl need to solder a third link between the two already on the cells. Ideally, the cells should be supplied with the links's pre welded to the cells. The type of link required already exists and is used for power tool batteries.

The best way to avoid damage is to sand the ends down a bit to rough them up, this helps the solder stick much quicker and easier and use a very hot high quality iron, if your not 100% confident you can solder them safely get someone else to do it, some companies now offer a soldering service for minimal fees.

i guess it's continuously being exposed to heat rather then actual temperatures that damage them?

I have always found that if you are fast with a hot iron then they don't know what's hit them.

Basically the cells resistance will stop the heat from travelling through the cell. Using a weak iron will heat up the whole cell before heating up the contacts to the required temperature.

I think another reason spot welds aren't used in racing batteries is because the welded tabs are incredibly thin and don't carry the current as effectively as teh chunky battery bars we are used to.

Of course, as well as soldering the cells we also massiveley exceed the charge rate compared to the manufacturers recommendations, no wonder they don't survive the 500/1000 cycles in the specs!

The cells we use are not capable of delivery hunderds of full 100% cycles. Cells such as Sanyo 1900SCR (RC2000) and 2400SCR (RC2400) are capable of this performance, but cells pushed to high capacity such as GP4300, IB4200 etc cannot cycle 500 times. It might say it in the data sheet but 100% cycles cannot be obtained. The IEC standard for cycle life is not actually a full charge and discharge and so helps ther manufacturer obtain a higher cycle count number.

Links capable of 30A+ are available, they are the links used on professional powertool batteries (Makita, Bosch Blue, Dewalt etc). These guys are as concerned as we are about making every tenth of volt available at the battery terminals and so have developed materials and processes which are suitable for these high rate applications. You can also weld copper braid to the cells but this is difficult, requires very very high current and a water cooled welder.. we used to do it at our factory in Mexico but it was a pain to make repeatable.

on a seperate note... I hear from my contacts in China that there is a new version of the IB4200 coming out this month which is meant to have better life. Also, GP4300 is available again. If anyone is interested, please drop me a PM. Will people go back to the GP cell if they are obtainable?

N

i won't not unless they increase there performance to at least match the ib's

just received 6 brand new replacement packs from mirage:) very pleased:)hope this batch is a okay:rolleyes: