NEVER use LIPOs in equipment not designed for LIPO batterys. There is a reason for the fire hazard warnings if they aren’t properly taken are of. LIPOs are great because they provide a constant output as they discharge, however you NEED to have a low voltage dectector to prevent the battery from over discharging, which will damage the cells. Damaged cells most likely won’t cause trouble until they are recharged and may catch on fire. Chargers should be able to balance the cells (this is why there is the small wires for charging), or the cells can become damaged if not correctly balanced.
Also, NEVER use a damaged LIPO battery. If the battery is damaged, it can take hours to a few days before it catches on fire. Always check the battery and make sure it is not swollen, puntured, etc.
Following the safety instructions and using comon sense will guarantee problem-free use of LIPO batteries
It’s not all bad, you just need to be sure you buy a proper charger to go with Li-ion batteries. The Digitrax throttles have no recharge circuitry in them for Li-ion or ANY battery chemistry so there’s no danger there. Putting Li-ion batteries in your PowerEx charge - no good. Another place they won’t work - I think it’s the MRC throttles have a rechargeable battery built in. It’s almost certainly a NiCad or Ni-mh battery. You absolutely can not swap in a Li-ion battery there, the charging circuitry is not made for Li-ion and Bad Things will happen.
However, until some alternative is found, these 9V Li-ion batteries seem pretty useless in Digitrax throttles anyway. With 3x the capacity of Powerex but no more life - there’s no point. If they really did last almost 3x as long on a charge as you might expect - it would be worthwhile switching.