I have two Simjets, a 2300 and a 1700.
I charge both without disconnecting the battery. Four years on the 1700 with an Astroflite 110D.
The 2300 for two years with a Trident charger.
Both of these seem to be OK. Check with Ed about this, but the only chargers that cause trouble are the ones that use a negative pulse to check the charge state. I read this some where, but like I said, check with Ed.
I never knew there could be trouble till recently.