NiMh battery total discharge - bad?

[CoggesRailway]

Today I worked from my garden office so I ran my LGB Alco with a 48 axle train at medium speed. I noted the time 1.53pm when I started running. I then timed a lap each hour ish and found there was no difference - it was literally like a clock. This continued until just before 5. I then got on a business call, it got dark, forgot all about it and I just found the train dead about 7pm.

The battery is (when running) two 14.4v 3600mah packs in paralell and has been charged/used lots of times but I have never actually run it out before.

Is this bad for them?

 

[Tony Walsham]

It is never a good idea to completely flatten them. Smart chargers require a surface voltage so they can actually start charging. Dead flat often means just that, dead.
All conventional advice is to NOT use NiCd or NiMh battery packs in parallel unless there are protection diodes between the two packs. Even slightly mismatched packs can end up charging into one another with potentially disastrous results.

 

[CoggesRailway]

Oh dear. Well hopefully it might charge fingers crossed. Interesting on the paralell point. It has been fine so far. But the warning is heeded i am going to but some more leds in it so i will fit some diodes as you recomend.