Found this out by accident. The little grey-ish plug on the end of my 510 battery fell off and was lost. This exposed the LED and some electronics. I have another bat on order but not arrived yet. I didn't want anything to get into the battery and fry it so I took the rubber, clear plastic cap from one of my 510 whistle tip carts and put it over the end of my battery. Voila....protected.
Now, once I started using that batt, I noticed that the light from the LED was refracted enough that I could see whether or not it was lit! Pretty handy when the ambient light is so bright that I would need to put my finger or hand over the light to see if it was activated or not. It would also seem that the rubber tip may offer some small protection should I accidentally drop my PV or battery. I re-did my other battery this way too. Just pop- out the stock plug and fit the cart "condom" over the end. Fits snug and looks cool too! Cheers!
Now, once I started using that batt, I noticed that the light from the LED was refracted enough that I could see whether or not it was lit! Pretty handy when the ambient light is so bright that I would need to put my finger or hand over the light to see if it was activated or not. It would also seem that the rubber tip may offer some small protection should I accidentally drop my PV or battery. I re-did my other battery this way too. Just pop- out the stock plug and fit the cart "condom" over the end. Fits snug and looks cool too! Cheers!