Is it true that if you put a new battery with an older one then the new battery will kill the old battery in a short time................

A qualified yes..... The reason is that the new battery will try and boost the voltage of the older battery unless there is diode protection between the pair. Batteries are a bit like a team, as soon as one member of the team (ie cell) quits the others try and make up for it and if the dead cell has an internal short then the others die trying to charge it. 2 batteries in parrallel = 1 large battery. 2 batteries in series will double the voltage but are still only 1 battery capacity wise.
It's actually the older battery killing the newer more competitive battery...

-- Edited by Basil Faulty on Wednesday 6th of May 2009 11:45:53 AM

yes it would be better to replace both batterys at the same time if there is a "marked" difference in holiding capacity of the older one, I would do them both just so one knows how old they are and get a rough idea of lifespan left

After squilions of hours sitting through tutorials on batteries, trying to understand which way the electrons flow, and how many bits do you need before you get a byte, I can justifiably say , as an experienced electronics engineer, when it comes to batteries...... call an electrician..... Now when its a question of logic..... well, us men rule

as long as the battery is charged ......

-- Edited by Ma on Friday 8th of May 2009 11:14:35 PM

batteries and the subsequent use of said item in most forums and by a lot of knowalls are over complicated, just keep your usage below your power input and the recharge above your daily use and you will have no problems, what can be easier "KEEP IT SIMPLE STUPID" if you cant understand it dont use it because when it breaks down you will have to repair it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!