Jump to content

Batteries joined together should match - Why?


Recommended Posts

We were asked today if it would be ok to wire a new Varta LFD90 to an existing Numax lv26mx 100Ah of unknown age or would it be a bad idea?


Our reply went something like :


Hello, a very bad idea, as the Numax is a very basic simple technology conventional battery, very different to the LFD90, with low efficiency and shorter 'real' life.


The Numax has a resting voltage of 12.6 and the LFD90 is 13.0v


50% discharged for Numax is 12.1v and the LFD90 is 12.5v so you can see issues if you discharge the LFD down to 50% at 12.5v when the Numax has hardly done a thing?

Conversely drain the joined bank to get the Numax to 50% at 12.1v and you will have destroyed the LFD with an almost full discharge.


The chart below, published by Yuasa, shows that a 50% discharged VRLA/Sealed/Powerframe battery is only 0.1v below a FULLY charged Conventional battery.


I don't know much about them but maybe pairing one of the high technology Exide Carbon batteries would be similarly disastrous, as might be any other new emerging battery technologies?


This demonstrates just how much battery technology has advanced in the last 5 years and the effects of that on how we use batteries.



That is only one of several reasons why batteries joined together should be the same age, size and technology. Ideally the same make and model.




Link to comment
Share on other sites


This topic is now archived and is closed to further replies.

  • Create New...