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Why 13.8v? Curious. (1 reply and 1 comment)

GG
4 months ago
GG 4 months ago

I've wondered about this since the days of CB back in the (ahem, late 70s). Equipment made for use in 12v cars and radio power supplies are rated at 13.8v.  Why not 12v  ?

Chris - M7CRM
4 months ago
Chris - M7CRM 4 months ago

I think it is to overcome a bit of internal resistance, a bit like when you charge a car battery you need to charge it at a rate > 12V to get it up to 12V.

If you test a new 1.2V battery, you will always find it a little over, I have just tested on and it's 1.28V.

 

MikeJ
3 months ago

13.8V is a typical vehicle charging voltage (up to 14.2V) so any kit designed for use in vehicles should be able to work (and take advantage of) the extra 1.8V. As "we" also need to use batteries that are not being charged during use, then any PSU must be able to cope with in input range of 11.5 to 13.8 - without significant performance changes. At least, that's my understanding which may be incomplete!

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