On 24/04/2021 00:27, Dave Plowman (News) wrote:
In article ,
Fredxx wrote:
On 23/04/2021 13:44, Dave Plowman (News) wrote:
In article ,
Fredxx wrote:
At 50mA that would be less than the self discharge rate of a lead acid
battery.

Not so. A lead acid in good condition has a very low self discharge
rate.

More than a 1,000 hours?

Yes.

A pal has a place in Spain. In better days goes there for at least 2
months at a time, leaving a car here. With the battery left connected,
totally flat on return. And toast. Disconnected, it will start the car
after re-connecting.

I thought the self-discharge rate was quite high but you're spot on, as
per usual.

This gives a self-discharge rate of 40% per year, I did see another
article that said 5% per month, but give or take they're both in the
same ball-park.

https://batteryuniversity.com/learn/...n_modern_times

Apart from a remote locking receiver being active I really don't see the
need for a current draw from anything else.

I would propose it would be cheaper to fix the current drain issues than
the cost of a second battery.