Amiga 4000cr Rev D CN181 EXT BAT. How to use it?

[Hanzu]

Amiga 4000cr Rev D motherboards have connector CN181 EXT BAT for external battery.

Original A4000 battery in Rev B schematic details battery is "Varta V80H Ni-MH" or in the scematic picture itself battery is marked detailed with "3/600K Ni-CD 3.6V 60MAH". Ni-MH and Ni-CD is same document is a little confusing.

From Anthonys nice theory I see A4000 Rev B will recharge its battery with 4mA current.

Because there are no schematics for Rev D where CN181 EXT BAT connector is visible I don't know if it will recharge its internal battery or external battery connected to CN181 EXT BAT. Does anyone know this?

I already tried SAFT LS14250 3.6V Li-SOCl2 and it seems to keep time and date, but this battery type is not rechargeable and all recharging operations to it are forbidden, so how can I check if recharging current comes to CN181 EXT BAT or not?

[Hanzu]

Found an article from 2001 by Robert Williams (?)
http://www.totalamiga.org/pdf/totalamiga_8.pdf
and from there page 34 of scanned paper (Page 18 of PDF)

"Lithium
These batteries are not rechargeable, they
are usually in the form of a single coin cell
and have the great advantage over NiCds
that they very rarely leak so even if your
lithium battery is dead you don’t need to
rush to replace it. As standard Lithium
cells were only used on the revision D
A4000s"

and later

"Fortunately this motherboard also has an
external battery connector (at the front left
marked EXT BAT) where you can attach a
3.6V lithium battery pack."

In pictures A4000cr Rev D internal battery seems 3V non-rechargeable Lithium coin type. So what puzzles me is why EXT BAT accepts 3.6V non-rechargeable Lithium?

[Hanzu]

Thank you both of you. Now I feel confident to plug 3.6V lithium to EXT BAT of A4000cr Rev D and A4000T too, if I ever manage assemble my empty PCB for it.

Still I don't understand why internal battery for A4000cr Rev D adn A4000T is 3V when EXT BAT is 3.6V. I guess the circuitry is not that picky about extra 600mV.