10 year old lead acid 36V e-bike needing an upgrade!

[monkeychops]

Hi Sam. Thanks for your suggestions.
I just measured the 2 batteries. Both showing 24.9V on one voltmeter and both 25.0V on another. When I plug them in to the battery box and check my handlebar mounted power analyser it shows 50.19V. So no voltage drop that I can see. Or is this only a valid test under load? Please excuse my ignorance.
Resistance I think I can measure with my multimeter, I will give that a try and report back.
I have a couple of little temperature probes which I can wire up. I could tape 2 of them to the crimp connections and go for a ride.
It's so cold at the moment in the UK, not fun cycling weather.

[Samd]

Voltage check sounds pretty good to a mug like me. Perhaps someone else will know?

The main thing is that you have a got a good bike to ride now I guess. Well done!

[monkeychops]

On a test ride yesterday I noticed voltage under load measured on the handlebar power analyser was about 0.5 - 0.7V less than that measured at the battery box.
Measuring resistance between the 2 points (battery box and handlebar power analyser) showed about 1.2 ohms.
The thermometers didn't show any temperature rise. But when I got back from the ride, I noticed the ring connectors where the wires exit the battery box were warm. I wouldn't say they were hot but noticably warm. The batteries the same.
I guess this is all ok?

[monkeychops]

The new kit arrived from cellman. I have started a new thread:
viewtopic.php?uid=22636&f=6&t=37142&start=0
should keep me busy for a while