2012 Gem eL charging problem

Newbie to your blog. Good afternoon. I am new to this blog and am anxious to know if anyone can help with a problem I have with my newly acquired Gem eL. When I turn the ignition on, the display shows a fully charged battery pack full green bars, but very quickly changes to 1 red bar although a meter across the pack shows fully charged. This problem has only occurred since I replaced the batteries to a new pack of 6 x 12 volt. I live in the UK and I do not think there are many owners over here like in the US. Can anyone help, please, also direct me to where I can obtain a wiring diagram for my 2012 Gem which has a Delta-Q charger.

Check all connections for bright and tight. What type batteries did you install. Flooded, AGM, Gel?. Brand and model number please.

Good afternoon Old Houseboater. I have installed 6 x 12 volt Trojan T1275+ 175amp batteries. All connection are clean and bright. Could you please tell me where the orange/blue and orange/black lead which is attached to a small black piece of plastic which I believe should be connected to a battery, but wasn’t and what the function of this is for.
Many thanks, Sealegs250

Don’t know the colors, but two small leads go to a thermal sensor which connects to a battery terminal.
One wire is B- the other connects to white from charger.
It is needed for some charging profiles. Reads about 10k at room temp.

Have you charged the batteries yet with onboard charger?
The soc will not go to full unless charging in the normal manner.

Batteries fully charged with on-board charger. Fault found with the display, discovered how to reprogram display sent in by another forum member and problem now cured. Thank you for your help with the thermal sensor, this is now connected to the battery pack. To make me a happy man, all I now need is where to purchase a wiring diagram with a delta-Q charger on board for a 2012 GEM eL vehicle.