Flat battery

[zeeshanzaki]

I was working on c5 to fix hydraulic suspension motor since last 2 weeks. Before removing pump I disconnected negative terminal of the battery. Today when I put back pump in the car to prepare car for salvage, but when I connected negative terminal of the car there was no power. I also forgot to switch off the ignition last when I removed the pump. Now battery reading 7.25v. Connected charger to see if it charge the battery but it stays at 7.25v which suggest that battery is dead as per charger manual. Does it mean car still uses battery even the negative terminal is disconnected when ignition is ON.
The battery is under warranty so I will get it replaced but my concern is is there any other fault could have developed in the car which damaged the battery.

[citro6hydra]

Hi,
The negative terminal being disconnected will certainly isolate the battery and prevent discharge. Working on the suspension pump which is a high current drain item without the battery being charged by the alternator can flatten the battery quite quickly, this may not be immediately obvious unless you try to start the car. It is I think unlikely that another fault has caused the problem

At 7.25v the battery may well be beyond hope but some types of chargers will not charge a flat battery.

Just as a general observation suspension pumps in my experience are pretty reliable but the motor is the weak link particularly so if there is hydraulic fluid ingress the usual result is a blown fuse.

[white exec]

Try charging that battery with an old traditional transformer-rectifier charger, rather than a new-type electronic one. As said, some of the latter read very low voltage batteries as unserviceable.
You might be lucky, or at least end up with a reserve battery if you have to buy a new one.

[zeeshanzaki]

Changed the battery and car started without any issue. So there is no issue with the electronics.