so, I do not use the '01 s-type enough for the battery to get charged. I only average 50 kilometres per week broken into 2-3x of 15-20 kilometres per run. is getting a portable battery charger a solution to the flat battery issue? Thanks

 

I can and often do leave my STR for over a month without use and it still starts with no problem. (Six weeks in the winter will sometimes give me a parking brake fault, but just turning off and starting it again sorts that out.)
If your battery is not charging or going flat there must be a reason.
Mellow

 

Look for posts about
quiescent current

 

thank you for this. in my new car, I got the same flat-battery issue and our local NRMA man told me to run the car long enough (30 min?) to get the battery charged. But I hear you, I'll get someone to look at it. Thanks

 

This advice isn't exactly wrong, but is not optimal. A vehicle's charging system is not really designed to replenish a depleted battery. It will kinda sorta maybe do it, but you're much better off to connect the battery to a proper charger. Excuse me while I get up on my soapbox, but I highly recommend an automatic charger with at least a ten amp output. Let it run overnight until the happy little green light illuminates, and then you know your battery is fully charged.

In theory, your car should be able to sit for several weeks with no issues. But that's assuming (Danger! Danger!) the battery was fully charged when parked. If only partially charged, such as if only driven sporadically, you might be behind the curve and can expect trouble. I would suggest checking for any quiescent drain running down the battery while parked, as explained here:

https://www.jaguarforums.com/forum/s...-drain-123535/

Don't let the test scare you. You're basically making sure all computer modules enter sleep mode within a certain time period. If one or more module stays awake, that can kill your battery. If that test checks good, a battery maintainer would be good for your situation of infrequent usage.

Note I said battery "maintainer". That's a special smart charger designed for a maintaining a full charge on a battery that is already topped off. It's not designed to replenish a run down battery. A battery maintainer is smart enough to check the existing charge level and only top off as needed. Stay away from a "trickle charger". Those are vile, nasty things that only have one constant output level. Typically they are not strong enough to charge a depleted battery, but do put out enough current to eventually cook a battery. A trickle charger is as useful as a spork. A spork is neither a good spoon nor a good fork. Likewise, a trickle charger can't function as a proper charger, nor can it properly maintain a charged battery without the potential for damage.

 

Thank you for this. I never had this issue with my '87 Sov but knew that I have to learn some new things when I got the Stype. It looks like I have to be a certified electrician to enjoy this car.

 

I should add that when I do use the S-type it is for about a 45min run out and the same back again later in the day, including some time at 70mph.
Mellow

 

The winter sidelining is a little long here. Occasionally hooking up the charger to keep the battery topped off was inconvenient. I hardwired one of the already mentioned maintainers and it works great. Once in a while I just connect an extension cord in the trunk and when the light goes solid it is done. Wasn't a must but it is nice to have. Outside of winter it isn't necessary at all.

 

Good idea, thanks