It's not a jimny so I need help.

Hi clever people I need assistance. We bought our 2018 land cruiser aged 2.5 years old from our local main dealer. When we bought it we told them that it was only really going to be used 4 times a year for its intended use of being our tow barge and that the rest of the year it would get occasional use as a Sunday car mostly because of the fuel consumption and it being a big old Hector for our country roads. When we first look it out we had to wait because the battery was flat. Long story short it's now on it's 4th battery and I have been told by the dealer to keep the voltage above 12.2v to protect the battery. The car has been back for leaking electricity multiple times for weeks at a time. I'm able to track the voltage drop over a week of inactivity using my tracking system. I have had a multi meter over it myself, the dealer has had increasingly indepth diagnostic tests on it, its been under an independent auto electrician and has finally been referred back to Toyota UK for 2 separate diagnostic sessions. They are saying they can't find anything out of tolerance and are now offering a trickle charger. This is to my mind an admission that something is wrong that they cannot find. I am resistant to a charger as one it's a sticking plaster solution and two the car lives with my parents and they hardly have the dexterity or technical aptitude for it and honestly it is a 6 year old land cruiser it shouldn't be necessary to trickle charge it if it's done less than 50 miles a week.  The alternator on these are apparently designed to only deliver 13.8v as an efficiency measure instead of the more usual 14.4v and the battery spec is a single 75Ah by virtue of it being the van version not the big twin battery car version with all the extra computers.  I'm partly venting but I'm also after some insight into what I have to do to make it work properly. And no I'm not dailying it instead of the jimny just to keep it charging. 

As an owner of 3 classic cars that get used infrequently I wouldn't expect the battery to remain healthy between use without the aid of a trickle charger of some form. These vehicles are old school, with no parasitic loads or a very low load, radio memory etc. The alternator's aren't smart, stuffing over 14v and as many amps it will take into the battery. Even on these, 4 starts a year without battery assistance would be pushing my luck.

No agreeing with your dealer, but modern cars have a higher parasitics loads and you are at the mercy of the " smart alternator map" however that's written. You also have natural battery discharge which everyone forgets, this increases with battery age and it's construction. I would have to go down the logging route, recording the parasitic load over a few days and doing some rough calculations based on this / battery capacity/ natural discharge to see if the Land cruiser has issues. But as we speak today my logging DVM is bust and the software won't run on windows 10, so it's no longer an option.

So I would just fit an external smart charger ( Aldi etc) or a window solar panel to it and go for a drive in the Jimny. If you go solar get one above 6W, the low power ones don't work well in the UK, not enough sun

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The new Jimny and our 2015 Swift has power management for added economy and this sounds like what your dealer was referring to.

This detects the load on the engine, particularly at first start up and switches off systems to give the engine a chance to warm up. One of the systems it manages is the alternator. This gets turned off during the first 10 minutes or so.

You may recall that a new Jimny owner in Australia had real issues with this as his battery never charged. He only drove very short distances and with the Aircon running etc. the car never switched over to charging the battery. This destroyed a couple of batteries for him.

We use a C-Tek charger on our vehicles as, on average, they do not get regular daily use. This not only charges but also conditions the batteries. The connector on the C-Tek disconnects if you accidently drive off with it connected.

Can you disconnect the battery earth lead?  Depends in the risk of theft where you live (no alarm).

It's not that I only use it 4 times a year but on those 4 days I want it to work without any intervention from me as they are my 4 busiest periods and I don't have time for messing with cars. The rest of the year I would like to be able to choose if it's the appropriate vehicle to take rather than feeling I have to use it every week to stop it going flat.

I have suggested a disconnect for the battery but apparently that's really not good for the computers.

The efficiency programme seems to be different to suzuki in that it does charge from engine start but I can't find any more information on what else it does.

My gen 4 stood for a month and it's battery was completely drained. The only parasitic thing above standard is national luna battery monitor.