Leaving a 93 XJS Convertable for a month. How should I handle the battery charge? Should I purchase a trickle charger of some type and any suggestions on a specific device and set up?

Matt

 

Go to Harbor Freight and get one of these. Make sure your battery is charged up pretty well, attach this, and go. I use these on several cars. Cheap, and work well.
Jon
https://hftools.com/app59000

 

If it's not important for you to run the alarm etc, I'd also disconnect the battery. Most XJS battery drain issues seem to be from the current draw when it's connected.

Paul

 

I used a Battery Tender brand to maintain a couple of spare batteries I had.
Always worked when I needed to have one ready to go.

 

Hi Mbower1967

I'd had it up to here with 'Trickle Chargers' as they seem to take for ever to Charge up a Battery that's gone 'Flat' and though ideally you could do with both to maintain a Battery if you intend to not drive the Car for some time

I bought myself an 'Old School' Heavy Duty Battery Charger (Amazon) that also has a 'Quick Charge' for those times when you may need it, that Charged my dead flat Battery in 8 Hours

But disconnect the Battery while you do so, just in case it Blows a Diode in the Alternator!

My Old School Heavy Duty Battery Charger

 

Apples and oranges (chalk and cheese for you Brits!). A battery charger, a trickle charger, and a battery maintainer are three different things used for different purposes.
A battery charger is used on depleted batteries to bring them to a full charge in a reasonable amount of time. They are not intended to be left connected for a long period. In fact, older chargers can cook batteries by continuing to charge after a battery is full. They had no ability to go to a float mode. Modern ones may or may not be capable of being left hooked up for long periods.

A battery maintainer is designed to maintain a fully charged battery in that condition for a long period of time. They do not charge unless the battery voltage drops slightly to a predetermined level, then they top off the battery and stop charging. Maintainers are often referred to as float chargers. They are designed to be left hooked up indefinitely, and will not overcharge a battery.

A third catergory are so called trickle chargers. They maintain a constant charge rate on the battery at around .5 to 2 amps. They have largely disappeared as float chargers have become common. They can also cook a battery over time.

There are also hybrid chargers/maintainers on the market. These may charge at a few amps to bring up a partially depleted battery to a fully charged state, then go into a float mode. They can be hooked up indefinitely. Some also have a desulphating mode which can recover some batteries which were left for a while in a depleted state. This mode pulse charges the battery with brief spikes of charge to essentially break off sulphated material covering the plates in a battery reducing capacity. These hybrid charger/maintainers cost considerable more than simple maintainers. CTEK makes a number of these as do other manufacturers.

If you have a relatively new battery in good condition and fully charged, all you need is a simple maintainer if you are going to leave the car in storage for awhile. In the US, a maintainer can be had for around $10 to $20. I have several that were under $10 on sale, and they work great. I also have a couple of the hybrid style which also work fine for long term storage. I have a big charger which has normal, fast, and starting charge rate capabilites for times when I may need it.

Leaving a battery hooked up to a car for long periods without a float charger gradually discharges the battery from slight draws from the radio memory, clock, etc. This draw should be under 20 milliamps. This also allows the plates inside to sulphate if the battery reaches a low state of charge. This reduces the capacity of the battery, and allowing it to do this several times can ruin the battery.

I hope this clears things up.
Jon

 

Good summary Jon!

I agree with your points about "trickle chargers". I haven't used one since it burnt out a battery on my motorbike after being left for too long. "Unintelligent" trickle chargers are more hassle than they are worth.

I have battery conditioners on all vehicles even if I think they won't be driven for only a few days. I then have my Big Boy charger which can also be switched to a jump-starting mode and throw out over 100amps to start a car.

The interesting thing is how much the price of quite reasonable-looking conditioners has dropped. I have high-quality (not cheap) Ctek conditioners on the cars, but I recently bought a cheap (£15) unit just to see what it can do. It seems to do a lot for the money, although not too sure as to its longevity or reliability as yet.

And of course, I carry a Noco power pack in the car for emergencies, although it's always been to help others out so far!

Paul