I am confused again! My Jag is going in to storage for six months and I was recommended by a member to connect a battery minder, rather than just disconnect the battery, as this would keep the computer(s).
happy. Sounded like a great idea to me!
Now, reading up on minders, it seems that most of them has some kind of desulfate state, sending high frequency pulses to the battery. Now, if the battery is connected to the car systems, these pulses will go straight to the rest of the car??
How will the computer(s) like that?? Sounds pretty scary to me.

So, my question is: Has anyone out there had a Battery Minder left of for six months, while the battery was connected to the car electronics? Any problems?? If success, what type and model did you use??

I don't know enough about this stuff and just being cautious!

 

I've left Delran's Battery Tender + hooked up to many different cars for periods of time varying from overnight to over a year. Nary a hiccup.

Battery Tender® Plus 12V 1.25 Amp Battery Charger

Z

 

the pulses will not affect the car's electronics. i have one car going on three years without an issue. they are designed so that they can be used with the battery connected.

 

My car has has been on a $5 Harbor Freight battery maintainer for a couple years now. I don't drive it because I don't want to put a lot of miles on it than I had a racing accident and didn't drive anything for months, but it starts and runs every time I get in it. I hook the charger up to the hot post under the hood and put a negative on a shock mount stud.

 

Better to use a battery tender than to disconnect the battery.

The tender of choice for the majority of members is one of the CTEK range. It is also the choice of Jaguar who will supply the same one with their logo on it for about twice the price.

There are many posts across the various model forums about using these for extended periods and I can't recall any negative comments. On the other hand, I can think of many posts describing the tortures of bringing a Jaguar back to life after the battery has been disconnected or discharged.

Graham

 

I use them on a variety of cars with no problems whatsoever.

 

Been using a Battery Tender Jr for years. Four years on my old Corvette and now three years on my XK8. No problems at all. Even during driving season, if I know the jag is going to sit for a while, I plug it in.

 

Ungn, I'm curious. How many miles on your 97?

 

I can vouch for the CTEK range. I have the type that checks your systems too. Have a look, though there are cheaper CTEK ones.

 

I've had over the years several classic cars and learned a few lessons the hard way on these devices:

1) You don't want to skimp on quality. After all, you're going to leave a very expensive car plugged into it, probably parked inside an even more expensive building, alot riding on a little electronic device. I've been lucky and caught the mid-priced devices overcharging before anything other than the battery itself was damaged. The cheaper devices can fail in the full on position while the better ones are designed with electronic circuits to detect charging problems and shut themselves off. Better to come back to a dead battery than one that has boiled over or worse.

2) You don't want to skimp on amperage either. If something goes wrong with the car's systems and lets say just for example a light bulb stays on by accident. If the bulb draws 2.0 amps and all the device is putting out is 1.0, then the battery is going to run down despite the charger. And if the charger isn't smart enough to shut itself off, the battery is going to boil dry and could create an internal short.

So that's why everyone on here recommends the CTEK brand units, a little pricey, but given the associated risks, its probably worth it. I've posted stories about my near tragedies with cheaper units but now I have four cars plugged into CTEK's. I bought an AGM battery last year that I thought the CTEK wasn't compatible with because it kept shutting itself off and flashing red, but turns out its own circuit tests were just detecting a bad extension cable connection. It was very frustrating trouble-shooting wise, but that's what you'd want it to do. Can't say I've left any Jaguar hooked up for six months at a stretch but Jaguar electronics don't seem to be negatively affected from much shorter periods in storage.

 

Thanks for all good inputs. There seems to be a good positive post at the fusebox just in front of left strut. Good place for hook up??? Do one need to worry about charging gases in the trunk?? I.e should it be left ajar and trunk lights unplugged??

 

Your vehicle should be fitted with a vented battery - it certainly left the factory with one. The vent tube takes the gas outside the vehicle.

The Jaguar installation procedure for CTEK is attached. No need to pay the Jaguar premium for their branded CTEK (plenty of suppliers of the identical models available at much lower cost) but the safe connections and cable routing should be followed. I use a CTEK extension which comes out through the plastic vent grille in the luggage compartment.

Graham

 

Thank you for that good info. PDF file now saved and Battery minder on order. Have read that some members connect under the hood rather than in the back.. Makes sense to me as trunk can be closed and no need to worry about inside trunk lights. There must be a main positive feed to the front where one can connect??? good grounds are everywhere up there..

So much to learn.

 

to be most effective, the battery tender or charger needs to hooked up as close to the battery as possible. That's one of the reasons why most owners are attaching the permanent connection to the battery and running it into the truck area. Then it's no sweat to connect that to the charger and just close the trunk lid over the charging cable. At first I was reluctant to do that. But as it was pointed out to me, it's plain to see that the cord is not being damaged or pinched in any way by the trunk lid when closed all the way. The rubber seal around the trunk has plenty of "give" to it, so the charging cable freely moves back and forth when pulled, demonstrating that nothing is being negatively affected by the closed trunk lid.

the MOST important thing I've learned about these cars is that the battery must be load tested and be at 100% capacity. If it's not, all the chaging in the world is not going to prevent the maddening gremlins that will continually pop up. Even prompting the dreaded "ENGINE FAILSAFE" light to come on and restricting the car's performance.

For me, even though my old battery was starting the car OK, buying a new battery solved all types of running issues and was well worth the cost. These cars must have the correct voltage or life will be hell.

Z

 

The Battery was new when I bought the car, so I should be okay there. Duly noted that connecting in the trunk in s best option.
Thanks

 

Strangely I have tried that and found it not to be effective on the XK8 - the battery tender doesn't seem to continue maintaining the battery, but I have no idea why. I do exactly the same on a BMW with the battery in the boot and connected to the terminals under the bonnet, and it works perfectly. I have to put the charger in the boot of the XK8 and close the bootlid on the wiring.

 

My understanding is that the bonnet battery connector (front left by the fuse box) is really just for jump starting the car. From this point at the front, the connection distance to the battery, at the back, is too long so you'll get voltage drop and a funny reading by the smart battery tender. Zray is right in that the battery tender should be as close to the battery as possible. I close my boot lid on the charger wire with no issues (after making sure the key works), avoiding the boot lid bump stop coming down on it.

 

never jump start the car from the under bonnet connections. they are only for introducing enough power to open doors and the boot lid. one can attach a well insulated pigtail with a covered connection to the positive source and run it somewhere easy to access such as behind the grille for situations where the car is dead and the bonnet is closed. ground is available everywhere. do not do this unless you know how to make a well insulated setup that will not short against anything.

 

FYI i had a brand new CTEK fail after about one year, used under ideal conditions. sometimes you just get a flawed piece of electronics. the way that it fails is that it will not leave what appears to be bulk charge mode, however there is no current flowing to the battery.

regarding battery venting. all flooded cells and most AGM have a vent port that connects to an overboard discharge. what many people fail to notice is that these batteries often have a vent port at the other end which is open from the factory. if it is not plugged, the gas could find an easier path of escape into the boot defeating the purpose of the overboard discharge. the ports are redundant, so one can be safely plugged.

checking with Bosch regarding the AGM. correct charging is using 14.4 V. snowflake mode is not needed if the average temperatures are above 25 deg F.