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[x25xe]

Hi all,

I subscribe to Car Mechanics and find it to be an excellent read.

This month they featured an article about battery chargers.  They recommend the CTEK 36 charger and state that this can be used with the battery still connected to the car.

As I have two cars, I would like to use the charger in this manner to keep the battery topped up in the car that is standing.  I always thought that the battery had to be disconnected before charging to save damage to the alternator diodes.  So, my questions are:

1.    Can this unit be safely used with the battery connected to the car?
2.    Has anyone got one of these chargers and are they as good as is claimed?

Thanks for any feedback

[JamesV6CDX]

must be honest, I don't like the idea of charging the battery while it's still on the car....

[Cornish Crow]

hi people, we charge all our batteries at the garage whilst they are on the vehicle, but if the battery has a green light indicator on the top, we have to use a special type of trickle charger or it damages the cells or something like that, i would say check what battery you got then decide.
from the crow

[Taxi_Driver]

must be honest, I don't like the idea of charging the battery while it's still on the car....

Must agree i dont charge my battery if its fitted to the car.....but depends on the charger....1/2 amp trickle charger is prob ok on the car tho i still take mine off if needed and then still charge it at 1/2 amp trickle charge.....dont like charging it at 4/5 amps.....but it prob gets at lot more abuse from the alternator when fitted on the car  :-/

[Markjay]

Hi all,

I subscribe to Car Mechanics and find it to be an excellent read....

Indeed - as some of you may know I am a regular reader and it is a great magazine. Highly recommended!

[JamesV6CDX]

Think about it, for the time it takes to get a 13mm and whip off one of the terminals, what's the point in risking loom damage?

[Marks DTM Calib]

10mm spanner for the terminals.....13mmm for the bracket......

Battery chargers are generally crude items....(switches in to Electronic/electrical Eng mode....)

Often they are little more than a transformer, rectifier and thermal trip......in this style they are not good for car electronics....and I am yet to find a cheap charger with any form of smooting or current control inside!

The rectified supply needs to be greater than 14-15V in order to put charge into the battery for the full period of charging......as a result, the un-smoothed supply peeks at 20V+.....and in order to charge at a higher current....the charger simply ups the supply!

As for sealed batteries.....these have a vent which releases excess pressure from the build up of gases inside.....if you charge them at a high charge rate they get warm, the gases build up and vent off.....your battery will now have less fluid in it meaning you have just shortened its life....

[TheBoy]

10mm spanner for the terminals.....13mmm for the bracket......

Battery chargers are generally crude items....(switches in to Electronic/electrical Eng mode....)

Often they are little more than a transformer, rectifier and thermal trip......in this style they are not good for car electronics....and I am yet to find a cheap charger with any form of smooting or current control inside!

The rectified supply needs to be greater than 14-15V in order to put charge into the battery for the full period of charging......as a result, the un-smoothed supply peeks at 20V+.....and in order to charge at a higher current....the charger simply ups the supply!

As for sealed batteries.....these have a vent which releases excess pressure from the build up of gases inside.....if you charge them at a high charge rate they get warm, the gases build up and vent off.....your battery will now have less fluid in it meaning you have just shortened its life....

Agree, most are quite crap.  Still, they are an improvement on the old plate rectifier type...

[Markjay]

I don't entirely understand why would you need a charger in the first place... unless the car is in storage for a long period of time, any need for charging suggests that there is a problem:

1. Something is drawing too much current with the ignition switched off
2. The battery is in need of replacing
3. The alternator does not charge properly due to a fault (damaged coil, faulty voltage regulator, etc)
4. The alternator does not charge properly due to auxilary belt problems (failed tensioner, slipage due to oil leak or glazing, etc)
etc, etc...

If this is the case, why not simply find and cure the source of the problem? If the battery needs replacing, for £30+ and a five minutes job, just get it done... it will be good for another 5 years or so. Why trickle charge a faulty battery?

As for storage, I found that I have no problems at all when the car is parked for up to 2-3 weeks (when on holiday etc). On my other car, I simply disconnect the battery - it's a very basic car with no alarm or radio code etc so the battery can just be connected and disconnected. In fact I even have a proper battery cut-off switch installed between the negative terminal and the car body, so no need for a spanner. You will be surprised how long can a car battery keep it's charge when it is disconnected - months is no problem.

And, in the unlikely event that the battery does go flat (e.g. when TB updated the firmware... lol), a quick jump-start and then a short blast on the motorway seem to cure the problem.

So, again, why do you guys need battery chargers in the first place?  

[TheBoy]

I don't entirely understand why would you need a charger in the first place... unless the car is in storage for a long period of time, any need for charging suggests that there is a problem:

1. Something is drawing too much current with the ignition switched off
2. The battery is in need of replacing
3. The alternator does not charge properly due to a fault (damaged coil, faulty voltage regulator, etc)
4. The alternator does not charge properly due to auxilary belt problems (failed tensioner, slipage due to oil leak or glazing, etc)
etc, etc...

If this is the case, why not simply find and cure the source of the problem? If the battery needs replacing, for £30+ and a five minutes job, just get it done... it will be good for another 5 years or so. Why trickle charge a faulty battery?

As for storage, I found that I have no problems at all when the car is parked for up to 2-3 weeks (when on holiday etc). On my other car, I simply disconnect the battery - it's a very basic car with no alarm or radio code etc so the battery can just be connected and disconnected. In fact I even have a proper battery cut-off switch installed between the negative terminal and the car body, so no need for a spanner. You will be surprised how long can a car battery keep it's charge when it is disconnected - months is no problem.

And, in the unlikely event that the battery does go flat (e.g. when TB updated the firmware... lol), a quick jump-start and then a short blast on the motorway seem to cure the problem.

So, again, why do you guys need battery chargers in the first place?  

Shortish journeys, esp in winter....

[Ghosts in my machine]

I've got a Draper Battery Master to keep the battery on my Landy topped up. only cost about £15. Keeps the battery fully charged and the alarm going. You don't have to disconnect the terminals on this unit according to the instructions and I never have.

It's been running for 7 years on and off and never had a problem.

[TheBoy]

I've got a Draper Battery Master to keep the battery on my Landy topped up. only cost about £15. Keeps the battery fully charged and the alarm going. You don't have to disconnect the terminals on this unit according to the instructions and I never have.

It's been running for 7 years on and off and never had a problem.

TBH, 9 times out of 10 you will get away with it on trickle chargers.  Fast charging can screw up the diode pack and regulators...

[Marks DTM Calib]

..........and its not like there is anything to complex on a Land Rover!

[TheBoy]

..........and its not like there is anything to complex on a Land Rover!

Hey, leave LR alone - they do the job they were built for, and do it better than anything else

[TheBoy]

..........and its not like there is anything to complex on a Land Rover!

Hey, leave LR alone - they do the job they were built for, and do it better than anything else

Except maybe Massey Tractors