Battery Charging in situ

[AMGeed]

^ I think the secret is to use a booster pack and not try to jump from another running vehicle.
Its the voltage spike that does the damage.

 

[M80]

I've bought one of these to keep the boat batterise on float (no pun honest)

Automatic Electronic Car Battery Charger 12V/24V Fast/Trickle/Pulse Modes 8 AMP | eBay

Impressed so far and would be happy to connect to the car with battery connected.
On Vito's / Viano's I have left charging with an Aldi charger plugged into the rear cig socket. Trouble is they don't restore to charge if power is interupted.

 

[flowrider]

a few common sense rules of engagement

never disconnect anything on modern cars, you'll just upset things unnecessarily
you should not go straight to the + - terminals on the battery,
modern chargers are clever enough to sense what happening and provide the right charge as and when required, but to do this as well as possible, it needs to sense the car's power usage with the key off. Going direct to the battery terminals circumnavigates this. Connect a charger to the positive terminal and the negative to a good earth away from the battery (or if its modern the + - points provided by the manufacturer)
it should be noted that modern cars need assistance all the time if its not a daily driver

Why do Ctek recommend connecting their chargers direct to the battery? I have always connected directly to the terminals on the consumer battery on my SL, no issues to date.

 

[EmilysDad]

I've bought one of these to keep the boat batterise on float (no pun honest)

Automatic Electronic Car Battery Charger 12V/24V Fast/Trickle/Pulse Modes 8 AMP | eBay

Impressed so far and would be happy to connect to the car with battery connected. .....

I like that but I already have 5 chargers (3 clever & 2 standard numb) ....

 

[LostKiwi]

Why do Ctek recommend connecting their chargers direct to the battery? I have always connected directly to the terminals on the consumer battery on my SL, no issues to date.

Exactly how mine is wired.

 

[EmilysDad]

Exactly how mine is wired.

And my Roadster ..... but extended the wiring to behind the nearside headlight where I can get to it.

 

[oigle]

As I understand it, it's OK to charge whilst connected, provided you are using a low amperage charger. Using a large commercial type charger is NOT recommended with battery still connected.

 

[S500 Pete]

I'm on the verge of ordering the CTEK CT5 charger which has the lower output voltage (MB handbook stipulates a maximum charging voltage of 14.8V) and is designed for start / stop batteries but can be used on standard units. There seems to be many conflicting ideas on whether you need to disconnect the battery or charge it in situ connected. My MB indy recommends disconnecting although CTEK confirm you can safely charge with it connected.

To confuse matters further I had to take the XC60 to the Volvo dealership this morning. Whilst there I took the opportunity to ask them about charging the battery as I frequently get a 'low battery charge' light after listening to the radio with the engine off (apparently a common Volvo problem). They advised disconnecting the batterybefore charging! Does anyone (indies included) have a definitive answer to this? Access to the battery on the W203 is a pain as you have to remove the filter housing to the heater fan as is the Volvo with various bits of trim / panels you have to remove.

When my wife had an Audi all of the brand new cars in their showroom were permanently plugged in so that they could have the running lights on.
I thought this was dodgy as surely it means the ignition is also on so coil packs would be charged up.

 

[EmilysDad]

When my wife had an Audi all of the brand new cars in their showroom were permanently plugged in so that they could have the running lights on. .....

Same as our local Citroen dealer

 

[Botus]

Why do Ctek recommend connecting their chargers direct to the battery? I have always connected directly to the terminals on the consumer battery on my SL, no issues to date.

they sell chargers, doesn't mean they have any idea what they are doing

television used to be aligned with the correct way to do it - here's some internet trash trying to explain why

In any circuit there can only ever be one point which is truly at 0V (the - terminal). Since the ground plane has a finite non-zero resistance, any current flowing through it will develop some voltage across it.

For example, consider a ground plane that has a resistance of 10mOhm/inch and points A, B, C, -terminal D in line, with currents Ia (20mA), Ib (10mA), & Ic (10mA).

Vc = (Ia + Ib + Ic) * 10mOhm = 400uV

Vb = Vc + (Ia + Ib) * 10mOhm = 700uV

Va = Vb + (Ia) * 10mOhm = 900uV

the further you get away from the negative terminal in terms of current paths crossed, the greater the voltage drop at that point on the plane.

 

[moosehead]

More confusion. The W203 only has one battery. I thought the way to connect the charger (as specified by MB in the owners manual) was via the positive connector that has a 'flip up' lid (not the positive terminal on the battery which is inaccessible) and via the earth stud which has the negative lead from the battery connected to it (not the negative terminal on the battery which is inaccessible).

 

[Botus]

More confusion. The W203 only has one battery. I thought the way to connect the charger (as specified by MB in the owners manual) was via the positive connector that has a 'flip up' lid (not the positive terminal on the battery which is inaccessible) and via the earth stud which has the negative lead from the battery connected to it (not the negative terminal on the battery which is inaccessible).

as I said in my first post... where it has these features you should always use them...

 

[M80]

Tbh I'm happy plugging a charger into my rear cig lighter. It'd be no good for boost style fast charging.
The higher the current flow the greater the volt drop, but the level of potential volt drop would moderate current flow. The result is a slower charge rate, and as the trickle charge brings up battery voltage the volt drop becomes minimal and so over a time the charged voltage of the battery becomes the voltage of the charger.
Wet cell batteries prefer trickle charge / discharge for longevity anyway.

To boost charge, to start from a flat battery I would and do use the extension posts under the bonnet, unless the battery is next to it. I connect up with a load pulling down voltage at the slave vehicle, although the voltage drop of jump leads should dampen spike voltage anyway. After leaving the donor to transfer energy to the slave for 5 minutes or more I would attempt a start. I would only start the donor car if the start fails due to a lack of energy in the slave.