Battery Maintenance Charger - Where to Connect?

J

Justinitus

Member
Hi All

Am looking for a bit of direction here. I bought a CTEK 3600 charger for the Zed and am wondering the correct route to connect it to the car. It came with 2 crocodile clip connectors, plus a second set of connectors that you can attach permanently to the battery terminals.

My local dealer tells me that you should never connect a charger via the cigar lighter socket (the CTEK doesn't have this plug anyway, but having searched the forum have discovered the original BMW one works via the cigar socket.....??) and he said I should connect direct to the battery terminals.

The Zed's owners manual states that battery chargers (and junp starting) must be connected at the posts inside the engine compartment and not directly to the battery.

Can anyone tell me the right way, so I don't do my Zed any harm? Thanks in advance....
 
I have the same setup. Connected to the Plus connector at the firewall and the negative connector at the nearside front. Works great.
 
Why would connecting the charger directly to the battery cause a problem? It is possibly more convenient to use the under-bonnet facility, particularly when using a standard battery charger as opposed to a battery maintainer.

I connected the CTEK lead directly to the battery terminals (on my wife's Z4 and my M3) and leave the connector plugs permanently installed. Connecting up the charger only requires the boot to be opened and a simple plug connected. The bootlid has fewer sharp edges and can be safely closed onto the charger leads.
 
I think the concern is that if you provide a peak voltage at the battery itself, that the entire electric circuit gets a peak. If you connect it to the charge points at the bonnet, if it peaks there, it is filtered out at the battery without it being passed on to the rest of the circuits. A very minor difference there.

I have on my other car, a classic Golf Carbrio, the CTEK directly connected at the battery. It does cause a bit of corrosion at the terminals themselves.
 
Justinitus said:
My local dealer tells me that you should never connect a charger via the cigar lighter socket (the CTEK doesn't have this plug anyway, but having searched the forum have discovered the original BMW one works via the cigar socket.....??) and he said I should connect direct to the battery terminals.
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Dealer is an idiot - BMW sells thousands of smart chargers made by BatteryTender for BMW that connect via the 12v.
 
Quote 'I think the concern is that if you provide a peak voltage at the battery itself, that the entire electric circuit gets a peak. If you connect it to the charge points at the bonnet, if it peaks there, it is filtered out at the battery without it being passed on to the rest of the circuits. A very minor difference there.'

I think you need to think a bit about the electrical circuit! The charging point is NOT a series connection, it is a parallel connection.

I rather think that Caddyshk has written a more succinct answer.
 
I know it is a parallel connection, but due to the length of the cable from the charging point to the battery itself there will be a voltage drop and somewhat of a filter function.
 
An old thread, but I unearthed this as I will be installing a solar Optimate shortly. Due to the way my car is parked in the garage and limited available space it will be far more convenient to connect to the battery direct.

Any further thoughts on this? I will use the supplied permanent connection to the battery terminals, which leaves a plug for the charger accessible within the boot. A simple case of pop open the boot, connect up the Optimate, without the need to squeeze/fight my way to the front and open the bonnet.

A ciggy lighter connection is also possible, but means I need to buy the extra wiring/plug which isn’t supplied with the charger.
 
ErrErrminator said:
An old thread, but I unearthed this as I will be installing a solar Optimate shortly. Due to the way my car is parked in the garage and limited available space it will be far more convenient to connect to the battery direct.

Any further thoughts on this? I will use the supplied permanent connection to the battery terminals, which leaves a plug for the charger accessible within the boot. A simple case of pop open the boot, connect up the Optimate, without the need to squeeze/fight my way to the front and open the bonnet.

A ciggy lighter connection is also possible, but means I need to buy the extra wiring/plug which isn’t supplied with the charger.
Click to expand...

I don't see a problem with it. I'd probably have it permanently connected at the terminals like Nick_in_Suffolk. Then just connect the two cables up when required.

I've opted for a dash one. Planning to add it through the fuse box. What wattage are you going for? Be interesting to hear how you get on?
 
The advice against putting a charger directly on the battery is probably two-fold:

1) Some cars (like the E89) have an IBS module which records the state of charge of the battery. By applying a charger directly (i.e. bypassing the IBS) then the IBS has incorrect information. It will sort it out again eventually though through it's live data readings. Fortunately the E85 / E86 doesn't have an IBS module.

2) There are a few safety issues when connecting wires directly to the battery. Primarily, if for example the charger wires were shorted out (by closing a bonnet / boot on them against a sharp edge for example) then the current that would flow is huge. Certainly enough to set the wires on fire which is obviously bad news. The connection point under the bonnet is impedance limited so the fault current is at least a little more controlled.
 
CTEK made the battery tenders in the e85/6 era (not sure if they still do) and they came with connectors for direct-to-battery installation. Ctek is strictly speaking a smart controlled 'conditioner' which delivers a max of 5 amps (hence the skinny leads). An average boost or jump starter will push over 400 amps which would knock down a horse! so this definitely requires big fat leads and the surge protection provided by the under-bonnet post.

The real risk with connecting the ctek to the battery in the boot is driving out of the garage with it still plugged in dohhhh :headbang:
 
ph001 said:
The advice against putting a charger directly on the battery is probably two-fold:

1) Some cars (like the E89) have an IBS module which records the state of charge of the battery. By applying a charger directly (i.e. bypassing the IBS) then the IBS has incorrect information. It will sort it out again eventually though through it's live data readings. Fortunately the E85 / E86 doesn't have an IBS module.

2) There are a few safety issues when connecting wires directly to the battery. Primarily, if for example the charger wires were shorted out (by closing a bonnet / boot on them against a sharp edge for example) then the current that would flow is huge. Certainly enough to set the wires on fire which is obviously bad news. The connection point under the bonnet is impedance limited so the fault current is at least a little more controlled.
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Irritable Bowel Syndrome ? ? :rofl: :roll:
 
Scooba_Steve said:
Ewazix said:
The real risk with connecting the ctek to the battery in the boot is driving out of the garage with it still plugged in dohhhh
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You're not alone, ask your local Fire Service... :lol:
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Uhh, no ribbing involve there then :rofl:
 
Hell, I’ll admit, I’ve done it. Tore the mains socket off the wall too. ( never do anything by halves ) :roll: :oops:
 
Jl-c said:
ph001 said:
The advice against putting a charger directly on the battery is probably two-fold:

1) Some cars (like the E89) have an IBS module which records the state of charge of the battery. By applying a charger directly (i.e. bypassing the IBS) then the IBS has incorrect information. It will sort it out again eventually though through it's live data readings. Fortunately the E85 / E86 doesn't have an IBS module.

2) There are a few safety issues when connecting wires directly to the battery. Primarily, if for example the charger wires were shorted out (by closing a bonnet / boot on them against a sharp edge for example) then the current that would flow is huge. Certainly enough to set the wires on fire which is obviously bad news. The connection point under the bonnet is impedance limited so the fault current is at least a little more controlled.
Click to expand...

Irritable Bowel Syndrome ? ? :rofl: :roll:
Click to expand...

Well I'm glad the e85 and e86 is free from IBS problem :rofl:
 
Would anyone with a SI confirm that this is the correct places to pop a trickle charger on?

I am pretty sure about the positive but just wanted to check on the negative?
 

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That looks like the correct hex bolt for the negative, mgrlane.
Funnily enough, I was looking at this thread earlier too, as I suspect this cold snap is going to affect my battery a little and I need to break out the trickle charger.
 
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