Trickle charge?

[Keaney]

looking to install a hard wired connection to plug a trickle charge in.

Positive wise I can attach to the battery however where does everyone connect the negative to that’s best as it’s obviously a no no connecting to the battery with all the signs on it

 

[Phil_G]

Is this the vehicle battery or leisure battery Keaney? Is there a particular reason not to connect neg to the battery? unless its a strange setup I see no reason why not, in fact 'maintenance' chargers such as Optimates are supplied with just such a lead. Make sure the pos has an inline fuse immediately after the connection, ie as close to the battery pos as conveniently possible, remember it may be only a 'trickle charge' lead but in the case of a short it has the full oomph of the battery behind it...
Cheers
Phil

 

[.50]

I might be talking out my backside, but wont a trickle charger maintain the battery at 100% charge, unlike the vehicles charging system that leaves the battery charge short of 100% to accommodate energy harvested from regenerative braking ?.

 

[.50]

I just did a quick search and you mustn't use the battery negative terminal as it bypasses the vehicles voltage control module. I am presuming you must use a body grounding point the same as if you were to jump start it.
Hopefully someone with superior knowledge will be along to confirm.

 

[Loz]

I just did a quick search and you mustn't use the battery negative terminal as it bypasses the vehicles voltage control module. I am presuming you must use a body grounding point the same as if you were to jump start it.
Hopefully someone with superior knowledge will be along to confirm.

Correct!

 

[.50]

Does the same apply for running an optimate ?.

 

[Loz]

Anything that takes or puts charge into the battery needs to use an earth terminal on the chassis so as not to upset the battery charge state monitor built into the battery negative clamp.

 

[rod_vw]

If you are wishing to connect a low current trickle charger why not connect via one of the cigarette lighter sockets, I think they are all now NOT via ignition switch control. They are designed (wired) for a good current 'out' so no reason why they shouldn't be OK for a small trickle charge current 'in'.

But thinking aloud, why do you need to trickle charge the engine battery, does your vehicle have long periods of no use? My T5 currently stands for weeks without being used but always starts OK, it had over seven weeks last summer without use and gave no starting problem.

Rod

 

[.50]

If you are wishing to connect a low current trickle charger why not connect via one of the cigarette lighter sockets, I think they are all now NOT via ignition switch control. They are designed (wired) for a good current 'out' so no reason why they shouldn't be OK for a small trickle charge current 'in'.

But thinking aloud, why do you need to trickle charge the engine battery, does your vehicle have long periods of no use? My T5 currently stands for weeks without being used but always starts OK, it had over seven weeks last summer without use and gave no starting problem.

Rod

My quick bit of research regarding the T6 found several cases of flat batteries after as little as 3 weeks.

 

[Pauly]

There was a known issue early on where vehicles got flat batteries after short periods of time stood up but VW recognised the fault and issued a product recall to fix it, mine had it done many months ago

 

[Keaney]

Hi thanks for the posts, I have a dash cam with parking mode wited to the starter battery at the moment and it may sit for a few weeks shortly so wanted to put a easy connection in.

Obviously I will wire he dash came to my second battery at some point but also plan on a solar panel so prob will be resolved

 

[Richard]

Soon after I switched the ignition ‘off’ yesterday, a message flashed onto the screen that the infotainment system was shutting down because the battery was low - or words to that effect. I thought this was strange because it was not ‘on’ but I did check the voltage at the cigarette lighter sockets. The voltage at the one on the top of the dashboard facing up was 13.2V but the one lower down beside the gear stick was 11.4V. I was rather concerned but the van started as usual this morning and within seconds the voltage at this socket rose to 14.4V as, presumably, the alternator started to charge the battery. I only drove about 10 miles so I was not surprised to find that the voltage soon dropped back to 11.5V after I switched ‘off’ the ignition.

From posts on the Forum, I understand that the ECU maintains 12.5V (80% charge) on the vehicle battery so that there is space for charge when braking [1]. I am sure that 11.5V is too low, especially since the infotainment system complained.

While I was searching the Forum looking for advice and warnings about charging the vehicle battery, I found that rod_vw had asked why a low current trickle charger could not be connected via one of the cigarette lighter sockets [2]. Unfortunately, no answer was posted.

It looks as though the socket beside the gear stick is connected directly to the vehicle battery although I don’t have a circuit diagram. If the battery can be charged via this socket, what charger should I use? I have a Defa SmartCharge 12V 4A charger which states that it is suitable for 12V Lead acid/AGM/GEL and Start-Stop batteries. It was supplied to charge the leisure battery via its 12V sockets.

Richard.

[1] Starter battery voltage.
[2] Tickle charge?

 

[Loz]

Should be fine, but might be better to find out what is draining the starter battery..

 

[Richard]

There appear to be two heavy current wires connected to the positive terminal of the starter battery. Using a clip-on AC/DC ammeter (resolution 0.1A), the current in one was 0.0-0.1A and the current in the other 0.3-0.4A. Nothing was switched 'on' so I assume that the VW alarm, etc. were drawing this current. Is this reasonable?

 

[Phil_G]

0.4A quiescent is a lot and will completely drain your battery in a week!
My lads local Scout troup bought a van, its battery wouldnt stay up, eventually on the second
replacement battery they found an interior light which had been left switched on under the ply lining!

 

[travelvolts]

I wouldn't trust the accuracy of a clamp meter at such low levels. Double check with an inline meter.

 

[Richard]

Thank you for the hint. After I had reached in to release the bonnet catch and then closed the driver's door, I had probably not waited for the interior light to go 'off' and I didn't notice it because the sun was shining brightly. I have now tried again and both readings are 0.0-0.1A which is comparable to the accuracy and resolution of the meter.

I am now back to wondering what is draining the battery. Is it just cold weather and short journeys (10-15 miles)?

Thanks again, Richard.

 

[Richard]

I agree with travelvolts comment about using a clamp meter at these low levels which is why I included its accuracy and resolution. Unfortunately, I did not see travelvolts' comments before posting the revised measurements. Sorry for any confusion.

I used the clamp meter because I hesitate to disconnect the leads from the positive terminal. What are the consequences of disconnecting the battery, please?

Richard.

 

[Pauly]

None, you will need to reset one touch windows and maybe reset click on radio/dash but it only takes a minute or two

 

[travelvolts]

Thank you for the hint. After I had reached in to release the bonnet catch and then closed the driver's door, I had probably not waited for the interior light to go 'off' and I didn't notice it because the sun was shining brightly. I have now tried again and both readings are 0.0-0.1A which is comparable to the accuracy and resolution of the meter.

I am now back to wondering what is draining the battery. Is it just cold weather and short journeys (10-15 miles)?

Thanks again, Richard.