Battery charging and relay (Beach)

[MattBW]

Monitoring the voltage of my 12v sockets with engine running i am only seeing 12.4/12.5v on both batteries. Very occasionally jumps Upto 13 when braking.

My limited knowledge of 12v suggests this is low for an alternator to kick out?

My leisure battery does not seem to be charging very well at present. Is this normal is or something faulty? The van is two months old and the leisure battery seems to be in medium charge with a battery tester. It's my daily driver so should be topped up.

 

[Hotel California]

I'm not that much in electric but the frist to charge is the main/engine batt .... if that is charged if goes to te lesure(s) to charge those .....
Could it not be an engine running or not is not visible on the lesure as it is tru the system and not direct from alternator?
Am i getting somewhere?

 

[MattBW]

It may be. The compressor fridge is triggering the low voltage very quickly sometimes but strangely on the second day it's now working without issue. Something strange going on with the leisure battery.

 

[SlidePods]

Probably not that strange. A t5 alternator is capable of in excess of 100 amps if my memory serves me correctly however like most modern vehicles it doesn't constantly create large amounts of electric only a big shot on startup then it settles down to trickle charge. This means if your leisure battery is flat you cannot recharge it from the alternator (only top it up if it's close to full) to charge it from flat you will need a 240v charger

 

[MattBW]

Seems a poor setup by VW on the beach to make the battery such a hassle to get to but no charger on hookup?

I've noticed it getting upto 14.5v this weekend so maybe it's working ok after all.

 

[estresao]

14.5 is the ussual when charging, and aroind 13.1 when it's already charged.

Main battery is charged first, then second one.

If your Beach has 230v outlet, when hooked only the aux battery will be charged.

It's recomended a slow charge once a month to improve battery life, so if you have no OEM charged it cold be recommendable to get a stand-alone charger and use it time to time taking apart your batteries.

 

[MattBW]

so there is a charger when on Hookup?

 

[estresao]

If you got the 230v inlet you got a charger.... what you don't have is an inverter.

If it doesn't work for you have a look to the fuses.

 

[MattBW]

Yes I have the inlet (I think it was standard after 2014), I'll put it on ehu and monitor it. Thanks

 

[Cumbrian_Cali]

Hi Matt.
How did you get on with this issue?
I have a 180 SE and have noticed on a few occasions now that the batteries (leisure and vehicle) are not charging when they really should be.
It appears that the split charge relay is energising once the engine is running but the the leisure batteries are actual discharging to charge the battery (see photo) at some point the alternator kicks in and both the leisure and engine battery voltage jumps up to 14.4volts, this is usually once all batteries are down to 12.1volts.
It seems very odd though....
Can anyone cast any light on this?
On other occasions the voltage is always 14.4 for the entire journey.

 

[MattBW]

I monitored it for quite a while (with the same device you have) and it seems to change regularly and there isn't an obvious pattern I could see. I have taken to hooking up for a day a month to keep it topped up.

For me the only time the voltage jumps up to 14.5v seems to be when engine braking or braking, I think this is part of the bluemotion regenerative tech? This is supposed to decrease the alternator use and thus improve MPG?

The rest of the time it seems to be 13v to one battery and 12.2-12.5v (i.e. discharging?), there seems to be something controlling what gets charged when. 5000 miles and everything is still working but the leisure battery never seems to get the charge indicator to full unless I plug in an optimate to top it up (apparently normal).

 

[Bramco]

Matt hi,

We're just back from 6 weeks around Italy in our Beach and although I haven't any of the devices you have used to check the charge I can report that we had no problems on our trip with the leisure battery.

We have a dual voltage coolbox that is plugged into the 12v socket behind the passenger seat when travelling or into 240v when on hookup. If we wild camp which we did a few times on this trip when supposedly open sites were closed for the winter we tend to leave the coolbox inside but disconnect it when sleeping so it's nice and quiet.

We also charge the usual array of tablets, phones and torches from the 12v sockets in the back, on hookup or not but they don't draw much from the battery.

I guess what I'm saying is, does it matter how things are managed if in normal use you don't get any problems. Of course now someone will point out that ours isn't normal use!

PS ours is a vehicle we use regularly, although it can stand for up to a week if I can't be ***ed to go to the gym.

 

[MattBW]

I think it's because I've came from a older style camper where I had to keep an eye on my leisure batteries so I didn't kill them. They were simpler but also more prone to damage.

You are right though, they seem to cope just fine with regular use and are far more able to discharge than the old lead acid batteries of my old van. My confidence has grown massively.

 

[robo]

A word of warning. I purchased 4 of those voltage measuring jobs from the Internet. I was going to leave one in the cali one with the car and one with the motorbike. As they were so cheap I also had a spare. I checked all 4 against a known power source, double checked with decent digital meter, and they all showed different readings. I told the online firm that they were not calibrated correctly, they were very good and sent me 4 replacements. The new 4 were also inaccurate. ( + - 1.5V). The ones I have look the same as the one in the photo. Might be part of a bad batch so worth checking the accuracy with a decent meter.

 

[MattBW]

You could be onto something there, I hadn't considered that cheers for the heads up. I had used that in the leisure and proper voltmeter on the leisure but I hadn't considered it could be way out. I've switched now to a CTEK Comfort Indicator on my leisure battery, permanently installed, can see at a glance how the battery is. Hopefully its reliable.

 

[Cumbrian_Cali]

Thanks for that Robo, I did check it against my fluke as for the price I was more than a little dubious. It was actually pretty close and for pure indication of when the battery is being charged or discharged it'll do.
The van is heading into the garage later in the week, I spoke to their master tech today and he agreed that it shouldn't discharge the leisure battery's whilst driving so I'll keep you posted.

 

[rod_vw]

I don't know where you get the impression that there is a sequential charging system for engine and leisure batteries. If you look at the circuitry for a T5 with camping equipment you will see that once the BCM (Body Control Module) provides voltage to the split charge relay all batteries are connected in parallel (engine and all leisure) with the alternator input. See the various diagrams on my website at http://www.vwbooks.co.uk/t5.htm .

Rod

 

[MattBW]

Interesting. The Vw dealer told me that the split charge relay would flick back and forth. It's certainly how the split charge relay works on my old van it can't charge two at once in my old one. He said when the vehicle battery is full it will switch to the other.

Certainly seems to do that from watching the voltages but he could have been mistaken or just blagging it cheers for diagram.

 

[MattBW]

Rod,

Sorry I've been pondering this, so basically its either charging the vehicle battery or when the relay kicks in both batteries at once? That probably explains why I was seeing different voltages at times.

 

[rod_vw]

Interesting. The Vw dealer told me that the split charge relay would flick back and forth. It's certainly how the split charge relay works on my old van it can't charge two at once in my old one. He said when the vehicle battery is full it will switch to the other.

Certainly seems to do that from watching the voltages but he could have been mistaken or just blagging it cheers for diagram.

Now have you ever heard of a dealer 'blagging it' ?

Those diagrams are direct from VW's own technical information (ELSAWIN) and are exactly as I have my present (and previous) camper wired with two leisure batteries etc. As far as I have monitored things the signal from the BCM comes +ve as soon as the alternator is charging but I believe there is some clever circuitry within the BCM which may in some circumstances remove that signal to allow the alternator to charge just the engine battery.
I do have a solar panel augmenting the leisure battery charge. The solar controller output is connected to the leisure side of the battery circuitry.

Rod

 

[sidepod]

Interesting. The Vw dealer told me that the split charge relay would flick back and forth. It's certainly how the split charge relay works on my old van it can't charge two at once in my old one. He said when the vehicle battery is full it will switch to the other.

Certainly seems to do that from watching the voltages but he could have been mistaken or just blagging it cheers for diagram.

The split charge relay is simple. It use the alternator feed to the little red dashboard light to trigger a relay.
When the engine is running both starter and leisure batteries charge.

When you turn off the ignition, the relay separates the starter battery from the leisure battery so you cant drain the starter.

Any Cali that charges both leisure and starter batteries whilst on hook up has a dual output charger. This has nothing to do with the split charge relay.

Pod

 

[rod_vw]

The split charge relay is simple. It use the alternator feed to the little red dashboard light to trigger a relay.
When the engine is running both starter and leisure batteries charge.

When you turn off the ignition, the relay separates the starter battery from the leisure battery so you cant drain the starter.

Any Cali that charges both leisure and starter batteries whilst on hook up has a dual output charger. This has nothing to do with the split charge relay.

Pod

May add a slight correction to Sidepod's description above. The split charge relay is not controlled by the charging indicator light but by a signal from the Body Control Module (pin T73a/3).
Although this is basically similar to the old fashioned method of monitoring of the alternator output I guess by doing it the way VW do now is that modern circuitry allows for load shedding in conditions of high current demands from essential items on the vehicle.
Diagram here www.vwbooks.co.uk/vw_info/T5_pdfs/T5%20Camper%20wiring%202009%20onwards.pdf, wire marked '47' connects to pin &73a/3.

Rod

 

[sidepod]

Rod, link doesn't work. Surely the body control module takes an input from alternator?

P.

 

[rod_vw]

Yes, you are correct in saying that the BCM has input from the alternator but it is able to monitor and control a great number of electrical consumers in the vehicle. I guess that the reason for the control signal for the second battery charging being generated there is so that in extreme circumstances of high current dray by vehicle essentials that signal can be dropped until the conditions return to normal.
The control output needs to be coded via the diagnostics (VCDS or similar) to bring it into action if you are converting a vehicle that was not supplied with a second battery from the factory.

I can't account for the link not working for you but if you visit www.vwbooks.co.uk and select the 'T5 Info' link at the left end of the thick blue line near the top of the page you will get to lots of bits and pieces that I have found whilst converting my own campers. One such will show the connections to the BCM and lists all of the control signals both outputs and inputs and there are almost 150 connections available!

Rod

 

[sidepod]

Yes, you are correct in saying that the BCM has input from the alternator but it is able to monitor and control a great number of electrical consumers in the vehicle. I guess that the reason for the control signal for the second battery charging being generated there is so that in extreme circumstances of high current dray by vehicle essentials that signal can be dropped until the conditions return to normal.

I think what you mean is, if the alternator fails during driving then you need to stop the headlights draining the leisure batteries. Simple. Hence the reason for utilising the alternator output to control the split charge relay.

S.