Advice re batteries losing 20% overnight T5

[David Eccles]

Been noticing leisure battery readings on display console seem to drop from 100% quickly,
T5.1 2012
New leisure batteries fitted about 8 months ago by dealership

Friday morning read
12.8v 100% -2a
Lunchtime today
12.4v 80% -2a

Thoughts?

 

[Steve1]

Been noticing leisure battery readings on display console seem to drop from 100% quickly,
T5.1 2012
New leisure batteries fitted about 8 months ago by dealership

Friday morning read
12.8v 100% -2a
Lunchtime today
12.4v 80% -2a

Thoughts?

If you have nothing turned on the -2A is a big current draw.
Either you have left something on of you have a serious problem.
Current with nothing on should be -0.2 or at worst -0.4

 

[yossarian]

The -2A looks correct.

Typical troubleshooting

• Unplug everything connected to a socket.
• Check inverter if fitted for a led.
• Pull, check current and replace fuses until the -2A drops to something sensible.

 

[BristolCali]

I am not sure that the readings are at all reliable. I don’t think there is a way of actually measuring battery charge level accurately. I think the figure is derived from a current transformer which just monitors current levels in and out over a set period of time and then it assumes a percentage. Can anyone confirm my hypothesis?

 

[yossarian]

I am not sure that the readings are at all reliable. I don’t think there is a way of actually measuring battery charge level accurately. I think the figure is derived from a current transformer which just monitors current levels in and out over a set period of time and then it assumes a percentage. Can anyone confirm my hypothesis?

The voltage is regarded as accurate. Current is measured by a shunt in this case, a transformer will only work on ac.

The voltage reading confirms excessive current draw.

 

[WelshGas]

Been noticing leisure battery readings on display console seem to drop from 100% quickly,
T5.1 2012
New leisure batteries fitted about 8 months ago by dealership

Friday morning read
12.8v 100% -2a
Lunchtime today
12.4v 80% -2a

Thoughts?

As has been said. Ignore the % reading as it is not very accurate. The Voltage is accurate as is the amps reading.
If you have a current draw of 2 amps then something is plugged in or you have a problem.

 

[Steve1]

I am not sure that the readings are at all reliable. I don’t think there is a way of actually measuring battery charge level accurately. I think the figure is derived from a current transformer which just monitors current levels in and out over a set period of time and then it assumes a percentage. Can anyone confirm my hypothesis?

You are right that the %charge isn't hugely accurate, but the current and voltage are and in a no load situation (if that's what it is) 12.4V would be about 75% state of charge.
But 2A of current usage is quite heavy unless something big is turned on like fridge or heater etc

 

[David Eccles]

DOH
its -0.2 not 2!!! visual memory old fool!!!
Nothing is on checked all that mid week...
and the 100% reading was followed by a 70 mile drive
doubt batteries are faulty, so is it the console
should I contact dealer?

 

[flying banana]

DOH
its -0.2 not 2!!! visual memory old fool!!!
Nothing is on checked all that mid week...
and the 100% reading was followed by a 70 mile drive
doubt batteries are faulty, so is it the console
should I contact dealer?

0.2a is normal. You only get around 80 % charge when driving. The leisure batteries often drain down a bit into the start battery when driving. Full charge is obtained by turning on the ac or a heated seat to keep the blue motion alternator engaged

 

[Azteccamper]

0.2a is normal. You only get around 80 % charge when driving. The leisure batteries often drain down a bit into the start battery when driving. Full charge is obtained by turning on the ac or a heated seat to keep the blue motion alternator engaged

Not sure this is the case with a 2012 T5.1?

 

[WelshGas]

Not sure this is the case with a 2012 T5.1?

If you have BlueMotion or Stop/Start then Yes. It was an option rather than standard.

 

[Steve1]

DOH
its -0.2 not 2!!! visual memory old fool!!!
Nothing is on checked all that mid week...
and the 100% reading was followed by a 70 mile drive
doubt batteries are faulty, so is it the console
should I contact dealer?

0.2A is normal. The best way to test it is to use the electric hookup to fully charge the batteries. Leave it hooked up for 12hours that should fully charge easily Then unplug and monitor the voltage. It should stay at 12.7 / 12.8 for at least a week with nothing turned on. If it doesn't then it's probably bad batteries.

 

[David Eccles]

I''ll try hook up overnight and see how it looks, good idea
batteries are only 8 months old
just standard 5.1 no ad blue etc

 

[Azteccamper]

I''ll try hook up overnight and see how it looks, good idea
batteries are only 8 months old
just standard 5.1 no ad blue etc

Did you change your own batteries?
if so did you check the cube fuse on rear battery - mine had blown.

 

[David Eccles]

was done by reliable VW dealership with Vartas and not cheap!
Last time had the issue we ended up replacing them 8 months ago
only noticed the % dropping so fast in past couple of months
think I will ring dealership, though they will say bring it in and pay £100 for diagnostic (refundable if pay to have any work needed done) but am now suspecting control panel issue as was mentioned last time as possible culprit... but batteries were 11 years old then!

 

[WelshGas]

was done by reliable VW dealership with Vartas and not cheap!
Last time had the issue we ended up replacing them 8 months ago
only noticed the % dropping so fast in past couple of months
think I will ring dealership, though they will say bring it in and pay £100 for diagnostic (refundable if pay to have any work needed done) but am now suspecting control panel issue as was mentioned last time as possible culprit... but batteries were 11 years old then!

The Cube fuse on the rear Leisure Battery is very sensitive to failure due to vibration or overtightening.
Also, batteries have a warranty for a reason, they can fail early on.

 

[David Eccles]

slight update been parked all week
Monday am 90%
left on hook up for 9 hours
Monday pm Tues Weds 100%
Thurs am 90%
hook up for 6 hours
Fri pm still at 100%
drain -0.2 each time volt varied between 12.3 and 12.9
will keep monitoring for another week