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Hi TimQuote:
Originally Posted by drivesafe
Thanks heaps for the info/diagnosis. It definitely seems like “low charge”.
I didn’t bring a charger with me, but will definitely give this a go when I get back home. In the meantime, I think I can keep “getting by” with the batteries the way they are - we drive most days so they get a reasonable charge to keep things running.
Thanks again
Rob
Hey ghost,
I had a cranking battery do that to me, was a super charge. Was a long time ago. The funny thing was even though it was at 12.4v resting, every tester including carbon pile had it at 1000cca. It lived a long life and got replaced when is cca eventually dropped
Hi TIm
I've been home for a few days, and managed to get the charger on the batteries on the weekend. It should 'float', to keep the charge at 100%... so we'll see how we go.
A couple of questions:
- Do you have any idea how long I should leave the charger on continously? 1 week? 2 weeks?
- And if this 'works', i assume I should see a higher resting voltage after charging (so maybe 12.6V rather than 12.4V) - is that correct?
Thanks for your help.
Rob
Hi Rob, if you follow the info in the link, it will give you all you need to know to rejuvenate both batteries.
https://www.aulro.com/afvb/the-verandah/246755-line-auto-electrical-info-8.html
BUT
Before you do the battery rejuvenation, if you can, can you carry out a simple load test on you cranking battery first?
To do the load test, have a note pad handy.
First disconnect the negative ( - ) lead on your auxiliary battery and then measure the voltage on your cranking battery and note it down.
Next, turn your ignition on, but do NOT press on the brake pedal. This will turn the ignition on without starting your motor.
Now turn your headlights on.
Go back to your cranking battery and measure the voltage every minute for 5 minutes.
After the 5 minutes, turn your headlights and ignition off.
This simple battery load test does two things.
First off it will indicate if your cranking battery is still in reasonable condition, and after a week of rejuvenation charging, it will also show if there has been some improvement in your battery’s state of charge.
With the first lot of voltages, regardless of what the actual voltage readings are, if your battery is still OK but may be in poor condition, the voltage should have dropped over the first couple of readings but should have then levelled out. You might even see a slight rise in the last voltage reading, if the battery was cold when you carried out the teat.
This would indicate the battery is still good.
If the voltage continued to drop over the full 5 minutes, it’s probable time for a new battery.
Don't forget to reconnect the negative ( - ) lead on your auxiliary battery.
Keep these voltage readings and after the week of rejuvenation charging, repeat the load test and you should see a similar voltage pattern but with higher voltage readings.
BTW, you can use your BM2 Bluetooth Battery Monitor Phone app to get the voltage measurements and take a Screen Grab of the graph while doing the test.
Quote:
Originally Posted by drivesafe
Hi Tim
Took the battery off charge this morning. Did the load test at lunchtime (with the Aux disconnected), as per your instructions. Seemed to remain fairly consistent over the 5mins. Data below.
I'll keep charging at night, leaving off the charger during the day over the next week, and repeat to see how we end up.
Thanks again for your insight and support - really appreciate how freely you give of your time/knowledge!
time 0 1 2 3 4 5 Main (4/8) 12.56 11.99 11.99 11.99 11.99 11.98
Attachment 172607 Attachment 172608
Hi Tim
Here's an updated set of voltages...
I've had the battery on charge almost every night for 2wks (since the original measurements). I take it off charge during the day.
Looks like maybe a very slight improvement on the cranking battery?
What are your thoughts?
0 1 2 3 4 5 Main 4/8 12.56 11.99 11.99 11.99 11.99 11.98 Main 16/8 12.67 12.05 12.04 12.01 12.03 12.02
Attachment 172887 Attachment 172888
The constant in and out of lockdowns has slowly been killing my own battery in the D3.
Even with the USI-160 disconnected I found the parasitic drain was still too much with the battery dropping about 0.1v per day - even after several rejuvenation attempts.
I have now connected mine to a solar panel and charge controller via the rear white plug whenever the car is parked up.
Hi Ghost, sorry for the delay in replying, I'm flat out.
I think your battery is fine but it would be interesting if other D4 owners could carry out the same load test so we could compare.
This is that really relevant but here is the load test results from my Tiguan this morning.
NOTE the cranking battery is nearly 5 years old.
Tiguan Load Test 21/08/21
11:14 - 12.51v, Tiguan locked
11:15 - 12.23v, After unlocking
Ignition turned on, headlights on.
11:15 - 11.68v.
11:16 - 11,68v
11:17 - 11.65v
11:18 - 11.64v
11:19 - 11.61v
11:20 - 11.61v
Ignition and headlights turned off
11:21 - 12.08v
11:22 - 12.29v
Exited and Locked Tiguan.
11:23 - 12.20v
11:24 - 12.35v
11:25 - 12.38v
12:08 - 12.47V
Load Test 23Aug21
D4, main battery 2.5 years old, test with main and aux isolated.
0 Locked 12.78
1 Unlocked. 12.43
2 Ignition and lights. 12.03
3 “ 12.17
4 “ 12.18
5 “ 12.17
6 “ 12.16
7 “ 12.16
8. Off and locked. 12.49
9 “ 12.53
10 “ 12.55
……
30 “ 12.77
Thank you Winglen and that is around what I should have seen with my battery, but I would guess that it is approaching the end of its life.Quote:
Originally Posted by winglen
