J11 Battery charging system problem

[gvmdaddy]

After 13 hours dormant, then engine idling, then on the road under load. Voltage dropped to 11.5 for a split second on cranking the starter.

[duncho]

Here is the video you asked for: http://youtu.be/EgMyuK8GvYQ

[chrisw99]

I checked my hidden menu screen to provide another set of results. At the end of an hours drive on the motorway and idling it was 14.7. Turned the engine off and it dropped to 14.3.

Went back out to the car after an hour, without starting the engine it was 12.86 which dropped to 12.8 when the AC kicked in

What determines when the stop start doesn't kick in? After that hours drive when I parked up, stop start didn't happen. It was dark so lights were on , heating was on, I guess that's why

[Deleted User 3871]

Stop / Start is designed to reduce fuel consumption / exhaust emissions. I guess there must be a set of parameters that need to be reached for the start/stop & battery charge to take place. The charging logic must be looking for the times when you have your foot off the throttle or at least have little throttle applied ,but with the car moving forward so it can efficiently regenerate the battery. Again, at a guess, the voltage will drop to a certain level that will over ride the start / stop logic force charging the battery. And I'm sure this is all temperature related also.

It appears that the car is happy with the battery @ 12.8v which is 100% charge. The 14.7v & 14.3v were when your battery was getting charged as its capacity was below 100%.

So in essence. 14v is battery charging & 12.8v is a full battery.

I checked my hidden menu screen to provide another set of results. At the end of an hours drive on the motorway and idling it was 14.7. Turned the engine off and it dropped to 14.3.

Went back out to the car after an hour, without starting the engine it was 12.86 which dropped to 12.8 when the AC kicked in

What determines when the stop start doesn't kick in? After that hours drive when I parked up, stop start didn't happen. It was dark so lights were on , heating was on, I guess that's why

[gvmdaddy]

I dont know anything about batterires, how they charge/retain/discharge, but using Daewar's logic as above, then if I go on a long run that constantly charges the battery, then after a while the voltage would drop to around 12 to 13v as the battery was holding a near capacity charge, but it doesnt, it still shows a figure between 14 and 15 volts. Immediately after a long journey, switch ignition off and it reverts to 12 to 13 again. Start the car again and it goes back to over 14v and never lowers as the battery gets charged.

[duncho]

Seems to me that every car behaves differently, which is not a good sign.

[chrisw99]

This stop start is confusing me. This morning when the car is cold, it stopped regularly at traffic lights etc. Last night after an hours motorway drive when you'd expect the battery to be full when I got home, it didn't.

I had just been reversing back and forwards on my driveway to test the proximity sensor, I wonder if the car is clever enough to think you are in the middle of a parking manoeuvre so it stays on.

[chrisw99]

Please send a photo of the battery, I will tell you whether it is genuine or aftermarket. Include also the label on the second photo.

Here is the battery that Nissan put in my car. Can't see any brand or manufacturer at all, maybe it's underneath or at the back but I can't be bothered disconnecting it to find out...

[duncho]

Yes it is genuine Nissan.

[Aanonymoss]

Thanks

Is a Nissan battery.
Is The same we have now.