J11 Battery charging system problem

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duncho
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Post by duncho »

Bob d:
The reason why voltage drops below 12.6V while engine is running is because in that moment alternator receives a command from ECM via LIN bus not to generate voltage higher than 12V and such the energy to power all car devices is drained from the battery unless the battery voltage would drop below or close to voltage generated by alternator and that ensures that the battery will not be drained below 11.8V (my measurements). Such scenario keeps the battery always undercharged which also is always proved by Nissan dealers when they run the battery test (result is always "need to be charged").
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Bob d
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Post by Bob d »

Duncho....If the current sensor is measuring flow in the ground cable then how about getting help from Mr Ohm and strapping a length of cable between the batt -ve and chassis to divert a proportion of the current away from the sensor, not too difficult to implement but calibration might be tricky!! ;)

Bob
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duncho
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Post by duncho »

Bob d wrote: Tue May 16, 2017 1:57 pm Duncho....If the current sensor is measuring flow in the ground cable then how about getting help from Mr Ohm and strapping a length of cable between the batt -ve and chassis to divert a proportion of the current away from the sensor, not too difficult to implement but calibration might be tricky!! ;)

Bob
Unfortunately the design is not that basic. Based on the current flow from / to battery, the sensor changes the output voltage approx +/- 1V. The mean value of the sensor is 2.5V. High drain from the battery equals to lower voltage, high charging current to higher voltage than the main value is.
I permanently lowered the voltage (by influencing the sensor output voltage by correctly adjusted magnetic field). I need to road test it on long distance (at least 2000km) to be sure to tell whether this is the right approach to fix the problem. I'm bit skeptical as I believe that programmed logic in IPDM-E (or ECM) will try to balance the calculated higher battery drain and not only increase alternator power output. Time will tell. So far no conclusions ;)
Last edited by duncho on Tue Jul 04, 2017 7:42 pm, edited 1 time in total.
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Aanonymoss
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Post by Aanonymoss »

So What have you do about this so fair?

Can you Explain it again?
What about The new qq - has it The Sam error? I Will Call it a error.
Aanonymoss
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Post by Aanonymoss »

Anything new in this case?
duncho
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Post by duncho »

Dear all, fix to insuficient charge of car battery has been found and was described in detail on Czech Nissan forum: http://www.nissanclub.cz/forum-tema/dob ... 695?kols=3

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Aanonymoss
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Post by Aanonymoss »

Why do Nissan not help with a solution On this problem?

I still havent find a useful solution.
chosan
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Post by chosan »

duncho wrote: Tue Jul 04, 2017 7:48 pm Dear all, fix to insuficient charge of car battery has been found and was described in detail on Czech Nissan forum: http://www.nissanclub.cz/forum-tema/dob ... 695?kols=3
Duncho, I wish you could translate the most meaningful stuff from that article. Am I right saying they just disconnected
the sensing circuit and bypassed it?
duncho
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Post by duncho »

chosan wrote: Sat Aug 05, 2017 6:59 pm Duncho, I wish you could translate the most meaningful stuff from that article. Am I right saying they just disconnected
the sensing circuit and bypassed it?
Here is translation to English: https://translate.googleusercontent.com ... Hkpemg88rQ

It is not bypassed, just point of full battery charge was re-adjusted to let IPDM think that battery is not fully charged yet.
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chosan
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Post by chosan »

duncho wrote: Sat Aug 05, 2017 9:13 pm
chosan wrote: Sat Aug 05, 2017 6:59 pm Duncho, I wish you could translate the most meaningful stuff from that article. Am I right saying they just disconnected
the sensing circuit and bypassed it?
Here is translation to English: https://translate.googleusercontent.com ... Hkpemg88rQ

It is not bypassed, just point of full battery charge was re-adjusted to let IPDM think that battery is not fully charged yet.
I goofed. The upper one is your modified system as I now understand. I saw it in reverse order. Are you still running with this values and it's OK?
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