Thread: D4's charging / battery problem

Originally Posted by Ferret

.... it does not behave that way all the time. Sometimes, even when at a high initial SOC, The BMS does not display that kinetic charging behaviour, it just displays a normal 'adsorption' type charging behaviour and the battery eventually reaches 100% SOC.

My experience matches yours pretty well Ferret, although getting beyond 90% is very rare.
Whatever is going on, the BMS cannot be trusted to get the batteries beyond about 85% SoC on any given drive (even a long one).

Cheers,
Scott

I’m going to throw a spanner in the works.

How do you know the battery is not being charged beyond 80-85%?

What are you using as a reference?

Originally Posted by drivesafe

I’m going to throw a spanner in the works.

How do you know the battery is not being charged beyond 80-85%?

What are you using as a reference?

The SOC as reported by the BMS system to the GAP tool. How the BMS arrives at the reported SOC though is a mystery, as is the algorithm which drives it's charging behaviour.

Originally Posted by Ferret

The SOC as reported by the BMS system to the GAP tool. How the BMS arrives at the reported SOC though is a mystery, as is the algorithm which drives it's charging behaviour.

Again, without data logging the operating voltage over the whole trip, those momentary readings don’t really indicate what is happening in the way of overall charging of the batteries.

Not that sure of the accuracy of the readout either. I remember seeing a readout posted up for a D4 a while back and it was showing the alternator current as being 220 amps.

Correct me if this is wrong, but a D4 has a 180 amp alternator?

Originally Posted by dukemasterpro

Had left the Traxide switch in the “down” position.

By "down" do you mean toward or away from the LED? I can't remember offhand which is for normal v winch but if you put the battery in for winch backup it might be set wrong? I'm guessing you had someone else do the traxide install?

Running a medium fridge and a few light strips for a couple of days should be nothing to the yellow top. My 2010 Sport does that after nothing but 4km commutes for months at a time (do you think SWMBO will catch a train?!?) and just a couple of hours drive to camp.

I do leave the tail gate up while around camp.

I consider the traxide the single most important upgrade for these cars both for going bush and city life. I don't know how the Toorak tractors survive, tbh. First time I had the footy on the car radio I drained the battery to warning level.

Originally Posted by surfingooner

Where I only use my D4 at the weekends, my battery keeps getting flat. I replaced my battery about a year ago and I am now having same problem with a warning message coming up, when I turn the car off after use, and then the car won't start again.

Matt.

Hi Matt, can you give me a call, today or over the weekend and if you have a multi meter available, I can talk you through some tests.


In the last month I have had to very strange faults located. One in a D5 and one in a D4.


Both faults related to the auxiliary battery not charging properly while driving, and in the case of the D4, the fridge would only run for a few hours before the low voltage shut it down.


In both cases, the initial feedback sounded like a bad connection and most likely a bad earth connection.


In both cases, with the motor running, the D5 had 14.7v across the cranking battery terminals, and the D4 had 13.8v across the cranking battery terminals.


But both auxiliary batteries were only at, or getting 12.8v to 12.4v across the auxiliary battery terminals.


After quite a bit of testing by the owner of the D5, we found a very strange fault.


When measuring the voltage across the cranking battery terminals, the voltage was 14.7v.


When measuring the voltage from the cranking battery’s positive ( + ) terminal to an earth point, the voltage was 14.7v.


When measuring the voltage from the cranking battery’s negative ( - ) terminal to an earth point, there was a the voltage 1.8v reading where the reading should have been 0v or very close to it.


The D4, tested last Monday, had a voltage difference of 1.4v when measuring from the cranking battery’s negative ( - ) terminal to an earth point.


So Matt, or anybody else interested in some testing of their setup, can you call on 07 5569 2557, day or evening.


While my L322 RR does not have a problem with earth points, I have had a couple of L322 customers who did have an earthing problem, but the bad earth was found to be caused by paint on the nut, on the rear bumper stud. With the paint removed, the problem was solved.

So here is a log of a 35 min drive. The battery has been initially charged via a battery charger to SOC 96%, according the GAP tool.

Whist driving and maintaining a relatively fixed speed the BMS allows the battery to be drained, note the long periods of negative battery current. Only under brakes or coasting is the alternator charging the battery. The strategy drains the battery, at the end of the drive the battery SOC is 88%.

D4 Battery Charging Behaviour.jpg

Thanks Ferret for the graph, but as I posted earlier, SoC readings are meaningless.

The SoC of any battery is determined by the battery’s condition at the time the reading is taken, and an instantaneous reading will give no genuine idea of the battery’s actual charge capacity.

While a voltage reading fulls into the same spurious results, but a voltage reading, when two or more batteries are connected to the alternator, gives a much more detailed indication of what is happening in the whole system, not just at the cranking battery.

I’ll post up some graphs shortly, showing what I mean.