Thread: lithium dual battery ideas

Hi Rod and that is all good and well but going to a lithium auxiliary battery is not going to fix Maca’s problem and he will still get a short cranking battery operating lifespan.

As I posted, with around 5,000 D3s and D4 with the Traxide systems and VERY few are having problems, particularly like Macas, and with a few hundred customers in Australia now using the SSB batteries and again, VERY few have had any issues, Macas problem is solely with his vehicle.

With the way Maca drives his D4, his batteries should be fully charged and in perfect condition and should last for years more than they are.

I have asked could he monitor the operating voltage while driving, and this is to see if there is a charging algorithm issue.

I have come across charging problems a number of times.

A while back there was a common issue where the D4’s BMS would operate the alternator at 12.2v and allow the D4’s own electrical load to discharge the cranking battery down to 12.2v.

As soon as the BMS detected the cranking battery had been discharged down to 12.2v, the alternators voltage was then be set at a constant 14.7v and remained there while the BMS monitored how fast the battery recharged and how much current was used to recharge the battery.

This was a very clever way to periodically determine the condition of the cranking battery.

BUT in a small number of vehicles, once the cranking battery discharged down to 12.2v, the BMS did NOT increase the alternator voltage and it sat continuously at 12.2v.

As an example of what was going on at the time. I had one customer, who had a pretty good idea of how the electrics in his D4 should be operating but was having a problem with low operating voltages and took his D4 to the dealers.

Like all good dealerships, the first thing they did was point at the Traxide system and told him “That was his problem” and that’s all they did to “FIX” his problem.

Out of frustration, he called me on his way home from the dealers and a plan was struck, to disconnect the Traxide Isolator’s Positive ( + ) cables from the two batteries and leave them disconnected.

I also told him about a software patch that should have been applied to his D4 during one of its services.

As he was not going away for at least a month, after disconnecting the cables, he gave the Optima a good charge, which would keep the battery in good condition for the month.

Then a month later, after seeing the voltage at a constant 12.2v and only rising to 12.3v on a couple of occasions, he took his D4 back to the dealers.

Right on form, the first thing the dealer’s service people said was that the Traxide Isolator was the problem.

He told them it had not been connected to the vehicle for the passed month and that the problem was most likely a software patch that had been overlook by the dealer’s service staff.

They check their records and sure enough, they had not installed the patch.

He was phoning me from his D4 as he drove home from the dealers and he told me his volt meter was displaying 14.7v

Maca, I am wondering if you have the opposite problem.

When the D4 was first sold in Australia, they came with a Wet Cell cranking battery, but part the way through the run, they changed to an AGM cranking battery.

With the wet cell battery, a D4 alternator voltage, particularly during cold weather, could see voltages in excess of 15.0v, which is fine for any wet cell battery.

Once they changed to the AGM cranking batteries, no matter how cold it gets, the voltage applied to the AGM cranking battery never rises above 14.7v

So I am wondering if your D4 was originally supplied with a wet cell cranking battery and the charging software to go with it and at some stage the cranking battery was charged to an AGM but the software has not been upgraded.

AGM batteries can tolerate 15v for a short time WHILE COLD, but once warm, 15v would progressively cook your batteries.

Again, you need to monitor your operating voltages because changing to a DC/DC and lithium battery, 15v would be OK for the lithium battery but if your voltages are high, your are still going to slowly cook your cranking batteries.


Just a suggestion.

Originally Posted by drivesafe

Have you monitored the voltage at your cranking battery, preferable with something that logs the info, like a BM2 monitor.

This is a seven day graph of the battery state. the first few days pictured are in shared mode and you can see how the aux battery is draining the *BRAND NEW* cranking battery down to a low state of charge in just a half day period. The last few days are in isolated mode and show the cranking battery maintaining it's charge without the drain from the aux/traxide.

battery.jpg

The only thing drawing from the aux battery during this time is a dash cam + one of your AGB25 which I have measured is only drawing 0.4a together.

While driving, the alternator is either pumping out ~12.2v, 13.1v or 14.4v (presumably depending on the state of the cranking battery) so I don't think the issue lies with the BMS/alternator charging.

Originally Posted by Macadamia

This is a seven day graph of the battery state. the first few days pictured are in shared mode and you can see how the aux battery is draining the *BRAND NEW* cranking battery down to a low state of charge in just a half day period. The last few days are in isolated mode and show the cranking battery maintaining it's charge without the drain from the aux/traxide.

battery.jpg

The only thing drawing from the aux battery during this time is a dash cam + one of your AGB25 which I have measured is only drawing 0.4a together.

While driving, the alternator is either pumping out ~12.2v, 13.1v or 14.4v (presumably depending on the state of the cranking battery) so I don't think the issue lies with the BMS/alternator charging.

Hi Maca and first off, the MAXIMUM current draw of an ABG-25 is 0.05a or 50 milliamps, not 400 milliamps, so you have a problem somewhere else?

Next, you alternator voltages are way WAY too low and you have found your issue.

Regardless of the state of charge of your cranking battery, shortly after starting your motor you should be seeing 14.7v, and as your cranking battery is always low, you should see 14.7v for quite a long time.

As I posted above, the 12.2v is something that only occurs periodically, and this would be no more than once every 3 or more months.

To see that 12.2v on a regular basis is a clear indication of either a software problem or a faulty alternator and my money would be on some form of software issue.

Thank you for that last bit of data because it rules out the Traxide isolator as the problem and also rules out the batteries as being a problem.

And as you have stated, your driving habits would not contribute to your battery short lifespans but those low voltages most certainly would.

Again as above, my money is on a software issue and I bet it has been that way since the vehicle rolled off the production line.

You need to get that sorted or it is just going to continue to cause more short battery life.

Sorry I can not help you with solving that low voltage issue but at least you have somewhere to start, to fix the problem once and for all.

Originally Posted by drivesafe

Hi Maca and first off, the MAXIMUM current draw of an ABG-25 is 0.05a or 50 milliamps, not 400 milliamps, so you have a problem somewhere else?

+ my dash cam. point is - it's a very low draw that definitely shouldn't be drawing down the HVT70LD from 12.7v to 12v in 24 hours

Next, you alternator voltages are way WAY too low and you have found your issue.

Regardless of the state of charge of your cranking battery, shortly after starting your motor you should be seeing 14.7v, and as your cranking battery is always low, you should see 14.7v for quite a long time.

It does tend to stay at 14.7v for most of trip. that graph is 7 days compressed down so it looks like brief blips but they're actually at least 20minutes to an hour long.
Here is the graph from today only.
battery2.jpg
A few points to note:
1: overnight I had a 10amp CTEK battery charger plugged into the rear anderson plug. It had finished it's cycles, indicated full charge and was in the maintenance stage. Hence AUX battery was higher voltage than crank.
2: 25 minute drive to work - voltage remained 14.7v for the entire trip
3: for the 10 hours at work in isolated mode the aux battery fell from 12.7v to 12.3v with [as above] only a 0.4a draw.
4: 40 minute drive home from work voltage for the most part remained 14.7v

My aux battery is clearly failing but with the driving I do and >monthly maintenance charging it shouldn't be in the state it is after only a little over a year.

Anyway, I'll check with the GAPIID if there's an update and source it from GAP or Bell.

Hi again Maca and your batteries are not holding a charge because they are stuffed, or at least your auxiliary battery is and it dragging your cranking battery down so quickly.

As I posted in the last reply, you have found your problem, and you need to fix it.

You virtually should never see 12.2v because when the BMS is carrying out the condition test, the instant your cranking battery dischargers down to 12.2v, your alternator voltage will jump to 14.7v, your obviation confirmed your issue.

Mate you have your heart set on fitting a lithium battery, go for it, but because of those low voltage readings, be aware you will still need to replace your cranking in a short time.

BTW, one of the voltage readings in you first graph is almost 15v, as stated, your alternator voltage should never go over 14.7, and note, this was not at the beginning of the days drive, so your battery would not be cold and that high a voltage is not good for AGMs once harmed up.

So once again, get your software looked at, thats where your problem is.

Originally Posted by drivesafe

Mate you have your heart set on fitting a lithium battery, go for it,

I'd rather not but my traxide setup is not working as intended and never really has. What you are suggesting is the cause does not marry up with what I am seeing.

1: I almost never see 12.2v from the alternator. It happened briefly after I reset the BMS when I replaced the cranking battery, it did the same when I replaced and reset it last time also. I haven't seen it since, it's not in a month of data logged by the battery monitor so it is definitely not the cause of my issue.

2: that blip of almost 15v I would suggest is caused by the ISU-160 suddenly isolating the batteries that were previously linked for some reason because the minute before they were linked, then isolated for a minute, then linked again. Is this normal operation. here are the voltages and time stamps.
traxide_1.jpgtraxide_2.jpgtraxide_3.jpg

And no there are no loose earth cables or loose terminals anywhere. I have checked them all.

For the majority of my driving it sits as ~14.7v and occasionally after a while drops down to around 13.something v. As I understand from what you described this is normal operation and should not be resulting in the premature failure of both of my batteries.

traxide_norm.jpg

Originally Posted by Macadamia

2: that blip of almost 15v I would suggest is caused by the ISU-160 suddenly isolating the batteries that were previously linked for some reason because the minute before they were linked, then isolated for a minute, then linked again. Is this normal operation. here are the voltages and time stamps.

Again, you don't really understand how alternators work.

The USI-160 turning off or on, would have absolutely no effect on the voltage level of you alternator.

BUT, the earlier versions of the USI-160 had a 15.1v Over-Voltage shutdown function and it is more likely that your alternator went over the 15.1v shutdown level and NOTE, the voltage has to be over 15.1v for more than 15 seconds before the isolator shuts down.

The 15 second delay is to make sure simple spikes do not shut down the isolator.

If a shut down does occur, the USI-160 will turn back on the instant the voltage drops back below 14.8v

Once again, you have confirmed the isolator is doing exactly what it was designed to do, and that your alternator is operating outside it's specs.

Maca, you posted this thread enquiring about changing the auxiliary battery to a lithium. But like many others, you blamed your Traxide isolator for causing all your continuous short battery life.

I respond to these types of threads as in the vast majority of cases the Traxide isolators are not the problem and I help whoever is having a problem to try to workout what the real issue is.

This thread is a perfect example of just such a situation.

You are obviously not interested in getting to the exact problem and just continually try to blame your Traxide isolator.

Do as you are planning and replace your Traxide isolator and then in a year or so, come back and tell everyone how your cranking battery has again died prematurely.

The isolator is doing exactly what it is supposed to but your alternator is not.

Best of luck to you.