Alternator SDV6, anyone upgraded for larger than stock 150A??

**imaz** · 12th July 2021, 11:40 PM

As the title states, has anyone upgraded the stock 150A alternator for something greater?

The stock alternator is inadequate for supplying charge to multiple DCDC charger(~40 - 60amp additional load) and insufficiently supply power to Redarc Tow Pro Elite brake controller WHEN the DCDC charger is in Boost stage. Mine and 2 other vehicles with similar setup suffers the tow pro elite (red blinking) while dcdc is boost stage demand. Each of these vehicles had their installations installed by different installers. When the dcdc charger are out of boost stage, the Redarc tow pro elite will stop blinking and become normal state.

During this time, the brake controller do work normally.

There is no other reason why the dcdc and brake controller correlate other than insufficient power supply charge to the starting battery.

Redarc tow pro elite trouble shooting suggests it a ground issue, but the fact this happens in multiple D4, with various combination of setup is leading me to believe it’s alternator related.

150A is in the small side.

Also, if we charge the camper battery’s 100% using AC/DC before attaching to the D4, the Redarc tow pro brake controller do not suffer the issue, since the DCDC is in either absorption or float charge state.

**rocket rod** · 13th July 2021, 12:56 AM

Could it be that your cranking battery is on it's last legs and that by chance the same is happening in the other vehicle? Just thinking out loud here.

**DiscoJeffster** · 13th July 2021, 04:29 AM

Hmmm. There are larger alternator options if that’s something you wish to try, however ….

Firstly get proof the alternator is the cause. I’m guessing you don’t have an IIDTOOL that you can actually see the alternator charge state/output at these times too verify it’s at 100% capacity?

Secondly, your DCDC charger isn’t any more drain than anyone else charging batteries whilst driving. In fact, your DCDC limits the possible charge compared to directly connected batteries and yet no one else has reported this issue.

So, about your tow pro installation - have you run it directly from the battery using its own heavy gauge wire?
Did you also run heavy down through the car from the controller for the brake power?
Where is it earthed?

**imaz** · 13th July 2021, 05:38 AM

Originally Posted by rocket rod

Could it be that your cranking battery is on it's last legs and that by chance the same is happening in the other vehicle? Just thinking out loud here.

Possibly, my starting battery was replaced in 2019. The other car is around Nov 2018. Unsure of the third car.

**imaz** · 13th July 2021, 05:43 AM

Originally Posted by DiscoJeffster

Hmmm. There are larger alternator options if that’s something you wish to try, however ….

Firstly get proof the alternator is the cause. I’m guessing you don’t have an IIDTOOL that you can actually see the alternator charge state/output at these times too verify it’s at 100% capacity?

Secondly, your DCDC charger isn’t any more drain than anyone else charging batteries whilst driving. In fact, your DCDC limits the possible charge compared to directly connected batteries and yet no one else has reported this issue.

So, about your tow pro installation - have you run it directly from the battery using its own heavy gauge wire?
Did you also run heavy down through the car from the controller for the brake power?
Where is it earthed?

Speaking of my setup, I’m using rated 30amp cabling to the tow pro supply, earthed at the ground stud near the starting compartment. The other cars are cabled similar it seemed.

I do not have the IIDTool.

josh.huber · 13th July 2021, 05:58 AM

Originally Posted by imaz

Speaking of my setup, I’m using rated 30amp cabling to the tow pro supply, earthed at the ground stud near the starting compartment. The other cars are cabled similar it seemed.

I do not have the IIDTool.

Have you got any sort of battery monitor to check voltage in these conditions?

josh.huber · 13th July 2021, 06:03 AM

Tim will chime in soon. But if you're car sees a perfectly full main battery at start up. It's going to put less in the battery on purpose. If the dcdc was drawing the main down to 12.3v for example. The charge rate would be higher.

Blue tooth battery monitors would be a great tool for these test. The free app will log your battery voltage