Lithium Aux Battery?

Car Builders sell aluminium heat shield that can be formed into shape as needed.

Still needs an air gap and ideally if you could feed some fresh air into the box you could create a space which is at near ambient temperature. Find a way to duct some tubing to direct cool air into the battery box.

Aluminium Heat Shield - Quality Materials to Keep Your Ride Cool

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Originally Posted by drivesafe

Hi John and first off, your Traxide isolator is NOT the limiting factor when trying to charge lithium batteries directly from a D4 alternator.

The D4 comes with a SMART alternator operation and will stop charging a lithium battery and the BMS in a D4 will actually cause the D4 to run its electric off the lithium battery while your are driving.

In D3s and the original defenders, you can charge lithium batteries directly off the alternator through a Traxide isolator.

Next, your idea of an aluminium battery box is far superior to a thermal blanket, because any heat that will get to the battery, particularly on long drives, will keep in battery hot, long after the motor has stopped.

An aluminium box, fitted no closer to the battery than 10mm, will reflect the radiated heat coming from the motor but will allow any heat in the battery to quickly vent off once the motor stops.

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So my D3 Traxide could utilize something like this? Or is there a lithium you recommend?

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Originally Posted by DiscoDB

Car Builders sell aluminium heat shield that can be formed into shape as needed.

Still needs an air gap and ideally if you could feed some fresh air into the box you could create a space which is at near ambient temperature. Find a way to duct some tubing to direct cool air into the battery box.

Aluminium Heat Shield - Quality Materials to Keep Your Ride Cool

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Thanks. I didn’t know that. Will look into it

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Originally Posted by Parso

So my D3 Traxide could utilize something like this? Or is there a lithium you recommend?

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Hi Parso and yes, your D3 will charge lithium batteries direct from your alternator,.

D3 alternators charge at no lower than 13.5v, so D3 will never run on the lithium battery while the motor is running.

You need a minimum of 13.8v to fully charge a lithium battery.

When ever you start your D3, it will run at a much higher voltage for at least 30 minutes. This will allow bulk recharging of the lithium battery during this period.

But should the alternator voltage drop down to 13.5v, it will not discharge the lithium battery while driving ( something that a D4 will do ).

If you have Traxide isolator, it will need to be one of th e newer versions, one supplied in the last 5 or so years.

Then when the auxiliary battery is a lithium, set the Traxide isolator to IGNITION/STORAGE mode and leave it there at all times.

Hi again John, and you do not need a BOX.

Just a reflective panel placed at the engine side of the battery will do what you are after.

Also, I would use a thin sheet of polished stainless steel instead of aluminium.

A little experiment for you.

If you want to see how hot it gets where you want to locate the battery, after a long drive, measure the temperature of the fluid in the reservoir, located just behind your headlight.

Drivesafe

How goes your investigation into a Traxide system for D4s to charge a lithium battery.

Also, while I've got you, I presume I can use your system for an AGM dual battery in a diesel VW Touareg , 2015.

Regards
Trevor

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Originally Posted by drivesafe

Hi again John, and you do not need a BOX.

Just a reflective panel placed at the engine side of the battery will do what you are after.

Also, I would use a thin sheet of polished stainless steel instead of aluminium.

A little experiment for you.

If you want to see how hot it gets where you want to locate the battery, after a long drive, measure the temperature of the fluid in the reservoir, located just behind your headlight.

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Things are getting easier and easier! Thanks Tim, I’ll try that

Why stainless and not aluminium?

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Originally Posted by John_D4

Why stainless and not aluminium?

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A polished surface is best as it reflects the radiated heat coming from the motor.

Polished aluminium will not keep its polished finish for long, while stainless remains polished and is easy to clean.

As well as an aluminium box, multi layer insulation, MLI, could be the go.

My Kings LiFeP04 battery in the D2 charges via a Traxide. No problems there.