Dual battery system

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Originally Posted by W&KO

How is his battery going to suffer and why will he be replacing batteries more often??

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Because the charging regime selected is based on the cranking battery’s charge state. If both batteries are discharged together then the BMS will apply higher voltage to increase charging to the cranking which benefits both batteries. If the cranking is full, then the drain of the other battery is perceived as only a parasitic load and not a battery that needs charging. This will see lower voltage applied and slower charging of the secondary battery. This in turn can see it always partially charged hurting it’s life.
Traxide and other that deplete the cranking battery work in the secondary battery’s favour.

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Originally Posted by DiscoJeffster

Because the charging regime selected is based on the cranking battery’s charge state. If both batteries are discharged together then the BMS will apply higher voltage to increase charging to the cranking which benefits both batteries. If the cranking is full, then the drain of the other battery is perceived as only a parasitic load and not a battery that needs charging. This will see lower voltage applied and slower charging of the secondary battery. This in turn can see it always partially charged hurting it’s life.
Traxide and other that deplete the cranking battery work in the secondary battery’s favour.

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I’ve ever had any issue over the last 20 years.

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Originally Posted by DiscoMick

Whatever system you choose, I recommend you add a solar panel on your roof rack to keep it topped up. Set and forget.

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Thanks but the roof isn’t an option as I’ll plan on putting a large roof pod up there so that I can lock my surfboard on top.

Ive never had a flat from the fridge from using just the main battery (I’ve come close!) so I’m confident the extra battery dedicated just for the fridge will do the trick.. time will tell

To close this out.. I ended up with the Narva voltage sensitive relay, front runner battery tray and optima yellow top.

Hasnt been tested properly yet for how long I can run the fridge but The car seems to start better

Total price $560

battery - $305
battery tray $115
Narva VSR - $140

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Originally Posted by Lukeis

To close this out

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It's not closed until there's photos :)

Scott

Because the Narva cuts out at 12.7v you have only the capacity of the yellow top to run your fridge. If your yellowtop is the d34 then it's 55amps which means you have a safe usable of about 45amps. This setup will require some careful management if your planning on stopping up any longer than 1 night.

Hi Lukeis, and just a work of caution, when I started supplying my D4 kits, I originally supplied them with that battery tray.

The tray actually comes from South Africa, and there was a problem with it.

The bracket can touch and rub the plastic bottle just in front of the battery location.

At the time I asked if the bracket could be modified, but as it was made for a specific purpose and they could not/would not change it.

If it is still the same bracket, you will need to make sure it clears the plastic bottle.

BTW, this is why we decided to make our own and make it out of stainless steel instead of painted steel.

I paid about $200 less for my traxide and 85ah agm, so by skimping you spent more.

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Originally Posted by loanrangie

I paid about $200 less for my traxide and 85ah agm, so by skimping you spent more.

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Really? $360?

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Originally Posted by DiscoJeffster

Really? $360?

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Yes, $330 to be exact. I already had the power and earth cable and twin core sheathed to run to the rear so even if you add $50 for that.