Can someone explain the benefit of doing this versus charging the auxiliary battery through my Traxide isolator? Feel free to treat me like I'm 3 years old....
Does it resolve the partial charging of the aux battery due to the "smart" charging on the vehicle?
Could you keep a manual isolator in the system to link the batteries for winching use or in case of discharge of the starting battery?
Hi avslash, the problem with DC/DC devices is the advertising they use to sell them.
They tell you all the good points like “a DC/DC device can fully charge your auxiliary battery” and this is true.
What they conveniently neglect to tell you, is just how long you have to drive, to fully charge your auxiliary battery from a low stated.
For example, if you have a 100Ah battery discharged down to 20% SoC, and your are using a 20 amp DC’DC device to recharging it, you will need to drive for at least 7 hours to get the auxiliary battery over 95% SoC.
But charging straight off the alternator ( via your Traxide isolator ) you can do the same think in about an hours driving.
Another actual example. My 2007 RR Vogue had a 140 amp alternator and a 110Ah cranking battery, plus a 55Ah Optima Yellowtop auxiliary battery, and a Traxide isolator. After slowly discharging both the cranking battery and the auxiliary battery down to the cut-out setting of the Traxide isolator, I then went for a 30 minute drive ( actually 33 minute ) and then carried out the same slow discharge of both batteries down to the same limits.
I have achieved a 47Ah charge in just 33 minutes of driving and 20 minute were in suburban streets and only 10 minutes was on the freeway ( where maximum charging would have occurred.
To try to do the same with with a DC/DC device, you would need at least a 120Ah auxiliary battery and a 100 amp DC/DC device, and it would still take a longer drive to get the same amount of charge.
NOTE because your LR4 has either a 180 amp or 220 amp alternator ( depending on the model ), you would be able to replace even more used battery capacity in the same drive time.
The only time you need a DC/DC device, is if the auxiliary battery is a lithium and then you have other drawbacks.