Looking to invest in battery system and need some help... (1 Viewer)

[filer5000]

OP, curiosity is getting the best of me: Why would you want to use an inverter to power a DC-DC charger?

I think I mightve gotten my thoughts messed up. I want to charge my external battery straight from my cars battery or from my alternator. Someone here said against it but I was confused.
Im trying to figure out a way to charge it off my alternator or battery.

 

[FrazzledHunter]

I think I mightve gotten my thoughts messed up. I want to charge my external battery straight from my cars battery or from my alternator. Someone here said against it but I was confused.
Im trying to figure out a way to charge it off my alternator or battery.

I've been following this thread with some interest as you're doing exactly what we do camping-wise.
We also have a travel trailer with big lithium batteries that we can charge from the tow vehicle.
We also had a 100 series LC but we never made electrical or any other upgrades to it.

To be clear, do you want a 2nd battery under the hood or portable battery system like a Yeti Goal Zero or Ecoflow? Both?

 

[e9999]

F, it probably is like this in ascending order of desirability, IMO:

- Easiest / Cheapest / no control / less optimal / somewhat cringy to electrical nerds: direct connection between the 2 batteries. Should work in most cases. But try to have both batteries at about the same voltage when you connect them to avoid surges.

- OK / not very elegant / probably less efficient: Inverter to AC charger

- Most optimal / expensive / elegant / probably most efficient / most control: DC-DC charger

There are more subtleties to this but I suggest that before you do anything for real, do some reading about the basics of 12V wiring and always be careful with wire sizing.

 

[Shoredreamer]

I think I mightve gotten my thoughts messed up. I want to charge my external battery straight from my cars battery or from my alternator. Someone here said against it but I was confused.
Im trying to figure out a way to charge it off my alternator or battery.

I think there may be some confusion or just non specific info here. It sounds like you are now asking how to charge a portable power station (Jackery, Ecoflow, Bluetti etc) off your vehicle charging system to get faster charging, as those units typically charge very slow from their 12v charge input. There’s plenty of YouTube “hacks” to get this to work, or not work, from your vehicle involving voltage converters and inverters. Not sure if that’s what you are after….

Most of the discussion on this thread pertains to installing drop in LiFePo4 battery setups and charging them.