Multiple vehicles - not wanting to commit to dual battery setup on both

[hour]

Hi guys-

I can't for the life of me find anything of substance on this on here (or amazon), which in my experience means it doesn't exist or isn't popular..

Is there any simple way to top up another 12v battery without doing a dual battery setup/isolator/whatever? My aux battery + solar + fridge will be swapped between two vehicles this summer pretty frequently (depending on whether I'm off roading and camping, or just camping/road tripping) so I'd prefer not have two setups in each vehicle.

I'm not really trying to fast charge the aux battery while driving as most people seem fond of, but rather just pump some juice back in to it while on the go (take fridge out of the equation for this). The ArkPak references this in their 'reasons to not build your own':

"Investing in a quality 6amp charger that runs off AC or DC power and that reliably indicates battery charge level: ~$150" - but I can't find any 12v battery charger that runs on 12v itself, unless a solar charge controller can make use of ~13.something volts from my vehicle's electrical system. Whatever they're doing, and whatever portable jump packs that you plug in to your cigarette lighter are doing - I'm trying to accomplish. If this isn't possible on 75ah+ batteries or something, understandable, but if it gained me .1v on a several hour drive I'd consider that better than nothing.

Sometimes I'll leave camp and have the engine running on trails for most of the day, so there's a lot of time to gain anything. I also know inverters->battery chargers are inefficient, but is it such an awful thing if I'm really not in any hurry?

Thanks!

 

[Happy Joe]

When I need to top off my auxiliary battery using the vehicle I just connect the aux. batt. in parallel with the vehicle battery then run the engine for a bit.
I never tried to do an extended charge while trail riding though; a simple (automatic) battery isolator would be prudent in this case, IMO.
I roughly monitor the charge level by using a DVM (Note; you need to wait roughly 24 hours after use or charge to let the battery "settle" (reach chemical equilibrium) in order to get a reasonably accurate reading).
Your current setup sounds like what I expect to do for the fridge, after I get a larger battery, I had planned on just using the solar charge controller with the vehicle although "small"/low current controllers might overheat & burn out if trying to handle a potentially large current from the alternator to charge a very low battery (another reason to use the controller for solar and the isolator for vehicle charger although I have heard of some expensive MPPT controllers that can do both).

Enjoy!

 

[DiploStrat]

???

Not totally sure I understand what you want to do, but it shouldn't be hard.

-- Run appropriately sized (and fused) cables from the stater battery to wherever you want to carry your portable aux battery in each vehicle.

-- Terminate the cable with some form of appropriately sized quick disconnect - think golf cart or forklift plugs. Some recommend Anderson Power Poles.

-- Connect the appropriate plug and jumper to the aux battery. Don't forget the fuse.

Notes:

-- You won't need any form of isolator as long as you remember to unplug the aux battery when the engine is not running. (You could leave it connected to charge the starter battery if your portable solar has enough output.)

-- Assumes proper mounting in each vehicle.

-- Charge rate will vary according to cable size, alternator output, state of charge of the aux battery, etc.

Does this help?

 

[PIC4GOD]

The only version of what your asking for that I've seen is made by Arkpak. I have an Arkpak but since you already have battery and case they make an external multi-stage charger that works off of 12 volts.


http://www.arkportablepower.com/pages/about-the-arkpak