Is there any way to charge an external deep-cycle 12v battery (not the starter battery) using one of the vehicle's 12v accessory ports and the alternator? I know an Arkpak does this, but I was hoping for a cheaper solution. The Arkpak has an inverter, etc., that I don't need -- I just need a basic charger. However, all the chargers I've found (e.g. https://www.amazon.com/gp/product/B00HWL4N08/ref=oh_aui_search_detailpage?ie=UTF8&psc=1) seem to be designed to plug into an accessory port to charge the main starter battery using 110v shore power, not to charge a separate battery via an accessory port while the car is running.
charging external 12v battery with accessory port
- Thread starter jk6661
- Start date
Really? People seem to use Arkpaks to charge batteries via accessory ports without a problem. Or maybe there are problems I haven't heard about (entirely possible)? Arkpaks reportedly charge at 7 A/hour.
Very very slow.
And the connector design is inherently dangerous.
Blue Sea has a nice socket design that twist-locks with the matching plug, but will also accept standard ciggie plugs for smaller (<10A) loads.
Also the BMW/ Hella/ Merit/ Powerlet "Euro-style DIN" (ISO 4165) style is very robust.
Anderson plugs are essential for high amps. If you standardize on one of the last two types, there are adapters for devices with ciggie plugs.
Make sure you have direct access to batt posts for fast charging.
Good chargers are expensive.
How big your bank? What chemistry batts?
And the connector design is inherently dangerous.
Blue Sea has a nice socket design that twist-locks with the matching plug, but will also accept standard ciggie plugs for smaller (<10A) loads.
Also the BMW/ Hella/ Merit/ Powerlet "Euro-style DIN" (ISO 4165) style is very robust.
Anderson plugs are essential for high amps. If you standardize on one of the last two types, there are adapters for devices with ciggie plugs.
Make sure you have direct access to batt posts for fast charging.
Good chargers are expensive.
How big your bank? What chemistry batts?
I have a 100 ah deep-cycle lead-acid battery that will run a Dometic 65. I could just use the battery and recharge it quickly with shore power every 4 days or so, but I'd rather charge it slowly (or even have a net zero charge with the load from the fridge) while I'm driving in case shore power is hard to come by wherever I happen to be when the battery gets below about 50 percent.
You need a bigger bank for sure, especially in hot weather. You will murder your bank if you don't get it back to 100% as often and as quickly as possible. Ideally driving in the early AM and then a full solar day.
You want to get as high a current rate into the bank as possible while driving. If AGM, higher amps helps longevity as well.
You also need an accurate SoC measurement, not just relying on voltage.
You want to get as high a current rate into the bank as possible while driving. If AGM, higher amps helps longevity as well.
You also need an accurate SoC measurement, not just relying on voltage.
That fridge will use 20-40AH per day.
So you only get one day per 100AH storage, assuming other loads are minimal, in cool weather maybe 300AH will get four days.
Driving how many hours per day average?
If AGM you need a shore charger up around 100A if you get a 300-400AH bank, 160A better for longevity.
The ArkPak charger is useless for that case.
So you only get one day per 100AH storage, assuming other loads are minimal, in cool weather maybe 300AH will get four days.
Driving how many hours per day average?
If AGM you need a shore charger up around 100A if you get a 300-400AH bank, 160A better for longevity.
The ArkPak charger is useless for that case.
Martinjmpr
Wiffleball Batter
FWIW I asked pretty much the same question here a couple of months ago. Lots of good discussion there as well:
.
http://forum.expeditionportal.com/t...v-power-socket-quot-Poor-Man-s-Goal-Zero-quot
.
http://forum.expeditionportal.com/t...v-power-socket-quot-Poor-Man-s-Goal-Zero-quot
I've read from people who own this fridge (on this forum and on Amazon (https://www.amazon.com/gp/product/B00HWL4N08/ref=oh_aui_search_detailpage?ie=UTF8&psc=1) that it uses about .5 amps/hour once cooled down to keep things cool -- maybe .7 or .8 on a hot day. A Dometic rep told me the same thing.
In some conditions maybe, sounds low to me. Yes precooling on mains def helps at the outset.
Other factors:
Temp difference ambient vs setting
Frequency opening
How full
Ventilation of condensor/electronics area
Improving that last and adding insulation help
Plan for worst case not best
Or start out cheap then add as needed, solar anytime, but bank should be same age batts, or at least very close.
Personally for my situation 300w solar and 200+AH bank would be my minimum for longterm free camping with even the most efficient fridge.
Other factors:
Temp difference ambient vs setting
Frequency opening
How full
Ventilation of condensor/electronics area
Improving that last and adding insulation help
Plan for worst case not best
Or start out cheap then add as needed, solar anytime, but bank should be same age batts, or at least very close.
Personally for my situation 300w solar and 200+AH bank would be my minimum for longterm free camping with even the most efficient fridge.
Ovrlnd Rd
Adventurer
Not sure that it will help in your situation but I have a built in invertor in the bed of my Titan. I'm not running a fridge (yet) but what I am doing is running a NOCO Genius 7200 charger off the invertor and charging the battery while driving. Since I'm not pulling as many amps out of the house battery I can easily get back to 100% in under an hour. So far the only draw I have is a tent fan, some LEDs for camp, and various electronics. I already had the charger but with everything else (including the battery) I've got about $100 in the setup. The pics are before I mounted the Blue Sea fuse block. Everything sits at the front of the bed now.
