I received my 730 a few days ago. I will not use it in a dual battery setup for the vehicle, but this is a quote from the manual: "The ArkPak can be used in a dual battery setup. The best method to do this is to connect the ArkPak to a dual battery wiring loom (not supplied) using either the positive/negative external terminals or the Anderson plug. Using these methods, the smart charge system is bypassed so the ArkPak cannot control the charging voltage. A voltage sensitive relay/solenoid must be used to ensure priority is given to charging the vehicle's main starting battery." So the answer to your question seems to be yes, you would need an isolator on the vehicle.
On another note, I was not sure if a Starkpower LiFePo4 battery would fit since the battery is 330mm long and the internal length of the ArkPak 730 was listed as 330mm. That seemed like a tight fit. The internal length of the 730 is actually substantially longer than that except for near the top of the lid. It appears the Starkpower battery will fit. However, I was still concerned about the height. I have tried contacting Starkpower by email to confirm whether their battery height measurement included the terminals or if it is just the case. I have received NO answer to my emails. I tried calling them several times and have gotten no answer at any of the extensions (sales, tech support, personal assistant, etc). I have left several messages and gotten no return call. With that obvious lack of concern for their customers, I will be going with a different (and substantially cheaper) battery.
Mobian,
I want to CONFIRM that the LiFePO4 battery I purchased from StarkPower does indeed fit into the ArkPak. If you need "confirmation" I can send you a few of the pics I took and sent to "Brett" at ArkPak. Simply ask and I'll post 'em if you'd find that helpful. I've been running experiments with the battery and ArkPak the past several days running a CDF-11 Dometic fridge/freezer and I have to admit, I've been stunned at the performance. I ran the CDF-11 on the lowest temp setting (0f) and it ran for 49 hours straight and still showed 12% remaining charge. To me...that's impressive! It froze SOLID 3 small (10oz or so) plastic containers of water making what I call "ice plugs". It took a room temp bottle of soda 2 hours to almost freeze from when I started the experiment with the temp show 73f on the fridge.
As you've mentioned, the one thing I have NOT been impressed with, is indeed the customer service, or lack thereof with StarkPower. Absolutely awful. I happened to get ahold of "Martin" when I called late one Friday night last week (Sept 25th). Wasn't tremendously helpful however I suspect that's due to the "one-man-show" he must be running over there. After doing some research on my own, I believe I and my mechanic can figure out the rest. The one IMPORTANT thing I learned is to take full advantage of the lithium technology, you really need to either purchase AC to DC converters designed for these batteries and/or wire the battery through the Anderson 50a port for recharging through the vehicles electrical system. What little I got out of "Martin" was I can basically recharge the 125ah model I got in about 2.5+/- hours. That kicks @$$. I've purchased two AC to DC chargers -- 20a and 40a -- from them as well for the purpose of being able to recharge this pak from an AC outlet at campsites, home, the outlet on the side of my ex-wife's house
or wherever I can grab juice on the fly. The 40a will be permanently mounted into my Jeep Wrangler with the 20a serving as the "portable" charger. Although the AC charger that comes with the ArkPak works, it isn't designed to push the kind of amps these batteries can take. Recharging quickly is one of the benefits of this technology. The batteries are supposed to have a BMS (battery management system) that protects from over/under charging and balances the charge between cells. I'll soon find out once the chargers arrive. These would either connect through the Anderson port or via direct connection to the external terminals on the ArkPak.
On another note, let me say again...and again...and again...the level of "support" and information I've gotten from Brett at ArkPak has just been outstanding. I've let go of the hostility I have for StarkPower 'cause I suspect the dude is overloaded. At the end of the day, he's getting the same battery as other vendors it's just he's private labeling his in green versus whatever other color other vendors are using. These are all made in China anyway. Hope this helps and I'll be posting more on my wiring experiences as the project comes together.