Setting your Trace Auto Gen Start Parameters

[davidbrady]

(02-22-2019 12:05)cubeman Wrote:  One question I do have remains . Is it ok that 1 inverter goes to float, while the other has remained at bulk ? Is this a setting issue ? Again thank you for the class

It's more of a nuisance. The Trace recommended way to use two inverters is to either series connect them or parallel connect them using the front panel SWI port. This way one inverter becomes a Master and the other a Slave and charging algorithm transitions are made synchronously. Well, the parallel mechanism never worked very well and it works even less well if the inverters are running different software, and the serial mechanism requires running the inverters as a 240VAC single phase centertapped source which then requires a big hefty transformer for balancing across the two 180 deg 'phases' which doesn't work very well in a coach that has few, or in my case any 240VAC loads. I'll be forever trying to balance the system.

So, the third alternative is what we have - two inverters working two separate legs but drawing from and charging the same battery bank. It's a nuisance because there's no Master inverter; i.e., they're peers. As such they have a limited view of the world. The inverter in Bulk wants to hold the battery voltage at 28.6 while the inverter in Float wants to bring the voltage down to 26.6. Luckily it can only go on for whatever time period is remaining in the Bulk inverter's Absorption timer, which in most cases will be short, but during that time period one inverter is charging and pushing current into the battery bank while the other is inverting pulling power out of the battery bank. It's a less than optimal situation. Remember the Float inverter can only bring the battery voltage down if there are loads to power. Many times there aren't any or are very few so it doesn't succeed in affecting the battery voltage. Also recall that each inverter will spend it's specified Absorption timer duration in Absorption. So the only way one inverter can end early is if it started early. This again gets back to the two inverters acting independently. The one that ended first saw an acceptable Bulk voltage level before the other. No big deal really. It just goes to show how each inverter is using it's own measurements to gauge battery voltage, current, and time. Is it bad for the batteries. I don't think so as long as we are conservative with our Absorption timer settings; i.e., err on the conservative side by adding in more time.

Like I said earlier, I think we tend to under charge more than over charge by not spending enough time in Absorption. When I'm driving and the 50DN is trying to keep my batteries at 28.8 and the inverters are in Float and they're trying to bring it down to 26.6 and the generator is running and I have heavy loads like 4 Cruisairs running, before I pull out I increase my Absorption time to like 8 hours. This keeps the inverters from fighting the 50DN and it keeps the genny powering all my loads instead of the inverters picking up some of it.

BTW, another way to minimize the Bulk/Float conundrum, at least when running the genny, is to fine tune your Absorption timers. Let's call the inverter that controls your generator Inverter_2 and the other Inverter_1. Reach into your "Battery Charging" menu for each inverter and set Inverter_2's Absorption timer to say 3 hours. Now go into Inverter_1's "Battery Charging" menu and set it's timer to 3 hours 30 minutes. This way Inverter_2 will expire it's timer first and it will then shutdown the generator. Shutting down the generator will push Inverter_1 out of Absorption. This works well for the generator but not so well on shore power. On shore power I simply reach in and work my magic with the timers to extinguish the Bulk charging LED.

Not the perfect answer. Maybe someday, in my infinite time, I'll find some way via software to make one inverter the Master and the other the Slave and this problem will be solved. Till then, happy motoring!

I think you're now seeing the power of these inverters and why they were wired in as the brains of your entire electrical system. They far eclipse anything that Wanderlodge ever used, and even to this day there's really nothing on the market that matches their configurability and their grunt or ability to start and power huge current sinking loads, ACs motors, etc.