Ted:

You may well be right, but I don't think so.

We have worked to completely isolate the Atlas,  to see if it would still fail. This has included shutting off everything on the boat, including the inverters, and even disconnecting the Simon monitoring system. It has failed when isolated, and with no load.

Our working theory is that the problem is a leak to ground somewhere in one of the five Atlas modules. On Friday, I put a current clamp on each of the ground wires looking for any current leaking to ground. I didn’t find any, but my current clamp was a high amperage clamp (1,000 volt Fluke). I needed something with greater precision.

On Wednesday the Atlas technician will be back on the boat. There were several ground wires I couldn’t get to, plus he will have a better current clamp.

The questions you raise on power management are ones I am constantly aware of. Power management is a non-stop part of running this boat. I always have to be aware of where the boat is getting power, and how much I have available. This is going to be even more critical as we move into hotter territories and need more air conditioning.

My inverters are programmable. I can decide how much power to give to the inverters for battery charging. Normally I keep this dialed down to about 60 24 volt amps. I can always ratchet it up when needed.

To control the air conditioning, I decide how many chillers to run (one to four) and how many air handlers to run. If I need more than one chiller I flip to the 25kw generator. As we head farther south, I may need to power on both generators to keep the a/c running with a comfortable margin for error.

Life gets much more complex when we have guests on board. Roberta and I understand how to be careful with electricity, whereas guests turn on things randomly. They leave air conditioning going in their cabins while not there, etc. I’ve done a lot to try to stop them messing me up, and do a briefing on power management – but, they tend not to listen.

Hopefully Wednesday I’ll know more on the Atlas!

-Ken W 

Hi

I was thinking about the shore power problems and have come to the conclusion that it may not be with the Atlas system at all, it may be because the boat does not have a active power management system.

Initially you left the air conditioning on and noted that the inverters in that situation pulled about 300 amps ie about 7kw. Assuming that the shore power is a 50 amp 220 volts supply the available power is about 9kw, allowing for inefficiencies in the Atlas unit and power factor.

This means that there is about 2 kw available for battery changing at most, yet when on the generator the invertors can pull 12kw. Initially the batteries do not need charging but there are some DC loads left on like the bilge pumps. Eventually the batteries will need a charge.

The question is now how to charge the batteries without exceeding the 2kw. One could program the inverters not to charge at all and simple use the 80 amp charger though this is still close to 2kw for comfort.

The problem is compounded when the shore power fails, the inverters switch in and when the batteries gets low the generator needs to put the power back in using the inverters as chargers and as quick as possible to reduce generator running time.

This is where active power management is needed, when in Atlas mode the inverters should be programmed to charge no more than 2kw or what ever the surplus is and in generator mode a higher charge current could be programmed in.

Even when you turned off the air conditioning the need to charge the battery will arise, albeit after a longer period of time, though the surplus for charging is probably about 6kw.

I am only speculating as I haven't seen the boats wiring diagram and are not familiar with the various units involved.

Ted