When dealing High load applications, it is important to look at the load limits from multiple perspectives: the battery, the DC/DC Control Electronics (PCB) and if applicable the Inverter.

Each Circadian battery can deliver 8A (120W) continuous and can go to a max of 12A (175W) for 60 seconds.  After that they will shut down. The battery needs to be toggled to reset. (Toggle is removing from C-Mount and replacing).

ProDurance blocks can achieve higher loads. Each ProDurance battery Module can deliver 12A (168W) as a max continuous and 14A (196W) as a max peak for 60 seconds. There is no toggle function.

Each DC/DC control PCB has a max continuous load of 150W. The max peak is 175W. After this the LCD will show Overload and there will be a 10 second countdown before shutting down.

The tables below show the max continuous (green) and max peak (yellow) ratings in Amp and Watts and a more cautious max in Grey.  Max continuous loads should ideally not be on the edge. Running batteries on the edge lowers life expectancy and can confront the user with issues as batteries age or ambient conditions (temperature) change. The Max peak can only be handled for short bursts – usually start up currents – and these are heavily impacted by age and ambient conditions. The grey rating is a better measurement.

The final table shows the electronics side.

If a 2nd or Piggyback DC/DC PCB is added, the theoretical max continuous load goes up to 300W. Users planning such high load applications should talk to DCPower4C service first. We will balance the 2 PCBs in voltage terms and explain workflow considerations.

When Hot Swapping, and thus leaving 1 battery on such a high load, time for the Hot Swap is limited. Furthermore, both batteries need to be relatively equal in terms of capacity, age, and charge status. If the differential is too great, the stronger battery will handle the load and may shut down. Hot swapping needs to be earlier, change as soon as the battery capacity is in the last 20%. (Yellow LCD)

When using an Inverter, remember that it too will use part of the available load, so the effective available load for the application is less. As loads increase, Inverters often need to add fans for cooling. Ideally an Inverter will not run continuously at over half the rated output. A 200W inverter, that can handle 300W peaks, should ideally not exceed 100W continuously.

If customers are considering powering high load applications or are having power down issues, there are usually ways to resolve this; by increasing the load capability, using a different Power supply or a DC cable. We strongly advise to test first. DCPower4C support is available for advice.


A further load related issue applies to AIOs and Laptops. Many of these monitors have inbuilt (Hot Swap) batteries. These batteries run the application at a significantly slower clock rate (performance), than if one plugs the AC-DC power supply in. The Circadian system plugs into the same DC input and is seen as a Power Supply, so the full performance of the AIO/Laptop is available. So, a new 80Wh “monitor” battery will seem to last longer than the Circadian 80Wh battery, simply because the performance and load permitted is at a much higher level with the Circadian.


Finally, if you plan to charge on cart by plugging in the GSM 220W Power supply, be aware that charging 2 batteries requires c 100W, leaving c.120W for the application. If the load is higher, then the power supply will stop charging and divert power to the application. This is an overload protection, Hiccup mode. This is not a concern but will theoretically shorten the Power supply life. Users need to be instructed to charge when not live with the application, or better Hot swapping with external chargers could be considered. The GSM 220 is the highest rated off the shelf power supply with medical approval. DCPower4C can provide a higher rated approved Power supply if required.