Hi everyone :)
We are looking for fitting batteries. We found an offer with the required size and capacity. Still, the distributor warns that the batteries are not suitable as a battery for motor-driven models. They state that the battery can handle a continuous discharge current of 0.5C (which I learned today correspond to discharge of 250 mA over 1 hour for the suggested 500 mAh battery). The maximum discharge current is stated with 2C for 10 seconds.
I then checked what the battery usage of the components would sum up to. We bought the S070M-RCG-40, powered at 3VDC and rated with 0.5 W power consumption. If I haven't made a mistake, this results in ~167 mA per valve. For a fully equipped FlowIO device (7 valves) this would results in 7 * 0,167 A = ~1,17 A. This seems quite a lot to me and definitely exceeds the 0.5C of the battery. Therefore, my question is if I miscalculated something on the way or if my assumption is correct and the very battery isn't suitable for the FlowIO?
Thank you so much for this very helpful elaboration on this topic!
Hi Sören. Good question. The current consumption is significantly lower and here is why.
-> There is a power-saving feature in FlowIO that reduces the current provided to each valve to about 50% after the initial ~100ms surge.
-> There isn't any circumstance where all 7 valves are open at the same time. Typically only a small subset of valves is actuated, and a maximum of 6.
-> Even when the maximum number of valves is used, it's typically for an event in a sequence of many events, thereby requiring higher current bursts for only a short time rather than continuously. Most LiPo batteries have a burst discharge rating that is about 2x the continuous discharge rating. Thus, if your battery is 0.5C and 500mAh, its burst current rating would be about 500mA.
We are now using 600mAh batteries with a rating of 2C, thus the continuous current you can draw from it is 1.2A. But those are custom-ordered.
The 500mAh battery at 0.5C would be ok for applications that use just a few valves at a time. But if the application needs would be more demanding then the better battery should be used.