I redid the test originally posted here. The data was taken with as 25 amp power supply and in taking another look it was highly likely the oscillations was an interaction between the Wolo and the Power supply. You will see at the bottom I redid the experiment this time with a well charged battery (even on a 2 amp setting of a 60 amp charger). I did the test two ways. Once with a standard 30/40 amp relay and the other using a single channel of the SSPB.
Basically what you see if the straight relay allows the Wolo to pull in excess of 50 amps for a short period of time while the motor spins up to speed. With the SSPB there is a current limit at about 14 amps and the motor is soft started. There is slightly less power going into the Wolo for the first 200 msec to reduce the current and as such it will probably be a little less loud for that time. However, there is dramatically reduce current flow and I feel pretty comfortable putting a Wolo on the AUX channel of the SSPB. My only concern is total current with light heaters and misc and then throwing a big 14 amps load into the mix.
I was able to do the SSPB testing using only a 15 amp fuse. I would guess give the smaller current draw, you actually can get away with a smaller main fuse with the SSPB whereas the relay might tend to blow the smaller fuses on motor spin up.
I did some testing to night on the cheapy Wolo horn I got off ebay for $24. It is load and the baffle part can be removed from the motor. This is an honest to garsh air horn and the motor spins right up.
Here is the start up current draw. In steady state in is about 15 amps but it peaks to 40 amps and oscillates before settling down in about 0.1 sec. The scope trace is 10 amps per vertical division and 50 msec per horizontal division.
I was contemplating running that through the SSPB 10 amps per channel but even the 15 amps will cause it to thermal limit. It requires a 30 amp relay with a 20 amp fuse for sure.
You can see here that even though it exceeds 20 amps, it doesn't blow the fuse because it is not over 20 amps for long enough to blow.
Updated tests using a 14 AmpHr battery . Now we see what really happens with the Wolo is started with a typical mechanical relay. On the right the Wolo is soft started using the SSPB 10amp channel. In a quarter of a sec it is down to a 10 amp steady state value.
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