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Looking for specialized selector switch...

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Externet

Well-Known Member
Hi.
Would like to find an industrial selector switch that will hook to four 12V batteries and provide connections

- all in parallel 12 V
- two series/two parallel for 24 V
- all in series for 48 V

No off position needed. ~15 Amperes or more would be great.
There is many rare items out there, perhaps someone knows/suggests one, I do not know where to search for such animal.

Edited - added: This is for two batteries only : https://www.texasindustrialelectric.com/T_114_12_series_parallel_switch.asp
 
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It may be easier to use three DPDT relays to control the switching and use a selector switch to control the relay coils. See below for example.

View attachment 64385
 
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Thanks crutschow, for a well elaborated alternative. You dedicated a good chunk of time for your answer.
 
Make sure you allow enough time for one set of relay contacts to open before you close the next set. Otherwise you may briefly create a short circuit connection.
 
Chandlers sell such an item at least I think, I've never seen a 48v version of what you mention, but I have seen 12,24 and 36.
Must be a fairly big motor if its got a 48v starter.
 
Make sure you allow enough time for one set of relay contacts to open before you close the next set. Otherwise you may briefly create a short circuit connection.
I believe there's no condition where one relay closing before the other opens will cause a short. Do you see one? :confused:
 
I don't know of a state that would cause a dead short across any of the batteries. I do however see a state where bad things could happen. If U1 is set for parallel (12V), and U3 is set for series (24V), then setting U2 for parallel would not be a good thing.

I was mostly advising caution against possible combinations, and pointing out that relays have significant response times a few orders of magnitude slower than the typical instruction time of a uC, or digital logic that might be used to control the relays.
 
I dont want to step on anyones toes here, however a practical approach to prevent the above condition would be use a relay with auxilliary contacts, and wire in an interlock so the coil of one goes through the normally closed contact of another preventing 2 closing together.
This is common in industry, overhead cranes use this method as well as a physical interlock, you cant even manually shove up and down contacts in togther (and cause a short).
 
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Unless the batteries are being switched under load, I see no cause for concern about the order of the relays being switched.
 
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