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Old 10-05-2014, 07:55   #1
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inverter transfer switches

cant believe how much they want for a simple transfer switch around here. decided to build my own. using a 40amp dpdt power relay a simple timer circuit i built with a few parts lying around and a weatherpak enclosure i came in at half of what it would cost to buy a premade switch. this setup gives me shorepower priority over the inverter so if i hook up my little yamaha genny to the shore power inlet it automatically kicks over.
my inverter is just an inverter not inverter charger so the 2nd issue i found was that i had to turn off the battery charger switch on the panel when using the inverter so i built a bypass switch using a 30amp spdt power relay to disconnect the hot feed to the charger when shore power wasnt available but turn on the charger when sp or genny was running.the first image is the transfer switch the 2nd is the bypass circuit. does anyone see any problems with this setup. thanks
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Old 11-05-2014, 18:37   #2
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Re: inverter transfer switches

a pass through inverter would have solved both of those issues...

have you fused the coil lines from the shore power plug?

I would probably have left the shore straight to the ac panel to the main. have it feed the charger, HWT, other non inverter loads direct from their breakers. then have the relay control between shore and an inverter only section on the panel that would be used on inverter. so split the ac panel buss.

the invertor should not be able to power the whole boat. the panel should be split into inverter and non inverter loads. it's easy with a passthrough inverter. but could be done with your inverter and relay as above.

if the charger is the only thing not used on the inverter then it's probably ok. but will confuse anyone coming to work on it in the future as it's totally non standard
(most boats have a HWT, range, and other stuff never used off an inverter)

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Old 11-05-2014, 18:55   #3
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Re: inverter transfer switches

+1 on the pass-through inverter.

We have our AC panels split into straight AC and pass-through AC. Only the latter panel can be powered from the inverter. The pass-through inverter is failsafe passthrough. Magnum Energy.

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Old 11-05-2014, 22:47   #4
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Re: inverter transfer switches

yes with my boat no hwt electric range etc so thought it easiest and cheapest not to subpanel this way just breaking the charger feed was simple. my small boat has 4 ac outlets basic setup and yes the boxes are well diagramed if anyone was to work on it other than myself
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