120AMP 24V Continuous Duty Relay, 4 Pin High Current Relay, Split Charge Relay Switch, Spst High Power On/Off Heavy Duty Starter Relay

It was a little hard to find a relay that takes the same voltage level as the main contactor. This way, I don't need a different power source or BEC or something for a different voltage. Overall seems like really good quality although I'm using a 200A relay for probably 40A in reality

This is for an off-grid cabin where the solar array and battery bank are at 24V but we step down the voltage to 12V using a buck converter and that is what the cabin runs on. We do not run an inverter. Running the core at 24V decreases losses and wire gauge requirements at that core, and also maintains a constant 12.3 volts throughout the cabin regardless of battery state. This approach works well for a small cabin and we don't have all of the inverter loss. (We can run a 680 sq ft cabin on just 400 watts of solar). I know this is not typical, but it has worked well for us for almost a decade now and has some advantages; when almost all of your loads are eventually DC (lights, devices, stereo, etc) it always seemed silly to invert to AC and convert it all back to DC. (we not have large appliances, because.....cabin, not vacation home. No microwave, instead just stove) I wanted a relay in order to have a remote power switch for the whole cabin that is in series with the load terminals on the charge controller, which has a low voltage automatic cutoff for battery protection, but that relay had to be able to handle a nominal 24V at the coil and is actually switching a 12V load. I also had to handle 30 amps @ 12V and wanted a lot of headroom. Yes, our entire cabin draws less than 360 watts peak, and we have a generator for the rare times when we need it for tools or other high loads or for emergency battery charging. We go months without using the generator. A prior cheap relay rated to 30amps got very hot and proved not to be durable. This is a sturdy relay with heavy terminals and never is warm to the touch. Thank you Amazon, for having all of the oddball parts that I would not know where to get otherwise.

To go along with the other off grid review here: Running off grid on 400W solar and batteries, but with AC cooking and AC chest freezer. Inverter even when on standby (turned off by remote) draws 3W or 9W when on and doing nothing. Would rather have chest freezer run when panels are generating for more efficiency/less battery capacity and wear. Also, 1 long chest freezer run is better for compressor than on and off through the day. Used a 24V timer with relay and this relay. The smaller timer relay drives this big relay. Inverter switch is always on, but this relay controls power. Soft start on inverter means no big inrush on startup and several inverter manufacturers have told me that turning power on and off this way is the same as turning the power switch on and off. So, cheap mass market chest freezer needs about 7h of continuous running per day depending on air temperature, so timer has relay closed 9am-6pm (roughly when the sun shines) which is also when I do any other AC thing like cooking, kettle, vacuuming, washing machine, stationary power tools, portable power tool batteries (if I haven't built an adapter to charge directly off DC), and other AC things that will never be affordably made in DC versions. Run computer, stereo, lights, USB device recharge, fans, pumps, portable refrigerator as well as solar dump load for water heating and other curtailable loads (when you have solar power, but batteries are already full) from DC. Can't speak to long term reliability, but works well. Small complaint is that for currents of this size, battery manufacturers use at least 5/16" terminals. This has 1/4" terminals so fits a bit loosely until you tighten them down. Probably is just fine, but having 5/16" cables and 5/16" terminals elsewhere with wiring rated to 150A and then hitting 1/4" feels wrong. Couldn't find another relay with 5/16" terminals at all never mind at this low price. Shout out to Amazon where I could buy these sorts of things when product descriptions weren't clear, testing was needed or I just didn't understand at the time what I needed. The return policy was very helpful in building up a system.

Using this in a circuit that has 115 amps at 28VDC to switch and doing the job with no issues.

Used this relay with a low voltage disconnect to keep my solar batteries from over discharging. Running 30a through the relay continuously does cause it to get a bit warm but never stopped working. Good product for the price.