What voltage is the relay swicthing and where in the circuit is it ?

A quick google brought up versions of HLS-T90 – a single pole power relay, so your 5 contacts would be 3 x contact (common, NO & NC) and 2 coil (you don't mention the coil voltage), but the listings I found had contacts rated 28V DC.

Nigel B.

What voltage is the battery?

30a 240vac 36vdc refers to the current carrying capacity of the contacts. A hls-t90 (15f) 30a 240vac 36vdc relay can safely switch 30 Amps at up to 240Vac or 30A at up to 36Vdc. (There's probably an additional 20% safety factor.)

If the battery is less than 30V, a 30Vdc 30A relay will be fine. If the battery is 36v, a 30V relay might arc until the contacts burn out, more likely it will work OK except that the contacts wear out sooner rather than later. You could risk it.

Arcs strike whenever a switch opens and the contacts are damaged if the arc persists for too long. The gap an arc can bridge is proportional to the voltage. However AC arcs tend to self-extinguish because a 50Hz voltage drops to zero every 20 milliseconds. DC arcs persist until the gap between opening contacts becomes too big for the voltage to bridge. Even though DC switches are often spring loaded to open with a rapid snap action, the voltage has to be kept down when breaking DC.

Dave

Manufacturer page for relay.

I wonder if the "36V" refers to the coil voltage if there are 3 x 12V batteries in series ? The illustrations in the link above show that the current versions of those relays have the coil voltage moulded in the case at about the place where the 36V is printed on yours. They don't list a 36V coil as standards, though, so that may be a special ? Can you measure the voltage on the two thinner wires (on the right on your first picture) when the relay is energised to check ?

I can't say I am suprised that a pin has come loose / pulled out of the relay in that installation – that relay is intended for PCB mounting, not dangling on cables. If the coil voltage can be confimed, then it should be possible to find a more suitable relay with eiither Faston or screw terminals – something like this, maybe.

Nigel B.