voltage sensitive Relay

[artie]

If I understand correctly a split charge system works by having a relay open until the main battery reaches a pre set voltage and then the relay closes to permit a second battery to be charged.
Should the main battery become depleted the relay opens again until the main battery achieves the pre set voltage, ensuring that "one" always has one properly charged battery.

For the application I have in mind I would like to have a charged battery in reserve which would be activated when the main voltage fell to a pre set level.
I can't find a suitable relay.?

 

[Jake]

You will need more circuitry. Nit sure what your application is but here's a low voltage one (you'd need a change-over relay in place of the SPST in that diagram which just breaks the circuit)

Low Battery Voltage Cutoff Or Disconnect | Circuit Diagram

 

[Sandyn]

depending on the application, something like this may do comparator I can't see the operating voltage range of the circuit. I think it is limited to 12V +/- 10% in which case you would need a boost buck converter, something like the XP JTM2024S12. 9-36V in, 12V out.

 

[Sandyn]

here is an alternative module, which has a better operating range, so you wouldn't need the converter, which I realised is very expensive. ( when I was using them, I didn't have to pay for them) The module is available from a few suppliers. It's a dual channel, there may be a single channel version available. The relay is a single pole double throw, so you would need a double pole double throw, or use the two channels in parallel to get the same configuration. All this depends on what you are trying to do and the currents. The relays are 10A, but I would derate to 8A

 

[Jameshow]

A split charge relay usually works in a vehicle typically a camper van so that the domestic battery dosen't drain the starter battery.

The relay will only connect the two batteries once the voltage is 14.4v which is generally the output of the alternator.

I think your after a different use and circuitry.

Cheers James

 

[artie]

A split charge relay usually works in a vehicle typically a camper van so that the domestic battery dosen't drain the starter battery.

The relay will only connect the two batteries once the voltage is 14.4v which is generally the output of the alternator.

I think your after a different use and circuitry.

Cheers James

Well I did say that.

 

[artie]

here is an alternative module, which has a better operating range, so you wouldn't need the converter, which I realised is very expensive. ( when I was using them, I didn't have to pay for them) The module is available from a few suppliers. It's a dual channel, there may be a single channel version available. The relay is a single pole double throw, so you would need a double pole double throw, or use the two channels in parallel to get the same configuration. All this depends on what you are trying to do and the currents. The relays are 10A, but I would derate to 8A

Thank you again.
It's not going to be as simple as I had hoped.
I imagined something like a split charge relay in reverse