Latching relays for protecting LiFePO4 batteries

[senormechanico]

Originally Posted by gpeacock

So I've worked out the circuit in theory. All I need to find is a time delay off relay now. Anyone know of a simple one that isn't 60 bucks? Less than a 1 second delay is all I'll need.
Once I get one and test it, I'll post the circuit so others dont have to go through the pain I just went through.
Thanks
Gary

How about a big electrolytic capacitor across the winding like 10,000uf ?

[s/v Thea]

Originally Posted by gpeacock

So I've worked out the circuit in theory. All I need to find is a time delay off relay now. Anyone know of a simple one that isn't 60 bucks? Less than a 1 second delay is all I'll need.

Once I get one and test it, I'll post the circuit so others dont have to go through the pain I just went through.

Thanks

Gary

Gary,

Here's one

https://www.amazon.com/GEREE-Module-...lay%2B12v&th=1

Doug

[exMaggieDrum]

Originally Posted by gpeacock

So lots of info on connecting a BS 7713 relay to the BMS and the 7700 was mentioned here a few times but nobody has posted a circuit that uses it.
I have a Bluesea 7700 solinoid and a Housepower BMS which has a +,- to power a relay/solinoid.
Using what I have on hand (automotive relays, the 7700, and various resistors and a few 470uf capacitors) I need to set this up so when the +,- circuit on the housepower BMS is pulled to ground, the 7700 gets a momentary + signal and disconnects the house bank.
Anyone able to help? I've tried a few of the options here:
https://www.the12volt.com/relays/relaydiagrams.asp
I know the answer is somewhere on that page but dont really know enough about circuits to pick the correct combination.
Thanks
Gary

I saved these as PDFs so may be they will be larger and easier to read. I had to register on the RV forum. Thanks for posting.

[gpeacock]

Originally Posted by s/v Thea

Gary,

Here's one

https://www.amazon.com/GEREE-Module-...lay%2B12v&th=1

Doug

Thanks Doug. I saw that one but wasn't sure if would work in a "marine" environment. Are you using one?
Gary

[s/v Thea]

Originally Posted by gpeacock

Thanks Doug. I saw that one but wasn't sure if would work in a "marine" environment. Are you using one?

Gary

Gary,

Haven't used this particular relay. I've used a fair number of 'non marine' devices in dry areas of the boat with very few failures.

Doug

[jram]

Great thread. And a clear winner on relay choices from the simplicity of implementation perspective. I chose the wrong one - the 7700 for hvc and lvc. Never mind. There wasn’t a battery protection system available to me at reasonable cost so it wasn’t a problem. The major difference is that the 7700 has 2 wires and needs a 7A pulse to switch rather than being held on or off.

I’ve been happily living with my 540Ah bank for over a month. Manually monitoring and living at a state of charge that means that it’s impossible for my solar to overcharge in a day. (The freezer and fridge make it even more impossible). In the mean time, I canned the battery protection system based on the celllog 8s since it showed inconsistencies and rolled my own. I’ll let you know how the testing goes but the breadboard version switches nicely.