CellLog 8 switching ss relay

[bagmaker]

Hi Scott
I used one of these for LV cut-off, drives directly off the BVM-700 and uses nothing whilst waiting for alarm.
May be manually turned as well for a battery isolate shut-off, 275 amp rated. Was cheaper than the price on the link so look about

https://www.waveinn.com/nautical-fishin ... h/584168/p

[exscott]

Thanks bagmaker I hadn't thought of them but they would do the job for sure.

[Barboots]

Hi Scott
I used one of these for LV cut-off, drives directly off the BVM-700 and uses nothing whilst waiting for alarm.
May be manually turned as well for a battery isolate shut-off, 275 amp rated. Was cheaper than the price on the link so look about

https://www.waveinn.com/nautical-fishin ... h/584168/p

Power Draw:
Switch off: 12mA.
Switch on: 15 mA
Switch operating: 120 mA for 3 seconds @ 12 v nominal.

Niiiiiice. [emoji106]

[jon_d]

The spec of the unit linked to is 500amps continuous

Just like electrical motors and rotor lock current, you need to be concerned about maximum current that the batteries will source if the big fat cable shorts out.

[Busman]

Yep, one of my controls is to totally disconnect the battery, like you say "till I work out what went wrong later"
I have used a Gigavac bi state relay, or latching relay. It is driven by a voltage measuring device, can set high or low, if exceeded up or down the GV is powered to change state. It only draws power during the change. No power is drawn otherwise. A button is fitted to change back to the "connected" state.
It can also be switched by the junsi, via a mini relay.
This is my last line of defence, other things happens before this.
The GV is rated at 350 amps, more than enough. You should have a fuse right at the battery as I have to protect the "fat" cable.

[Barboots]

I have used a Gigavac bi state relay, or latching relay. ///snip/// It only draws power during the change. No power is drawn otherwise.

Which model Gigavac is that mate? Mine is quite hungry...

Cheers,
Steve

[T1 Terry]

We tried 175 amp 12v coil Gigavacs for a while, every one of them welded themselves closed and I'm guessing it was the surge load charging up the inverter capacitors. we now use the bigger 350 amp continuous load units and haven't had an issue with them.
The motorised switch looks good but more expensive than the Gigavac and actually requires power to turn it off, this doesn't fit in with my fail to safe design so I decided against going down that path.
As far as using the Junsi to trip a relay, the contacts can't handle very much at all because it's only a tiny transistor that does the switching. the next issue is the alarm isn't just on or off, it pulses because as soon as the load is remove the voltage jumps up, the alarm stops and the relay sees another signal and then the alarm is triggered by the sudden voltage drop........ and so on. The Victron 700BMV is a far better driver for a ratcheting relay, the Junsi works better triggering a mini SSR that triggers a timer circuit cutting the charge for the HVC (High Voltage Cell) signal and if needed a second unit to do the low cell voltage cut or a voltage sensing circuit that determines if the alarm is a high or low cell voltage event so the correct relay is tripped for the required timer period. False Junsi trips do happen so not really suited to triggering a ratching relay.
The total battery isolation is the very last resort where every other control circuit has failed to sort the problem. Not something you really want to ever trigger because the fridge full of food is lost and/or the van is in total darkness when you arrive home from a big days site seeing. SWMBO is never in the best of modes at around this time because her work is about to start again making dinner and is very unlikely to be a happy camper to find there is no power and the fridge full of food is now suspect. The level of understanding is severely diminished when you attempt to explain that you can't just turn it back on until you find out why it tripped....... not the way to start out a pleasant evening The battery isolation system we use has a bypass setting so at least you still have the last 5 % of battery capacity available to turn the lights back on and survey the potential damage and cause in some sort of peace

T1 Terry

[exscott]

Hmm so maybe the cellog as the final failsafe triggering the relay barboots posted won't work as it needs 3 seconds to switch.

[BruceS]

Need to clarify the 3 seconds? Which one is that? I think it's referring to the Blueseas one?
The Gigavac I'm using is the normally open one. (no power breaks connection)
Model GX14BAB.
http://www.gigavac.com/catalog/power-products/gx-series
You really don't need the B one.... GX14BA (the last B refers to the extra 2 wires ... could trigger an alarm?)
I seriously question the 900V that EVPower reckon theirs is!!! Gigavac specs say only 350V DC.
http://ev-power.com.au/webstore/dc-cont ... x14ba.html

[Barboots]

The 3 seconds for the Blue Sea motorised could be addressed in the buffering circuit between it and the Junsi.

However the MXL14 range looks nice. [emoji106]

My Gigavac is the MX14B, and I'd rather not have the ongoing coil consumption.