80 Amp Low Voltage Cutout Kit for $18 - no idle current

Submitted: Thursday, Jan 12, 2006 at 12:26
ThreadID: 29606 Views:9066 Replies:6 FollowUps:7
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If you like building your own, Oatley have just come up with a kit for a Dual Battery Isolator, but it actually makes an excellent Low battery Cutout to put between your Auxiliary Battery and all loads.

What is unique about this as a Low Voltage Cutout is that it _Affordable_Storage_Drawers.aspx miniscule current from the Auxiliary Battery when it is on - most others use 1/10th amp or more, continuously. It uses an 80 Amp Latching Relay which _Affordable_Storage_Drawers.aspx NO current, except when it is switching On or Off.

The kit is only $18 - less than the cost of an 80 amp Solenoid !

http://www.oatleyelectronics.com/kits/k227.html

Mike
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Reply By: Member - Jeff M (WA) - Thursday, Jan 12, 2006 at 14:23

Thursday, Jan 12, 2006 at 14:23
What a little ripper, looks like an absolute pearler. Might change mine over for that price! The arrid _Affordable_Storage_Drawers.aspx 500ma when engaged.... Anyone want to buy an arrid smart relay?? ;-)
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Follow Up By: BenSpoon - Thursday, Jan 12, 2006 at 14:49

Thursday, Jan 12, 2006 at 14:49
for $19?
I'll even throw in a roll of duct tape to use as a makeshift case for your new isolator- thats gotta save you $200... give or take a few hundred.
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Follow Up By: Mike DiD - Thursday, Jan 12, 2006 at 18:27

Thursday, Jan 12, 2006 at 18:27
Because there is no heat output from a continuously energised coil, you can use any type of housing (even VERY thick duct tape)

Mike
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Reply By: tonysmc - Thursday, Jan 12, 2006 at 15:27

Thursday, Jan 12, 2006 at 15:27
Read carefully
"What is unique about this as a Low Voltage Cutout is that it _Affordable_Storage_Drawers.aspx miniscule current from the Auxiliary Battery when it is on - most others use 1/10th amp or more,"
and from the web page
"Without the LED connected the stand-by current of this unit is around 50uA. Adding the indicator LED increases the average stand-by current to 500uA."

Is 500uA = 500mA or 5/10th of an amp? that would be 5 times more power than most others.
AnswerID: 148056

Follow Up By: Mike DiD - Thursday, Jan 12, 2006 at 15:39

Thursday, Jan 12, 2006 at 15:39
500u=microamp is one-thousandth of 500m=milliamp

500uAmp=1/2000th Amp so it uses one-twohundredth of those that use 1/10th Amp.

Mike
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Follow Up By: tonysmc - Thursday, Jan 12, 2006 at 15:59

Thursday, Jan 12, 2006 at 15:59
Thanks Mike, That is miniscule, I might get one myself !!

Cheers Tony

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Reply By: Ken - Thursday, Jan 12, 2006 at 15:40

Thursday, Jan 12, 2006 at 15:40
Mike, this looks like an excellent device. I'm wondering how it would be connected to use it just as a Low Battery Cutout. Would you would connect the Aux battery as for the battery isolator application and the Aux load to the terminal used for the main battery ??

Regards,
Ken
AnswerID: 148059

Follow Up By: Mike DiD - Thursday, Jan 12, 2006 at 18:13

Thursday, Jan 12, 2006 at 18:13
As Low Battery Cutout connect the "Main" terminal to the Auxilairy Battery and connect the "Aux" terminal to the appliance sockets.

Mike
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Reply By: Mad Dog (Australia) - Thursday, Jan 12, 2006 at 16:03

Thursday, Jan 12, 2006 at 16:03
Can't complain about the price, almost too cheap :)
is this another case of "you get what you pay for" or do "get more than what you pay for"
AnswerID: 148068

Reply By: porl - Thursday, Jan 12, 2006 at 16:36

Thursday, Jan 12, 2006 at 16:36
Hope you all know, having bought stuff from oatleys before and having had to get my mate at work to help me put it together - him having previous job of soldering stuff on combat aicraft for the RAF in the UK - point being the "how to" instructions are for people that don't need to buy diode charts etc to tell what goes where.

How do i say it, download the instructions and if you can't by sight identify everything by name in the packet (cause you don't get a directory) then before you buy line up someone else to put it together for you.
AnswerID: 148080

Reply By: Tim HJ61 (WA) - Thursday, Jan 12, 2006 at 23:47

Thursday, Jan 12, 2006 at 23:47
Mike,

Do you know if the low [cutout] voltage is adjustable? This is useful when you want to actually use some of the capacity in the main battery instead of it being fully charged up and sitting just waiting to turn the key. You can drop it to 12v, therefore using some of it's capacity, and it'll still start the car.

The other thing I'd like to see in these types of units is a time delay device, so when the fridge cuts in and the voltage drops from the start up load, the isolator doesn't cut off the battery- when in fact there is still pleny of juice in the battery to run the fridge. The delay only needs to be say five seconds.

Tim
AnswerID: 148217

Follow Up By: Mike DiD - Friday, Jan 13, 2006 at 07:32

Friday, Jan 13, 2006 at 07:32
Tim

There is a screwdriver-control so you can set the switch-on voltage to what you want - between 13.2 and 15.2 volts. The switch-off voltage is 0.5 lower. You can even set it up for 24 volt systems.

If you are using as LowVoltage Cutout between Aux Battery and appliances, then the switching voltage needs to be even lower and they suggest using different resistors to achieve this. Dropout can be set between 10.0 and 11.7 volts with cut-in voltage 0.6 volt higher than this.

There is a holdon-delay after it first switches on, but there is no holdon-delay after low-voltage is detected. It will only take a dollar's worth of components to add a feature like this.

That's the great thing about building something yourself with full documentation - you can modify it so it works the way YOU want it to work !

When I have some time, I will experiment with these variations.

Mike
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Follow Up By: Tim HJ61 (WA) - Friday, Jan 13, 2006 at 09:16

Friday, Jan 13, 2006 at 09:16
Thanks Mike,

Sounds like a good option. I built a Dick Smith low voltage cutout kit (K3124) to control the output from my aux battery (12v) in my 24v HJ61 and that works well.

I have a Redarc isolator to control the charging of the aux battery. Redarc kindly changed the cut in/out voltage for me and it works well, but the drain when the controller is on is too high for my liking and I suspect the Redarc is not quite suited to my requirements - perhaps a bit of an overkill.

My problem is that I draw the 12v from a centre tap in my 24v system, and have a Redarc Charge Equaliser to balance the charge between the two batteries. So every time I stop the motor, the Redarc isolator is draining the lower 12v battery at half an amp until it cuts out at 12.2v. Then on restart the charge eqaliser (rated at 20A) has to balance the charge between the high and low batteries. If the aux battery has been drained too, then essentially the lower 12v battery is charging the aux battery itself and the equaliser has to balance THAT load as well. Often the vehicle is not run for long distances - another completely different issue! But when it is run for a long time, the system works okay. Strangely the aux battery reaches 12.7/8V when the main batteries are less than 12.6v buts that a separate mystery. At least I know my wiring is up to scratch and it's a differnt problem to most, who have problems getting enough volts to their remote battery!

The half amp drain of the Redarc is not helpful in these circumstances, and as I said, it may not be the right piece of equipment in these circumstances. I get around the drain problem by hitting the starter after I've turned the vehicle off and am going to park it up for overnight or more. The Redarc Isolator then drops out because of the sharp high drain of the starter - thereby maintaining full charge in both high and low batteries for the next week or whatever until I use the vehicle again. I could probably get away with another Dick Smith kit in place of the Redarc, but the Oatley kit would also be good and has a higher power relay already supplied. It's low current draw is very attractive.

The instructions/description are over my head, so I'd need Dick Smith/Jaycar type instructions regarding adding the timer delay.

Tim
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FollowupID: 401484

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