DC Switch looks Great!

[WisTech]

Have it tied to a 12V battery for testing in house as we speak! This thing is legit. Can't wait to get it deployed after some testing! Thanks guys for getting it delivered as soon as you did, I sure appreciate it!

[lligetfa]

What? No picture of what's on the Power tab?

[sirhc]

Now keep in mind we do not recommend a 12V dc site as the efficiency is low, the total watts budget is less than 150 watts and drops to 100 watts by the time you hit 9V but to the have the ability to run a 24V or 48V battery bank into the ground down to 9V if need be and keep some radios up is really valuable when you are off grid and you have been dealing with over cast for 5 days and your solar cells are unable to charge enough until the weather breaks.

[rockhead]

Chris, if you run a 12V battery down to 9V it will never take a charge again, ever. I assume you know this, but you will do your naive clients a disservice if you encourage excess discharge.

I guess its too late to ask for a settable LVD on the switch, LOL, not to worry they are available as standalone devices.

[sirhc]

Chris, if you run a 12V battery down to 9V it will never take a charge again, ever. I assume you know this, but you will do your naive clients a disservice if you encourage excess discharge.

I guess its too late to ask for a settable LVD on the switch, LOL, not to worry they are available as standalone devices.

The switch allows you to set how low you want to drain your batteries.

HOWEVER if you are using DEEP CYCLE or AGM batteries they are designed to be discharged in this manner without damage.

When I used to work at a marina we sold a LOT of trolling motors and batteries.

When I went fishing I would run my trolling motor sometimes until the batteries would no longer run the trolling motor....DEAD BATTERIES.

But let's remember the idea of being able to run the batteries down this low is for in an emergency such as your off grid site up on a mountain has not been able to charge properly because you have had 5 days of overcast.

We give you the ability to run all the way down to 9V, we are not holding a gun to your head and telling you that you have to, this is a conscious decision people will have to make.

A deep-cycle battery is a lead-acid battery designed to be regularly deeply discharged using most of its capacity. In contrast, starter batteries (e.g. most automotive batteries) are designed to deliver short, high-current bursts for cranking the engine, thus frequently discharging only a small part of their capacity. While a deep-cycle battery can be used as a starting battery, the lower "cranking current" imply that an oversized battery may be required.

A deep-cycle battery is designed to discharge between 45% and 75% of its capacity, depending on the manufacturer and the construction of the battery. Although these batteries can be cycled down to 20% charge, the best lifespan vs cost method is to keep the average cycle at about 45% discharge. There is a direct correlation between the depth of discharge of the battery, and the number of charge and discharge cycles it can perform.https://en.wikipedia.org/wiki/Deep_cycle_battery#cite_note-2

https://en.wikipedia.org/wiki/Deep_cycle_battery


Like I said this is a conscious decision on the user to decide at what point the switch will shut off, IT IS A SOFTWARE SELECTABLE VALUE!

However with that said if I had an OFF GRID site on some mountain top that is hard to get to especially in the winter I would like to know I "can" run the bank into the ground if I need to and we give you that choice!

[lligetfa]

Ja, Chris and I had this conversation over the phone.

However with that said if I had an OFF GRID site on some mountain top that is hard to get to especially in the winter I would like to know I "can" run the bank into the ground if I need to and we give you that choice!

Just remember that dead batteries can easily freeze.

[sirhc]

This is true, the further a liquid cell battery is discharged the lower the freezing point becomes. When a battery is not fully-charged, the sulfuric acid and distilled water inside the battery are not properly-mixed and the distilled water can freeze.

HOWEVER while a battery is discharging or charging it is unlikely that it will freeze as the process generates heat and to some degree circulation inside the batteries.

A dead or even very low battery that is no longer discharging or being charged can freeze at a much warmer temperature but once again this is a choice by the operator what to do but if your batteries are of good quality the manufacturer will provide you with a scale of when the batteries will freeze based on charge level.

Personally I use OPTIMA batteries.

OPTIMA YELLOWTOP® batteries are protected from freezing down to -30°F when fully-charged to about 13.0-13.2 volts
OPTIMA REDTOP® batteries are protected from freezing down to -50°F when fully-charged to about 12.6-12.8 volts.
OPTIMA BLUETOP® batteries are protected from freezing down to -50°F when fully-charged to about 13.0-13.2 volts

Discharging DEEP CYCLE BATTERIES to a reasonable threshold such with as 20% or more charge left does increase the freezing point but it is not a super dramatic increase.

I use mostly OPTIMA BLUETOP AND YELLOWTOP BATTERIES.

[rockhead]

Take a read through http://www.solar-electric.com/deep-cycl ... y-faq.html to get a better grounding in battery technology. Running a 12V battery below 10.5 volts or a 24 Volt series pair of 12's below 21 volts is simple straightup battery murder. The 45% discharge you mention above is not 45% of total voltage (12.7 for a fully charged battery) but 45% of the usable range ie 12.7 - 10.5 or 45% of 2.2 Volts giving you a cutoff of 11.49 Volts.

When you take a (12V) battery below 10.5 Volts the weakest cell will experience cell reversal and will never charge properly again. Double the #'s for 24, quadruple for 48.

Avoiding going up a mountain by discharging a battery below 10.5 is gauranteeing you will be making a trip up with new batteries.

[Dave]

Yes, we agree, and we are not recommending people run battery into the ground (so to speak). Key is, if user really needs to or wants to, our DC based switch can run down to 9 volts.


Big thing with our DC based switch is that we let the user decide at what voltage he wants to shut ports off, and even the switch itself!

[sirhc]

Well as I said the user can chose to have the switch stop discharging the batteries at whatever voltage they chose, they should consult the battery manufacturer to see what voltage is recommended as a lower threshold. Also verify that if their batteries are designed to recover from deep discharges that their charger is sufficient to do so. Some batteries require a 3 stage charger to recover from a deep discharge. Since my towers are on gird I have Minkota 3 stage intelligent 10A per battery (x4 ports) chargers for deep discharge recoveries.

But this still does not take away from the fact that the user may "chose" to keep the tower up in an emergency at any cost if need be.

Also they can use 12, 24, 36, or 48 to power the switch powering 24V or 48V devices.

If you want your tower to shut down at a specific voltage then simply configure it to shut down at that voltage.