controller question

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treefiddy

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Hi guys and gals, I'm dave. still a wet behind the ears nooby.
I'm converting a horse hauler to boondock in and am mostly still working on layout.
 My ? is: do they make a controller that auto shuts down when the battery reaches the level that I need to be aware of, or possible an alarm to get my attention? 
  or, is that something that i absolutely have to constantly check on it so that i don't draw my batts down to the killer level?
  Please excuse me if this is a dumb question, i'll no doubt have more of this sort!
  I've done a lot of reading here and do usually search if i don't find it mentioned in the first 2 or 3 pages.

  Great site and helpful folks here, and a shout out to BOB for making it all available!!!
 dave
 

jimindenver

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Some controllers have load terminals that can be programmed to shut off if you get down to a certain voltage. You can not put a big load on them. They do also make relays that will cut the power if you drop to a certain voltage.
 

treefiddy

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jimindenver said:
Some controllers have load terminals that can be programmed to shut off if you get down to a certain voltage. You can not put a big load on them. They do also make relays that will cut the power if you drop to a certain voltage.

thanks for the answer jim, i'll file that under 'can do'.
 

treefiddy

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ratfink56 said:
Do you mean an inverter going from 12v to 110v? If so I think the answer is yes. Fairly certain I read it in the electrical section.

 Yes rat, that's the place i guess, but say I walked off and left a draw on 12v? like a fan, if i wasn't back in time to handle it?
 i do have pets who'll need some cool, and since the reason i'd not be there sometimes is that i'll be out on my mocycle.
 

John61CT

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You need to get intimate with your usage patterns. Get an AH counting meter to measure your draws and a volt gauge for now, ideally a full-blown clamp ammeter and DMM later on.

Say you have 215AH when full, that will give you about 100AH between recharges to work with.

Going below 100AH will reduce the bank's lifetime.
 

John61CT

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If you rely on an LVD (low-voltage disconnect) then your fan just stops, maybe the dog dies?

Those built into SCs are low-current, don't overload. Also not adjustable, likely let the batt go down too low.
 

Canine

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If you buy quality equipment, that makes life easier. You can adjust them to give you the longest battery life and the best charge so you get the most out of your batteries every day. You-get-what-you-pay-for applies fairly strongly in the area of solar components.
 

treefiddy

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John61CT said:
You need to get intimate with your usage patterns. Get an AH counting meter to measure your draws and a volt gauge for now, ideally a full-blown clamp ammeter and DMM later on.

Say you have 215AH when full, that will give you about 100AH between recharges to work with.

Going below 100AH will reduce the bank's lifetime.

Thanks John, but as I said before, i'm still planing my layout...got to have a draw before i need to measure.. d
 

treefiddy

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Canine said:
If you buy quality equipment, that makes life easier. You can adjust them to give you the longest battery life and the best charge so you get the most out of your batteries every day. You-get-what-you-pay-for applies fairly strongly in the area of solar components.

  Thanks k9, i do plan to buy quality stuff, my breakout date is somewhere around the middle of may, lot's to do!!
 

treefiddy

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treefiddy said:
Thanks John, but as I said before, i'm still planing my layout...got to have a draw before i need to measure.. d

that sounded blunt, if so i'm sorry. i really was just curious. by the time i break loose, i'll prolly be able to do it from my phone :D aint tech grand?
 

frater secessus

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John61CT said:
Those built into SCs are low-current, don't overload. Also not adjustable, likely let the batt go down too low.


All the configurable controllers I've been in allowed setting LVD on the LOAD output. Even the $8 one.
 

Weight

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Sorry I did not read all the posts on this thread. I have a Victron battery monitor that has a relay that can be programed to many parameters. I use mine to start a fan when the batteries are charging. (I use a voltage trip setting) This could trip an alarm, could shut down a disconnect, all kinds of stuff.
However. With my solar and sizable battery bank, I don't worry much about low batteries from a small fan.
 

John61CT

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treefiddy said:
that sounded blunt, if so i'm sorry.
no worries

As you start to buy, get the measuring gear early days, as you get your consumer loads you can flesh out a fairly accurate AH per day budget guesstimate.

Then use that to spec your bank and charge sources.
 

treefiddy

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Weight said:
Sorry I did not read all the posts on this thread. I have a Victron battery monitor that has a relay that can be programed to many parameters. I use mine to start a fan when the batteries are charging. (I use a voltage trip setting) This could trip an alarm, could shut down a disconnect, all kinds of stuff.
However. With my solar and sizable battery bank, I don't worry much about low batteries from a small fan.

-thanks weight!!!   that's what i'll do. i knew there HAD to be a way
 

treefiddy

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John61CT said:
no worries

As you start to buy, get the measuring gear early days, as you get your consumer loads you can flesh out a fairly accurate AH per day budget guesstimate.

Then use that to spec your bank and charge sources.


 thanks john, i think i'll go for overkill, got some more studying to do for sure!
 

DLTooley

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The better quality chargers have this function built in, you'll also get more power from them so it will be less likely to happen.

You do want to watch the levels anyway - best to design your system, and your use, to match your charging/battery. Use the cut-off as a back up for unusual situations. Battery management systems do also watch your input and output, probably worth the expense on a bigger bank.

There are cheaper ways of precisely watching input and output, I've not had enough experience to feel comfortable recommending a standard for a beginner.
 

jimindenver

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DLTooley said:
The better quality chargers have this function built in

Which feature? load terminals?

I have always felt that the higher end controllers skipped the "look at the shiny features" like load terminals that hid the fact that you could set the load terminals but not custom set the controller itself. A properly sized system with a properly set controller will keep you from getting to the point that you need a LVD. Pure and simple.

Now how do you have a properly sized system without knowing what you need? That is a rough one because things change over time. You think you have it all figured out and then you add a booster or fridge and wipe out all that you have imagined. The reality is that you have to set up as much as you can, spend the money on more solar rather than waste it on fancy toys and adjust from there. Believe me, if a amp counter says you didn't put enough amps back in, you didn't need a amp counter. You needed to spend the money on more solar.
 

Canine

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jimindenver, Regarding an LVD, it varies what it can and can't do. Depending on which controller you get, you can get a nearly infinite amount of adjustability. With my system for example I can set the LVD to turn on or off at most any voltage. I can have it turn on at 12 volts and shut off at 12.2 volts, which is the opposite of what an LVD is originally set up for. Should I set up my controller like that, the LVD would be a misnomer.

An LVD can also be useful not just for shutting a battery bank down due to low voltage, it can power small appliances. In fact I have plans to hook up a very small DC heater so that during sunny days when I have extra power, it will help heat the trailer. 50 watts of heat is almost a pittance, but over time it will pay for itself in propane saved.

If I wanted, I could set it up to power and turn on a security camera during the day when I am gone at work then have it automatically shut off at night when I am at home. There are other uses for an LVD; these are just a couple of examples.

The higher end controllers can do some of this- features vary from manufacturer to manufacturer. BUT this is technical stuff that doesn't matter at first. DO NOT get hung up on all of this technobabble. What you need is what Jimindenver said: Make sure you have enough solar to charge your batteries fully as often as possible; this may be the most important thing you can do with your system.
 

treefiddy

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Thanks guys, keep 'em coming!
Canine...I really like the dc heater idea, you could get some thermal gain out of that in several ways..
 

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