along the lines of an inverter charger

[jayw900]

I was sitting here thinking, cause that's what i do, and have tried to do a search however it seems i'm not asking the right question.

Is there something that does the opposite of an inverter-charger? Instead of prioritizing shore power to battery, i'm looking for something that will choose battery over shore until the battery voltage goes below a user chosen set point.

For example, always running on battery(solar) until 12.0-12.1 volts when it switches over to shore power while batteries charge up to float(~13.2) then changes back to battery. All i need is a name or phrase and i can do the rest. The search i've done so far have only brought up "normal" inverter-chargers.

[time2roll]

MrWizard wrote:
That's going to be a long recharge and it isn't going to happen overnight on solar

Now that is funny right there :B

[MrWizard]

Your right he did mention solar
He also said use battery until 12.0 and switch to shore until the batteries reach float 13.2v

That's going to be a long recharge and it isn't going to happen overnight on solar
His batteries will sit overnight at 50 percent discharge of he does not use the converter and then recharge at an unknown rate during the next day and may not fully recover, he failed to mention the amount of solar the amount of batteries, and whether he intends to use the converter charging or solar only
Way to little info to expand beyond what I and others have stated
If he uses solar only recharging, then yes he could save an unknown amount on the electric bill, xx number of use hours, then go xx days on shore power while the solar recharges the batteries to full

[2oldman]

MrWizard wrote:
The OP didn't even mention solar

yes he did.

[jayw900]

Sounds like taking care of it manually is the better(easier) idea for now.

[jayw900]

2oldman wrote:

dahkota wrote:

Why we do it? Some places charge for electricity usage and can get expensive. Why should I pay for electricity I don't need when my solar panels can provide 90 percent of it.

That's fine.. but sounds like OP doesn't have that much solar.

Obviously the cheapest solution is to simply not plug in. If it's cost he's worried about, shore power has to be used eventually to charge his batteries anyway, so I don't know what difference it really makes.

Perhaps he'll chime in.

You're correct in assuming i don't have a lot solar right now. I'm just dipping my toes in. A bit more information; It is not an rv set up although i figure they are close enough where the thoughts provided will be useful.

The current production is enough to cover needs for 2 days before i need to charge. I do have land line power but i actively choose not to use it if i can. Cost isn't a huge deal as it's more of a hobby however if i can save a few dollars the happier my better half will be when i buy more solar.

As a side note to others trying to get into solar; Walmart batteries are grossly mislabeled. They are 100 amp hours at a 1 amp rate which i should have read into more. The true capacity is more like 65-75 amp hours depending on how hard you use it.

On Edit: I knew walmart batteries wouldn't be great but i'm making it work. I'm more annoyed that they would rate them at a 1 amp rate and say yep that's good.

[MrWizard]

The OP didn't even mention solar
He asked about using his batteries, then switching to shore power
Which means using power to recharge the batteries
20 percent more power than using shore power alone, directly for the same loads

[time2roll]

Could add a timer on the converter to just charge an hour every morning and let the solar finish the charge.
Adjust the timer as needed.

[2oldman]

dahkota wrote:

Why we do it? Some places charge for electricity usage and can get expensive. Why should I pay for electricity I don't need when my solar panels can provide 90 percent of it.

That's fine.. but sounds like OP doesn't have that much solar.

Obviously the cheapest solution is to simply not plug in. If it's cost he's worried about, shore power has to be used eventually to charge his batteries anyway, so I don't know what difference it really makes.

Perhaps he'll chime in.

[wa8yxm]

The answer is yes.. But I'd be hard pressed to tell you where to find it.

IF you have a stand alone inverter... Then when the battery voltage does too low it will shut down

Feed the 120v Out to the GENERATOR in on an auto transfer switch and then so long as the inverter has been working for at least xxx seconds (usually 30-60) it will be selected.. When the inverter shuts down it will "Drop" down to mains power. NOTE: I'd not run an air conditioner through that switch, or any other big ticket item. They do not like big load switching.. But everything else should be OK.

[dahkota]

We have a magnum inverter charger and solar.
If I want to run (mostly) on battery power while plugged in, I turn off the charger side and leave the inverter side on. The solar controller continues to charge the batteries while the sun is out and the inverter side powers everything plugged in to the outlets using the batteries. I am still able to use the a/c and microwave (on shore power) if needed.
Why we do it? Some places charge for electricity usage and can get expensive. Why should I pay for electricity I don't need when my solar panels can provide 90 percent of it.

[2oldman]

Would you care to share with us why you'd want such a setup?

[GordonThree]

Lead batteries have a limited cycle life as well. Especially "deep" cycles all the way down to 12v.

[MrWizard]

Assuming you want to run off battery and solar then charge batteries, trying to reduce electric charges?
Then solar must come into play, and be sufficient amount, and night rates electric charges preferably less than daytime charges
Remember take out 1kwHr and it takes 1.2kwHrs to recharge the batteries
Conversion losses come into play
With out solar it cost less to just use the utility power direct
Than to run down batteries then recharge them

IF you have the Solar to keep the batteries while running what ever
then only power being used is at night when the solar goes to sleep
and that is still cheaper than draining the batteries, then recharging them, the recharge power is cost more than the direct use power by a factor of approx 20 percent, unless you have say night rate that is over 20 percent less. and then you only brake even unless it is 30 percent or more less costly

[hedge]

My Victron battery monitor has the ability to signal a relay when the battery gets low, I would guess that the trimetric can as well.