The critter known as the "inverter/charger"

[PcHistorian]

Here's a question though, on inverter chargers.
1. Are these things flow through, like a backup power system for computers, 120 in, battery, 120 out.
2. Or are they back and forth through the same set of wires. 120v is in if commercial is present and out if commercial is not present, 12 volt is charge if commercial power is present and discharge if commercial power is not present.

Basically the battery is wired the same, but is the 120 in and out the same wires or separate? Should my commercial-power-in go right to the inverter/charger or can it be across the trailer with all of my 120 volt wiring in-between? I have a 120 v "closet" right at my door to the trailer, and my 12v "closet" is at the front of the trailer, inside. My 120-in is right below the 120v closet. But the inverter(/charger) should next to the batteries, in the 12v closet, to prevent line loss over dc.

Here's the $20 question. Should I reroute the power in, to go directly to the inverter/charger only, then feed the trailer separate, or can the battery inverter/charger be anywhere in the AC loop? (yes I realize that this is a strange question as about 99.9999% of everybody has both together. Try doing that in a space half as big as a medicine chest though and you get what I'm up against...

schematic
https://sites.google.com/site/pchistori ... -110v-schm

[Shadow Catcher]

Inverter chargers tend to be very expensive and you see them most in BIG RV's http://www.tripplite.com/en/products/mo ... delID=3718 is one example. It has an internal relay that switches from shore power to inverter automatically providing 120AC all of the time. A converter takes 120AC and converts it to 12V http://www.progressivedyn.com/all_in_one_pd4000.html and does it automatically. For a small trailer my feeling is you are better off with a converter and add an inverter if you need it for a specific purpose.

[PcHistorian]

@Shadow Catcher, ok, you got me on that one, too.

I was thinking more along the lines of a small cabin with solar panels and windmill. Chargers are dirt cheap, inverters are a little more, but that critter ... I wonder if for the connection to commercial power it does the phase synchronize for reversing the meter?

But still then how do I interface both and inverter and commercial power with my single set of 120v outlets then?

I suppose I'd have to have a relay that would cut the inverter in when the relay was off, and power the relay on the commercial in wires. Then if commercial power came in, it would throw on the relay, switching out the inverter and switching everything to the commercial in power. Hmmm... then I have to slip in more relays so that my batteries don't charge (separately now remember) while I'm on the inverter, which is taking power from the batteries to make the 120v in the first place.

Now I can do that, I'm just wondering if that's the only way to go and then I need to find some heavy amp DPDT relays, at 120v coil, to run both the chargers in, and the commercial/inverter to 120v main. (that's as far as I have so far...)

[PcHistorian]

So for those who want to automate the existence of both commercial power and the inverter, with auto switchover, here it is.



I was just kind of wondering what I do if I got a "inverter/charger."

[Shadow Catcher]

The only 30A DPDT switch I could find was at Allied. I do have a Progressive Dynamics automatic transfer relay I did not use If you are interested we might be able to work something out, fair warning they don't come cheap. BUT really you only need the DPDT switch.

[perkgana]

Hi guys, Im pretty new to this and I have a question. What charger should I use? I found one on ebay that is a 1.5 amp charger/maintainer. Charges and when the battery is full turns to float mode and just maintains the battery topped.

[Shadow Catcher]

A great deal depends on how quickly you want to recharge the battery, how fully, and if you plan on using 12V when on shore power. I personally have a Progressive Dynamics 45A power center that will charge the battery quickly and fully and provide the circuits to power lights and the stereo and provide power for the fan(s). Depending on which fan you use (I use computer case fans) you can more than double the power consumption of what the 1.5A trickle charger can put out.

[PcHistorian]

@perkgana, ok, here's the computation. You can run on battery, if there's no 120v available. If there is 120v available you want to get all your batteries to the "charged and maintain" point. Now, at 45A charging, you can not only "fast charge" (watch the charge rate for some smaller batteries) but you can still have enough energy to run all your 12v appliances while the batteries charge. (usually you don't put a lot of "big drain" items on the 12v circuit.) The other half of that coin is that you now have 120v access, and you can run all your 120v stuff. So you kind of have a mixture of the various levels, 120v (air conditioning, TV, microwave, (chargers), radio, power tools,...), 12v major (tv-radio-fans-"dome lights") and 12v minor (like LED lights). So what you have to do is balance the ability to run at any given level, with what you want to run at any given level.

Such as, "do I want to run the tv (television) while charging, and it's a 12 volt only tv." then you'd want more charging power. But if you can go totally off the 12v to 120v, while charging batteries at 1.5 amps, (over night for a full charge) then you should have no problem. If you HAVE TO charge in 2-4 hours full charge, (drained to maintain level) then you'll need more amps. Some people have the ability to charge from their car (tow vehicle/TV) through the tail-light connector (7-pin, put in bigger wires for the 12v lines, 10 gauge wire). Get indicator lights as to how your charge is doing. If you disconnect to drive somewhere, and someone is staying at your camp and using 12v, no 120v available, then just recharge from the tow vehicle when you get back. We are kind of "over lapping systems" to prevent getting caught short. It's our way.

Bottom line, if you can get the 120v to run the charger then use batteries only as a back up, you should never have any problems. Just make sure you charge fully before you go, so if you can't get a site with 120v you still have your battery back up anyway. (and if you don't have 120v to charge the batteries, it won't matter how many amps your charger has anyway.) So you are going to weight the two sides of your own, personal electrical situation. Do I have to have 120v, or can I do with 12v for 90% of the time. Solar panels are getting popular (I have even seen "solar ivy" that looks like ground ivy but is solar panels) and so you can go 12v and keep charged that way. Then when you get home from the weekend, just make sure you charge up fully. If you get stuck with a "No 120v" site and have a 45amp charger, you can pull over to a friend's site and fully charge in a few hours, when you need to. With 1.5 amps you can't do that, you'd need overnight for a full charge.

I am using 2 small batteries at this point, rechargeable. One is an auto-booster battery, which is about 300 amps for 10 seconds, or 50ah (amp/hours) for radios, dome lights, recharge the usb phone,..., etc. The other is a building "emergency light" type battery (3ah) for led's only. My total charge and maintain is 0.8 amps. I also have a full 120v wiring scheme in the trailer though.

Personally, I will only be using 120v, "have to have" for heating in cold weather. I'll have an optional "hot plate" but I can always cook in the camp fire (ex-boyscout). I can even go without the 12v and just use flashlights. But it is nice to have the "leave on" lighting, even if it is only LED's, which are getting to be really bright, and use almost no power, especially from large batteries. You can probably run LED only, continuously, from a large, deep cycle battery for months, without recharging. I have a 10 amp automobile charger, booster that does auto maintain, but I probably won't be using it or even bringing it. It won't fit in my "medicine chest" type sized cabinets and so I don't normally choose to lug it along. Over kill. 0.8 amps is fine for me.

This level of camping and TD'ing is so much more "the experiment" than the "make it and change not" situation. Invest small until you know for sure is the best plan. Scrounge, pick brains and make an educated guess.

I hope that helped. If you have any more specific questions, ask. This is the place to pick brains. If I can think of another forum or web page to get you better information, we'll give you that, too.

Oh, one more thing, with the "maintain" part of that charger, you can leave the battery plugged in over the winter and between trips, and never have to worry about charging it up at the last minute or getting caught without a charge when you want to go, or accidentally not maintaining the battery charge and having a battery get ruined because it wasn't trickle charged. You'd have the trickle/auto maintainer.

[eamarquardt]

I'm not sure what your objective is but there are a couple of things to remember about the care and feeding of batteries.

Unless they are true "deep cycle" batteries (like golf cart batteries) they shouldn't be discharged beyond about half their capacity. Batteries, for optimum life, should not be charged at a rate more than about 10% of their amp/hour capacity which rules out charging a battery in 2 to 4 hours if you want to optimize the life of your battery. A lot of converters and chargers are rated at a bazillion amps but the battery's internal resistance will limit the charge current to something far less than the charger's capability. The converters put out their rated output when there is a 12 volt drain (things plugged in) beyond the battery charging current.

Also when using a converter, the 120 volts will make roughly ten times as many 12 volt amps as it uses 120 volt amps. So a 45 amp converter will only use less than 5 amps of 120 volt power.

I suggest that you make a chart of what you want to run at any given time and see what the totals are.

Keep in mind that your not going to run any 120 volt doo dads from batteries via an inverter for any length of time (such as a heater, hot plate, microwave, etc) as the high current drain for an extended period of time will drain the battery in a short time and shorten it's service life.

Hope this helps.

Cheers,

Gus

[PcHistorian]

Gus,
Well, for ME, ultimately, I am going to be running two 12v deep-cycles in parallel, in a full width battery box, and a 2000 watt inverter. When I work my trailer is a portable 120v handyman / construction shop, hauling my tools and voltage into the woods, literally, electric chain saw, circular saw, table saw, drills, paint sprayers, the works. My portable shop. But, when I play, it plays. I unload the tool boxes, load up the camping gear and hit the road. (Unless of course I have to do both and live in the trailer during a job (construction), which may happen.) Granted, you are right, these things are each non-continuous operation. I wouldn't use the heater off of battery unless I had a LOT of solar panels and a windmill to charge the batteries.

But this line of topic is really about hooking in an inverter / charger into the AC/DC loop of the trailer. I want the inverter charger next to the batteries at the box, so I am surmising I would eventually have to move the AC (shore) input to the battery box. I'm just trying to figure how it is different from the separate pieces/units.

[eamarquardt]

Gus,
Well, for ME, ultimately, I am going to be running two 12v deep-cycles in parallel, in a full width battery box, and a 2000 watt inverter. When I work my trailer is a portable 120v handyman / construction shop, hauling my tools and voltage into the woods, literally, electric chain saw, circular saw, table saw, drills, paint sprayers, the works. My portable shop. But, when I play, it plays. I unload the tool boxes, load up the camping gear and hit the road. (Unless of course I have to do both and live in the trailer during a job (construction), which may happen.) Granted, you are right, these things are each non-continuous operation. I wouldn't use the heater off of battery unless I had a LOT of solar panels and a windmill to charge the batteries.

But this line of topic is really about hooking in an inverter / charger into the AC/DC loop of the trailer. I want the inverter charger next to the batteries at the box, so I am surmising I would eventually have to move the AC (shore) input to the battery box. I'm just trying to figure how it is different from the separate pieces/units.

If it works for you, it works for me. These "half duplex" communications with a "time delay" sometimes make it difficult to get the "big picture".

Cheers,

Gus

[PcHistorian]

ok, well that was my next guess, is to say, go with a 2000 watt generator. so 100 amp-hour battery to 50% charge rate, actually gives me 50 amp-hours at 12v? So if I want to run for 10 hours that's 5 amps for 10 hours. So if a portable tv takes, 2 amps, @ 120 v, that's 240 watts, for an hour, converting back is 20 amp hours, so I have 2.5 hours of tv at 2 amps and 120 v ac. (after the inverter.) (unless I have a thin screen which would probably take less.

So, I can maybe run a radio and the dome/swivel lights off of a full sized deep cycle battery without the need to charge it several times a weekend.

What I probably need is a 50 amp. meter to test things out on so I know for sure.

[eamarquardt]

You're on the right track now. Determine your amp/hour needs beforehand, how much battery you'll need to meet that demand (keeping in mind discharge/charge rate), and how you're going to recharge the batteries. Then you'll know if your plan is workable.

Here is an inexpensive ampmeter/voltmeter with a shunt (a shunt is usually required to measure high currents):

http://www.ebay.com/itm/100V-100A-DC-Di ... 588wt_1037

Cheers,

Gus