Some Electrical Design Questions

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Some Electrical Design Questions

Postby misu55 » Mon Nov 28, 2005 4:35 pm

Hi,

I am new to this Forum. My Fiancee and I are planning on building a Tear to take on a 4-6 week journey cross country for our honeymoon next fall and I have some electrical design questions for those of you who have already built your Tears.

I want to be able to use DC power and AC power regardless of whether or not I'm connected to shore power. I would also like the system to switch over automatically when I connect to shore power.

This is how I would like the system to operate:

WHEN CONNECTED TO SHORE POWER:
Shore power charges on-board batteries.
110v AC to the high voltage system from shore power source
12v DC (via an inverter) to the low voltage system from shore power (not through batteries). I don't want the batteries to provide low voltage power when connected to shore power.

NOT CONNECTED TO SHORE POWER:
Tow vehicle charges batteries
On-board batteries provide 12 volt DC to the low voltage system and 110 Volt AC (via an inverter) to the high voltage system.

Is there a device that is "smart" enough to isolate the on-board system from the tow vehicle when using shore power or a generator (other than physically disconnecting the harness to the tow vehicle)?

Are there harnesses that have pins for 12Volt power in addition to pins for the turn signals/running lights/brake lights?

Thanks for your help.

Nick Peetros
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Postby Frank » Mon Nov 28, 2005 5:00 pm

Welcome to the board Nick. You have a lot of good questions, most of which have been asked in the past on this board. On the main page go down to "Electrical Secrets", click on this some of your questions are there, also go to the top of the page and you will see "Search" you can click on this and then put in word or words to search for. Have fun, your goals are achievable, although to make everything automatic, will cost a little. Sometimes simple is best.

:)

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Postby goldcoop » Mon Nov 28, 2005 5:08 pm

Nick-

Welcome!

Sounds like quite a Honeymoon!

I'm not quite sure why you don't want to run off of your batteries when hooked up to shore power as a charger will keep them topped off?

I'm sure others will be able to offer you a bunch of advice on this one!

BTW there are trailer plugs available for more than normal turn-stop-running, the following may help clarify:

http://www.etrailer.com/faq/wiring.asp

Have you settled on a design, etc. yet?

Cheers,

Coop
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Postby GeorgeTelford » Mon Nov 28, 2005 5:15 pm

Hi Nick

Your first part

Shore power charges on-board batteries.
12v DC (via an inverter) to the low voltage system from shore power (not through batteries). I don't want the batteries to provide low voltage power when connected to shore power.


Is all achieved by buying the correct 4 stage charger, I use sterling Charger but I know they design similar stuff for an American company.

110v AC to the high voltage system from shore power source

this requires an automatic change over switch, Mine is made by sterling it selects the mains source like so

First it uses shore power, if this is not available it uses the Genny input, If no genny power available it reverts to Invertor all done automatically.
Not cheap but safest and most reliable system.

Is there a device that is "smart" enough to isolate the on-board system from the tow vehicle when using shore power or a generator (other than physically disconnecting the harness to the tow vehicle)?

If you mean disconnecting the 12v system this would automatically be done when the ignition is switched off, there should be a relay in place to disconnect.


NOT CONNECTED TO SHORE POWER:
Tow vehicle charges batteries
On-board batteries provide 12 volt DC to the low voltage system and 110 Volt AC (via an inverter) to the high voltage system.


If you are going to "charge" from the vehicle you really need to get a smart regulator to turn the vehicle alternator into a smart 4 stage charger, an alternator unmodified will not put more than 70% into your batteries and whats worse if you have charged on a campsite (to 100%), driving will then discharge your house batteries into the vehicle system and they will eventually drop back to 70%.


Are there harnesses that have pins for 12Volt power in addition to pins for the turn signals/running lights/brake lights?

Not sure about this I am from UK not up on what you Merkins use for lighting and trailer sockets
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Postby madjack » Mon Nov 28, 2005 5:21 pm

Nick, welcome to the board...I am sure you will get alotta info on that question since it is debated hotly here...the electrical secrets section is an area you should become familiar with...to do what you want, you need to run most every thing off of a converter powering and inverter...a converter takes 120vac and turns into 12vdc and an inverter does the opposite... here are some convertors be sure and get one that includes a 3/4 stage charger ...you should get plenty more info before this thread is done...
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Postby bledsoe3 » Tue Nov 29, 2005 4:48 am

Read this thread. http://tinyurl.com/ao6wt Lots of good ideas.
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Postby cracker39 » Tue Nov 29, 2005 7:09 am

madjack wrote:...here are some convertors[/url] be sure and get one that includes a 3/4 stage charger ...you should get plenty more info before this thread is done...
madajck 8)


I haven't decided to use my tow vehicle for chaging, but that may be an option down the road. For now, I've decided to use the CS6000 converter. It provides dual power, protection, automatic switching of 12VDC/110VAC, and battery charging while on shore power. And, best of all, it is reasonably priced. I have a source to get it for $50 plus shipping (w/o AC breakers), far lower priced than many converters. If you want more info on this, PM me.
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Postby GeorgeTelford » Tue Nov 29, 2005 7:41 am

Hi Cracker

The Centurian CS 6000 is a convertor and NOT a battery charger ( I have just looked it up and from what I can see it outputs 13.4 volt constant ) this will probably never fully recharge a battery

I have tested A UK convertor 13.8 Volt and after 4 weeks the battery was only charged to 90 % (ish)
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Postby GeorgeTelford » Tue Nov 29, 2005 7:46 am

Hi Cracker

Forgot about the tow vehicle "charging" part. A standard alternator is not a good battery charger, like a convertor its a power supply that has a by product puts a tiny amouny of charge back, to make a vehicle alternator into a real charger requires the addition of a smart regulator.

If you were to fully charge a battery (with a real charger) and then connect to a vehicle alternator within a short while the battery will have lost about 30% down FROM FULL, for an alternator thats about max charge.
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Postby Wright » Tue Nov 29, 2005 8:49 am

Just to prove I'll need to hire an electrician.....
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:BE Wright

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Postby cracker39 » Tue Nov 29, 2005 10:26 am

GeorgeTelford wrote:Hi Cracker

The Centurian CS 6000 is a convertor and NOT a battery charger ( I have just looked it up and from what I can see it outputs 13.4 volt constant ) this will probably never fully recharge a battery

I have tested A UK convertor 13.8 Volt and after 4 weeks the battery was only charged to 90 % (ish)


I am going by the description and diagrams on the the link Madjack provided above, and I have the same information from the buy I was planning to buy from. The description for the CS6000 says it has a full battery charger. The 2nd diagram shows the battery charger hookup. Did you find other information that contradicts this one? I want to be sure of what I am buying if I get one.
Dale

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Postby Spadinator » Tue Nov 29, 2005 10:48 am

Wright wrote:Just to prove I'll need to hire an electrician.....
Image


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Postby madjack » Tue Nov 29, 2005 11:49 am

...Dale, I went digging around for info on the convertors I linked to. The info I found is this...these units are close to being standard issue in many pop-up and RV's and the battery charging set-up is listed as automatic...so it has at least a 2 stage chaging circuit(charge/maintenance)...they may or may not have a 3rd stage(anti-sulfation/wakeup)... here is a link to a model with a 3 stage charging circuit...
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Postby vairman » Tue Nov 29, 2005 1:07 pm

Is there anything wrong with using this type of charger??
http://www.batterychargers.com/images/F ... -520MA.jpg
I used one for over 2 years, and I lived in my camper for about a year... And here's the funny part, my lighting was all 12 volt and my battery was one for a riding lawnmower, I could run the lights for about 12 hrs on a charge...

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Postby GeorgeTelford » Tue Nov 29, 2005 1:18 pm

Hi Cracker

I checked Centurians own information which states that it outputs constant 13.4 Volts this is a one stage poor trickle "charge", this is a con that goes on worldwide by the looks of it.

Here is what I use http://www.sterling-power.com/htm/ced.htm

The 1230CED


People actually think an alternator is a battery charger too, but it suffers from the same problem lack of inteligent control. Thats why when I use the alternator to charge I use one of these

http://www.sterling-power.com/htm/ar12vd.htm

The one that Madjack as posted in his last post is a 3 stage Charger, the centurion is definately not any kind of staged charger, the WFC one is set to charge Gel etc I would prefer if it was set for lead acid (all stages would have higher voltage)

I know that sterling do the design work for an American company too and they both use the same manufacturing facility, but I cannot remember what Charles Sterling said the USA company was called.


Many chargers are called "automatic", but they only work like an alternator, ie after an initial inrusch of current the batteries internal resstance changes which considerably lowers the ampage thats drawn across, this is a function of Ohms law and is not any kind of "inteligent" change of charging parameter's. Many on this basis also claim to be 2 stage which is utter rot.

BTW the ones I have linked to work the world Over.

gotta get some grub catch you all soon
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