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Old 04-07-2014, 10:02 PM   #1
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Help with my electrical design?

Warning: I am a complete and utter amateur. I apologize in advance if this is a super annoying post. I very well might just be in over my head.

Summary:
  1. I am adding a second battery in my van to charge devices, power lamps, etc. (I will call the second battery the house battery from here on out.) I'm attempting to design a system where this house battery is charged off the starter battery. [/*:m:5ozau1dk]
  2. There must be a mechanism in place that prevents the house battery from draining the starter battery while the ignition is off and I am using power. [/*:m:5ozau1dk]
  3. To do this I plan on using a solenoid to make sure the house battery is only charging when the engine is on. This will also ensure that the house battery doesn't draw off the starter battery. [/*:m:5ozau1dk]
  4. I'll be using an inverter so I can use AC, and a circuit breaker of sorts so I don't harm the battery. [/*:m:5ozau1dk]

Diagram:

Here is a diagram of what I have so far: http://imgur.com/i9aqdiQ
While I did my best in making this diagram, I know it is hard to follow. I apologize.

Notes:
  1. What I plan to power initially: A lamp or two, my laptop charger (60W AC), and my phone charger.[/*:m:5ozau1dk]
  2. What I’d like to be able to power eventually (with help of added solar panels): A stereo system with a record (vinyl) player, a small fan or two and a hot plate. I’ve been told to forget about the hot plate because they run on an upwards of 1000W and are extremely inefficient. However I would like to be able to cook in my van without opening the windows as I’d like to do some stealth camping in cities.[/*:m:5ozau1dk]
  3. Inverter: As of right now I plan on using a 1500W inverter. This should be able to handle my biggest future load, if I choose to pursue it: the hotplate.[/*:m:5ozau1dk]
  4. Circuit Breaker: I’ve been told I should use a 150 Amp fuse with the correct fuse holder. (I don’t know if Circuit Breaker is the correct term for what I need.)[/*:m:5ozau1dk]
  5. Wiring Size: Based on the size of the inverter I’ve been told I should not go smaller than 2 AWG between the inverter, circuit breaker and house battery. I’ve also been told it would be best to use 0 AWG between batteries to “minimize voltage differential between the two batteries.” (I don’t know what this means.) I don’t know what gauge the green wire in the diagram is as it’s already wired. I assume this doesn’t matter. I also assume that the grounding wire should be the same gauge as the wire coming off the positive terminal.[/*:m:5ozau1dk]

Questions:
  1. The blue wire is my mystery wire. It would be there to turn the solenoid on and off when the alternator goes on and off.[list:5ozau1dk]
  2. What gauge should this wire be?[/*:m:5ozau1dk]
  3. This wire needs to be hot when the alternator is running. How do I do this? Splice it into a wire attached to the alternator that is hot only when the engine is on? How would I find this? I have a 2003 Ford E150.[/*:m:5ozau1dk]
[/*:m:5ozau1dk][*]Are the other wire gauges correct?[/*:m:5ozau1dk][*]The simplest question: how do I attach the wires to the batteries, the solenoid, the circuit breaker and the inverter? Especially wondering about this for places where there are two connections to one place, such as the positive terminal on the house battery. I have been told to use a heavy duty copper lug between the house battery, fuse and inverter.[/*:m:5ozau1dk][*]I was planning on purchasing an AGM Deep Cycle battery for the house battery, maybe around the 220 Ah range. Does it matter if the starter battery and house battery are completely different?[/*:m:5ozau1dk][*]I'd like to be able to monitor how many amp hours are left in the house battery so I don't go below 50% charge and damage the battery. What would be best to do this and where abouts in the wiring does it go? I’ve been told to attach a “voltage meter with a dial.” Where does this go? The same person also suggested getting an “auto shutoff” to stop the battery from giving off any power once the voltage meter gets to 50%. How would I go about doing this?[/*:m:5ozau1dk][*]Someone said that they “recommend running house side ground wires back to a single ground lug to avoid ground loops and separating the house and car systems as much as possible.” This confused me as I only have one ground coming from the house battery. What exactly does this mean?[/*:m:5ozau1dk][*]Am I making this completely overly complicated and there is actually a very simple answer for all of this?[/*:m:5ozau1dk][/list:5ozau1dk]

To anyone who reads this or who takes the time out of their day to answer any of these questions or just generally help me out: thank you so much!
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Old 04-07-2014, 11:43 PM   #2
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Re: Help with my electrical design?

This is a basic configuration most use.



There are more complex systems you can design but I like to keep things as less complicated as possible.

First off the separator is the charging relay most SMB's have. If they didn't work SMB wouldn't use them. There are some manufactures considered better than others and some come with different options. Most activate (close) when seeing a specific voltage and deactivate (open) when the voltage drops. Take a look at the top thread in this section. Also take a look at the linked info in the electrical FAQ's. There are load charts and distance calculators.

Rated lugs are a good choice.

Mixing batteries can be OK but it's best to keep the same types. A standard wet cell might not be able to handle a continuous solar charge at least I've found that to be the case. Others might disagree. Since going all AGM house and starters I have not had the issues I had before. They actually don't need to be the same size because once separated they stand alone. Batteries of different makes/size & ages that are banked together all the time often have issues with each other. The separator takes care of that.

The voltmeter such as a link pro or others should be on the house side of the separator. Other meters and gauges such as those found on high end inverters help.

SMB routes the house ground wire to a grounding distribution block that is also grounded to the chassis. Same as Ford does with the starting battery ground. My 2000w inverter has 4/0 copper from the house to the inverter and its a short run...probably way overkill. What I don't like is it's not fused. I'd like an inline 300-400A fuse on both hot and ground.

Greg's probably got some more in his post.

[edit] Also note that if you plan to use the house to be used to jump start the engine, the correct size wire must be used so it does not melt down due to heavy cranking loads. I think this is a flaw in the SMB design (which might be change now) as they used #4 copper and I'd like it to be at least 1/0. In my case I let the batteries combine to level each other out before attempting to crank the engine. It's like using too small of jumper cables trying to start another cars dead battery...sometimes you have to let the engine run for a while to charge up the dead battery. There is a reason separators are rated for 200-600 amps.
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Old 04-08-2014, 08:09 AM   #3
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Re: Help with my electrical design?

I think Dave's diagram is spot on. I will try to add some information and I am sure you will have follow up questions.
Quote:
To do this I plan on using a solenoid to make sure the house battery is only charging when the engine is on. This will also ensure that the house battery doesn't draw off the starter battery.
See topic http://www.sportsmobileforum.com/vie...hp?f=14&t=8842 for information on the device you are looking for. There are a number of options, the BlueSee 7622 or 7620 are the big hitters, and are very good products for what you intend to use it for

[quoteWhat I plan to power initially: A lamp or two, my laptop charger (60W AC), and my phone charger.
][/quote]
I would look at getting 12 volt versions of chargers you need, most phones have a USB charging port, Blue sea makes one that converts 12 to 5 volts and can handle 2 amps (covers most Pads even) http://www.bluesea.com/products/1016...Charger_Socket
You should also be able to find a 12 volt charger for laptop. The reason you want to look at those is because a DC to DC conversion is going to be more efficient then inverting to AC and the using the AC supply to convert to DC. Also with your larger inverter that you are looking to install, the lower wattage range would be even more inefficient. The first 30% of any inverter is pretty low on efficiency.

Quote:
Inverter: As of right now I plan on using a 1500W inverter. This should be able to handle my biggest future load, if I choose to pursue it: the hotplate.
There are a ride range of inverters out there, I suspect that if you really are using a turntable you will want to go with a Pure Sine Wave unit. You may want to go for a Inverter/Charger so you can plug in and charge that battery also as a back up to solar. There have been some post on Inverter/Chargers recently that I would look at. I think Magnum Energy MS2000 is a good choice.

Quote:
Circuit Breaker: I’ve been told I should use a 150 Amp fuse with the correct fuse holder. (I don’t know if Circuit Breaker is the correct term for what I need.)
Wiring Size: Based on the size of the inverter I’ve been told I should not go smaller than 2 AWG between the inverter, circuit breaker and house battery. I’ve also been told it would be best to use 0 AWG between batteries to “minimize voltage differential between the two batteries.” (I don’t know what this means.) I don’t know what gauge the green wire in the diagram is as it’s already wired. I assume this doesn’t matter. I also assume that the grounding wire should be the same gauge as the wire coming off the positive terminal
Although I know I am starting to sound like a add for Blue Sea, they have a nice circuit wizard on their website, it is very good help about that sort of thing. What ever Inverter you purchase should have information on wire gauge and fuse size in their installation instructions.
http://circuitwizard.bluesea.com/

Quote:
I'd like to be able to monitor how many amp hours are left in the house battery so I don't go below 50% charge and damage the battery. What would be best to do this and where abouts in the wiring does it go? I’ve been told to attach a “voltage meter with a dial.” Where does this go? The same person also suggested getting an “auto shutoff” to stop the battery from giving off any power once the voltage meter gets to 50%. How would I go about doing this?
For this I will point you to a Sportsmobile Wiki page on Battery Monitors that I recently made.
http://www.sportsmobileforum.com/med...attery_Monitor
I also have a post on using one of those to have a low voltage disconnect.

Probably missed a lot of things, but that is a start.


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Old 04-08-2014, 04:37 PM   #4
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Re: Help with my electrical design?

For Phase I you may not really need a house battery. Just get 12v cell phone chargers and make sure the starting battery is in good condition. Or get the biggest AGM starting battery you can find and upgrade. Use LED lamps, they draw very little.

For phase 2, cooking with batteries is an extreme use. But you could use 12v applicances made for truckers. For instance, I saw a 12v electric frying pan for $27. It pulls 13 amps. Maybe consider a butane hot plate. It could be safely used indoors just by cracking a window.

Not sure what to say about the vinyl record player.

Maybe get a portable USB player where the arm is the whole thing?
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