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Charge Controller for House and Start-up Battery


PeterCutter

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Hello everyone and thanks for having such a great forum. This is my first post though I have been trolling and learning for some time now.

 

I have a 34 Ft. Airstream Cutter with a Ford 460. I would love to install a solar panel system to charge the batteries. I have two 12V house batteries located inside the RV under the doghouse and one 12V battery under the "hood" that starts the RV.

 

I would like to know that is use the TriStar MPPT 60, will I be able to use that controller to charge all three batteries or will I need two separate controllers one for house batteries and another for the engine's start-up battery? If I need two do I need MPPT for both (two Tristar MPPT 60)? Can I go with something more affordable with Tristar MPPT 30 or can I even use something like a Xantrex C35 charge controller for the truck battery?

 

Frankly, I am electrically-challenged (flunked out of electrical engineering school) and I am super confused about this whole process.

 

Thanks in advance,

 

Peter

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Hello everyone and thanks for having such a great forum. This is my first post though I have been trolling and learning for some time now.

 

I have a 34 Ft. Airstream Cutter with a Ford 460. I would love to install a solar panel system to charge the batteries. I have two 12V house batteries located inside the RV under the doghouse and one 12V battery under the "hood" that starts the RV.

 

I would like to know that is use the TriStar MPPT 60, will I be able to use that controller to charge all three batteries or will I need two separate controllers one for house batteries and another for the engine's start-up battery? If I need two do I need MPPT for both (two Tristar MPPT 60)? Can I go with something more affordable with Tristar MPPT 30 or can I even use something like a Xantrex C35 charge controller for the truck battery?

 

Frankly, I am electrically-challenged (flunked out of electrical engineering school) and I am super confused about this whole process.

 

Thanks in advance,

 

Peter

https://www.amazon.com/Blue-Systems-Automatic-Charging-Relays/dp/B01LEHLINK/ref=pd_lpo_263_tr_img_3?_encoding=UTF8&refRID=VN2XH59YSP6EASP2D04Q

 

Easy installation,[3 wires] whichever batteries getting the charge, will charge the other ones and disconnect if neither are being charged.

Just hook up between both banks, no extra controllers needed.

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Welcome Peter!

 

That TriStar is a very good controller, but wouldn't be able to charge your 460's battery without additional equipment.. and.. probably wouldn't provide the best charge due to the distance.

If your engine battery is really of that great of a concern I would likely go one of two routes. Either run a small battery tender type charger to the chassis battery via my house inverter... or... install a separate solar battery tender type setup. (Note: I have never used a solar battery tender and don't specifically recommend the unit I linked to. It is more just for general information of type. The 120v battery tender I "would" recommend.)

Seeing that your 460's battery should be more than capable of holding an extended charge, IMO, it wouldn't be close to worth the expense of adding a second "full on" solar controller or a battery management module to utilize your existing TriStar. I would go cheap n dirty.. but highly effective.

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Hi Peter. I will take a first run at answering although there are others more knowledgeable who will hopefully stop by.

 

Just a few points to kick things off:

 

1. Generally, the size of your panels total wattage/amperage determines the size and type of your controller so you need to start by determining the size of your proposed system. Setting aside cost, the size of the solar system will be determined by your available roof space, your actual daily need for electricity and the size of your battery bank to store that electricity. If you are usually plugged in and just want to top off that would be a small system. If you are looking to boondock and be self sufficient for a few days we would be talking about a larger system.

 

2. You mentioned two very good controllers. The MPPT 60 would handle a larger system but you do not need MPPT unless you will be installing higher voltage panels. There will be no benefit. So we get back to the need to first know your proposed panel set up.

 

3. Generally, you want your controller as close to the pack as possible. Usually a single controller is used to each bank.

 

4. Your starter and Rv batteries are different types of lead acid. You should not be using your starter battery for electrical needs other than starting. If you do want some solar to keep you starter topped off I would look at something cheap (very cheap) and have a separate panel and controller dedicated to that.

 

5. To determine you system needs I would review Jack Mayer's website http://www.jackdanmayer.com/Sample%20Solar%20and%20Electrical%20Systems.html.

 

6. If you can tell us your anticipated needs we can be a lot more help. Dave

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Thanks for all of the replies.

 

A bit of background.....

 

I purchased my first RV about three months ago. About a month after I purchased it I lived in it for a month while they were remodeling my home. That is where my wife and I fell in love with RVing. After spending a month in the RV I put in storage. I live in Miami and I can't keep the rig at my condo so I have it a storage lot about 30 minutes away. I go every week or so to check on her and let her run for a 15-20. I run the generator and the A/C's.

 

This past weekend I went to check her out and the chassis battery was DEAD. I was shocked and worried. Since I am a newbie at this I didn't realize that I could use the "Aux Start" button to have the house batteries assist. I had my truck so I jump started her right away with no problem. Then I got worried.

 

What if....

 

What if I got stuck in the middle of nowhere with no electricity. So I started doing research on a solution.

 

A few Google searches led me to Jack Mayer and Handy Bob. I decided to follow Handy Bob's advice. Develop a "phase in" system. One that I can buy some basic components and then add-on as I need.

 

Right now I need to trickle charge my battery. Based on the responses here and on other forums. Sun Electric is a few mile away. So after I measure my roof I am going to select a high voltage solar panel and probably buy all that I need at one time to avoid mismatch later. I am leading toward buying PWM charge controller now and bump up to MPPT as I add panels and need for remote power.

 

I really don't plan to do a lot of long-term boondocking. I may stay at a Walmart or a nice remote site every now and then but it it is hot, I am running the generator. No way the misses is living without A/C. So I long-term I need enough juice of 2000 watts of usage (I only have to run lights, charge cell phone, a few hours of TV, water pump, CO2 and Propane alarms, short spurt of microwave, laptop and maybe a fan. My biggest short coming is batteries, with only two 12 volt house batteries I am relative under supplied.

 

One thing I notice about these self design projects is that I seem to over engineer. Like I said earlier, I really don't plan to do a lot of boondocking. A/C is really important to me (we live in Florida and we plan to use the RV monthly within the state so heat is an issue). So frankly, the best advice to myself may be to keep it simple and cheap and only spend more if I REALLY need to.

 

Thanks again and I appreciate the input,

 

Peter

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The simplest solution is to buy an inexpensive 15 watt amorphous solar panel and connect it directly to your chassis battery. At approx. 1 amp output you don't need to worry about overcharging the battery and there's very little leakback overnight so you really don't need a solar controller. Just tie it directly to the battery through a 5-10 amp fuse that will blow if there's a catastrophic wiring short.

 

Parasitic loads like the engine computer on standby and the station memory in the radio are what's draining your battery. I've had one of these connected to my starting battery for a couple of years and it solved the parasitic drain problem.

 

http://t.harborfreight.com/15-watt-12-volt-solar-panel-96418.html

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https://www.amazon.com/Blue-Systems-Automatic-Charging-Relays/dp/B01LEHLINK/ref=pd_lpo_263_tr_img_3?_encoding=UTF8&refRID=VN2XH59YSP6EASP2D04Q

 

Easy installation,[3 wires] whichever batteries getting the charge, will charge the other ones and disconnect if neither are being charged.

Just hook up between both banks, no extra controllers needed.

Similar to a relay is the diode approach. this http://www.lslproducts.net/ALS_Overview_Page.html works well. I used its little brother and was very satisfied with its performance.

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You could add a Trick-L-Start, http://www.lslproducts.net/TLSPage.html, Xantrex Echo Charger, http://www.xantrex.com/power-products/power-accessories/auxiliary-battery-charger.aspx or AMP-L-START, http://www.lslproducts.net/ALS_Overview_Page.html, to the chassis battery so that what ever is charging the house battery's ( Solar, Converter/Inverter) will also charge the chassis battery with out causing a battery drain on either system. One of these should solve your problem. Ed

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