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Old 08-25-2017, 06:47 AM   #11
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I've had a Lifeline for a couple years from bestconverter.com and it has been great. I would buy a premium battery and then make sure your charging strategy is completely squared-away. Treat it right and it will return the favor.

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Old 08-25-2017, 09:52 AM   #12
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Hey there 86Scotty -- glad to be back here where folks are friendly and very helpful .

Thanks to everyone for the replies. Sounds like I have two paths to research: Lifeline (and co-brands) and Duracell/co-brands. I will be in the Austin area for the first part of September, where there are BatteriesPlus stores as well as a battery distributor for Lifeline and other brands in Bastrop, so I will do more learning and my shopping there.

I will also be looking for solar panels, for about 200-300W. I will post a separate thread about that.

Figuring out an electrical plan for scratch is ... Daunting!
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Old 08-25-2017, 11:32 AM   #13
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One more quick question: I plan to use either a pair of 12v or a pair of 6v batteries at the outset.

Am I right in understanding that I could add a third 12v battery to a 12v configuration, but that if I wish to expand a 6v configuration I would need to add another pair of batteries?

Thanks
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Old 08-25-2017, 11:57 AM   #14
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Quote:
Originally Posted by GreyDawg View Post
One more quick question: I plan to use either a pair of 12v or a pair of 6v batteries at the outset.

Am I right in understanding that I could add a third 12v battery to a 12v configuration, but that if I wish to expand a 6v configuration I would need to add another pair of batteries?

Thanks
These days the energy density of a pair of 6V size batts and a single 12V is similar.....so I don't see the point of 2 6 volts in series (I'm sure others will disagree for some reason)

Since the 6V batts are wired in series, if you fry one you have no power.....a couple of parallel 12V batts allow 1/2 the capacity if you have a problem with one...at least on paper....Typically a shorted cell, etc can pull the good battery down and possibly damage it. If the other batt has an open circuit failure, you still have 12V with half the capacity of two batts.

I would parallel a couple of large 12V batts together (that's in fact what I did).....the more the merrier.

There is no reason that you couldn't parallel a 12V batt with a pair of 6V batts wired in series. They may have slightly different charging profiles but it would likely be minor.

If you use an ACR, you will be paralleling the series wired 6V batts to your 12V starting battery.......
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Old 08-25-2017, 01:05 PM   #15
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Thanks for taking the time to explain, BoyWonder.

So, it sounds like the most flexible path will be to start with two 12v 105Ahr batteries, and make sure there is room in my battery box for a third later if I decide to expand to 315Ahr.

Note to self: make sure the solar controller, etc can handle 300Ahr+ battery bank. Probably means an MPPT controller rather than a PWM .... ?
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Old 08-25-2017, 09:28 PM   #16
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Not necessarily. Your solar controller doesn't care anything about your battery bank, it just sends the proper voltage to whatever batteries you have in order to not cook them. Your solar controller cares about what panels are attached to it though. That's the most important thing.
In my opinion, which is a KISS (keep it simple....) opinion, PWM vs. MPPT is not incredibly important, but if you're going for AGMs you probably want MPPT. Also, I understand your confusion/hesitation after hanging out on the Transit forum for awhile. It seems those guys like to make things overly complex.

Here's a simple system that will work for 2 batteries (+/-) 200 amp hours.

Blue Sky 30 amp MPPT controller:

Blue Sky Energy Inc. | Solar Boost 3000i

200-300 watts of panels. The sky is the limit here, I'll just link what I've worked with mostly. Cheap and effective. Choose as many as you like, I would go for 2-3 with the above controller.

https://www.amazon.com/Renogy-Watts-...enogy+100+watt

10 gauge solar specific wire from panels to controller with 30 amp fuse/breaker in between.

10 gauge from controller to batteries with 30 amp fuse/breaker in between.

2 AGM or deep cell batteries of your choosing. I like what I'm seeing from Duracell lately value-wise.

From chassis battery to house batteries run 4 gauge cable through an ACR (automatic charging relay) WITH a 80/100 amp breaker. I prefer the Blue Sea stuff. It's top notch and not expensive. I get breakers from Amazon these days.

https://www.amazon.com/Asdomo-12V-24...amp+dc+breaker

I just got a Blue Sea 7610 from this place the other day. Lowest price I could find, very quick shipping:

Blue Sea Systems 7611 Battery Link Automatic Charging Relay

Here's how I did my van between chassis and house batteries:



If you want shore power or an inverter the system gets marginally more complex but not much. What I've shown is a simple chassis battery to house battery system to charge your house while driving, and then solar to house batteries to charge while sitting. All for well under $1k including batteries.

Keep in mind your Transit is not really any different than any other car. There's no magic there. It's got a chassis battery and charging system just like any vehicle before it. Just branch off your chassis battery and add what you like.

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Old 08-26-2017, 07:54 AM   #17
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^^^^ what he said.....you can put lots of batteries behind the solar controller...it doesn't care...

One thing a quality MPPT controller allows is the use of a house-type solar panel (open circuit voltage around 37V, 300W...big)......1der has this setup.....using a midinite solar kid controller. MPPT also allows series wiring of two RV type panels, this reduces resistive heat loss since you have less current flows through the wires. Personally for 200-300W of solar power I don't think it's very significant....but YMMV.

PWM controllers need RV type (17-18V or so open circuit voltage) panels...you can have more than one, but need to keep the RV style panels wired in parallel to keep the Voc (voltage open circuit) around 17-18V. You can parallel panels until you exceed the current rating of the controller which is typically around 30A.

I'm happily using a Samlex PWM controller and three panels (2 100W renogy eclipse panels and a 120W kyocera) wired in parallel. I'm also using the Blue Sea 7610 ACR.

Whether you go MTTP or PWM buy a quality controller...Plan on spending at least $140 or more. I've had first hand experience with crappy $30 Chinese controllers frying a 350AH AGM battery bank on the neighbor's RV. Morningstar, Samlex, Midnite Solar, and many others that I can't think of right now......all good stuff..
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Old 08-26-2017, 09:22 AM   #18
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I agree with Eric, your choice of battery does not necessitate you to choose MPPT controller, your choice of panels would be the driving force behind that. You do want to make sure that your controllers output will match the recommended voltages for the specified charging phases. Typically they give you somewhat limited choices, AGM, GEL , Wet cell. Some may give multiple AGM settings, what you want is one that will match whatever battery you choose as close as possible, Some controllers give you the choice of programming those values in, which is even better.

Also when looking for a controller, unless your battery and controller are in the same environment (temperature) I highly recommend a controller that has a battery temp monitor. All those set points your battery manufacturer and controller state are based on ambient temp of 77°F, and will be higher or lower based on temp. Eric's choice of the Bluesky unit supports those things.

The choice of MPPT is really driven by your choice of solar panel, specifically the specified Vmp @STC , this is usually around 16 - 19 for 36 cell and 24 -31 for 60 cells, you may also fine some 40 cell units but they are still in the range of 16-19 volts. In simple terms if you have a 60 cell unit you need to go to a MPPT. If you are using 36 cell units then a PWM unit will most likely be just fine. if your panel is on the higher end of Vmp voltage you may still be able to get benefit out of MPPT.

For MPPT to work it's magic you need to have enough headroom between Vmp voltage and your charge set point, let use 14.4 absorption for the calculations . Using the mentioned renogy panels Vmp 18.9 , Imp of 5.29.
a PWM controller will put out a maximum of 5.29 (minus some cost for conversion) at 14.4. As you can see 14.4 X 5.29 = 76 watts, where did the other 24 watts go, well its here 18.9 - 14.4 = 4.5 volts X 5.29 amps. A PWM controller does nothing to catch the extra head room. So it looks like you are pretty much throwing away 24 watts of power.

In theory the panel with 18.9 Volts X 5.29 amps will give us 100 watts, at 14.4 volts a MPPT controller will give us 100/14.4 or 6.94 amps (again minus some conversion cost, the conversion cost will be higher then what a PWM controller was) so in this case we see a 23% increase. As you would expect a 60 cell panel with a Vmp of of 31 volts would be even higher, which is why it makes it a necessity.

Now when we get back to reality we realize that we don't always have conditions that let our panels produce to their stated maximum test conditions, temperature of the panel brings down the the voltage considerably, and as the headroom get's smaller so does our added value of a MPPT controller. In fact many people like the consistency of a PWM controller, as their output spread will much smaller in variable conditions.

You may also see some MPPT controllers that let you overdrive the controller, or supply more PV panel power the the controller will put out. With vans it is hard to get enough panels to make use of this.

I hope this helps and does not make things complex.

-greg
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Old 08-26-2017, 09:52 AM   #19
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Awesome info Greg. I was hoping you'd chime in. Hopefully Graydawg will see this soon.

Thanks for explaining the PWM vs. MPPT difference. Great info.
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Old 08-26-2017, 11:25 AM   #20
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Quote:
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Now when we get back to reality we realize that we don't always have conditions that let our panels produce to their stated maximum test conditions.......

-greg
...great point that everyone with panels becomes very aware about after installation....

I have 320W of panels on the roof.....and the max I've seen is a bit less than 200W with the sun blaring directly overhead......like 17 amps or so.....which I'm happy with...
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