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Sprinter RV's & Conversions Talk Common features found in Sprinter RV's and Conversions.


 
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Old 09-27-2016, 07:16 PM   #51
outbound
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Default Re: Another Electrical Thread: Don't let me catch it on Fire!

Quote:
Originally Posted by scooter1942 View Post
...

since you've been pencilwhipped into a frenzy by now scooter, hell, i mights well throw in too!

(since i've put together - from scratch - at least 100 battery systems - aboard boats, typically 40-60foot bluewater cruisers - and with amphour monitors to boot - and despite the opinions of some here, really am an 'expert' in this stuff - at least thats what my customers have told me, noting their satisfaction by paying my hourly rates at upwards of 80bux/hour for my .02 ;)

IMHO?
i would NOT have a switch in the main neg tween the batts and the shunt (the euros do this on boats, but genly speaking, if the vessel is wired correctly, it isnt necessary and if left disconnected? can lead to 'meltdowns' when BIG loads are forced to find their way back to the battery - one way or another, like thru 'common grounded' stuff not run via a neg 'return conductor to the main/engine neg or its buss' - as the ABYC puts it.

(adding) if you're going to have a switch ANYWHERE in the 'primary circuit' (as i prefer to call it), it should be in the main POS conductor, going from the battery to the POS buss.

why there?
because if you sense a 'problem' (as in: the not so sweet aroma of burning plastic) you want to be able
to KILL ALL current flow as quickly as possible (or when one needs to work on stuff that might spark)

would also have the house bank connected directly to the engines neg or its buss (and i always attach the engines main negative directly onto a bolt that mounts the starter to the block = NO voltage drop due to haphazard/halfassed connections via who knows where, or thru rusted metal, sandwiched with gaskets etc)

i also typically connect the PV output to a breaker on the main DCpanel - that way you always KNOW that its hooked up and can easily disconnect it if/when its necessary to see what your background loads are (or work on stuff without sparking anything)

but o/w your basic layout looks pretty good.

now i realize the typical RV system components dont come anywhere near the more robust build of a typical yacht - reason for that would be - and why my airline pilots tend to be my best customers?

if one is 1000miles from the nearest beach out in the middle of the pacific - or cruising at 38000feet, goin 5or600mph - one cant just pull over and look under the hood, if one has a problem with their electrical system.

my specialty (and reputation) being the 'bullet proof' electrical system
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Last edited by outbound; 09-27-2016 at 09:58 PM.
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Old 09-27-2016, 08:49 PM   #52
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Default Re: Another Electrical Thread: Don't let me catch it on Fire!

Perhaps there's fire!

I don't particularly like the Blue Sea ACR. I'll take a 200A relay instead.

Here's the scenario. Engine is off, and disconnect switch by house battery is open. You're solar is still hot and producing power. House power is still HOT! Solar current will back feed through the ACR to the chassis battery. Chassis battery gets charged to 14.7V. Can the engine electronics handle the higher voltage? Can the battery?

If you use the disconnect switch then you MUST disable solar. I personally do not use a disconnect switch. My switch had too much voltage drop. I'll disconnect the battery lead if I want to disconnect and pull the fuse to solar.
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Old 09-27-2016, 09:48 PM   #53
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Default Re: Another Electrical Thread: Don't let me catch it on Fire!

calbiker:

this is precisely why i dont particularly care for the 'auto-magic' schemes involving voltage-sensing relays.

and with a boat type 1-2-both switch, thats MOUNTED IN A LOCATION THATS ALWAYS VISIBLE, one doesnt have to worry about that kind of stuff

its also why i typically connect the PV output to a breaker on the main DC panel (assuming its also always visible, vs buried somewhere under a setee or in a cabinet) - makes it very easy to just flip off the breaker and no more PV

again - this stuff isnt rocket science, mostly just common knowledge on boats (where if one is 1000 miles from land, it MATTERS)
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Old 09-27-2016, 10:29 PM   #54
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Default Re: Another Electrical Thread: Don't let me catch it on Fire!

Perhaps this is a stupid question, but couldn't one just turn off the charge controller, provided it has an on/off button to prevent the solar from providing power to the battery when you don't want it? If not, then it makes sense to have a switch or pull a fuse between the charge controller and the battery.
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Old 09-27-2016, 10:40 PM   #55
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Default Re: Another Electrical Thread: Don't let me catch it on Fire!

Quote:
Originally Posted by scooter1942 View Post
Perhaps this is a stupid question, but couldn't one just turn off the charge controller, provided it has an on/off button to prevent the solar from providing power to the battery when you don't want it? If not, then it makes sense to have a switch or pull a fuse between the charge controller and the battery.
other than they dont typically have an on/off switch?
or having to go hunting for a fuse, that would typically be buried somewhere inconvenient?
or having burnt the fuse, after sparking/bumped into something POS while messing around in that inconveniently located spot the fuse sits?

and/or NOT having a spare to replace it with = why IMHO having a breaker/switch on the main DC panel is the best bet.

but thats the nice thing about this kind of stuff: there's always more than ONE way to do anything...

just my .02
(ps: the only 'stupid question' tends to be the one that doesnt get asked)
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Last edited by outbound; 09-27-2016 at 10:42 PM.
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Old 09-27-2016, 10:45 PM   #56
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Default Re: Another Electrical Thread: Don't let me catch it on Fire!

That may work OK on a boat, but I want to control power sources while I'm driving. You can only do that with a relay. I have the capability to charge house battery from the alternator or solar. In addition I can combine house and chassis battery to start the engine. All from the drivers seat.

To OP: You need a disconnect switch between PV and charge controller. Just don't forget to open the PV switch when operating the battery disconnect. Sparks can fly if you don't! What happens if you open the battery disconnect switch and then start driving? Why do you need a disconnect?

Quote:
Originally Posted by outbound View Post
calbiker:

and with a boat type 1-2-both switch, thats MOUNTED IN A LOCATION THATS ALWAYS VISIBLE, one doesnt have to worry about that kind of stuff
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Old 09-27-2016, 11:00 PM   #57
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Default Re: Another Electrical Thread: Don't let me catch it on Fire!

I didn't realize the ACR was "automatic" - just assumed it was simple solenoid isolator relay. I have to agree, I wouldn't use it, especially with solar and a battery monitor. What you really need starts at $20 and connects to the D+ terminal under the driver's seat.

Have to say I agree with outbound about the PV, although I've already posted this 2x upthread so he's really agreeing with me.

What I disagree with is putting the disconnect on the + terminal. MB puts the start battery disconnect on the negative side, and you want to match this, and that's enough of a reason there to be done with the discussion.

outbound's explanation of current flowing through a disconnected battery makes little sense. If the battery is disconnected, current will not flow through it, either side.

For automotive, the general reasoning for disconnecting the negative side first, is that if a tool is used on a live portion of the plus side, perhaps while doing the disconnect itself, with the minus still connected, and the tool touches metal as it is being used, it will cause a potentially violent short. A heavy duty tool is a horrible fuse. This actually happens a lot and is the reason every repair procedure starts with "remove negative battery terminal"
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Old 09-27-2016, 11:02 PM   #58
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Default Re: Another Electrical Thread: Don't let me catch it on Fire!

cal:

my motto = what ever works best for your app.
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Old 09-27-2016, 11:08 PM   #59
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Default Re: Another Electrical Thread: Don't let me catch it on Fire!

NBB:

i'm not here to sharpen my debate/argument skills, only to share what i've learned thru decades of doing it and to try to give back to the forum anyway i can.

peace.
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Old 10-04-2016, 11:40 PM   #60
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Default Re: Another Electrical Thread: Don't let me catch it on Fire!

Ok, here's an update.

I think I may hold off on charging the house batteries from the alternator/starting battery for the time being. Here's why...in doing some further research, it appears that 2014 and newer Sprinters utilize some wizardry with regard to the 220A alternator. There is also some disagreement as to whether this impacts anything at all, whether it provides very limited charging, a 40A limit etc. etc. I can't find any valid (guaranteed) information that running a wire from the #4 spot at the starter battery, through an 80A fuse to a 120A Blue Sea ACR and then on to a (+)POS buss will work as it should on a 2016 Sprinter given the new "smart" systems in place.

It appears that Sterling-Power has come up with a device that seems to specifically address some of the issues related to MB's new alternator wizardry here...http://www.sterling-power-usa.com/BB...r12vto12v.aspx I've found the 60A model for as little as $380, but that's still a helluva lot more than the $73 Blue Sea ACR! I suppose the one benefit is that it does provide 3-stage charging to the aux battery.

I've already purchased my solar...Renogy 200W kit with 20A MPPT controller. I called Renogy today and asked how much amperage/charge I can expect to receive per day. They said about 80-85Ah of charge daily. Considering my estimated usage is around 50 Ah daily, I thought...hmmm, why bother with the alternator? I'll be running a Maxxair fan, ARB 50qt. fridge, and about 5.5A of LED's provided they're all on at the same time. That adds up to the 50Ah figure, then I'll occasionally need to charge camera batteries but I might do that off the starter battery with my Bestek 300W inverter? I also confirmed that it was no issue upping my battery bank size from 220Ah to 300Ah, so long as I didn't go over 300. Theoretically then, I could go about 3 days without sun and still have sufficient power (at 50Ah/day) without going below 50% discharge.

At any rate, I thought I might give it a try and see how it does. I suspect I could always add charging from the starter battery/alternator at a later date?

What say the hive?
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