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Old 10-10-2017, 10:29 PM   #11
Kiltym
 
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Default Re: Wiring idea for charging house batteries

Yes, familiar with Bruce and Solbian. Good stuff, but pretty pricey as you know.

I looked to find onemanvan's posts about what he did regarding the converter, but have been unsuccessful. Maybe there aren't any...? Or do you know where his info might have been posted?


The other reasoning with the dc-dc charger is that two I posted include built in MPPT solar controller. So when solar is added, I can use the same dc-dc charger already in place. Certainly will add solar in the future, but I still feel there is advantage to adding the dc-dc charger if I can get the converter to supply power also. And it would mean better charging all around, but maybe overkill as you are implying.
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Old 10-10-2017, 10:33 PM   #12
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Default Re: Wiring idea for charging house batteries

"For bigger drains or discharges, driving around with the engine alternator would provide the big amps charging the batteries like."

My hang up is the voltage from the alternator is not high enough to charge the batteries well. I think your solar is doing more then you think when/if you were to drain your batteries down 50%. But based on your usage, this never happens, and in turn, your solar is 100% adequate for your needs and you don't really ever rely on alternate charging sources.
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Old 10-10-2017, 10:42 PM   #13
OldWest
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Default Re: Wiring idea for charging house batteries

Try looking for what OneManVan did on the Yahoo Westfalia group (I have no luck there ever since they changed the format years ago.). As I remember it, he provided detailed diagrams and parts info.

I searched this subforum for the info and could not find.
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Old 10-10-2017, 10:58 PM   #14
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Default Re: Wiring idea for charging house batteries

DC-DC is not overkill if it works for your situation. Different folks, different needs, etc.

Some folks love the gel batteries (and last time I checked years ago, Westfalia was still using gel batteries in the new James Cooks) while others prefer AGM batteries.

I was gung-ho on lithiums for their light weight and depth of discharge, but balked at their high price. Then I learned from OneManVan and others that lithiums are not a drop-in and ignore so lithiums are off my list for now as too many complications.

I and many others thought the Fantastic Fan replacement for the bathroom vent was the cat's meow. But some folks in the Pacific Northwest didn't seem to need or want one.

The rear seat mod for folding down the back portion is my favorite mod thanks to an East Coast Westy owner. But not recommended for folks who seat passengers back there.

Solar does not seem as popular in the Paciific Northwest (let there be light). Probably not cost-effective.

And for many Westy owners who don't boondock extensively or who drive a lot or plug-in when using their Westies, solar doesn't make sense.

Solo travellers find the black tank big enough, but families wanted bigger black tank. I like Foster's composting toilet for more freedom from dump stations.

Several folks have done the VanCompass lift and I'm debating whether worthwhile. TNeuer did.the 4x4 conversion (he does NOT recommend the company).
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Old 10-10-2017, 11:19 PM   #15
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Default Re: Wiring idea for charging house batteries

Another option add-on.

There is a high-idle option which can be retrofitted. Believe Ted and several others may have done.

The high-idle option may be an alternative to the generator (compare to see which is louder).when using the DC-DC charger.

Also, for folks who use the Sprinter air-conditioner and/or the Kerstner rooftop unit.
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Old 10-11-2017, 12:17 AM   #16
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Default Re: Wiring idea for charging house batteries

Here are some links to what I posted on the Yahoo forum back in 2012.

https://groups.yahoo.com/neo/groups/.../messages/9958

https://groups.yahoo.com/neo/groups/...messages/13675

That was five years ago - since then I've realized that some of the modifications I made turned out to be less effective/useful than I'd hoped for... Chalk it up to the high price of education:-)

If I had it all to do over again - knowing what I know now - I would probably run a 6~10 gauge wire from the Mean-Well output directly to the house batteries. There is a fair amount of line loss between the converter output and the house batteries when you take the long way around - at charge currents of around 30 amps I'm seeing a .5~.7 volt drop! And as CptnAl pointed out - a disconnect switch and a Schottky diode would probably be a good idea. Maybe something like this:

http://www.mouser.com/ProductDetail/...%252bFWQ%3D%3D

Be forewarned that even a Schottky diode induces a voltage drop of about .4 volts - which is almost as bad as taking the long way around!

If you crank up the output voltage of the Mean-Well converter to 14.4 then you might not even need the DC to DC converter for a bulk charge.

Leveraging the Mean-Well converters to perform a bulk charge does seem logical on the surface - but there are a few caveats...

To get the most bang for your buck - ie: minimize generator run time whilst maximizing current into battery.

1) It helps to let the house bank voltage drop down to 12.4 or less ( ie: 4 bars or less on central electronic console ). Reason being the acceptance rate of most lead acid batteries is inversely proportional to state of charge. IE the deader it is the thirstier it is...

2) It also helps to crank up the output voltage of the Mean-Well converters. Reason being the acceptance rate is directly proportional to the charge voltage. IE: the higher the voltage the harder you're pushing juice into the battery. The fuller the battery gets the harder you have to push to cram electrons back into their cage:-)

If you can do both of these things you might be able to stuff 30 ah into your house batteries with 1 hour of generator run time. However - this will only get you from about 50% state of charge up to 75% state of charge. Beyond 75% the acceptance rate is so low that it's not really not worth it to keep running the generator.

Herein lie the most compelling arguments in favor of lithium over lead acid! Lithium's will take whatever you have to offer - whether it be 10 amps or 100 amps - from 0% state of charge right up to 100% at a voltage of 13.7~14.1 -

But of course Lithium's have there own caveats - that's another story:-)

John...

Last edited by onemanvan; 10-11-2017 at 03:00 AM.
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Old 10-11-2017, 01:14 AM   #17
Graphite Dave
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Default Re: Wiring idea for charging house batteries

Another choice that works well is to power a pure sine inverter with the vehicle 12 volt system. Use the inverter output to power your 3 stage shore power charger while you drive. The house battery is always charged with the correct 3 stage charge profile. This is actually my backup method of charging if weather forces its use.

My primary charging system is a single 300 watt high voltage panel with a Morningstar Sunsaver 15 amp MPPT solar controller. Solar provides more than enough power for my application in my climate. The original 8D Lifeline 255 amp-hr in the sold Sprinter is still in operation after 8 years. Built the same system for the current Transit conversion.
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Old 10-11-2017, 03:40 AM   #18
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Default Re: Wiring idea for charging house batteries

Thanks for the links and the "reflections" on what you did.

One thing I note is that it appears that you had to circumvent the relay under the seat to get the power to flow to the house bank. I suppose the relay is only engaged by the engine running, and in turn, power will only flow to the house back if the engine is on.

The dc-dc chargers (at least the CTEK one) will perform this function. So I think I would need to permanently circumvent the relay under the seat (no need for a manual switch), and then let the dc-dc charger take care of connecting, and disconnecting the two banks as needed. Not a big deal, but something I did miss in my original thinking.

Being able to adjust the voltage on the main converter unit is good, as 13.25 is not quite high enough for the dc-dc chargers. If that can be raised to 13.8 or so, that would be better. Will have to try it.

Your mention of the voltage drop is a bit surprising to be honest. The cable running to the start battery should be handling 30A without much loss. But I guess there are some connections and relays/switches also involved before the house bank is reached. I would think the dc-dc charger again would help this problem however since it would raise the voltage back up to 14.4 (or whatever was needed).

And, the relay you added to prevent running the A/C on the start battery is also a good idea.

So, I think this will all work, just have to put together the shopping list together.

I think the main decision point for me is driving the van and running the generator would result in the same charge. So having the option to charge from the generator, for $10 worth of parts, seems like a nice add-on.

Your point of just running a cable from the converter to the house bank has some positives as well as it avoids any type of switch/relay installed with the converter, just add the wire, and your done. Not sure why the diode would be necessary, unless the converter is going to "consume" DC power and cause harm somewhere.

Decisions decisions....
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Old 10-11-2017, 04:21 AM   #19
onemanvan
 
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Default Re: Wiring idea for charging house batteries

Ideally there would be an isolation switch inline between the converter output and house battery to be switched on when performing a bulk charge via the converter. The diode could serve as a 'failsafe' in case you forget to turn the switch off after the bulk charge was finished. When the roof A/C is powered by the converter you don't want the house battery in that circuit as a parallel current source. It's difficult to advise as I don't know if you still have the Kissling relay in circuit or if you substituted or are planning to substitute the Kissling with a battery switch.

The majority of the .5~.7 volt drop on my Westy occurs between K52 and the house battery - it appears to be a 6~8 gauge wire - couldn't be more than 10 feet - shouldn't be inducing that much of a voltage drop - it's a puzzle Iv'e yet to figure out. Might need to trace the Mean-Well converter ground.

Last edited by onemanvan; 10-11-2017 at 04:45 AM.
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Old 10-11-2017, 04:58 AM   #20
OldWest
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Default Re: Wiring idea for charging house batteries

Well, my head is spinning so have not gone through these threads which might be interesting.

https://sprinter-source.com/forum/sh...erling+charger

https://sprinter-source.com/forum/sh...erling+charger

https://sprinter-source.com/forum/sh...erling+charger

https://sprinter-source.com/forum/sh...erling+charger
https://sprinter-source.com/forum/sh...erling+charger

https://sprinter-source.com/forum/sh...erling+charger
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