# Use 12v trickle charger on 6v battery?



## mightybooboo

Im wondering,could I use a 400 milliamp 12 volt solar charger to trickle charge a 6 volt lead acid battery on my VW without hurting anything?It would be cables direct to battery.

Thanks,

BooBoo


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## Fire-Man

mightybooboo said:


> Im wondering,could I use a 400 milliamp 12 volt solar charger to trickle charge a 6 volt lead acid battery on my VW without hurting anything?It would be cables direct to battery.
> 
> Thanks,
> 
> BooBoo



BooBoo-----I think something will give----maybe battery----In time if it stayed connected a long time, but if you keep the solar charger out of direct sun----it might work. Go for it---keep monitoring battery voltage and water level and report to us in a few weeks. Randy


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## skruzich

Not a good idea. Most likely you will blow the battery up or in the very least boil it. 

Uhmmm you could tap into the 12v by using a resistor creating a voltage drop at the resistor. 

Umm Use ohms law to figure out what resitance is needed to drop the voltage to 6 v.


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## 12vman

Hey BooBoo..
I don't think it would hurt a bit. 400 mills isn't going to make the battery boil much, if any. The internal resistance will hold it down. I would put a diode in there somewhere though..


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## Jim-mi

Ditto the diode,
say that three times fast
Assuming its a "regular" "large" 6v bat. ?

And just smile if the pannel has enough balls to take the bat voltage up to 7 v.


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## mightybooboo

This is the panel.The solaris 6,part of my battery FAQ thread at self reliance forum,if you could look at that too and give me an opinion Im leaning towards the solaris 6 over the solarport 4.4
Randy,havent bought it yet.

http://www.energyfederation.org/consumer/default.php/cPath/1034_1567_1433

these are the connections for it

http://www.ascscientific.com/solar.html

The SR forum thread
http://www.homesteadingtoday.com/showthread.php?t=147480

BooBoo


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## mightybooboo

Jim-mi said:


> Ditto the diode,
> say that three times fast
> Assuming its a "regular" "large" 6v bat. ?
> 
> And just smile if the pannel has enough balls to take the bat voltage up to 7 v.


Its the largest 6 volt automotive size battery they carry,but dont know the specs.

BooBoo


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## 12vman

Hey BooBoo..
Save yourself some money..

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=41144

I've been using two of these for a couple of years now with no problems..
(You still need the diode though..)


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## mightybooboo

12vman said:


> Hey BooBoo..
> Save yourself some money..
> 
> http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=41144
> 
> I've been using two of these for a couple of years now with no problems..
> (You still need the diode though..)


Nope,that wont work,portability as a AA,AAA battery charger is a primary use for this charger.I thought of ebay and a used solar panel from a VW,good prices too but not really the portability Im looking for.

But that HF would be a super trickle charger,I agree.

So,look at the one I listed without the money aspect,and what do you think of it?

Also,Im lost on the diode part,can you talk me thru that completely,part number and installation?

Thanks 12vman and others for your ideas on this,its really appreciated.

Actually,this thing will live on the dash of the motorhome charging the engine battery,and be pressed into AA,AAA charger mode should the need arise,ie camping or CHTF type use.If it can do 6v VW too would be a nice bonus.

Other option is the solarport 4.4(watts) as it is switchable 6/12volt,but at the expense of 1.6 watts charging,which I really want for the AA,AAA charging part,thats a big difference when charging those fella's.
Also,if i get the solarport 4.4 it charges at 2x the milliamps at 6 volt,what would happen to the charging output on the other one(solaris 6,the 6 watts/ 12 volt panel) with a diode?

BooBoo


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## 12vman

I didn't see the whole intent of what you wanted to do. As for the VW, Do you just want a trickle charge to keep the battery topped off during extended storage times?

I would look at it as two seperate issues.. ("VW"-"Small Cell Charger/Camper Trickle Charger").. And plan from that standpoint.

Personally, I would avoid flexible, roll-up panels. Movement and electrical connections doesn't give me a warm, fuzzy feeling inside.

Is it in your intent to be able to move the small cell charger from the camper at will to another location to keep it portable?


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## michiganfarmer

why not buy a spare 6 volt battery, wire the two in series, then put your 12 volt charger on the two batteries. It would give you a spare, keep both charged, and save you from boiling the single 6 volt dry.


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## Ross

I was thinking the same thing Michiganfarmer was, keep a spare 6 v inside where it's warm so you can jump start the cold 6 v. Might be cheaper and easier than any modifications anyhow.


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## WisJim

Yes it will work fine. The panel won't put out more than battery voltage with that small of current output.


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## mightybooboo

Im trying to maximize the use of the portable solar battery charger is all.
I can charge 6 volt lead acid at home with my 120v car charger thats 6/12v selectable,or pull off 6v from the L-16s from the home battery back-up system(ive done that,works pretty slick).

The portable solar would just be another option for the VW 6v,say we were camping and the battery were flat,or grid power were unavailable. 

Lots of good points gentlemen,thanks.Very good points actually,its really appreciated.Brainstorming these things with a group sure helps.

Im going to try the 12 v solar on it,and watch for boiling or water loss issues.
It will probably be a while before I do this though.I need to purchase one,and then get the battery in an area with good solar,not easy at this site.When I do,I will do as Randy asks,and keep an eye on how its going and report back the results.

Good point on the foldable and connections,need some more research on the durability of that panel,though so far all Ive seen are a few good reports on that particular panel,and quite a bit more on Brunton products of the genre.Must look deeper into that,thanks.

This could be a pretty interesting experiment.

BooBoo


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## mightybooboo

I didn't see the whole intent of what you wanted to do. As for the VW, Do you just want a trickle charge to keep the battery topped off during extended storage times?
Not for that vehicle,I would trickle charge the motorhome that can sit for months unvisited.Its at a different location than our house.


I would look at it as two seperate issues.. ("VW"-"Small Cell Charger/Camper Trickle Charger").. And plan from that standpoint.
True


Personally, I would avoid flexible, roll-up panels. Movement and electrical connections doesn't give me a warm, fuzzy feeling inside.
Good point

Is it in your intent to be able to move the small cell charger from the camper at will to another location to keep it portable?
Exactly,primarily used on MH as a trickle charger,then solar charge small batteries as the need arises.

Saw the coolest thing.A guy went on a horseback trip and used Unisolar flexible panels on his horses to charge electronics along the way,now that was a slick setup.Might do something along those lines,under a different circumstance?Yes,way out there planning,but who knows.Something Im enjoying about this is all the possible options,there is a lot that could be done along this line.

Oh,I did see one review where some guy was amazed at how well the solaris 6 held up,said it was a tough little son of a gun.He was a backpacker.I will look deeper into it though.

BooBoo


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## 12vman

BooBoo..

I was looking around and found this link. Many options to choose from for the MH..

http://www.affordable-solar.com/solar.portable.htm

For the V-Dub, I'd just get an El'Cheepo and leave it in there all of the time to keep the battery topped off..

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=44768


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## Jim-mi

Boo, up a ways you said something like "if the bats go flat"...well that little-- what 400ma pannel...?--- is gonna take a very very long time to ever get enough umph back into a "flat" bat. You could be stranded for a couple weeks...lol
Lets see, A quarter amp an hour (roughly) times a 6 hour solar day equals====yup a long time.

On the other side of the coin, those flexible pannels will take a lot more abuse than a glass covered pannel. Something to think about if the pannel is on\off a dashboard. They will be pretty much "kiddie" proof. Yes the kids might pull on the poor wire connections............but theres no glass to shatter.


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## mightybooboo

Jim-mi said:


> Boo, up a ways you said something like "if the bats go flat"...well that little-- what 400ma pannel...?--- is gonna take a very very long time to ever get enough umph back into a "flat" bat. You could be stranded for a couple weeks...lol
> Lets see, A quarter amp an hour (roughly) times a 6 hour solar day equals====yup a long time.


LOL.Guess youre right.Im sitting here at home with 8000+ amp/hrs in L-16s,I forget 400 ma isnt much.Point taken.  

BooBoo


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