Date: Sun, 9 Aug 2009 19:44:36 -0700
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: Battery charging question... will this work?
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my thoughts.........
I am not the ultimate battery guru, or aux battery systems charging guru.
but I have read that you are never supposed to run a battery, even a deep
cycle, down to nothing.
Like never take it below about half ......or even below 60 % .
they are not designed to deliver until flat dead.
I'm sure that harms the battery some too.
yes, if you put a dead battery in parallel with some 12 volt battery
......that might work, BUT ....
the dead battery will suck power out of the lantern batteries,
and the charger will get confused seeing two different types of batteries
there.
I had a battery charged in Mexico a long time ago. In an 'old world' type
of shop ......
their method was to put my battery in parallel ( not series I don't think )
with some other battery or batteries, and charge the whole mess of them at a
very low rate, for a long time - overnight.
that worked real well.
I would say that the first issue is running your aux batt dead flat. My
advise is just don't do that,
unless it's a special battery of a different type built to take that.
Normal batteries suffer permanent damage from being run down to dead flat.
They were never designed for that.
As I said, I'm not the ultimate battery guru, but I have a sense of what
works pretty well and running them dead flat is not goof for them at all.
I think a deep cycle battery is just a conventional lead-acid battery with
some small tweaks to make it a little better at putting out moderate levels
of juice for a long period - but they are not radically different than a
starting battery.
They start cars just fine too.
about that 300 amp starter/booster. Yes, I believe it will start you diesel
, with glow plugs, nicely. I think the CCA ( cold cranking amps ) of a
diesel vanagon battery is about 600 ........even up to 800.
Any starting battery that is 800 or 900 CCA for a normal car, and not a huge
truck or something ...........that's a pretty robust starting battery.
A small car would have 300 to 400 CCA.
so it will probably work, but perhaps not at zero degrees F so well.
I like the simple 'the relay closes' the aux battery is being charged,
system.
low tech, but works nicely.
I prefer to do this though .......
I wire in the 2nd battery with regular size battery cable. With a big fat
on/off battery switch on the aux batt.
I start the van up, off the starting battery, then when the alt light is
out, I close the switch. I'm charging both batteries.
and here is why I like that system - if my aux battery is charged up, but I
say, left the lights on , I just disconnect my starting battery ( so it
won't suck power away from the charged up aux battery ) and start of the aux
battery.
once running I connect the starting battery.
if I put a switch on both batteries.....
then I can chose any time which is starting, and which aux.
or start off both in parallel, if individually they are each weak, but
together they are enough.
just one thing to mind ! - always make sure at least one battery is in the
circuit when the engine is running.
it can ruin an alternator to not have a battery in the circuit with engine
running.
that's what I suggest - don't run one down full flat , ever,
and rig up a simple charging circuit for the aux battery.
little related story - my 'new' 85 Adventurewagon. has two batteries and a
battery isolator, which is supposed to automatically switch in the aux
battery after start up, which it does.
Only trouble is....it eats voltage. Without it, I have 13.8 volts charging
voltage on my starting battery.
with it wired to both batteries per the instructions ...........I only get
13 volts, too low, on my starting battery.
Back to the relay or battery switch system !
hope this helps,
Scott
----- Original Message -----
From: "Jim Felder" <jim.felder@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, August 09, 2009 6:58 PM
Subject: Battery charging question... will this work?
> This is related to the question about digital chargers I posted last week.
>
> I was recently camped in the same spot for four days, running lights,
> fans, sink, rechargers, stereo, etc. and finally ran the battery down
> so low it wouldn't run the clock. So low that my digital charger did
> not even sense that it was hooked to a battery. It failed to charge.
> My friends sharing the site pulled out a big analog charger and
> charged my battery right up. But they have a huge van they pull a boat
> with, I don't want to carry a huge heavy charger if I can help it.
>
> This gave me pause to think about what am I really going to
> replace/supplement my charger with? I like the digital charger, and I
> am often in state parks where there is electricity to charge with (but
> not always). I like the lightweight, small digital charger. I am
> wondering if I should get one of those 300 amp boosters they sell
> everywhere, but will that just provide a measurable presence for my
> digital charger, or will it actually run the glow plugs and crank my
> diesel? If it would, I wouldn't mind going for one of those because it
> would cover me even in the woods.
>
> If a 300 amp charger won't do the job, what would be the minimum setup
> to let the digital charger know there is a battery there to be
> charged, and how must it be hooked into the system? I'm thinking of a
> very small 12v battery, maybe two lantern 6v cells, to provide the
> necessary capacity for the digital charger to sense.
>
> What I really need to do is get my second battery and hella relay
> re-installed but what to do till then? And, is there a reasonable way
> of installing a smart charger so that the battery is continuously
> being charged when shore power is plugged in?
>
> Thanks,
>
> Jim
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