Date: Wed, 19 Mar 2008 11:48:23 -0700
Reply-To: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Subject: Re: Battery and alternator - generic auto electric
In-Reply-To: <de48c0be0803190616g4ca4a369ka8d022678361f24f@mail.gmail.com>
Content-Type: text/plain; charset="us-ascii"
It's very simple to put a volt meter on your battery to check chrarging
voltage, while the engine is running, from the alternator.
You want to see 13.8 volts DC minimum, and 14.5 max - I like it at 14.5 and
even sell adjustable voltage regulators sometimes to be able to adjust it.
This is an incorrect notion :
"a battery have so little charge that it can draw
enough current away from the alternator to cause the engine to die?:
If the alternator is charging, it will keep proper voltage in a GOOD
battery. If it's not, battery voltage will go down until there's barely
enough current to operate the fuel injection and ignition systems.
If the battery does not easily take a charge- like you know it's low, and
the needle on the charger doesn't' jump up to ( if it's a 10 amp charger )
to say 8 or 9 amps ,the battery might not be any or very good anymore.
'sometimes' they'll recover.
If the battery has sat dead, or strongly discharged, that does permanent
damage to it.
You 'really need' at least a 10 amp charger with a charging gauge on it.
A miniature cell testing hydrometer is inexpensive and a valuable
testing/diagnostic tool. You can identify a bad cell that way.
You could try disconnecting the battery while the van is not in use. The
clock would be the only thing that should be drawing 'key-off' current and
amounts to almost nothing, but short of knowing your charging voltage,
having a good battery in it, and driving it enough with decent charging
voltage , there's not much else you can do right now.
A really good battery can sit 2 months easily and start the van.
If from a full charge, it won't start a week or two later, either battery is
not good, or there is a current draw with key-off.
If you only have a 2 amp charger with no charging scale on it, you can't
tell what's going on really. If you can't read the charging voltage at the
batt. While it's running, you can't really tell what's going on.
There is a very simple test for current draw with key-off, but you need a
test light for that.
My list of basic testing and diagnostic tools :
Digital ( preferably ) volt ohm meter
12 v test light
couple of jumper wires
remote starter switch.
10 amp ( at least ) battery charger with meter on it
small simple battery hydrometer
with those 6 I can thoroughly and quickly identify almost all
charging/starting/battery issues.
Another really nice one to have - I think mine only cost $ 52 - a Battery
Load Tester - I waited decades to own one, but with one of these you can see
if the battery will maintain at least 10.5 volts under load, like while
cranking on the starter, you just connect it to the battery, hold a switch
to one side, watch the volt meter on it and see how the battery can stand up
to steady load.
Another small useful tool - but I use this one about once every 10 years- an
inductive amp meter - you hold it over the starter main battery cable to
check how many amps the starter draws while cranking - 150ish would be fine,
300 would be quite high - indicating a possible very tired starter.
Jumper cables are not on the tool list - those are emergency devices only,
and it is NEVER good to be a jump startER, or a jump startEE.
Scott
www.turbovans.com <http://www.turbovans.com/>
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
mordo
Sent: Wednesday, March 19, 2008 6:16 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Battery and alternator - generic auto electric
I have a generic query about automotive electrical systems. I recently had
the experience of driving with a battery that had a very low charge. Twice I
had the engine die when coasting up to a turn. After rolling to a stop
safely out of traffic, the starter would not turn but a jump start would
immediately kick the engine over.
So, the question is, can a battery have so little charge that it can draw
enough current away from the alternator to cause the engine to die? Or have
I jumped to the wrong conclusion? Another thing I find puzzling is that my
battery seems to be able to hold enough of a charge that it will crank
strong to start the engine once but if I shut it down and try to restart, it
won't turn it over again. I suppose a test of the alternator output is in
order.
Both conditions were cured when I did a slow charge on the battery. But, as
this is not my daily driver, it often doesn't get driven enough to maintain
a healthy battery. I also can't park it any where near an outlet to keep a
float charger on it. So, if I want to maintain the battery's charge, I have
to take it out of the van.
cheers,
--
mordo
1990 Carat
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