I have a 99 Suburban that has been having a battery problem. If I leave the
battery connected it sometimes discharges enough to need to be jumped. I
normally use the quick disconnect I put on it every time I shut it down for
any length of time. It was so bad yesterday that I needed to jump it 3
times. I took it to Walmart and the battery was bad, the 3rd one in 2
years. Is it possible that the problem is all in the battery?

Related question, I would like to set up a dual battery system. Instead of
a battery isolator, could I just put in 2 power diodes in the charging
cables?

Mike D.

On Thu, 30 Jul 2009 18:01:49 -0500, Michael Dobony
<survey (AT) stopassaultnow (DOT) net> wrote:

I had a similar problem earlier this summer when the battery in my '01
Blazer wouldn't maintain a charge. My mechanic found that the starter
had a short that was drawing a charge and draining the battery.

Hi Mike
No expert here...I think I would get a small 12V bulb and jumper wires to it
and remove a battery cable and put in series....if bulb lites you know
current is flowing from the battery.
If so, then start putting bulb in series with other circuits to find the
leak to ground.
I think the alternator can leak if it's going bad, but not sure...you can
check with the bulb hookup.
Good luck
Pete

"Michael Dobony" <survey (AT) stopassaultnow (DOT) net> wrote

How long do you let it sit disconnected? Its 10% per month or so
discharge in this state.
Below %50 charge you will get sulfation. A battery maintainer would be
a good investment under these conditions.

Otherwise, there is a short, or a bad load in the system. Or even just a
dirty battery.

I gather by 1999 they figured out that the lead washers on the side
terminal posts compressed to the point the screw caused a leak in the
terminal. Might want to see if there are there and replace them if they
are.


Good luck

If the diode thing would work, the factory would do this. But they don't.
They use a relay.

Best to get a factory shop wiring diagram and connect everything like the
factory does. Use the same size wires, relay, fuses, fusible links, etc.

Best would be if you can find the same vehicle in a wrecking yard and pull
all the wires/fuses/relay for the 2nd battery. (Look at wiring diagram for
what to pull.)

Also you can get an amp meter like this one (enough amp capacity)...
http://www.testequipmentdepot.com/extech/clampmeters/38394.htm

Then measure the amperage draw on the battery and pull one fuse at a time
and see where the drain is.

Or you can get a solar battery maintainer which plugs into your cigarette
lighter...
http://www.siliconsolar.com/12v-solar-battery-maintainer-5_5w-p-16678.html



"Michael Dobony" wrote in message

I think that is Retained Accessory Power - meaning that it stays on for a
bit after you shut off the vehicle.

Also watch it with these fuses. One fuse will frequently go to many
different things. I don't know if it says in the owner's manual everything
each fuse goes to? It does in the GM shop manual though...

"Michael Dobony" <survey (AT) stopassaultnow (DOT) net> wrote

Very possible on a bad battery.
I've had to replace 2 AZ batteries in 3 yrs. due to internal bad connections
in the battery. My fault for buying cheap A Zone batteries but when I needed
one they were open and convenient.
Use a isolator if your going to be starting with the 2nd battery., the power
draw on cranking will blow diodes, that's why most isolators are relay
based. Not too many diodes will withstand several hundred amps of draw.

On Fri, 31 Jul 2009 08:09:49 -0700, Bill wrote:

?????? The second FACTORY battery is for diesels, not gas motors. Relays
cause a good battery to drain into a bad battery. Totally a stupid idea.
Battery isolators keep this from happening by individually charging the
batteries and prevent the good one from draining into the bad one.

On Mon, 3 Aug 2009 09:38:24 -0400, Repairman wrote:

????? The diodes in an isolator go between the alternator and the
batteries, not the battery and the starter. It never sees "several hundred
amps of draw." A 100 amp alternator will only feed a total of 100 amps.

On Fri, 31 Jul 2009 19:14:28 -0400, Stormin Mormon wrote:

been there, done that. Nothing seems to be drawing the power when I test.
It is an intermittent thing. Most days it is fine, then every once in a
while, about 1-2 times a week . . .