Date:         Fri, 29 Jul 2011 16:29:39 -0600
Reply-To:     ralph meyermann <ralphmeyermann@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         ralph meyermann <ralphmeyermann@GMAIL.COM>
Subject:      Re: Inverter/Aux Battery question
Comments: To: Rocket J Squirrel <camping.elliott@gmail.com>
In-Reply-To:  <4E33300F.80503@gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

Maybe a blue top marine deep cycle may be better suited for that
application?

On Jul 29, 2011 5:27 PM, "Rocket J Squirrel" <camping.elliott@gmail.com>
wrote:

On 07/29/2011 02:17 PM, Daniel Rotblatt wrote:
>
> Well, I just got back from a trip to Mammoth Lake...

> Hook-up: -brand new yellow top battery

Over-rated battery but people like them.



> -Stock attachement to the starting battery (had to replace the
> relay)

Okay.



> -Inverter hooked directly to the terminals of the yellow top [...]
> about 4' of wire, (I tried ...
Nothing unusual there.



> -Inverter is a 375 watt Tripp-lite (good reviews on amazon).

And you said you got same or similar results with another inverter.



>> -Voltage at the battery (when new) was ~12.7 , with car running
>> it's ~13.6, with car not run...
What's the voltage at the battery with the car not running and no
inverter attached?



> -All the inverters I saw shut off at a little over 10 Volts....

Yup, s'posed to.

There is no way a 375 watt inverter can suck a healthy battery down to 8
volts unless the battery is sick.

So here's my guess: If you see normal charging voltage of 13.6 volts on
the aux battery with the engine running and the inverter connected, but
it sags quickly and heads towards 8 volts once you turn off the engine
with the inverter still attached, then the yellowtop is a goner. Can't
hold a charge.

-- RJS