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Date:         Tue, 21 Sep 2004 13:40:08 -0700
Reply-To:     Doug in Calif <vanagon@ASTOUND.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Doug in Calif <vanagon@ASTOUND.NET>
Subject:      Re: dual battery isolator / Optima Batteries
Comments: To: Vince S <gipsyflies@COMCAST.NET>
Content-Type: text/plain; charset="iso-8859-1"

Vince, I agree, I had a deep cycle model battery in the drivers well and had it linked at the starter post to the whole system the two batteries went bad in about two years, I believe they were constantly working against each other. Especially when sitting for long periods.

The factory relay is so simple, I dont know why folks feel the need to not use it.

Doug

----- Original Message ----- From: "Vince S" <gipsyflies@COMCAST.NET> To: <vanagon@GERRY.VANAGON.COM> Sent: Tuesday, September 21, 2004 11:47 AM Subject: Re: dual battery isolator / Optima Batteries

> Using stainless screw to bridge the gap is not the best solution. > Stainless steel is not exactly known for good electrical characteristic. > It has very high resistance. This is especially of a concern with the > staring battery. Starter draws upwards of hundred amps and the tiny > contact surface may get so hot that may even melts the lead around it. I > don't recommend performing the top posts removal of the Optima for the > starting battery due to such high current demand unless you can > reconstruct the gap with a very high power soldering iron. > > Combining two batteries of exactly the same brand, model, and age may > work well in most situations but I won't preach it like a gospel. It is > not a recommendation any reputable battery manufacturer would recommend. > > Why not just go with the Westfalia intended relay isolation for a house > battery and the starting battery? Simple, safe, and effective. > > > > - Vince > > http://gipsyflies.home.comcast.net > 1989 Vanagon GL Camper > 1993 Mazda Miata (for sale) > 1996 Land Rover Discovery > 2005 Mini Cooper S > > > > > -----Original Message----- > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf > Of Fin Beven > Sent: Tuesday, September 21, 2004 11:02 AM > To: vanagon@GERRY.VANAGON.COM > Subject: dual battery isolator / Optima Batteries > > > The simple solution is to just combine the two batteries. Use large Ga. > wire (2 ga, minimum). But I believe that it is important that the > batteries be identical. The result is ONE BIG BATTERY. > > To complete the system, add a good volt meter. JC Whitney sells a LED > panel-mount voltmeter which seems reasonably accurate, and which can run > all night while using virtually zero amps. (I actually have an > on-off-on switch on mine, allowing it to operate when the ignition is > on, or directly from the batteries). It actually makes a rather nice > "night-light" at night. > > The system is not idiot proof. It requires that you actually look at > the volt meter occasionally if you are using significant equipment (like > watching a DVD on a computer being powered by an inverter). Depending > on the particulars of your starting system, you should still be able to > safely start and re-charge with "at-rest" votage that has dropped to the > 11.5 range. > > Optima Batteries: This one is not for the faint-of-heart. I decided > that I would prefer to install them in the up-right position, but this > would involve cutting off the top-mounted terminals and attaching to the > side-mounted screw-in terminals. I looked at the renderings of the > Optima Batteries on their website. It appeared that the top-mounted > terminals were a solid piece, such that cutting them off should be no > problem. > > Not So, at least not exactly. > > When I cut off the negative terminal of the first of my two new "yellow > tops" I noticed that the terminal was, in fact, not quite solid. It was > as if there was an inner core (about 1/2 of the overall diameter) and an > outer ring. There was a very small gap between the core and the outer > ring. And I now had ZERO voltage at the screw-in terminals. After some > brief testing (this only seemed to matter on the NEGATIVE terminal) I > determined that there was insufficient contact beteen that inner core > and the outer ring. Believing that I may have destroyed the battery, > and further believing that I had little to lose, I screwed a #4 x > 3/8ths" stainless steel pan-head/phillips head screw into that very > small gap between the core and the outer ring. This seemed to force the > inner core into better contact with the outer ring. Happy with by my > results, I inserted another screw along-side the first, just for good > measure. I then completed the same operation on the #2 battery. > > After a week of camping in the Lake Tahoe / Blue Lakes area that ended > with snow on Saturday morning, I'm satisfied with the results, and with > the Optima Batteries. The installation looks like it was "meant-to-be", > and I detected no lack of voltage using the side terminals. This may be > especially so because I'm using the two batteries. > > Fin Beven > '90 Carat, Custom Camping Conversion > Pasadena, CA > > > > > > ----- Original Message ----- > From: Dennis Haynes<mailto:dhaynes@OPTONLINE.NET> > To: vanagon@GERRY.VANAGON.COM<mailto:vanagon@GERRY.VANAGON.COM> > Sent: Sunday, September 19, 2004 8:07 AM > Subject: Re: dual battery isolator > > > If not a defect, then either you are getting a false reading or the > advertising is misleading. I have seen regular isolators drop that > much > voltage but I was being conservative and my experience shows the 1.1 > to > be normal until things really heat up. Anyway, thanks for proving some > of my points. > > Dennis > > -----Original Message----- > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On > Behalf > Of Gnarlodious > Sent: Saturday, September 18, 2004 9:10 PM > To: vanagon@GERRY.VANAGON.COM<mailto:vanagon@GERRY.VANAGON.COM> > Subject: Re: dual battery isolator > > Entity Dennis Haynes spoke thus: > > From 23 Aug 2004 > > > after they get warm the actual voltage drop is closer to 1.1 volt. > Well, I just installed the Hellroaring model BIC-95150B and I am > dismayed to > se a 1.4 volt drop across the switch at ambient temperature. > > At $174.45 for the high technology and much touted product this is > disappointing. The specs page didn't mention voltage drop. I'll try to > communicate with them about it during the week, maybe it's a defect. > > -- Gnarlie > > > At 90 amps, the isolater is dissapating almost 100 watts. This is why > they > need heat sinks. You are paying for this power. Now, with this voltage > drop, > you are getting less than 13 volts to the batteries and accessories. > Ok, > so > now you can modify the regulator to increase the voltage or use a > remote > sense wire to compensate. At full load the limiting factor of an > alternators > capacity is its own resistance. Thus at full load, it is only slightly > more > than 50% efficient. Yes, 1/2 the power produced is given off as heat > in > the > alternator itself. That is why they have a big fan and they still get > hot. > So, we increase the voltage of the alternator by 1.1 volt so at 90 > amps > the > alternator dissipates an additional 100 watts of heat. Can we say > shorter > life? So at full load, we are wasting ~200 watts of power due to the > use > of > the isolator. Under ideal conditions, 1 HP = 746 watts. Not that you > will > notice but we are wasting .26 HP here. The big issue here is the load > on > the > alternator.


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