Date: Mon, 22 Aug 2011 14:24:05 -0700
Reply-To: mark drillock <mdrillock@COX.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: mark drillock <mdrillock@COX.NET>
Subject: Re: auxiliary battery wire gauge
In-Reply-To: <FF4E2F66DE0A4EB9A7B93D4E1DA075C1@troyb5bff49d63>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Assuming quality wire, the 8 awg wire is probably all you need. Even 10
awg wire would do the job, just more slowly. Using long runs for the
charging wire means a larger gauge wire is needed to get faster charging
time. You absolutely should charge the rear battery set with a shorter
run directly from the alternator through whatever relay device you
choose. Another option is to beef up the wire from the alternator to the
starter and then charge the rear set from the starter post. Beefing up
that alternator to starter wire is a good idea for all vans with front
aux batteries and all pre 88 vans with or without aux battery.
Marine grade 8 awg is good for 70-80 amps continuous and quite a bit
more than that for shorter time periods. Most of the heavy amp flow is
in the first minute or two of starting the engine or during starting
itself if the batteries are combined to help the starting battery in a
pinch. There is no way to know how many amps will typically flow in your
charging setup other than by measuring. The batteries will only draw a
certain amount during charging no matter how many amps the alternator is
rated for.
Some of the standard VW relays used in Vanagons are rated at 50-70 amps
and one of these can be used with decent size wire to get a well working
aux battery setup without using the clunky monster "solenoid" such as
that purveyed by GW. The radiator fan high speed relay for 86+ with A/C
and the rear A/C fan relay from the same models are stout relays that I
have used for this purpose.
By the way, the 12220 batteries have a checkered history when used in
sets in Vanagons, with various reported early failures of individual
batteries in the sets. Because the package fits well for many
installations people still use them but for installs where that is not a
critical aspect I would use a generic deep cycle from a big retailer
that offered a no questions asked replacement warranty. The mighty W
chain has deep cycle marine batteries and stores all over the continent
if a problem comes up while you are on the road. If you have a problem
with one of their batteries it is best to carry it in for replacement
rather than let them touch your van or see what you are doing with the
battery.
Mark
Troy wrote:
> I just ordered another 5 deep cycle wheelchair batteries (Universal 12220) so that I can get rid of my standard lead acid battery I've been using for the past 3 years, which will bring me up to a total of 7 of this little critters, and should provide lots of reserve power (154 AH) for my DC fridge, furnace, etc. 3 will live behind the driver seat, and then an extra 4 under the rear seat.
>
> I know a lot of list members are using the 1315 Surepower relays, but before I ever knew about them I ordered one of the solenoid kits from Go Westy. I do not plan on using these auxiliary batteries to start the vehicle. If the main ever starts to go, I currently have a switch so that I can connect the main and auxiliary batteries together to trickle some battery back to the main, but again I do not start the van this way, and would break the link before starting.
>
> With that said, is there any reason to use super heavy duty 4 or 6 gauge wire to connect the main and auxiliary? Currently I use an 8 gauge wire (much easier to work with), and have not had any issues that I am aware of. 8 gauge can handle nearly 50amps, so is there any problem here? In a pinch, I probably could start the car if I didn't go more than a few seconds. There is a 50 amp breaker installed anyway.
>
> As to charging the auxiliary batteries from the alternator, what's the maximum amount of current that I would see? I typically charge batteries at no more than 4 amps, using my 3 stage charger. What kind of amps does the alternator put out? I'm just trying to determine why the super heavy gauge wire is needed if you're not using the auxiliary batteries for starting the van.
>
> As to the 2nd set of batteries under the seat, I would think I would be better to use a separate 1315 relay there hooked directly to the alternator, although I guess I could route a wire up to the front. This is the way I currently have things set up, and I believe there is a 10 gauge wire between the two. I will change out this cable, but this one is protected by a 30 amp fuse, so have not been losing sleep over my setup in general.
>
> So, could somebody please advise if this setup is okay or if I need to change things. With new batteries on the way, I want to make sure this is done correctly.
>
> Troy
>
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