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Endopotential
Samba Member
Joined: February 13, 2012
Posts: 186
Location: Pacifica, California
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 Posted: Mon Mar 28, 2022 6:20 pm Post subject: Re: Weekender Auxiliary Battery Upgrade |
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| Sorry I'm out of town. But pretty much yes that's what I did |
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nbrass
Samba Member
Joined: May 06, 2019
Posts: 5
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| Posted: Fri May 20, 2022 8:33 pm Post subject: Re: Weekender Auxiliary Battery Upgrade |
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| nbrass wrote: |
| Endopotential wrote: |
In case anyone is still following this thread, I could never get my '02 cooler to achieve much coldness. What finally did the trick was bypassing the LVD by connecting the two red wires together, as mentioned above.
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Can you post a photo of how you connected the 2 red wires to bypass the LVD? Did you just pull them out of the black box by the fuse, cut off the connectors, strip and wirenut them together? |
I ended up connecting the 2 red wires together with a 10a fuse. The cooler now works, and now I'll just have to make sure I don't run the auxiliary battery down. Thank you Endopotential!
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VanGeek
Samba Member
Joined: September 25, 2022
Posts: 226
Location: New England
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| Posted: Fri Jun 09, 2023 8:02 am Post subject: Re: Weekender Auxiliary Battery Upgrade |
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Just finished checking out the weekender for a long-weekend camping trip where we'll likely spend a fair amt of time inside due to rain. Checked the original 22 year old coach battery and it works but was near-dead. Could only hold just over 12v after sitting on the charger.
Would like to get a LiFoP04 battery and charger but the lower cost and plug-n-play capability of a Walmart 94R AGM battery was appealing. $169 later it fit into the compartment under the driver's seat perfectly. Secured with original mounting hardware and the OEM cables aligned just-right with the posts. Walmart has an excellent 4 year replacement warranty as well: https://www.walmart.com/ip/EverStart-Platinum-BOXE...om=/search
Also pulled my under-seat cooler. Was actually quite clean -- just some lint in the outer head sink and fan blades. Cleaned it all up and tested it -- It gets quite cold in there although didn't measure temp.
I may spring for a 100aH battery, DC-DC MPPT charger, thicker wire between enging compartment and coach battery, etc in the future. But want to run with the lower cost "easy button" solution for awhile to see how it works for us. |
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VanGeek
Samba Member
Joined: September 25, 2022
Posts: 226
Location: New England
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| Posted: Tue Jun 13, 2023 12:01 pm Post subject: Re: Weekender Auxiliary Battery Upgrade |
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UPDATE: Just camped from Fri afternoon thru Monday afternoon. Threw some seltzers, beers, etc in the weekender cooler and let it run all weekend. After reading a lot of complaints here, I didn't expect much.
The cooler performed really well -- all items were very cold and the 80Ah AGM walmart battery easily kept up with it. It was relatively quiet as well. We drove the van every day to trailheads and a few misc local destinations which likely helped with overall performance and battery draw.
So a clean, well maintained cooler without mods and a fresh 94R AGM battery is a very useful solution IMO! |
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Endopotential
Samba Member
Joined: February 13, 2012
Posts: 186
Location: Pacifica, California
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| Posted: Wed Aug 02, 2023 4:29 pm Post subject: Re: Weekender Auxiliary Battery Upgrade |
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| jjvincent wrote: |
The stock harness is fine if you are not going to use the battery that often and using a regular lead acid battery. The main issue is that you just can't get past the wire diameter when it comes to charging the battery. Plus, I know mine had a pretty good voltage drop from the main battery to the coach and then another voltage drop to the 12v cooler.
... Thus, the reason why I rewired it with some old BMW battery cable, a battery isolator . |
@jjvincent @swsl or anyone who has upgraded the wire from the main battery to the coach battery - I see the hole in my floor pan where that cable runs but can't see it from the bottom of the car easily. Seems to exit above the gas tank?
And for installing a battery isolator instead of the relay - is it simply a matter of connecting the two positive leads correctly, along with the small blue trigger wire? there's also a small 4th brown/red wire adjacent in the OEM setup, whose function I don't understand. |
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bigfoot_ev
Samba Member
Joined: March 13, 2018
Posts: 158
Location: Anacortes, WA
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| Posted: Thu Aug 03, 2023 10:45 am Post subject: Re: Weekender Auxiliary Battery Upgrade |
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| @jjvincent @swsl or anyone who has upgraded the wire from the main battery to the coach battery - I see the hole in my floor pan where that cable runs but can't see it from the bottom of the car easily. Seems to exit above the gas tank? |
Here was another post about running an upgraded wire between the start battery and aux/house battery. The short answer is yes, it exits on top of the gas tank. I would definitely recommend upgrading the wire and it's not too hard for any contortionist without dropping the gas tank: https://www.thesamba.com/vw/forum/viewtopic.php?t=781960
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| And for installing a battery isolator instead of the relay - is it simply a matter of connecting the two positive leads correctly, along with the small blue trigger wire? there's also a small 4th brown/red wire adjacent in the OEM setup, whose function I don't understand. |
The isolator I installed had it's own wiring requirements which were as simple as you mention with no trigger wire. My point being that each isolator might be different so you just need to adapt to what it needs. If I recall correctly, under the driver's seat are 3 OEM wire functions. The cooler, the rear fluorescents, and the rear 12V outlets. Would the brown/red wire run the rear fluorescent? You could always unplug it and see what doesn't work. |
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VanGeek
Samba Member
Joined: September 25, 2022
Posts: 226
Location: New England
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| Posted: Thu Aug 03, 2023 2:57 pm Post subject: Re: Weekender Auxiliary Battery Upgrade |
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Can anyone confirm the OEM wire gauge from main battery to aux battery? I'm guessing it is 10ga but not certain.
If yes, most wiring charts suggest a 10ga wire can easily support a 30amp load for 12 to 13 feet and 50amps for 7 to 10 ft. Just guessing, but the cable run from engine compartment to under the seat is very likely well under 10 ft.
I THINK my new H7 AGM battery probably accepts a max charge current of about 8 amps. A LifePO4 battery can accept far more charge current but would be limited by the DC to DC charger and I would likely limit to 30 amps anyhow since that's still a fast charge and I wouldn't want to load the alternator too much.
If this is correct, is it worth upgrading the cable? Seems very little value for a weekender 80ah agm battery and smallish value for a weekender 100ah lifepo4 battery limited to 30 (and possibly 50?) Charging amps. |
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bigfoot_ev
Samba Member
Joined: March 13, 2018
Posts: 158
Location: Anacortes, WA
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| Posted: Thu Aug 03, 2023 9:09 pm Post subject: Re: Weekender Auxiliary Battery Upgrade |
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I tried to find the charging circuit in the bentley wiring diagram but no luck. I'm not sure where they have the weekender wiring in all those diagrams. So, I went out to my van, a 2003, since I still have the original wire that is used to charge the aux battery. I would guess the size to be at least 10 AWG. I compared it to a 8 AWG wire, not that big but close.
I think most everything you say is valid. The OEM wire should definitely be good for 30 amps. I don't think I would be comfortable with 50 amps. My only caveat would be to consider all loads concurrently. For instance, if you had a DC-DC charger rated at 30 amps and you were running other dc loads while charging you might want a little more overhead.
For me, upgrading the wiring came down to 2 considerations 1) what is the voltage drop at max current load (meaning I want little to none) and 2) future proof for a lifepo4 battery bank. One other thing to consider, even if you keep the OEM wiring, is a circuit breaker on the charging wire at the alternator end. |
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Endopotential
Samba Member
Joined: February 13, 2012
Posts: 186
Location: Pacifica, California
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| Posted: Thu Aug 03, 2023 9:16 pm Post subject: Re: Weekender Auxiliary Battery Upgrade |
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Hey Bigfoot, thanks for finding that battery cable thread for me, I had missed it in my search.
I too wonder if the standard 10ga cable is sufficient for my humble needs - just to power the 12v fridge for 1-2 nights, with the aid of a solar panel.
In regards to the battery isolator, here's the existing wiring for the 426 relay on my '02 Weekender. The blue one is active with ignition on, so guessing that's the trigger. Anyone know what the adjacent little red wire does?
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