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Jake59
Samba Member
Joined: June 13, 2007
Posts: 241
Location: Seattle, WA
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 Posted: Sat Mar 30, 2024 10:51 am Post subject: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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Yes I think we can do this, a DIY 173ah LiFePO4 under driver's seat for less than $400.
We start with 4 X CATL 3.2vdc 173ah cells and a JBD (same as Over-Kill) Smart BMS 4S 12V 100A with UART RS485 and BT dongle. This BMS also has a output for heating if desired. With a DIY setup one must first top balance the cells to 3.65 vdc max or one can just get to 3.50-3.60 as long as the cells are the same.
So I have received the cells and BMS and have done the top balance with a EBC-A40L charger test (more on this unit later). Now the fitting, this is a work in progress as I have swivel seats and I was hoping to place the Renogy DC-DC 50 amp charger under the driver's base so maybe I do need to cut anyway but that is not my intention.
Here are links to the US based supplier.
https://batteryfinds.com/product/us-stock-catl-173ah-lifepo4-prismatic-battery-cells-4pcs/
https://batteryfinds.com/product/jbd-lifepo4-smart...art-rs485/
Here is the setup thus far.
_________________
Curent ride: 87 2WD Westy, 2012 Jetta Sportwagon 2.5S
Past Rides: 62 (23 window) Bus, 64 Ghai convertable, 68 single cab, 72 Super Bettle, 78 Bay window Bus, 84 GTI. |
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OlisGarage
Samba Member
Joined: June 01, 2022
Posts: 240
Location: Indianapolis, IN
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| Posted: Sun May 26, 2024 10:29 am Post subject: Re: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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This looks fantastic, nice work! Thanks for posting!!
How have the batteries been treating you? Isn’t it supposed to be not ideal if the batteries lay on their side?
This seems like the ideal setup. Nice amount of power to keep most fridges going for days and it fits under the hard to access drivers side seat.
_________________
1981 VW Vangagon TDI (in progress)
1984 VW Rabbit Convertible (daily)
2003 VW Jetta Wagon TDI (recovering from a hit and run) |
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Jake59
Samba Member
Joined: June 13, 2007
Posts: 241
Location: Seattle, WA
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| Posted: Sun May 26, 2024 1:45 pm Post subject: Re: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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| OlisGarage wrote: |
| This looks fantastic, nice work! Thanks for posting!! |
Thanks
| OlisGarage wrote: |
| How have the batteries been treating you? Isn’t it supposed to be not ideal if the batteries lay on their side? |
So far I have not come even close to getting them close to discharged. The LiFePO4 batteries are a not required to be maintained in any particular orientation.
| OlisGarage wrote: |
| This seems like the ideal setup. Nice amount of power to keep most fridges going for days and it fits under the hard to access drivers side seat. |
I have bee posting to another battery thread.
https://www.thesamba.com/vw/forum/viewtopic.php?t=788674
Here is a copy of my last post as it was pointerd out the aluminum casting can short out.
danfromsyr's photo
After seeing this I went back and checked and you are 100% correct the aluminum jackets are all connected to the positive terminal of EACH cell
So I rewrapped the cells. These cells came with several .020 composite dividers (see yellow packards) which I had placed between each cell on my initial assembly. But after seeing the possibility of electrical shorting out I took an additional 5 sheets and wrapped the entire outside using Gorilla tape on all the corners.
I also added a layer of black 1/4" PE foam liner to the battery location.
So here is a 172ah DYI LiFePO4 house battery with the 100 amp BMS along with a Renogy 50 amp DC-DC charger all tucked under the driver's swivel base.
The lid is now a little ajar but should lower as the PE foam takes a set but now things are solid and no shifting of the battery is permitted.
danfromsyr, Thanks for the heads up.
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Curent ride: 87 2WD Westy, 2012 Jetta Sportwagon 2.5S
Past Rides: 62 (23 window) Bus, 64 Ghai convertable, 68 single cab, 72 Super Bettle, 78 Bay window Bus, 84 GTI. |
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danfromsyr
Samba Member
Joined: March 01, 2004
Posts: 15351
Location: Syracuse, NY
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| Posted: Sun May 26, 2024 4:54 pm Post subject: Re: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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happy to help and spread the word
maybe it's benign but it's under one's behind.. best to protective wrap these luxurious blue batteries.
it's great to see alot of DIY builds out there..
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| Abscate wrote: |
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Jake59
Samba Member
Joined: June 13, 2007
Posts: 241
Location: Seattle, WA
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| Posted: Sun May 26, 2024 6:48 pm Post subject: Re: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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| danfromsyr wrote: |
happy to help and spread the word
maybe it's benign but it's under one's behind.. best to protective wrap these luxurious blue batteries.
it's great to see alot of DIY builds out there.. |
This is far from a "benign" issue. I have also added a battery cutoff switch down at the seat belt latch. There is an awful lot of energy stored in this little package, just ask a vape smoker who's have them go off in their pocket. Or the airlines for that matter.
_________________
Curent ride: 87 2WD Westy, 2012 Jetta Sportwagon 2.5S
Past Rides: 62 (23 window) Bus, 64 Ghai convertable, 68 single cab, 72 Super Bettle, 78 Bay window Bus, 84 GTI. |
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MarkWard
Samba Member
Joined: February 09, 2005
Posts: 18745
Location: Retired South Florida
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| Posted: Sun May 26, 2024 7:05 pm Post subject: Re: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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| 50 amp DC to DC charger seems high for a stock alternator. What alternators are being used? |
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Jake59
Samba Member
Joined: June 13, 2007
Posts: 241
Location: Seattle, WA
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| Posted: Sun May 26, 2024 7:17 pm Post subject: Re: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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| MarkWard wrote: |
| 50 amp DC to DC charger seems high for a stock alternator. What alternators are being used? |
I believe stock 2.1L alternators were rated at 90 amps.
The Renogy DC-DC charger is capable of taking energy from the alternator once the starter battery is charged and redirect some of the excess to the house battery. As well as charge your starter battery from the solar panels once your house battery is near full charge. Quite the little black box for dealing with two very different battery chemistries.
_________________
Curent ride: 87 2WD Westy, 2012 Jetta Sportwagon 2.5S
Past Rides: 62 (23 window) Bus, 64 Ghai convertable, 68 single cab, 72 Super Bettle, 78 Bay window Bus, 84 GTI. |
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OlisGarage
Samba Member
Joined: June 01, 2022
Posts: 240
Location: Indianapolis, IN
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| Posted: Sun May 26, 2024 8:43 pm Post subject: Re: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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Other users on here have also reported that with the bluetooth module and Renogy app, one can adjust the max charging current to the battery when on alternator power.
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1981 VW Vangagon TDI (in progress)
1984 VW Rabbit Convertible (daily)
2003 VW Jetta Wagon TDI (recovering from a hit and run) |
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 13478
Location: West Coast, USA
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| Posted: Sun May 26, 2024 10:45 pm Post subject: Re: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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| OlisGarage wrote: |
| Other users on here have also reported that with the bluetooth module and Renogy app, one can adjust the max charging current to the battery when on alternator power. |
Yep. Not sure about Renogy, but Victron bluetooth units can ease into the charging to prevent alternator strain on a cold engine too.
Robbie
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One-on-one tech help for your vintage Volkswagen:
www.airschooled.com
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jimf909
Samba Member
Joined: April 03, 2014
Posts: 8166
Location: WA/ID
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| Posted: Mon May 27, 2024 12:01 am Post subject: Re: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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| OlisGarage wrote: |
How have the batteries been treating you? Isn’t it supposed to be not ideal if the batteries lay on their side?
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There are hundreds if not thousands of posts at DIYSolar on 'correct' orientation of LiFePO4 prismatic cells. 100% will agree that terminals up is okay. Many will say that the narrow side up is okay. Fewer will agree that orienting the wide side up is okay. EVE salespeople have told me any orientation is fine with EVE cells but the EVE data sheet doesn't spec acceptable orientations.
I tried to get a definitive answer when building my van's battery but got lost in all the inconclusive information so I built mine terminals up even though it costs me space in the Westy closet. After a year of more contemplation I'll reorient me cells to wide side up to regain the storage space.
The issue isn't short-term performance, it's lifetime cycles that may be compromised. If orienting the batteries wide side up results in 2500 cycles v. 3000 cycles (a 17% reduction) it will be meaningless to me because I'll be shocked if I run these cells to 1000 cycles before changing to different cells for the van. If I do exhaust these cells there will be a dozen cheaper alternatives to replace them with.
(I live off-grid and run two homes on LiFePO4 batteries. The cells for the heaviest consumer, 8 - 10 kWh/ day, are oriented narrow side up. After hundreds of cycles they're operating as expected.
I'd love to hear definitive info on cell life based on different orientations by mfr.
Cells running my house on short sides with 400+ cycles doing fine:
)
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- Jim
| Butcher wrote: |
| This is the main fault with DIY'ers, they get together on these forums and pat themselves on their backs spreading bad information. |
Guilty as charged.
Current: 1990 Westy Camper - Bostig RG4, 2wd, manual trans w/Peloquin, NAHT high-top, 280 ah LFP battery, 160 watts solar, Flash Silver, seam rust, bondo, etc., etc.
Past: 1985 Westy Camper - 1.9 wbx, 2wd, manual trans, Merian Brown, (sold after 17 years to Northwesty who converted it to a Syncro). |
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Chilepines
Samba Member
Joined: October 11, 2022
Posts: 231
Location: New Hampshire
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| Posted: Mon May 27, 2024 5:38 am Post subject: Re: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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I think this is a new world record for capacity under the seat!
Where did the BMS end up? I’m not sure from the pics. Did you add a shunt? Those are quite chunky and mine took a lot of extra space. I also have a fuse on the battery positive which took more space. The wires to the cutoff switch are also huge - how did you get those in there? And then you need a breaker for the DC-DC - is that under the seat?
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White 89 Westy with 2004 Subaru EJ25 and Subarugears 5MT - Betty |
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Jake59
Samba Member
Joined: June 13, 2007
Posts: 241
Location: Seattle, WA
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| Posted: Mon May 27, 2024 12:45 pm Post subject: Re: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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| Chilepines wrote: |
I think this is a new world record for capacity under the seat!
Where did the BMS end up? I’m not sure from the pics. Did you add a shunt? Those are quite chunky and mine took a lot of extra space. I also have a fuse on the battery positive which took more space. The wires to the cutoff switch are also huge - how did you get those in there? And then you need a breaker for the DC-DC - is that under the seat? |
Yes I believe it is. I have absolutely maxed out the height and width so unless they begin making an alternative size this it, at 173ah.
I mentioned not cutting, well that was not completely true, as I did cut the welded bar across the seat base that had the threaded hole for the bolt securing the OEM battery setup.
I also used a hole saw to gain access to where I would screw down the DC-DC charger and the BMS under the swivel base, which was removed to gain more access.
You can see in this photo that I mounted the Renogy supplied 100 amp shunt on the side of the DC-DC charger. Doing so meant I only had to secure the charger to the frame as the space under the swivel base was quite tight.
.
_________________
Curent ride: 87 2WD Westy, 2012 Jetta Sportwagon 2.5S
Past Rides: 62 (23 window) Bus, 64 Ghai convertable, 68 single cab, 72 Super Bettle, 78 Bay window Bus, 84 GTI. |
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1988M5
Samba Member
Joined: January 23, 2016
Posts: 843
Location: Tucson, AZ
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| Posted: Mon May 27, 2024 3:53 pm Post subject: Re: DIY 173ah LiFePO4 under driver's seat w/ no cutting |
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Folks, check out the site jag35.com
He’s a VW electric bus conversion DIY guy and gets his hands on killer deals for the DIY crowd.
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1991 tin top GL
2002 Winnebago Vista. VW VR6 24V Eurovan front clip powered class C 21' RV.
Some BMWs. |
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