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blackglasspirate
Samba Member
Joined: June 24, 2006
Posts: 1612
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 Posted: Fri Nov 20, 2020 10:37 am Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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I'm trying to wrap my head around the wiring setup for BMS/BMV/Etc. and sketched out a quick diagram to get a visual. It's pretty sloppy, partly because I did it while we were driving, but you get the idea.
Do I have the basic wiring correct for hooking up the BMS and BMV? You can ignore most of the wire gauge/fuse stuff, as I was just putting some things in for reference. I'm just wondering more about the paths of the wires, particularly for the BMS/BMV.
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'87 Vanagon GL Westfalia
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shagginwagon83
Samba Member
Joined: February 07, 2016
Posts: 3796
Location: VA/TN
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| Posted: Fri Nov 20, 2020 11:18 am Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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I think it would help if you imagined the cells and BMS as a complete battery.
For example, a battleborn battery is essentially cells and a bms in a plastic box. Also BMV...are you talking like a victron 712 monitoring system?
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Brandon
"Jo Ann" - '83.5 Westfalia EJ22e w/Peloquin
Instagram @joannthevan |
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blackglasspirate
Samba Member
Joined: June 24, 2006
Posts: 1612
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| Posted: Fri Nov 20, 2020 11:26 am Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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Yeah, it's the BMV-712. I'm still not 100% sure I'll install it but a friend gave it to me for free after they redid their setup, so I figured I may as well use it if I can. Not really sure if it's necessary though.
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'87 Vanagon GL Westfalia
IG: @holidayatsee
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DirtyBlueVan
Samba Member
Joined: April 19, 2013
Posts: 122
Location: Oregon
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| Posted: Fri Nov 20, 2020 2:47 pm Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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This might be a stupid question. Can a Lifep04 battery be dropped into place of an AGM battery? I have a 50ah agm under the seat that is at the end of its life, Uses a blue seas relay, has a 100w solar w/ controller. I was under the impression that I needed to swap my equipment around for it to work. But reading into it on gowesty they seem to imply I could drop it in there but I wont get 100% of the performance. Is there any truth to that?
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1989 Syncro Westfalia 2.5 smallcar subie |
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dabaron
Samba Member
Joined: June 21, 2018
Posts: 2559
Location: Philly, mang
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| Posted: Fri Nov 20, 2020 4:34 pm Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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| DirtyBlueVan wrote: |
| Can a Lifep04 battery be dropped into place of an AGM battery? I have a 50ah agm under the seat that is at the end of its life, Uses a blue seas relay, has a 100w solar w/ controller. I was under the impression that I needed to swap my equipment around for it to work. |
yes, you can drop in with a small change in your setup; replace the Blue Seas relay with a DC to DC charger. if you can get one with a voltage sensing relay, you should as it eliminates running a wire to the alt.
the DC to DC charger provides some protection and will automatically stop charging once the battery is full. the Blue Seas relay will keep applying voltage and it will be the job of the BMS to handle it, which is not ideal.
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1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo
BiWerks Design, LLC |
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owokie
Samba Member
Joined: May 21, 2003
Posts: 533
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| Posted: Fri Nov 20, 2020 6:44 pm Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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| dabaron wrote: |
yes, you can drop in with a small change in your setup; replace the Blue Seas relay with a DC to DC charger. if you can get one with a voltage sensing relay, you should as it eliminates running a wire to the alt.
the DC to DC charger provides some protection and will automatically stop charging once the battery is full. the Blue Seas relay will keep applying voltage and it will be the job of the BMS to handle it, which is not ideal. |
Uh, kinda. Most good DC/DC simply have a voltage you set. It doesn't "stop charging" any more than your alternator/blue seas does as the voltage you specify for LifePO4 is very unlikely to be lower than what your stock alt puts out and the "not charging" for either really is only a product of the voltage delta. The advantage over the Blue Seas is throttling of current to a specific amperage and a higher charging voltage than a stock alternator is likely putting out. |
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Sodo
Samba Member
Joined: July 06, 2007
Posts: 9604
Location: Western WA
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| Posted: Sat Nov 21, 2020 9:16 am Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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If you have a 40A DC-DC charger, the charger itself will never pull more than 40A.
But if the start battery is hungry, mega-headlights ablaze, defroster fans on HIGH, then all that stuff is ahead of the DC-DC charger.
In that condition, the alternator load is all that stuff PLUS the 40Amps.
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'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb |
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kguarnotta
Samba Member
Joined: April 01, 2004
Posts: 1160
Location: Woodstock, NH
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| Posted: Sat Nov 21, 2020 5:57 pm Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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ok - I just got my batteries yesterday (120ah). They are super cold from sitting in the UPS truck and then my mud room. The holes on the top look to be M6, I think the batteries in the Will Prowse video look to be M8. Should I be worried about that? is M6 a large enough stud?
I've taken them inside, and have the Tuffiom Power Supply - I think I'll let the batteries sit inside for a while to warm up. They should be ready to take a charge/get balanced tomorrow.
Unfortunately the instructions I got from the charger are not in english...If I understand Will Prowse's video - I see to connect the batteries in parallel, then set charger to 3.65 and let it sit for a long time - until the amps readout says 0.
Do I need to watch this constantly, or should it just stop charging once batteries get to 3.65?
thanks for tips on this...
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-Kevin
Lincoln, MA
'86 Triple Knob Syncro w/EJ22
'78 Westy
'69 Single Cab
'65 Kombi - EZ-Camper |
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fxr
Samba Member
Joined: December 07, 2014
Posts: 2321
Location: Bay area CA
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| Posted: Sat Nov 21, 2020 7:01 pm Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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| kguarnotta wrote: |
ok - I just got my batteries yesterday (120ah). They are super cold from sitting in the UPS truck and then my mud room. The holes on the top look to be M6, I think the batteries in the Will Prowse video look to be M8. Should I be worried about that? is M6 a large enough stud?
I've taken them inside, and have the Tuffiom Power Supply - I think I'll let the batteries sit inside for a while to warm up. They should be ready to take a charge/get balanced tomorrow.
Unfortunately the instructions I got from the charger are not in english...If I understand Will Prowse's video - I see to connect the batteries in parallel, then set charger to 3.65 and let it sit for a long time - until the amps readout says 0.
Do I need to watch this constantly, or should it just stop charging once batteries get to 3.65?
thanks for tips on this... |
If the amps go to zero, then it's stopped charging...
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Jim Crowther
1984 1.9l EJ22 Westy Wolfsburg Edition
Vespa GTS 300 |
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kguarnotta
Samba Member
Joined: April 01, 2004
Posts: 1160
Location: Woodstock, NH
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| Posted: Sun Nov 22, 2020 6:21 am Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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Got it. Can someone explain why we charge at 3.65V - when the cells are rated to 3.2V? or point me to a website that explains it?
Thanks...
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-Kevin
Lincoln, MA
'86 Triple Knob Syncro w/EJ22
'78 Westy
'69 Single Cab
'65 Kombi - EZ-Camper |
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owokie
Samba Member
Joined: May 21, 2003
Posts: 533
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| Posted: Sun Nov 22, 2020 7:56 am Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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| You take them to the steep part of the charge curve (top or bottom) to ensure they're as close to equally charged as possible. On the flat part of the curve voltage may be nearly identical with large differences in SOC. |
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Sodo
Samba Member
Joined: July 06, 2007
Posts: 9604
Location: Western WA
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| Posted: Sun Nov 22, 2020 9:32 am Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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| Quote: |
| You take them to the steep part of the charge curve (top or bottom) to ensure they're as close to equally charged as possible. |
This statement needs a pic. The charge curve could be considered “flat” at 3.65v and 0 amps.
This is a hard subject for new LiFePeople to grasp, but gets pretty easy once understood.
If you want to operate a bunch of individual cells based on a “fully charged” state, ya gotta start with all cells, balanced, from the top.
Think of each cell as a hill that four Skateboarders will race to the bottom.
Four hills.
Four cool dudes/dudettes.
Cool shoes, lingo, hair, everything, all thinkin’ they’re displaying their individuality, unaware of how similar they actually are in a composite sense.
A Grade A group (the coolest!) being even more similar than “grade B” but whatever. With everything some group is always cooler than another.
Unbalanced is like this:
The BMS fires the start gun when the #2 boarder arrives at the top (3.65v) because he’s afraid for that one boarder #2 (not to get overcharged).
Its not a good way to conduct a race but the BMS has safety rules to follow.
If boarder #3 was only halfway up the hill then #3s gonna be at the finish line first, right?
Not going very fast, but taking the win at 90 (Ah).
1,2,4 may have hit 105, 120, and 115 but so what?
The race is called at 90Ah by the BMS, when #2 crossed the line.
With top-balancing, the race start is delayed until all skaters have arrived at the very tiptop, in exactly the same place.
And the next time they all climb the hill, they all have appx the same State Of Charge (SOC).
The BMS is able to give small encouragements, nudges during the climb, so they arrive at the tiptop at the same time.
BMS does this during the climb in case the start gun gets fired before all boarders reach the top.
Think of it this way. The race to the bottom is a win by the one cell with the lowest State Of Charge. If one cell is at 90ah.... thats all you will get.
The BMS will try to help during the NEXT charge cycle.
So next time, the race will start again when #3 arrives at the top.
Boarder #2 wins again at 90.01 Ah
And #1 is in 2nd place at 105.01Ah, but who cares?
The BMS called the race at 90.01 Ah.
This will go on for a long time.
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'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb |
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kguarnotta
Samba Member
Joined: April 01, 2004
Posts: 1160
Location: Woodstock, NH
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| Posted: Sun Nov 22, 2020 10:29 am Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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I think I sort of understand this - what I don't understand is the 3.2V and the 3.6V - ie we are charging these to 3.6V, but they are rated as 3.2v? Why the discrepancy?
If you answered it in your previous post - then I guess I don't understand it at all.
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-Kevin
Lincoln, MA
'86 Triple Knob Syncro w/EJ22
'78 Westy
'69 Single Cab
'65 Kombi - EZ-Camper |
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Sodo
Samba Member
Joined: July 06, 2007
Posts: 9604
Location: Western WA
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| Posted: Sun Nov 22, 2020 11:02 am Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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Your lead-acid start battery is rated at 12.6v
It has 6 cells in series, each rated at 2.1v
2.1v x 6 = 12.6v
Charge voltage is ~13.8
Each cell charges at 2.3v.
2.3v x 6 = 13.8
It can charge faster at 2.5v. ( per cell)
But charging at 2.7v can shorten the cells’ useful lifetime.
Anyway don’t put too much into the numbers, they are ranges, pidgeonholed into “standards” ..
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'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb |
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owokie
Samba Member
Joined: May 21, 2003
Posts: 533
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| Posted: Sun Nov 22, 2020 12:01 pm Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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[quote="Sodo"]
| Quote: |
| The charge curve could be considered “flat” at 3.65v and 0 amps. |
Not really. Apply voltage or load at that number and V goes quickly up or down. The curve ain't "flat" just because you're not moving along it. Are you skateboarders suddenly on a flat street if they stop riding midway down your hill?
You're nicer than I am. This is thesamba not diysolar. Plenty of info already out there for those who care to learn. |
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kguarnotta
Samba Member
Joined: April 01, 2004
Posts: 1160
Location: Woodstock, NH
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| Posted: Mon Nov 23, 2020 3:57 pm Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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The charging is happening, albeit slowly - which is fine, as I'm in no rush.
I've got the charger set to 3.6 - after a little over 24 hours - the amps have decreased from 4.04 to 3.05. If it continues at the same rate - it should hit zero on the 30th...which works fine for me. I could probably speed it up by increasing the volts, but as I'm not in a rush - I think it is safer to keep it slow and steady.
I don't know for sure, but I imagine it is better for battery to charge it slowly?
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-Kevin
Lincoln, MA
'86 Triple Knob Syncro w/EJ22
'78 Westy
'69 Single Cab
'65 Kombi - EZ-Camper |
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owokie
Samba Member
Joined: May 21, 2003
Posts: 533
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| Posted: Mon Nov 23, 2020 6:39 pm Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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| kguarnotta wrote: |
The charging is happening, albeit slowly - which is fine, as I'm in no rush.
I've got the charger set to 3.6 - after a little over 24 hours - the amps have decreased from 4.04 to 3.05. If it continues at the same rate - it should hit zero on the 30th...which works fine for me. I could probably speed it up by increasing the volts, but as I'm not in a rush - I think it is safer to keep it slow and steady.
I don't know for sure, but I imagine it is better for battery to charge it slowly? |
At the rates we're talking, no, charging slowly isn't better or necessary for this chemistry. |
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kguarnotta
Samba Member
Joined: April 01, 2004
Posts: 1160
Location: Woodstock, NH
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| Posted: Sat Nov 28, 2020 9:26 am Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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ok - all fully charged. Then I lieft is disconnected for about 10 hours, reconnected - and it charged a little bit more, but back down to 0 amps.
Now time to study those wiring diagrams, and figure out how to connect mine. I still need to order a BMS and DC to DC charger, and probably a new aux fuse panel...
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-Kevin
Lincoln, MA
'86 Triple Knob Syncro w/EJ22
'78 Westy
'69 Single Cab
'65 Kombi - EZ-Camper |
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bobbyblack 
Samba Member
Joined: May 21, 2015
Posts: 4348
Location: United States, Iowa
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| Posted: Sun Nov 29, 2020 6:39 pm Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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Its been quite a good weekend. Weather outside was great, but I spent the daylight hours in my garage installing my LiFePO4 house batter system. I had a lot of 'thinky time' so the 14 or so hours I was "Working on it [Honey]" should have been more like 6?
Wires are hard. Fear is REAL. Triple checked everything and when I finally set the breaker, and it didn't pop and did power up the fuse panel and inverter, I was relieved.
Here are a few things I did:
Heater pad under battery location (driver side)
Stowed Victron 5A AC charger under driver seat.
Got frustrated sticking my head in the cupboard and decided to make a easily removable sub panel to mount the inverter and fuse panel.
Used some roofing rubber to make a flappy box to both secure and isolate the cells.
And turned on the Reactor!!
D pillar DC-DC charger / Breaker setup. I couldn't figure out how to use the Orion's 'switch' so I added a relay. I ran a blue/white wire along with my #8 up behind the cabinets, and hooked it to the blue wire on the Westy kitchen relay.
Cheers !!!
-bobby
_________________
'87 Westy 'Flossie','86 Westy 'R1','86 tintop GL - Subi2.2 'J2','83.5 stock tintop L 'ZoomBus','74 Karmann Ghia, '63 Notch
Last edited by bobbyblack on Mon Nov 30, 2020 7:43 am; edited 1 time in total |
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dhaavers
Samba Member
Joined: March 19, 2010
Posts: 7756
Location: NE MN (tinyurl.com/dhaaverslocation)
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| Posted: Sun Nov 29, 2020 8:48 pm Post subject: Re: LiFePO4 Batteries: Discussion Thread |
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Looks awesome, BB! 
- Dave
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86 White Wolfsburg Westy Weekender
"The WonderVan"
<EDITED TO PROTECT INNOCENT PIXELS> |
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