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Wed Jan 06, 2021 7:52 pm

Hi FXR:

Nice to see you`re moving forward on LiFePo4 which I am still `researching`. Up here in the Great White North, we have a lot less local access to LiFePo4 batteries for people, like me, who don`t want to wait. International shipping to Canada is always far slower than to the US, so I often address my packages to Blaine, Washington, just across the border, for speedier pickup. With COVID, this is off the table for now.

So, instead of installing, I have been reading up on LiFePo4 cells and what I have read recently suggests that you and Sodo may eventually have a problem with installing your cells flat. Some of the big-name manufacturers advise against installing LiFePo4 cells flat. Apparently, the electrolyte pools on the lower side of the cells, leaving the upper sides short of electrolyte and causing premature aging. I am also going for 200Ah or 280 Ah and I can`t see a way to use the under-seat space for the profile of these larger cells. I am thinking of installing in the cabinet housing the water tank, next to my
fridge.

Here is a link to the site I found to be well-researched and specifically the segment addressing install orientation of LiFePo4 cells:

http://nordkyndesign.com/assembling-a-lithium-iron-phosphate-marine-house-bank/

The author of that article deals with LiFePo4 installations in blue-water yachts which experience heavy pounding at sea, so he is perhaps more carfeul than we Van folks need to be. But on the install orientation, he states:

``Mechanical Installation
It was once thought prismatic cells could be operated in more or less any position as they do not really contain free liquid. Nowadays manufacturers are a lot more prescriptive with installation position. In most instances, the only acceptable position is upright, vent cap and terminals on top (Sinopoly, Winston). Sometimes it may be acceptable to mount them on edge, with the terminals on the side (CALB). This may vary not only between manufacturers, but also between cell models, so seeking specific guidance is a sensible step if an odd installation position is being considered.

When questioned, Sinopoly indicated that installing the cell in any other position than upright would cause some of the plates to run dry after a while, damaging it. Installing them flat on their side is out of the question in all cases.

The cells must be installed securely in such a way that no movement is possible in relation with each other, or it will stress the terminals and link plates. Prismatic cells should also be clamped together between compression plates as the application of a modest amount of pressure helps with preventing electrode delamination, even more so in the presence of shocks and vibrations as found on marine vessels. It also helps with preventing the internals of the cells from shifting in case of violent shock, which can lead to internal cell short-circuits. Clamping is a common warranty condition from manufacturers. Strapping the cells together is simply not good enough for that matter.

The bank must also be installed in such a way that it can’t shift and nothing can come and short-circuit the cell terminals. This can involve fitting a cover over the cells.``

The 280Ah cells are much thicker than the 100AH units, meaning that the available space for eletrolyte to pool in the lower part of a cell laid flat is that much geater. The interior of these cells has a significant air space above the anodes to accomodate some degree of expansion and this air space is where the elctrolyte can hide when the cell is oriented on the flat. Imagine a flooded lead acid battery laid on its side to envision this.

Just when we all thought the holy grail of high capacity under the driver seat was found . . . :cry:

Having lamented, I should say that 100Ah or possibly 120Ah seems to fit nicely under the driver seat, is still pretty darn good!

The Samba is a great community! Before seeing this whole LiFePo4 series of threads on the Samba, I had no idea how great these power systems are nor any idea of the fast-charging technologies that are developing specifically to serve this battery type. For weekend warriors with a 280 Ah system and a quality DC to DC charger, it wont even be necessary to set up your solar panels.

Wed Jan 06, 2021 8:27 pm

Consider relocating the starter battery from under the passenger seat to the engine bay or a under the bench with a smaller yet high power unit like;
https://www.aircraftspruce.com/catalog/elpages/odysseydry7.php
Then you have two empty bays available to allow 2 big dog LifePO4 to stand up straight on each side.

BK

Wed Jan 06, 2021 8:29 pm

Howesight, good info. My battery will be under the rear bench. The storage under the driver’s seat is for spare parts. I do not know why the fixation that this must be a battery area. Space is space.

Wed Jan 06, 2021 8:37 pm

1988M5 wrote: Consider relocating the starter battery from under the passenger seat to the engine bay or a under the bench with a smaller yet high power unit like;
https://www.aircraftspruce.com/catalog/elpages/odysseydry7.php
Then you have two empty bays available to allow 2 big dog LifePO4 to stand up straight on each side.

BK

Another small starter battery of the same chemistry to allow folks to tweak the alternator voltage to possibly eliminate the expensive DC-DC convertor;
https://antigravitybatteries.com/products/starter-batteries/oem-size/ytx12-16/

BK

Thu Jan 07, 2021 10:24 am

1988M5 wrote: 1988M5 wrote: Consider relocating the starter battery from under the passenger seat to the engine bay or a under the bench with a smaller yet high power unit like;
https://www.aircraftspruce.com/catalog/elpages/odysseydry7.php
Then you have two empty bays available to allow 2 big dog LifePO4 to stand up straight on each side.

BK

Another small starter battery of the same chemistry to allow folks to tweak the alternator voltage to possibly eliminate the expensive DC-DC convertor;
https://antigravitybatteries.com/products/starter-batteries/oem-size/ytx12-16/

BK
Sadly, no good if the temperature goes below freezing. :(

Thu Jan 07, 2021 10:29 am

Howesight, thanks for that. I'm still going to go with the under seat arrangement - every other space in the van has been spoken for. However I'll keep a close eye on the performance, and maybe in time my experiment will inform others.

Clamping the batteries will need to be very carefully considered. There's need for insulation, both thermal and shock, yet ensuring the busbars between the cells don't put any stress on the terminals. I'm considering using braided 'busbars'.

Thu Jan 07, 2021 4:05 pm

Howesight wrote:
Here is a link to the site I found to be well-researched and specifically the segment addressing install orientation of LiFePo4 cells:

http://nordkyndesign.com/assembling-a-lithium-iron-phosphate-marine-house-bank/

Thank you again for that link. I've just spent the last two hours reading through all his articles - and most of the comments and subsequent questions. Very interesting! I'm now mulling over several different methods of securely clamping the cells to add extra rigidity to them while still allowing that assembly to have some shock insulation. Lots of chin-stroking to be done!

Thu Jan 07, 2021 8:41 pm

Very interesting Howesight.

Since I've already done my install....I'm inclined to ride it out, and see if other corroboration to that guy's positions pop up.

It could take time.
And we don't know the severity.
Like do i have degradation after 800 recharge cycles instead of 1000 cycles?
and how much is lost?
We don't even know if these grade B cells are any good anyway.

I guess we just gotta wait for the reports to come in.

Fri Jan 08, 2021 6:21 am

Howesight wrote:

Here is a link to the site I found to be well-researched and specifically the segment addressing install orientation of LiFePo4 cells:

http://nordkyndesign.com/assembling-a-lithium-iron-phosphate-marine-house-bank/

That article is 5 years old. Being ignorant on this type of battery, is it fully releveant or is there newer info?

Fri Jan 08, 2021 12:20 pm

Yowsa.

A single one of those cells @$118/280AH would be a nice addition to my BattleBorn 100AH.

I wonder if it's possible to use the BMS on the BattleBorn for the additional battery or can two batteries linked together that have two separate BMSs?

Fri Jan 08, 2021 12:23 pm

izzydog wrote: Yowsa.

A single one of those cells @$118/280AH would be a nice addition to my BattleBorn 100AH.

I wonder if it's possible to use the BMS on the BattleBorn for the additional battery or can two batteries linked together that have two separate BMSs?
What use would a single cell be?

Fri Jan 08, 2021 12:34 pm

I double-checked the dimensions, and provided there aren't any mistakes made in any published measurements, it looks as though I can fit four of these big cells under the seat in the 'correct' upright position. I might have to raise the seat by 6mm or so, but it is already 20mm below its old height with the removal of the swivel. The new battery will need to have a new cover made of course, as they'd be proud of the existing hole.

Fri Jan 08, 2021 3:57 pm

fxr wrote: What use would a single cell be?

My bad... didn't realize each cell was 3.2V :roll:

Fri Jan 08, 2021 6:00 pm

The Nordkyn Design article is indeed 5 years old, but newer posts on other fora confirm the need to install LiFePo4 cells upright. Having said that, the prices appear to be dropping and even with somewhat reduced life for Sodo's cells, he might still be dollars ahead. Maybe flipping the battery pack over occasionally will limit any damage.

On the various LiFePo4 fora, it seems a current debate is concerned with the torque one should apply to the bolts or other fasteners used for clamping. I don't mean to trivialize the issue by suggesting the discussion is picayune, with attempts to determine the exact psi to be applied to cells. The theory is that high charging (over 90% SOC) and deep discharging (below 10% SOC), especially at higher rates of charing and discharging, causes some displacement of the layers inside the cell which over time reduces capacity of the cell. Restraining the expansion, the theory goes, (like a compression bandage, for example, reduces swelling) reduces damage to those layers. This all makes good sense to me.

But what also makes good sense is the notion that by oversizing your DIY battery (280Ah instead of 100Ah), the depth of most discharges is lessened and the potential damage that clamping is intended to prevent is also lessened. With a 100Ah DIY battery deeply discharged and quickly re-charged, the expansion effects inside the cells are that much greater. This also points to the usefulness of NOT going hog-wild on rapid charging. Just because your 280 Ah DIY battery can be charged at .5C or 1.0C (140 amps or 280 amps respectively), does not mean you should do so. Conservative charge rates (0.2C or 0.3C) will reduce or prevent the expansion and damage that high charge rates cause.

Anyway, as I learn about these units, that is my understanding. I am stoked about this technology and happy to see the positive experiences many volks are having so far. No more fretting about constantly moving my solar panels around to slow-charge my lead-acid battery.

Fri Jan 08, 2021 6:09 pm

Howesight wrote: No more fretting about constantly moving my solar panels around to slow-charge my lead-acid battery.
That will be a huge plus for me!

I'm now told my cells should arrive within the next 30 days. Until then there's nothing much left for me to do, except I've a few things still to acquire - a DCC50S and some wiring bits'n'bobs (wire, fuses, switches, connectors etc).

Fri Jan 08, 2021 6:33 pm

fxr wrote: Until then there's nothing much left for me to do

Liberate two more boxes of Fort Point Beer?

Howesight flipping the batteries periodically is a great suggestion.
But if I flip my batteries (every season?) and they don't degrade after (X) years, then I'll never really "know", and won't have anything to report on.
We need reliable experts to tell us. And someone to tell us which experts are reliable. This is 2020 ! 👀

My DC-DC charger is huge - 60A thats (~?) 60/150=0.4C. Its too big for a van. I wish I got the 40A but much of my charging is less than 7 amps solar = .046C.

Sat Jan 09, 2021 5:23 pm

Sodo wrote: fxr wrote: Until then there's nothing much left for me to do

Liberate two more boxes of Fort Point Beer?

Somehow a couple of boxes of Lagunitas Daytime became available...

There's 7mm clearance to any seat metal from the boxes - I'll raise this to 12mm which should mean at least 14mm room for the actual batteries. Some thin insulation/heating pad might reduce this somewhat, but I can always raise the seat more if I need to.
Quote:
Howesight flipping the batteries periodically is a great suggestion.
But if I flip my batteries (every season?) and they don't degrade after (X) years, then I'll never really "know", and won't have anything to report on.
We need reliable experts to tell us. And someone to tell us which experts are reliable. This is 2020 ! 👀

You are a brave pioneer. ;)
Quote:
My DC-DC charger is huge - 60A thats (~?) 60/150=0.4C. Its too big for a van. I wish I got the 40A but much of my charging is less than 7 amps solar = .046C.
The DCC50S '50A' charger from Renogy looks like it's a maximum of 25A from either solar or alternator if both are connected. I'm going to add a switch on the solar input so that I can get the full 50A charging from the alternator if necessary - though I can't see that happening very often with these 'infinity' batteries! I've just seen Will Prowse's video in the other LiFePO4 discussion thread, and I can't see us ever using anything near the full capacity even after a week's camping under cloudy skies and being profligate with our usage. :D

Sat Jan 09, 2021 6:13 pm

fxr wrote: ....I can't see us ever using anything near the full capacity even after a week's camping under cloudy skies and being profligate with our usage. :D

This "arms race" could start to get kinda silly.
Who camps for a week not running the engine?
Maybe some WBX feller, broken down by the river. Etc.

Weekends are appx 2 1/2 days.
2 days capacity was not enough, and no headroom.
5 days capacity probably is enough for a weekend parked, not running.
There's decent headroom.

If I have 5 days capacity at 150Ah , then I need to run my engine about 3 hours every five days, and then I have "infinity".
36 minutes of engine per day = "infinity."
And I have 100W Solar which makes it something like 10 days (if sunny)

Who camps for 5 days not driving?
Of course it's been done. I've camped a LOT and can't remember the last time I did THAT.
You fellers getting 280AH, you'd better be posting SAMBA camp stories to prove this.

Anyway I was kinda kicking mysef cuz 280 became the new 150 while I was still patting myself on the back for 150.
But I think 150 is still good.
Solar panel scratches a well-known vanagon camper's itch too (like foraging).

fxr if you lay down your batteries we can both commiserate about loss of charge cycles someday, but you won't have to mess with your lid, right?

Sat Jan 09, 2021 6:26 pm

Sodo wrote: []
Who camps for 5 days not driving?
Of course it's been done. I've camped a LOT and can't remember the last time I did THAT.
You fellers getting 280AH, you'd better be posting SAMBA camp stories to prove this.

We've stayed at a couple of places for a week or more. Find a nice isolated beach...

Quote: Anyway I was kinda kicking mysef cuz 280 became the new 150 while I was still patting myself on the back for 150.
But I think 150 is still good.
Solar panel scratches a well-known vanagon camper's itch too (like foraging).

:D I'm sure 150Ah will be more than adequate - but I'm afraid I'm one of those who can't help the occasional impulsive buy, and this was one of those occasions. ;)
Quote:
fxr if you lay down your batteries we can both commiserate about loss of charge cycles someday, but you won't have to mess with your lid, right?
I'm determined to see if I can get this to work. A self-imposed challenge! I enjoy solving problems. ;)

Sat Jan 09, 2021 7:06 pm

Maybe I need to start thinking more like a retired guy...