diy solar

diy solar

Last fire.. :-(

......

I am curious about this statement.
Why should pre-tinned copper wire be a bad thing????
Pre-tinned copper wire by itself is not a bad thing. It makes soldering on thru holes or pcb pads easier for some. But when the pre-tinned copper wire is crimped on terminals, the soft solder sometimes makes the connection loose over time. If I remember it is a no-no in the aerospace industry.
 
:)
The where soldered into / onto 6mm lugs. (Crimped and soldered, to avoid problems)
Protected with shrink-wrap at the joint...

Crush a wire between washer and terminal is never a good idea.

When you have the busbar strong enough clamped down in the terminal, you are "cutting" the wire.
and when you aren't cutting...
the busbar isn't clamped down enough :)

even when you find the balance, just wiggle the wire a few times and it will snap.
 
Pre-tinned copper wire by itself is not a bad thing. It makes soldering on thru holes or pcb pads easier for some. But when the pre-tinned copper wire is crimped on terminals, the soft solder sometimes makes the connection loose over time. If I remember it is a no-no in the aerospace industry.

The typical marine-grade wire is Tinned factory wire. I don't know the process but by inspection, the "tinning" is very thin and not the result of the hand soldering iron with a roll of solder. I would much prefer marine grade wire that is tinned over the non-tinned wire for solar applications and would not be deterred or have any concern for crimping the thin soft "tinning".

The only thing I like to do is spray some Deoxit into the crimp and the open end of the wire to be crimped just to remove any surface corrosion. A proper crimp is supposed to create a gas-tight seal, but I suppose it will not last forever so a glue-type heat shrink helps to further encase the crimp and prolong the integrity of the gas-tight seal despite any concern of the tinned wire.


If you visualize the individual strands in for example Figure 3, and consider the small amount of thinning on each strand and the compression that should exist in a proper crimp, there is very little weakness that the tinning is going to create. The crimp terminal will create an outer circumference to tightly hold the pinned bundle of wire strands. If the solder is softer than the copper it will be displaced during the crimping process such that nominally the internal pressure of the gas-tight seal is relatively homogeneous with little impact of the thin factor tinning.

If there is still a concern, that could be further mitigated by securing all wires. generally, even a non-tinned wire undergoing flex and motion will pull on the soft copper compromising the gas joint as well. The little bit of marine wire tinning should be inconsequential considering these other best practices.

Ancor Marine Grade Wire and Cable

Manufactured from tinned copper stranding for maximum protection against corrosion and electrolysis. Ultra flexible (Type 3) stranding resists fatigue due to vibration and flexing.

 
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From experience with high amperage equipment, any tinning should only be pure silver. Tin or lead/tin solder is a guaranteed time bomb. Silver has better conductivity than copper. And be absolutely sure it is real silver. If I see tinned terminations, I cut or scrape them before terminating.
 
From experience with high amperage equipment, any tinning should only be pure silver. Tin or lead/tin solder is a guaranteed time bomb. Silver has better conductivity than copper. And be absolutely sure it is real silver. If I see tinned terminations, I cut or scrape them before terminating.
If you rule out "tinning" altogether then you are ruling out most if, not all marine wire which is generally a higher quality wire than automotive wire.
Please be more specific about wire type and what failures you think to occur with thinning or more specifically marine wire.
 
What the picture I referred to was already made stranded wire pre-"tinned" with soft solder(lead) by the user and not wires tinned with something else during manufacture.
 
What the picture I referred to was already made stranded wire pre-"tinned" with soft solder(lead) by the user and not wires tinned with something else during manufacture.
If what you are trying to discourage is, melding solder into the end of a stripped piece of wire before crimping, then I would agree. Compared to for example marine wire, the very thin amount of "thinning" (I do not have a spec) is going to have almost zero mechanical effect on a crimped wire as compared to the uncontrolled melting from a roll of solder. The main point I would make is that crimping a blob of solder is not how you form gas-tight crimps. Wicking a little solder into a crimped joint is distinctly different, however. I am aware of aerospace practices with crimping, but those are much more controlled manufacturing and environmental situations.

However, for a lot of motorcycle applications for charging systems (where there is a lot of sensitivity to corrosion) for what is typically less than 15 amps, I also would recommend soldering connections. If there is a crimp on the connection, I first crimp the bare wires, then wick some solder into the connector side (apply heat here) of the crimped open barrel being careful to wick the heat away to avoid melting the insulation. The main thing is to avoid wicking solder way up the wire which will stiffen the end and make it susceptible to breaking.

Hopefully, for most solar applications, the installer has a decent set of crimpers to form the appropriate gas-tight seals, which you may not have available for working on a motorcycle. If I was doing BMS cable sense wires, I would also do the solder wick after properly crimping the connector end and covering it with glue-filled shrink tubing.
 
Maybe something like this:


After reading about the OP experience I'm going back to review what I should do better for fire supression
Did you ever find a solution to the potential heat problem of a cascading thermal runaway. I've put FR-4 fiber sheets between cells in compression. 16 cells divided 8 and 8 in each of two carbon steel boxes is the plan but I think a .5" ceramic fire board in the bottom of each box might be helpful in dealing with extreme temperature.
 
Did you ever find a solution to the potential heat problem of a cascading thermal runaway. I've put FR-4 fiber sheets between cells in compression. 16 cells divided 8 and 8 in each of two carbon steel boxes is the plan but I think a .5" ceramic fire board in the bottom of each box might be helpful in dealing with extreme temperature.
Your biggest problem is duration.

A fire door has time rating before it gets too hot to hold.
Usually 30 minutes or so.

The selfdischarge usually last longer.

I guess one should be able to calculate how much heat will be released, in joules or what ever you like to use
You know the mass that needs to be heated up, and if correct the heat restrictive properties of the fiber sheets.

Also know roughly the problem zone for LiFePO4, over 80c you get damage. It doesn't like 60C but can do.

Depending on the casing you build for the cells, air ventilation, possible additional cooling ,you can calculate how long it will take before the next cell reaches critical temperature.

In electrical cars they use coolant, not for selfdischarge, it does fix the dangers.

Several (hydrolic) oils have high combustion temperature.
Small DC pump to move the oil around, based on temperature (sensor per cel)
(Water cooling pumps will do just fine)

Depending on the size of the array, you would spread the heat to all other cells.

With 16 cells, that is a lot of mass to heat up! You won't reach the dangerous temperature.

How often does selfdischarge happen?
Especially with cells without any pre-existing problems?

Probably "never"
Neglectable risk.

When you do have some issues, you know you are playing with fire...
Sometimes real fire ?
 
I'm not familiar with oil cooling LiFePO4 batteries. These batteries will ride in a Ford van to power a mini split air conditioner which I'm working to install on the back bumper. Got the solar panels installed last week and I'm waiting for a bumper base to be fabricated. Really glad I bought the steel boxes now after reading potential for fire.
 
I'm not familiar with oil cooling LiFePO4 batteries. These batteries will ride in a Ford van to power a mini split air conditioner which I'm working to install on the back bumper. Got the solar panels installed last week and I'm waiting for a bumper base to be fabricated. Really glad I bought the steel boxes now after reading potential for fire.
:) As long as you don't need to power the engine of your Ford van, additional cooling is not needed.

If you really want to stop affecting other cells when one would go bad and self discharge, thermal runaway.....
That will take a lot of efords. There is a (potential) powerful heatsource.
Not easy to block heat a long time.

Ther iron casing will protect your fan if something would go wrong with the batteries.
Happy that you found a good solution!!
 
I'm not familiar with oil cooling LiFePO4 batteries. These batteries will ride in a Ford van to power a mini split air conditioner which I'm working to install on the back bumper. Got the solar panels installed last week and I'm waiting for a bumper base to be fabricated. Really glad I bought the steel boxes now after reading potential for fire.

So after reading up on various issues with LiFe battery construction for my mobile 200 amp battery I decided on a primarily metal construction to include an aluminum heat sink with a steel compression structure to maintain a 12 psi force across the cells. I also used some G-4 fiberglass on all sliding surfaces and a Hardi board cover. Given the close quarters in a Ford E-350 van, the best you can hope for is a delay in the spread of any fire.

In any event here is my solution, it is a little involved, but I feel the design is sensitive to the various issues of mobile applications and compression related to cell swelling. Unfortunately, my van 1997 E-350 RB was totaled, so this will now be going into a 2000 E-350 EB where I have more room. I will also be using some ceramic fiber insulation:

https://www.amazon.com/gp/product/B07ZQMV5RC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

There is also an accommodation for liquid cooling (on the battery) where I have a cold plate at the base of the battery and a liquid heat exchanger in a 120V dorm refrigerator.

 
Given the close quarters in a Ford E-350 van, the best you can hope for is a delay in the spread of any fire.

How about vent to exterior, and seal the enclosure?
That way noxious fumes are released outside, don't immediately fill van interior.

Primary issue I think of is that it delays you realizing the cells are giving off fumes.
LiFePO4 can spill electrolyte (especially if not upright, Will's experience) or give off some aroma.
If damaged they outgas, usually without burning.
Shorting to surrounding metal, or poor contact of cables while carrying current, would be the likely sources of ignition.
 
How about vent to exterior, and seal the enclosure?
The Sportmobile Forum has a popular addition which is an aluminum storage locker where the OEM spare tire would be located. It is certainly possible to allocate this as a 200-300 amp-hour battery pack.


My 200 Amp-hr battery is getting to be pretty heavy (I have not weighed it) but i assume it is about 75 lbs. Wrestling anything like that below the vehicle is going to need a floor jack.

Ford has frame-hung battery boxes for lead-acid batteries. These are acquired for a simple Group 24 battery 100 amp-hr that ways about the same as the life 200 Amp-hr in a metal dress.
 
Shorting to surrounding metal, or poor contact of cables while carrying current, would be the likely sources of ignition.
This is why for a mobile application I look for some structural vibration isolation in the overall mounting (i.e. a flexible sheet of plywood) and all crimped cables eliminating rigid bus bars.

The cheap grade B cells I bought arrived with some swelling so I'm trying to accommodate what is probably excessive swelling vs SOC.
 
The Sportmobile Forum has a popular addition which is an aluminum storage locker where the OEM spare tire would be located. It is certainly possible to allocate this as a 200-300 amp-hour battery pack.

Maybe a temperature sensor or smoke alarm with remote connection to alert when there is a problem.

If you will use it in freezing locations, insulation and possibly heating could support charging by keeping it above 0 degrees C. Make sure BMS has low temperature charge cutoff.

Ford has frame-hung battery boxes for lead-acid batteries. These are acquired for a simple Group 24 battery 100 amp-hr that ways about the same as the life 200 Amp-hr in a metal dress.

Frame will carry more vibration. Rubber mounts for the box plus battery weight should filter out higher frequencies.
Lining the box with Durock could provide additional electrical insulation and fire resistance. Or maybe something lighter. Rubber sheet and asbestos? Rock wool?
 
Thousands of members are using the cells.
Just a few use the 152Ah cells
The ones who do, I guess I'm the only one with 48 of then.

They are no longer build.
The 120 and 135 are.
Guess why.

At that time it seemed like a good buy.
Sadly pushing 152 in 120Ah housing does has a limit.

Like pushing 350ah in the 280Ah, by simply adding more sheets.

You might be able to build it
And in laser welded casing and bus-bar, it probably will work.

In the "out side of specification" installation we do, it doesn't.

Making parallel is increased difficulty, a lot.

I can only advice people to buy more BMS and build single strand.

2 sells parallel is doable.
3 is really pushing the edge.

And that the cells are already "edge"..

You have the recipe for my troubles.

18 months ago no one talked about not to use the screws, use grubscrew.

Compression was also something a few talked about, nothing serious yet.

And tape a few rolls, isn't compression :)

Sure, I'm sad that I lost my cells.
Also relieved.

After a few mishaps your walking on quicksand, it's not strong anymore and failures cascade.
39 of 160 terminals needed new threads...
That's my quicksand.

Many have seen my failures, and learned from it
Helping them not to make the same "mistakes".

Is it a mistake to use the screws provided by the seller?
Or thinking that you can use the thread 10 times?

Especially... New, uncharted territory.

Now we know.

I wish everyone loads of success.
My build is finished.
And I truly wish it would have been available 18 months ago.

Open your eyes and see what you are playing with isn't build or intended for this.

Yes, it can work.
One installation Only.
No playing around.
Not change location that need to redo the bus-bar and no BMS failur
@Bob B ,

No absolutely not trying to pick a fight with everyone.
People who parrot to tend to P. me off..

When I get called iron plate in my mind... I'm not picking a fight, responding to accusation.
I guess I got drawn in that by @Luthj ....

It's fine to have difference of opinion about using stained steel or not.
Pointing it to "the source" of the fire, without any further knowledge...
And that suddenly seems to be the standard?? Without any proof that it would increase to the dangerous levels that it was claimed...
I guess I got dragged into that by @Supervstech also...

Obviously, I disagree and challenge him to provide proof for his statements.
My multimeter tells he is wrong.
But that can be misinformation also :)

Reason for the fire:
(Choose one or all below)
- cascade of smaller errors in 18 months tinkering
- failure of BMS (3 times)
(No after 3 days wasn't my fault, all units got returned. Yes, 250A Daly can stop after 3 months successful working,
And new 150A Daly smart BMS can not be functional from the start)
- Bad batch of Eve cells (152A)
- too long screws pushing on the bottom, not the bus-bar.
(Adding additional washer fixed this, and no visual damage, no strange electrolyte smell, so not perforated. Still... Something I think should not have happened if the seller would have provided studs
- Thailand!
Heat, moisture, dust, so much dust, rotents, amphibians and insects.
(While insects usually don't make direct (short) damage, their presence does)
- Learning curve.
Many things I can't call an error or accident, but they do add up. Like relocation 4 time, and re-wire of BMS after failure...
Releasing the compression, weak threads, replace BMS wires, clamping again..
till many threads failed.
- not using torque meter at start, and not having the knowledge available how many it should be (3.5-4Nm)
- not using grubscrew, and Loctite, using Loctite without primer
- not compress the cells.
February/March 2020 was "all about" keeping the cells cool and how they best should have space between them...
True for CalB, not Eve....
- use materials available.
That includes uneven length of grubscrew. Why? Because there isn't even size available and post order takes 2-4 months (start Corona time)

I guess that's the whole list :)
Choose what suits you best.

In my opinion, being there, living it, doing it.
Combination of all above.
Not one BMS wire, or rotent.
Perhaps it was damaged and did short.
The type of wire should have made it a small "dent" in the abuse a cell can handle.
With the 18 months past, the drop that made the bucket overflow.

I never thought the cells weren't safe anymore to use.

The cells that got hot in the previous fire, got replaced.
That was smoldering wood on top of the cells (6 got replaced)

Living off grid is also no fire department to safe our ass..
As I don't have a death wish for me or family.
You can be sure that I did not take any more risks then any responsible father would take for his family.
Wow… I think I wandered into a cat fight here… sry…I think I will go watch some Seinfeld re-runs… this is over my head… BTW, I on Will‘s side , whatever he says .good luck to everyone .
 
Wow… I think I wandered into a cat fight here… sry…I think I will go watch some Seinfeld re-runs… this is over my head… BTW, I on Will‘s side , whatever he says .good luck to everyone .
Lol...
If that is the best you can get from this topic..

Yeah, watching seinfield will help you prevent fire ?

Godspeed !
 
Lol...
If that is the best you can get from this topic..

Yeah, watching seinfield will help you prevent fire ?

Godspeed !
I see you totally missed the point i was making… about 10 very smart people were telling you what MAY have went wrong with your build and all I heard from your side was a resistive and somewhat combative denial of what was being said….
I have no interest in witnessing a one sided argument .. lighten up a bit, laugh again.good luck with your build.
bye bye..Jim.
 
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