280ah Lifepo4 Leisure Battery - Build Thread

[Haugen]

Stainless is much more cathodic than aluminum. Better off with zinc plated steel if you are worried about galvanic corrosion. Honestly if you use plenty of loctite thread sealant, you won't have moisture or oxygen present at the interface. In aerospace applications where moisture is present, stainless fasteners are not used in contact with aluminum. Especially 7 series. Physical isolation with a neutral material or sealant, or use of cadmium or zinc plated fasteners is used.

A good quality silicone grease (heavy body) on the contact areas will do wonders.

Sounds like the sermon I've been preaching here the past month or two.
I spent much of my career in avionics where corrosion is an ever present danger. Navy corrosion control school always stuck with me.
I'm going with all aluminum until the lugs and wires. F-16 fighters crashed due to gold sockets being mated to tin plated pins inside "sealed" connectors. I'm keeping the opportunity for corrosion where I can inspect for it.

 

[Mrdanielmh]

Yeah that's not much. I can't use a torque wrench as I am using an hex key to keep the stud from turning while tightening the nut. I am using a nylock nut which would probably mess up the torque reading anyway. The cells will be in a wooden box preventing movement in any direction, and under compression from the end of the pack.

Sorry for posting in this thread, but I feel it is relevant to @Mrdanielmh installation if his cells have M4 terminals, especially in vehicle usage.

Hey there, sorry its taken so long to reply! Im looking at this now and im not sure if the threads are m4! Have you confirmed this?

 

[sduser]

Hey there, sorry its taken so long to reply! Im looking at this now and im not sure if the threads are m4! Have you confirmed this?

I have the 105Ah cells and they are M4. The 280Ah cells may be M6 not sure.

 

[Mrdanielmh]

I have the 105Ah cells and they are M4. The 280Ah cells may be M6 not sure.

Ill have to take a screw out and measure! Im planning to change for threads nuts and lock washer

 

[BenCos18]

I think the bolts would be m4 tbh

 

[Mrdanielmh]

They look pretty wimpy ?

 

[Haugen]

Please see the bottom of page 4 of the attachment. This is the datasheet for the EVE 280Ah cells.
Definitely M6

 

[BenCos18]

Please see the bottom of page 4 of the attachment. This is the datasheet for the EVE 280Ah cells.
Definitely M6

Thanks for that info
I think I got the screw types mixed up as even my cells have the same screw type

 

[Haugen]

Thanks for that info
I think I got the screw types mixed up as even my cells have the same screw type

I also took one of my bolts to the hardware store and confirmed the threads.
The nice thing is, they even give you a torque spec. I'm not sure I believe that I can put 30inlbs on my 6063 bolt, but I'll see what happens at lower torque and work my way up.

 

[tim0shel]

I can confirm that the 280ah cells are M6 I had bolt stainless setscrews for them.

 

[Mrdanielmh]

Upgraded the battery yesterday to all aluminium busbars, nuts and bolts!

 

[tim0shel]

Upgraded the battery yesterday to all aluminium busbars, nuts and bolts!

View attachment 19849

Nice, I see where as the torque specs for the M6 that there are no reasons that you could not go this way. For what you are using it for its plenty of connection. I still have the mix beans with mine of Copper, Aluminum and Stainless Steel.

 

[David Pocock]

Upgraded the battery yesterday to all aluminium busbars, nuts and bolts!

View attachment 19849

I'm sorry to be that guy, but you have used heat-shrink terminals but not heated the shrink to seal it to the cables.

 

[JoeHam]

I'm sorry to be that guy, but you have used heat-shrink terminals but not heated the shrink to seal it to the cables.

Looks like electrical tape to me.

 

[tim0shel]

Looks like electrical tape to me.

No hes talking about the ring terminals. You can buy them that have heat shrink on the ends and just need to apply heat.

 

[redmessengerbag]

Upgraded the battery yesterday to all aluminium busbars, nuts and bolts!

View attachment 19849

why did you upgrade the bus bars, did the xuba ones run really hot?

 

[fafrd]

Upgraded the battery yesterday to all aluminium busbars, nuts and bolts!

View attachment 19849

How much did the aluminum bus bars, nuts and bolts cost you and from where did you source them (especially aluminum nuts and bolts)?

Also, what conductor type are you using for the leads to the BMS and what material is used for the lugs on those leads?

 

[Mrdanielmh]

I'm sorry to be that guy, but you have used heat-shrink terminals but not heated the shrink to seal it to the cables.

Haha, yes i know - its on my to do list!

 

[Mrdanielmh]

why did you upgrade the bus bars, did the xuba ones run really hot?

Not really, however they don't look like they could take many amps and i was concerned about galvanic corroaion.

How much did the aluminum bus bars, nuts and bolts cost you and from where did you source them (especially aluminum nuts and bolts)?

Also, what conductor type are you using for the leads to the BMS and what material is used for the lugs on those leads?

Everything was from ebay UK, probably cost me £15 all in.

 

[Zigzag]

Everything was from ebay UK, probably cost me £15 all in.

Hi, Any links to the ebay items would be great, thanks

 

[Nakedian]

Hello, how is this build going? Did the most recent diagram you posted work as expected? I am interested in building one of these for car camping to power a CPAP machine for several days. I think my current inverter is 750W, 500 running, but I'm not even using that, so very low amps. If anyone who has done this can give me a rough estimate on weight, by my calculations it's looking like roughly 46 lbs. for the batteries alone, that would be great. Also, I will need a charger as I don't have solar panels, so suggestions there also. Help for somewhat of a n00b please. Thanks!

 

[Haugen]

Hello, how is this build going? Did the most recent diagram you posted work as expected? I am interested in building one of these for car camping to power a CPAP machine for several days. I think my current inverter is 750W, 500 running, but I'm not even using that, so very low amps. If anyone who has done this can give me a rough estimate on weight, by my calculations it's looking like roughly 46 lbs. for the batteries alone, that would be great. Also, I will need a charger as I don't have solar panels, so suggestions there also. Help for somewhat of a n00b please. Thanks!

You're about right on the weight. The cells are 11lbs each. By the time you add BMS. Bus bars, bolts, washers, etc., you are probably close to that.
For a charger, there are a lot of different variables. Are you going to charge it every day? How fast will you need to charge? Is this a vehicle system? AC, or DC input?
If you are going to charge it from your vehicle, you will need to boost your voltage and use a charge controller.
If you are talking about AC charging, there are plenty of chargers for lithium batteries out there.
Either way, be sure to think of your future configuration to be sure that it will be compatible with what you ultimately build into your system. Overbuying for your current needs with quality products ensures that you can install them into a larger setup later.

 

[Nakedian]

Not going to charge every day probably only about 10 times/year in summer months. Overnight charge is plenty fast for me. Not a vehicle system and will charge at home before taking out camping. I'd just like to charge this thing and take it camping for a week or so, several times per summer.
So this set up will work huh? I've seen 100Ah builds that cost very similar, so it seems like a good deal. Also, did you buy the same very cheap batteries from the link? Are they any good? Thanks for your quick response.

 

[Mike H]

Hello Mrdanielmh. This is a wonder thread. I am following it as it is very helpful . You do a great job updating. I can't wait to see you finish. I am new to this and love reading everyone's post.

 

[SunSolaris]

This was discussed earlier in the thread about the separate wires coming off the BMS. This is how I dealt with them.
View attachment 18956View attachment 18957View attachment 18958View attachment 18959View attachment 18960View attachment 18961View attachment 18962

FYI many companies uses 2+ cables inside a single "conduit" for better heat dissipation. Tesla supercharger cables have such a configuration.

Based on these 2 calculators :

Wire Combination Calculator

Wire Ampacity Calculator

This wire ampacity calculator will determine the maximum allowable ampacity for a given wire size based on conductor and insulation.

wiresizecalculator.net

If I eye ball the wires from the BSM above at 12AWG, from the first site :

- 3 x 12AWG = 7AWG
- 7AWG cables don't exist, so average between 6 (75A) & 8 (55A) = 65A
- 12AWG = 30A

The original 3 cables could handle 90A and the combined one only 65A.

[edit] just realized the numbers above are for copper but the theory/practice stands for aluminum.