270ah DIY LiFePO4 build

[Kelpie]

I've seen your posts on two of the forums. It can take a while for the knowledgeable people to pipe up. Keep the conversations there going. If the answer isn't satisfactory ask for clarification. On all forums those quickest to answer aren't always the most helpful. Rod Collins (Marine How To) steps in sometimes.

Yup it's like that old saying, advice on the internet is worth exactly what you paid for it.
Tbh I'm finding this thread to be the most helpful source of information so far.

So in that vein, one more question which so far has gone unanswered elsewhere: is there anything wrong with protecting individual loads using their own relay? This would allow me to run smaller and more readily available relays to each high current load.

 

[Poey50]

Both chemistries are safe, but LiFePO4 is safest. As you said, with the right BMS a Li-ion bank can be perfectly safe, especially if measures are taken to observe safe operating temps. Pricing certainly favors the Li-ion stuff, but you may get 3x the life span out of LiFePO4 cycle-wise, so they tend to be worth the extra money AS LONG AS you foresee using the batteries for many thousands of cycles.

Welcome to the forum!

I'm not sure which post you are responding to or which chemistries you are comparing. LiFePO4 is itself a member of a broader family of lithium ion chemistries as explained in the linked article. It's a less excitable, more reliable member so generally seen as suitable for marine applications - although in truth, no battery is perfectly safe. An LFP accidentally left on charge, with no BMS to disconnect at high voltage, will eventually go into thermal runaway. And even with a BMS a dead short (e.g. dropped tool) across terminals would be an awesome event given the high energy density.

Comparing Lithium-Ion Battery Chemistries | EnergySage

 

[Poey50]

It's remarkably rare that those who sell LFP batteries make clear the limitations of drop-ins for marine installations due to load and charge circuits not being controlled separately by the BMS. This guy gets it.

 

[sailaboutvic]

I be joining the club very soon , order 8 Calb 200ah cells from china .

 

[vas]

how much vic? (delivered to EU I mean) specs, etc?

 

[sailaboutvic]

how much vic? (delivered to EU I mean) specs, etc?

I was going to order them from gr

how much vic? (delivered to EU I mean) specs, etc?

del to EU , 1200USD, DDP, there are 200AH Calb cells express delivery or so they say , we will see .
could had been cheaper if i had them by train upto 60 days

 

[vas]

interesting, is there a cheap dealer in Greece? got any link?

cheers

V.

 

[sailaboutvic]

interesting, is there a cheap dealer in Greece? got any link?

cheers

V.

Not in Greece so çant help you , if you don't want to get them from China there a dealer in Germany who at a pinch can get 200ah Calb cells 8x200 ah for 1350 euros plus shipping

 

[vas]

ok, thought that gr meant greece but you meant germany.
1350, by the time you get a bms et al, you end up with over 1500euro for 200A@24V (ok, you go for 400A@12V)
I'll wait a bit more for the prices to drop further I guess

 

[Kelpie]

The deals I'm seeing at the moment work out at £400 for 4x280Ah cells delivered to UK inc VAT, shipping, and duty. That's not branded CALB cells but it is from a seller with a good reputation on the DIY Solar forum.

 

[Poey50]

The deals I'm seeing at the moment work out at £400 for 4x280Ah cells delivered to UK inc VAT, shipping, and duty. That's not branded CALB cells but it is from a seller with a good reputation on the DIY Solar forum.

That is cheap! Over a 1/3 less than I paid for mine in March. (Aluminiium cased, of course, for that price, compared to plastic cased Calbs.)

 

[vas]

Poey,

other than size and weight, is there anything else wrong with plastic cased cells?
Assume you built a decent case compressing them all together in one big thing.
Talking about 8cells circa 200A (I'm 24V)

 

[sailaboutvic]

ok, thought that gr meant greece but you meant germany.
1350, by the time you get a bms et al, you end up with over 1500euro for 200A@24V (ok, you go for 400A@12V)
I'll wait a bit more for the prices to drop further I guess

I think by the time you buy a good BMS , B2B and other bits you not going to get much change out of 2.5k

 

[Poey50]

Poey,

other than size and weight, is there anything else wrong with plastic cased cells?
Assume you built a decent case compressing them all together in one big thing.
Talking about 8cells circa 200A (I'm 24V)

Plastic cells also cost more than aluminium cased ones but other than these factors I think plastic casing (especially 200ah versions) is more suitable for a marine environment because of potential corrosion issues. These can be guarded against (I hope!) but are a complete non-issue for plastic casing.

 

[sailaboutvic]

The deals I'm seeing at the moment work out at £400 for 4x280Ah cells delivered to UK inc VAT, shipping, and duty. That's not branded CALB cells but it is from a seller with a good reputation on the DIY Solar forum.

I seen cells for 50 USD but how good their are is another thing

 

[sailaboutvic]

Plastic cells also cost more than aluminium cased ones but other than these factors I think plastic casing (especially 200ah versions) is more suitable for a marine environment because of potential corrosion issues. These can be guarded against (I hope!) but are a complete non-issue for plastic casing.

I read a lot over the last six week aluminium cells in marine use not for me , I rather stick to LA .

 

[Kelpie]

That is cheap! Over a 1/3 less than I paid for mine in March. (Aluminiium cased, of course, for that price, compared to plastic cased Calbs.)

Seller is called Shenzen Basen, quite a few people on the solar forum have bought from them and as far as I can tell all very happy.
3.2v 280ah Batteries Cell Prismatic Plate Lithium Ion Battery Lifepo4 280ah - Buy Rechargeable Lifepo4 Battery,Prismatic Lifepo4 Battery,Lifepo4 280ah Product on Alibaba.com
Since I first found them, I see that they no longer specify a shipping cost to the UK. A week or so ago, it was working out at about £320 plus taxes/duty.
(If you enter an EU country as the destination, the cost hasn't changed, so it's probably fallout from Brexit).

 

[nfluester]

The main reason people suggest Aluminium prismatic cased are not suitable for marine is because the terminals are M6 into soft aluminium and the vibration may cause them to strip where as the plastic cased Calb and Winston cells have larger M8 or M10 with deeper threads so a lot more rugged.

 

[Poey50]

The main reason people suggest Aluminium prismatic cased are not suitable for marine is because the terminals are M6 into soft aluminium and the vibration may cause them to strip where as the plastic cased Calb and Winston cells have larger M8 or M10 with deeper threads so a lot more rugged.

The soft aluminium terminals are certainly one reason, especially with smaller cells that sometimes are tapped as small as M4. (These should be avoided, IMHO.) But that can be mitigated by fixing studs into the the M6 terminals with Loctite (rather than using the supplied machine screws) and using a graphite based corrosion inhibiter between busbar and terminal (e.g. Ox-gard) so that over-torquing to get a good contact is not needed. People stripping out the threads of their new cells is a common cry on the DIY Solar Forum alongside messing up the initial top-balance.

But the other concern is that the aluminium case is positively charged and the blue wrapping is a minimal protection (the base of my cells was raw aluminium). So if any water or damp got in that could allow stray currents between positive case and ground, causing electrolysis of the case. There's a photo of this earlier in the thread - cells which, incidentally, were then changed by the R J Energy, the supplier, under warranty despite this being a user error in building and installing.

In my build, shown at the start of this thread, I used thin (0.5mm) fibreglass sheets between and around all cells to add additional insulation and ensured that the cells are in a dry secure place. So although I would prefer plastic-cased it is possible, I think, to manage with aluminium-cased (a large number do judging by the threads on the Lithium Batteries in a Boat Facebook Group) and of course the cost savings and saving of space is considerable.

 

[steveallan]

I be joining the club very soon , order 8 Calb 200ah cells from china .

Hi do you have a link for your supplier?