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Fogstar 12v DIY kit

Canal321

By Canal321
in General Boating

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Canal321 Collaborator

Canal321

Posted
Posted

Hi.

Just looking up new batteries for when the time comes. Came across these self build lithium kits (Link), work out around half the price of a prebuilt 300ah Fogstar Drift. Has anyone bought one of these and built their own? 

Thanks. 

David Schweizer Veteran II

David Schweizer

Posted
Posted
11 hours ago, Canal321 said:

Hi.

Just looking up new batteries for when the time comes. Came across these self build lithium kits (Link), work out around half the price of a prebuilt 300ah Fogstar Drift. Has anyone bought one of these and built their own? 

Thanks. 

 

I read somewhere that you need rto be qualified to make and set up Lithium battery banks, but do not remember what the qualifictaion involved.

Alan de Enfield Veteran II

Alan de Enfield

Posted
Posted (edited)
16 minutes ago, David Schweizer said:

 

I read somewhere that you need rto be qualified to make and set up Lithium battery banks, but do not remember what the qualifictaion involved.

 

Go on, I'll ask - what is RTO ?

Nothing I find on google looks relevant (Real time Optomiser - traffic light controller, or Recovery Time Objective - how much data a company can afford to lose in a 'crash')

 

OR - reading it again - is there an extra r and it should just read to ?

Edited by Alan de Enfield
Alan de Enfield Veteran II

Alan de Enfield

Posted
Posted
32 minutes ago, David Schweizer said:

 

I read somewhere that you need rto be qualified to make and set up Lithium battery banks, but do not remember what the qualifictaion involved.

 

 

The ISO specification quoted in the RCD / RCR runs to many pages but, in summary, can be covered in these two paragraphs. 

 

TECHNICAL SPECIFICATION ISO/TS 23625 

First edition 2021-03

Small craft — Lithium-ion batteries

 

4.1 All battery system design should be done in a way that ensures all installed lithium-ion batteries
are kept within the battery manufacturers specified safe operating limits.
4.2 There should be a BMS installed to control all installed lithium-ion batteries and maintain the
battery manufacturers specified safe operating limits.
NOTE A BMS can be internal or external to the battery

 

No mention of a 'qualified' installer, I'd be guessing that any such stipulation is coming from the insurance industry.

 

Note :

There is a different ISO specification for 'electic propulsion'  Lithium batteries  installation

 

INTERNATIONAL STANDARD ISO 16315

Corrected version 2021-11

Small craft — Electric propulsion system

magnetman Veteran II

magnetman

Posted
Posted

"1 year warranty on all 12V DIY Kits"

 

Interesting given that their packaged products have a ten year warranty.

 

 

Not sure what grade A and B mean but in the blurb it says 8,000 cycles for the cells yet they only offer a 1 year warranty. 

 

 

The cynic in me says this is a convenient way to sell cells which are going to cause problems. 

 

 

magnetman Veteran II

magnetman

Posted
Posted

I suppose the warranty difference is because with a DIY built system one could charge or discharge at higher rate than recommended and kill it fast.

 

If it it is packaged with a BMS then presumably that limits the current in or out thus keeping the C rate within the recommended range. 

 

 

David Schweizer Veteran II

David Schweizer

Posted
Posted (edited)
1 hour ago, Alan de Enfield said:

 

Go on, I'll ask - what is RTO ?

Nothing I find on google looks relevant (Real time Optomiser - traffic light controller, or Recovery Time Objective - how much data a company can afford to lose in a 'crash')

 

OR - reading it again - is there an extra r and it should just read to ?

 

Why do you do it?  Your subsequent post indicates that you clearly understood my post despite the obvious typo, making foolish comments does you no justice.

 

 

Edited by David Schweizer
  • Greenie 1
David Mack Veteran II

David Mack

Posted
Posted
13 hours ago, Canal321 said:

Hi.

Just looking up new batteries for when the time comes. Came across these self build lithium kits (Link), work out around half the price of a prebuilt 300ah Fogstar Drift. Has anyone bought one of these and built their own? 

Thanks. 

The assembly of a set of components into a completed battery cannot cost Fogstar as much as the components alone. So you are not going to end up with an equivalent product. My guess is that this is Fogstar's way of shifting cells that don't make the grade for their assembled batteries.

  • Greenie 1
Alan de Enfield Veteran II

Alan de Enfield

Posted
Posted (edited)
23 minutes ago, David Schweizer said:

 

Why do you do it?  Your subsequent post indicates that you clearly understood my post despite the obvious typo, making foolish comments does you no justice.

 

 

When I first read it I was trying to understand what the rto was / is and hence went on a search.

I then posted I could not find anything 'sensible'.

 

Reading it again a few minutes later it came to me that it was maybe a typo with an 'extra letter'.

 

So many times folks are posting strange (unknown to me) acronyms and I try to understand them - when I cannot find them, I ask.

It is very unfortunate that the world of texting has led the use of 'non-words'.

Edited by Alan de Enfield
  • Greenie 2
magnetman Veteran II

magnetman

Posted
Posted
41 minutes ago, David Mack said:

The assembly of a set of components into a completed battery cannot cost Fogstar as much as the components alone. So you are not going to end up with an equivalent product. My guess is that this is Fogstar's way of shifting cells that don't make the grade for their assembled batteries.

 

Yes. They are grade B Envision cells. The assembled products contain grade A EVE cells. 

 

Apparently all of the Envision cells have a 1 year warranty. 

 

Not sure what the warranty is on EVE grade A but I expect bare cells will always have a shorter warranty than an assembled product with heating and BMS. 

 

Being able to prevent charging at excessively low temperatures in an assembled product probably helps with the warranty. 

David Schweizer Veteran II

David Schweizer

Posted
Posted (edited)
2 hours ago, Alan de Enfield said:

When I first read it I was trying to understand what the rto was / is and hence went on a search.

I then posted I could not find anything 'sensible'.

 

Reading it again a few minutes later it came to me that it was maybe a typo with an 'extra letter'.

 

So many times folks are posting strange (unknown to me) acronyms and I try to understand them - when I cannot find them, I ask.

It is very unfortunate that the world of texting has led the use of 'non-words'.

 

Alternatively, having realised it was a typo, you could have edited your post to remove the unfortunate comment.

 

 

Edited by David Schweizer
MtB Veteran II

MtB

Posted
Posted
10 hours ago, Alan de Enfield said:

It is very unfortunate that the world of texting has led the use of 'non-words'.

 

I've defiantly noticed this too. 

 

 

MtB Veteran II

MtB

Posted
Posted
25 minutes ago, ditchcrawler said:

It has been going on for years, it use to be I have not I've

 

The inventor of predictive text died the other day. 

 

I've just heard his ... oh, forged it! 

 

 

 

IanD Veteran II

IanD

Posted
Posted
23 hours ago, magnetman said:

 

Yes. They are grade B Envision cells. The assembled products contain grade A EVE cells. 

 

Apparently all of the Envision cells have a 1 year warranty. 

 

Not sure what the warranty is on EVE grade A but I expect bare cells will always have a shorter warranty than an assembled product with heating and BMS. 

 

Being able to prevent charging at excessively low temperatures in an assembled product probably helps with the warranty. 

 

Anybody buying cells that are *admitted* to be "grade B" is asking for trouble, they're likely to be the lowest of the low -- it's well-known that a lot of "grade B" cells (meaning, factory rejects) get re-labelled and sold on as "grade A" by unscrupulous suppliers***, especially cells sourced directly from China, and they can be bad enough -- inability to be balanced, rapid loss of charge...

 

They might be cheap, but you need to think *why* they were factory rejects in the first place, and is answer is unlikely to be that they're functionally sound but cosmetically damaged... 😞 

 

*** not suggesting Fogstar do this, but for sure some other companies do -- and anyone buying cells direct from China is taking part in a lottery that they're unlikely to win... 😉 

cheesegas Rising Star

cheesegas

Posted
Posted
On 10/02/2025 at 10:57, magnetman said:

If it it is packaged with a BMS then presumably that limits the current in or out thus keeping the C rate within the recommended range. 

It's a common misconception I keep on seeing, that a drop-in battery's BMS dynamically limits the charge/discharge current. It doesn't - think of it like two switches, which can stop current flowing in or out of the battery.

 

When it detects that there's too much current flowing in/out, it simply opens the relevant switch, stopping the current flow entirely. It can't dynamically limit the current, it's either on or off as the switch opens or closes.

  • Greenie 1
IanD Veteran II

IanD

Posted
Posted (edited)
1 hour ago, magnetman said:

Yes Fogstar have a page saying exactly that on their website. 

 

Obviously they are claiming to be only selling good grade B cells ! 

If they were good, surely they'd be grade A... 😉 

 

Remember the John West TV ads for tinned fish? ("It's the fish John West reject that makes John West the best!")

 

Unless Fogstar provide each cell with documentation showing what's wrong with each "grade B" cell that stops them being "grade A" I wouldn't touch them with the proverbial bargepole -- and even if they did have such documentation, this assumes the purchaser understands what it means -- which most won't.

 

The only exception would be if the cell had passed all electrical tests as "grade A" but was cosmetically imperfect (e.g. scratched) -- I've bought ex-demo electrical appliances this way at bargain prices in the past with no problems... 🙂 

 

P.S> Yes I know Fogstar say this -- but still with zero information about why "grade B" cells are labelled as such... 😉 

 

https://www.fogstar.co.uk/blogs/fogstar-blog/the-real-difference-between-eve-grade-a-and-grade-b-lifepo4-prismatic-cells

Edited by IanD

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