lustyd
Well-Known Member
He’s a reseller, I doubt he knows a lot of detail. If he was involved in the design and manufacture it’s unlikely he could have done so from an AWB mid Atlantic.
Lithium and fuses
- Thread starter wazza
- Start date
pandos
Well-Known Member
To be fair to the guy I don't think he was always on an awb mid Atlantic. He claims to be a cofounder of Dakota Lithium.
lustyd
Well-Known Member
I watched their whole series, they were at sea when it started and he didn’t take time out to go and design batteries. He certainly is a cofounder I wouldn’t disagree there, and he’s a nice guy too but I don’t think he’s an electrical specialist. Probably good at running the business though.
noelex
Well-Known Member
The company had these for sale at one stage, although it was something you could DIY with copper bar and a suitable T class fuse holder. I agree they look like a good solution especially for larger batteries.
Below is a photo from their ad. They are no longer listed on the website (maybe they are just out of stock), but the photo may help anyone who wants to go the DIY route:
This is the website:
Electrical - Fuse Blocks & Fuses
Last edited:
pandos
Well-Known Member
That's a very interesting bit of research...can't claim I understood or even read all of it but the short circuit part is pretty self explanatory.
I am going to go with 150A class T fuses in holders fitted directly on the batteries as in the video in #59.
Mousser Electronics sell these with holders cheaper than MRBFs so a no brainer for me.
Guess it is better to move slowly in case one is going in the wrong direction..
noelex
Well-Known Member
That should be a good solution.
It is the T-class fuses themselves (rather than the fuse holder) that is often expensive. Do Mousser have a good price on the fuse or just the fuse holders?
Also be aware that unlike some other fuse types, such as ANL fuses T class fuses are different sizes depending on the amperage rating:
Length: 61.9mm (110-200A), 69.9mm (225-400A), 77.8mm (450-600A)
Bolt hole size: 8.7mm (110-200A), 10.3mm (225-400A), 12.3mm (450-600A)
The fuse holder has to be the appropriate size for the amperage rating you wish to use.
Last edited:
pandos
Well-Known Member
noelex
Well-Known Member
Thanks for the link in my region they are still expensive.
€167.72 For a 300A T class fuse.
Last edited:
Sea Change
Well-Known Member
I was paying £50 for a class T and £5 for MRBF, so I'll admit that did sway my decision a little...
pandos
Well-Known Member
There's a 325Amp fuse and holder for just shy of 50 euros. I am going to use 125Amps for 37 euros..including holder
what region are you?
noelex
Well-Known Member
We are in the Caribbean at the moment. For reference the cost of a 400A T class fuse is typically around $40 from Amazon USA. There are likely cheaper sources, but I have not done any serious shopping.
Last edited:
john_morris_uk
Well-Known Member
The problem is Amazon don’t deliver to many places in the Caribbean. In St Martin can get stuff sent to an address in Miami and ‘Business Points’ gets it shipped over for a relatively small fee. It takes a week or so.
RogerJolly
Well-Known Member
12V planet are have separate listings for 'Cube Fuses' at £5 and 'MRBF fuses' at double the price. Dangerous potential for confusion? Not sure if the two are physically compatible, but I wouldn't want to be fitting the cheaper one thinking it up to MRBF spec (am assuming it's not).
geem
Well-Known Member
They can't. As the battery Ah rating goes up, so doesn't the aic fusing requirements. There is lots of evidence from smarter people than me that the short potential on a 100Ah lithium will generate circa 1000A or so. This is well within the capability of low AIC fuses. Put together a 16 x280A cells and you are in totally different territory.
noelex
Well-Known Member
Thanks John.
Agreed, it is the place for parts and deliveries.
RogerJolly
Well-Known Member
I have a low current domestic system scaled around just powering instruments, radio, lights etc.
Has appropriately low power BMS (JDB, 60A maybe) and thin wires. Charged by Victron 20A DC-DC charger. 100Ah LifePO4 battery. Fitted with 40A MRBF fuse. Fusing on domestic side is just as it was before LifePO4, apart from fuse on battery.
Hence low fuse current requirement. Bit frustrating when Class T won’t go low enough. Seems like I’m in a minority of one. Class T would be 20x over-specified if reports of 1000A peak current above are true.
Hopefully the regs do/will accommodate my situation. Will think about trying to look up exactly what regs say.
noelex
Well-Known Member
Your particular installation will help reduce the required IC rating.
The thin wire adds to the total resistance a short is likely to experience, and hence it reduces the peak short-term current that is possible. Naturally, a thinner wire demands an appropriate and lower fuse rating, but it also, at least in theory, reduces the IC rating needed for the fuse.
PaulRainbow
Well-Known Member
What are "thin" wires ?
NH fuses go lower/
You're confusing the max current rating of the fuse (40A in your case) with how much current can pass through the fuse without it welding itself together and failing to break the circuit. That's the point of class T and NH fuses.
If you are in the UK, regs do not currently specify the type of fuse for Lithium installations. The US regs apparently say Class T only.
PaulRainbow
Well-Known Member
What's thin wire ? What's the current carrying capacity of "thin" wire ?
noelex
Well-Known Member
The current capacity of any-sized wire is easy to look up.
Regardless of your definition of a "thin" and "thick" conductor (assuming identical materials), what I have written in the quoted post (post #77) is accurate. Quantifying the values, any way you wish, does not alter the soundness of the principle.
Can you think of an exception?
Last edited:
