@Dellmassive and other Roamer customers! We've just introduced a couple of new fusing options for the 230Seatbase battery which may be of interest....
MRBF (Marine Rated Battery Fuse)
The first one is an MRBF (Marine Rated Battery Fuse) with busbar/holder. To save space inside the seatbase, you can flip this upside down and cable from underneath. This method fits perfectly when the battery has terminals at the front of the seatbase - it does fit the other way (terminals at the back of the seatbase) but it is very tight and there is a risk of shorting to the seatbase frame.
Roamer sell these as a kit including Eaton Bussmann fuse holder (1 pole), an Eaton/Blue Sea MRBF (30A to 300A) and heat resistant rubber cover as a kit for £45. Note there is a whole bunch of cheap imported fuses out there on Amazon/eBay, even one of the biggest lithium battery brands (mention no names) is selling them. They all claim to be MRBF or have the same spec but they are either completely fake, CF or CFM fuses. These are not appropriate for fusing a high power lithium battery, they are are poor quality at best and downright dangerous at worst - we've seen several of these cheap fuses melting due to how they sit on the holder. The certification sheets are often fake too which means there is no guarantee they will actually protect you in the event of a short circuit. You don't need to buy these from Roamer but please only buy genuine MRBF and holder from Eaton/Bussmann/Blue Sea.
Class-T (the gold standard)
The next solution is a Class-T fuse and holder. We have machined a custom Z link busbar that extends the terminal connection to the front of the battery. Roamer supply this as a kit for £95 including BEP Pro Marine fuse holder (225A-400A), a Class-T fuse (225A, 300A or 400A), Z-Link bar and some 3M VHB tape to allow you to mount it on a block. The Z-link bar is 4mm x 25mm tinned copper so is equivalent to 100mm2 copper cable, more than enough to carry 400A. The pic shows how this works on the seatbase, there is also a cover for the fuseholder which clips on top of this. We recommend the Blue Sea 4018 covers for the actual battery terminals (£10). This Z link bar works with any battery model, not just the seatbase.
Why use MRBF or Class-T at all?
The general consensus on lithium battery fusing has changed over the years mainly due to the emergence of very high power, low resistance batteries - in a dead short situation, a single battery can deliver current surges of over 5000A - thats enough to melt your spanner or weld it to the seatbase so be very careful! This high current is too much for a normal fuse, it will arc across the fuse contacts which makes the protection of the fuse pretty pointless. The main battery fuse should therefore have an AIC (Ampere Interrupt Current) rating that ensures the fuse will blow in the event of a dead short. For Mega fuses this rating is 2000A at 12V, MRBF terminal fuses its 10,000A at 12V (5000A at 24V and 2500A at 48V) while class T is 20,000A (voltage rating varies but most will provide this at up to 125VDC). More info on this support hub article: Battery protection fuses for LiFePO4
How to buy
Roamer can supply these fuse kits as needed, either as part of a new battery purchase or as a retrofit kit for previous Roamer customers (we're not selling to non-customers sorry - margins are pretty tiny so this not a commercial thing, we're just trying to help our customers stay safe). Not listed on the website yet but if you want one, please drop us an email to [email protected] and we'll send a link.
MRBF (Marine Rated Battery Fuse)
The first one is an MRBF (Marine Rated Battery Fuse) with busbar/holder. To save space inside the seatbase, you can flip this upside down and cable from underneath. This method fits perfectly when the battery has terminals at the front of the seatbase - it does fit the other way (terminals at the back of the seatbase) but it is very tight and there is a risk of shorting to the seatbase frame.
Roamer sell these as a kit including Eaton Bussmann fuse holder (1 pole), an Eaton/Blue Sea MRBF (30A to 300A) and heat resistant rubber cover as a kit for £45. Note there is a whole bunch of cheap imported fuses out there on Amazon/eBay, even one of the biggest lithium battery brands (mention no names) is selling them. They all claim to be MRBF or have the same spec but they are either completely fake, CF or CFM fuses. These are not appropriate for fusing a high power lithium battery, they are are poor quality at best and downright dangerous at worst - we've seen several of these cheap fuses melting due to how they sit on the holder. The certification sheets are often fake too which means there is no guarantee they will actually protect you in the event of a short circuit. You don't need to buy these from Roamer but please only buy genuine MRBF and holder from Eaton/Bussmann/Blue Sea.
Class-T (the gold standard)
The next solution is a Class-T fuse and holder. We have machined a custom Z link busbar that extends the terminal connection to the front of the battery. Roamer supply this as a kit for £95 including BEP Pro Marine fuse holder (225A-400A), a Class-T fuse (225A, 300A or 400A), Z-Link bar and some 3M VHB tape to allow you to mount it on a block. The Z-link bar is 4mm x 25mm tinned copper so is equivalent to 100mm2 copper cable, more than enough to carry 400A. The pic shows how this works on the seatbase, there is also a cover for the fuseholder which clips on top of this. We recommend the Blue Sea 4018 covers for the actual battery terminals (£10). This Z link bar works with any battery model, not just the seatbase.
Why use MRBF or Class-T at all?
The general consensus on lithium battery fusing has changed over the years mainly due to the emergence of very high power, low resistance batteries - in a dead short situation, a single battery can deliver current surges of over 5000A - thats enough to melt your spanner or weld it to the seatbase so be very careful! This high current is too much for a normal fuse, it will arc across the fuse contacts which makes the protection of the fuse pretty pointless. The main battery fuse should therefore have an AIC (Ampere Interrupt Current) rating that ensures the fuse will blow in the event of a dead short. For Mega fuses this rating is 2000A at 12V, MRBF terminal fuses its 10,000A at 12V (5000A at 24V and 2500A at 48V) while class T is 20,000A (voltage rating varies but most will provide this at up to 125VDC). More info on this support hub article: Battery protection fuses for LiFePO4
How to buy
Roamer can supply these fuse kits as needed, either as part of a new battery purchase or as a retrofit kit for previous Roamer customers (we're not selling to non-customers sorry - margins are pretty tiny so this not a commercial thing, we're just trying to help our customers stay safe). Not listed on the website yet but if you want one, please drop us an email to [email protected] and we'll send a link.
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