Connecting to batteries in parallel - fusing

DIY
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1

Hello everyone,

I have two batteries connected in parallel, with cross connections to help balance the currents between them.

I would like to add fuses directly on each battery to protect the system in case of a potential fault on one of them.

I was considering using CF8 fuse holders for this purpose, but their connection is M10, while my battery terminals are M8.

Do you have any recommendations for properly connecting these fuse holders directly to the battery terminals? Are there suitable adapters or a reliable and safe method to achieve this?

Another option would be to place a fuse on the cable linking the two batteries. However, unless I’m mistaken, this would mainly protect the connection between the batteries rather than providing individual protection for each battery output.

Thanks in advance for your advice and feedback.

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2

A common way of adding a fuse directly to the battery terminal is to use MRBF fuses and the respectife holders

https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A

3

Hi, thanks for your answer.

MRBF and CF8 fuse holders and fuses are the same type I’m referring to.

MRBF fuse holders are designed for M10 bolts, but the batteries I want to connect them to have M8 terminals. I’m wondering whether that could be an issue, and whether there is a proper solution for connecting them safely.

4

The specifications say M8 terminal stud, and the technical drawing shows a 9.5mm hole, which does not fit an M10 bolt

5

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M10 for the connection to the battery. So is there as safe way to connect it to a m8 battery terminal?

6

But tats not the one ive linked

7

It’s the same as the one I linked. Here is the technical drawing from your link and it also shows m10.

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8

I understand the confusion now. 0.375" is 9.525mm, which is not enough to fit an M10 bolt. So either of the two dimensions are wrong. On the BlueSeaSystems website theres also a drawing showing 0.375"/9.525mm hole diameter

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9

Ok but the gap between 9.525 and m8 isn’t an issue?