Bolt-shaped connections on the battery too short

[boatelectronicsdiy]

Hello,

I just purchased two 100Ah LiFePO4 batteries from Flypower to replace two old AGM batteries on my sailboat.

My plan was simple - to swap out the batteries: unplug the existing cabled from old batteries and reattach them to the new batteries.

As you can see in pictures, battery connections on new batteries are short and bolt-shaped (not round like on the old batteries). Standard battery terminals on cables are have a round eyelet and require a longer connection on the battery to establish a proper contact.

Bolts seen in pictures can be unscrrewed and removed. They are M8 bolts.

I figured out that I can get battery posts to install. Where can I find high-quality ones (stainless steel)?

 

[FilterGuy]

Welcome to the Forum.

Just do a search for M8 Stainless Steel Grub screws. You can get them in many different lengths.

Note: When you get them.... make sure *Not* to get the pointed ones. You want flat or cupped ends.

 

[time2roll]

You want this?

eBay

 

[FilterGuy]

You want this?

eBay

Those look like a really bad idea. The bumps on the shoulder of the M8 Side would keep them from mating flush with the battery terminal pad.

 

[HRTKD]

OP, how many cables are you trying to connect to the battery terminal? Those terminal bolts may be just fine, you need to run a single cable from it to a common bus bar where all the other cables can connect to.

 

[MisterSandals]

Here is a link to M6 posts that were recommended here and they worked perfectly for me. Maybe the seller also makes M8.

Bolt Base 6mm A2 Stainless Steel Grub Screws Hex Socket Set Screw Cup Point DIN 916 M6 X 20 - 30: Amazon.com: Industrial & Scientific

Bolt Base 6mm A2 Stainless Steel Grub Screws Hex Socket Set Screw Cup Point DIN 916 M6 X 20 - 30: Amazon.com: Industrial & Scientific

www.amazon.com

And the nuts:

https://www.amazon.com/gp/product/B08BCHJ25Q/

 

[boatelectronicsdiy]

Thanks everyone for helpful replies. I've ordered M8 and they are too big. I ordered M6 and they are too small. I guess I need M7 screws.

For some reason, I expected this to be standardized to M8 but it is not.

 

[HRTKD]

Are you sure it's metric???

 

[boatelectronicsdiy]

Since I am not finding M7s anywhere, it is probably not metric. I measured it just now and the screw is 1/4" wide. I need to have battery posts for my installation. My entire project is held up because I cannot find battery posts in this size...

 

[HRTKD]

If I was in that situation, I would take a cell to my local Ace Hardware and find the right size bolt/stud in their hardware department. If they don't have it, you're outta luck!

 

[time2roll]

M6 and M7 have the same 1mm pitch thread so check if the M6 threads mesh properly.
M7 definitely exist. My local Ace Hardware has some.

search here

 

[reg]

Thanks everyone for helpful replies. I've ordered M8 and they are too big. I ordered M6 and they are too small. I guess I need M7 screws.

For some reason, I expected this to be standardized to M8 but it is not.

It might be easiest to ask Fly-Power at this point. I gather that this info is not in the battery data sheet.

 

[reg]

M7 definitely exist. My local Ace Hardware has some.

search here

M7 is why 11mm wrenches exist. They just aren't that common.

 

[time2roll]

And I thought 11mm was American metric

 

[reg]

And I thought 11mm was American metric

German, for M7 hex head screws

 

[HRTKD]

And I thought 11mm was American metric

I could probably take half my F-350 apart with a 10mm wrench.

 

[reg]

Since I am not finding M7s anywhere, it is probably not metric. I measured it just now and the screw is 1/4" wide. I need to have battery posts for my installation. My entire project is held up because I cannot find battery posts in this size...

If you're looking for metric fasteners on Amazon, it's not the best place. M7 screws are not hard to find elsewhere. McMaster-Carr, for one, sells them on this page. But I think that you should ask Fly-Power before you go ordering more stuff.

 

[reg]

If you have an ordinary 1/4"-20 lying around, try screwing it into the terminal.

 

[FilterGuy]

I found this Fly Power on amazon. Is this what you have?


Notice that it says M8 for the terminals. M8 comes in both 1mm and 1.5mm pitch. I am guessing the M8 studs you purchased are the wrong pitch.

I would take one of the bolts to a hardware store and check it with their thread sizing tools. (Or better yet, go buy one)

https://www.amazon.com/Lug-Wheel-Stud-Thread-Checker/dp/B009UZ7S60/

I have one similar to this and find I use it all the time.

 

[FilterGuy]

Hello,

I just purchased two 100Ah LiFePO4 batteries from Flypower to replace two old AGM batteries on my sailboat.

My plan was simple - to swap out the batteries: unplug the existing cabled from old batteries and reattach them to the new batteries.

As you can see in pictures, battery connections on new batteries are short and bolt-shaped (not round like on the old batteries). Standard battery terminals on cables are have a round eyelet and require a longer connection on the battery to establish a proper contact.

Bolts seen in pictures can be unscrrewed and removed. They are M8 bolts.

I figured out that I can get battery posts to install. Where can I find high-quality ones (stainless steel)?

Did you ever find studs?