DIY Busbar

[HRTKD]

Did you have any luck finding aluminum flange nuts with the norlock type flange? I found some aluminum lock washers but stopped looking.

I'm keeping it simple and going with aluminum lock washers. I sourced them from Home Depot, of all places. I went with 1/4" size, which were much more readily available than was a metric size. $.59 for a bag of five, free shipping. I ordered six bags. They'll be here before the bolts arrive.

I don't have ANY lock washers on my terminals at this time and the torque hasn't changed after a 1400 mile trip that included 10 miles of dirt road.

Bus bar stock arrived today. I ordered stock of two different thickness, .25" and .375". Both 1" wide. I thought I would experiment a bit. I was ordering other stock, so adding the thicker bar didn't add much to the order.

 

[Haugen]

I've been dabbling a bit at making aluminum bus bars for a while.

I've decided to get serious about it and get some made that should never need to be removed no matter how much current I want to pull.

I'm making them from aluminum, so galvanic corrosion will not be an issue. 3/8" thick, 3/4" wide and radiused ends will make them attractive and cover the entire terminal.
One hole will be elongated by 0.100" to allow slight differences in distance between the terminals.

I need 2 different lengths. One to bridge between cells side by side. The other longer to bridge cells situated end to end.

Getting bar stock delivered is not cheap, though. Just the material is going to cost about $1 each. Depending on the cost to machine them, they could add up to about $3.

This stuff is usually more economical in bulk. If anyone wants to get in with me, send me a PM.

Here is the design. I would appreciate feedback from anyone who checks them against their cells.

 

[johntaves]

I've been dabbling a bit at making aluminum bus bars for a while.

I used aluminum bus bars and aluminum threaded rod for the bolts. I used an aluminum lock washer and torqued them finger tight with my socket. This flattened the aluminum lock washer, but I am not sure that this is good enough.

I was hoping the lock washer would provide some spring action, but the aluminum seems rather weak. I found that I have poor connections.

I am thinking of putting a stainless lock washer on there to provide more spring action. I don't think I care if there is corrosion at the end of the rod and top of the busbars, because those are easily replaced/cleaned. I like the idea that only aluminum touches the battery contacts.

I am a afraid of too much torque on the nuts. It does not feel like the rods can take a lot.

Does anyone have advice?

 

[Hedges]

I used aluminum bus bars and aluminum threaded rod for the bolts. I used an aluminum lock washer and torqued them finger tight with my socket. This flattened the aluminum lock washer, but I am not sure that this is good enough.

I was hoping the lock washer would provide some spring action, but the aluminum seems rather weak. I found that I have poor connections.

I am thinking of putting a stainless lock washer on there to provide more spring action. I don't think I care if there is corrosion at the end of the rod and top of the busbars, because those are easily replaced/cleaned. I like the idea that only aluminum touches the battery contacts.

I am a afraid of too much torque on the nuts. It does not feel like the rods can take a lot.

Does anyone have advice?

Check out the article in this link:

Xuba Electronics: DEAL - 280AH LiFePo4 cells. Purchase & Review

This is where common sense and experiycome into play. Tighten up tire and snug . It's a feeling you learn the hard way. Tighten it snug , then give it a sckosh more. See that....... Technical jargon right there

diysolarforum.com

And consider how lugs bolt to (aluminum or copper) busbars in Square-D breaker panels.

What I don't like is bare aluminum. I see it tinned in any listed electrical products I use.

 

[johntaves]

Check out the article in this link:

Sorry, I don't see what I should look at. Are you saying I should read the whole thread, or just the post about the washer tightening stuff? Are you telling me about those cool looking spring washers?

What I don't like is bare aluminum. I see it tinned in any listed electrical products I use.

I don't see why this matters. The terminals are bare aluminum, right? So, if I manage to clean off the oxidation on both the battery and the bus bar, then put noalox on it, I should be good with the connection, right? The noalox conducts and will keep the two surfaces from oxidizing and thus losing the connection. All the visible aluminum can oxidize for all I care, because it is just on the surface and won't affect the bulk conduction.

Am I confused?

Maybe the battery is a different aluminum alloy and it will be better with stainless busbars and bolts?

 

[Hedges]

Sorry, I don't see what I should look at. Are you saying I should read the whole thread, or just the post about the washer tightening stuff? Are you telling me about those cool looking spring washers?

The link "scientific paper available from the Copper Alliance"
It shows the amount of pressure required to achieve good electrical contact, and goes into detailed explanation about pressure contacts.
Calculating area, pressure, torque to achieve that for your design would help get it in a good range.

 

[Haugen]

I am thinking of putting a stainless lock washer on there to provide more spring action. I don't think I care if there is corrosion at the end of the rod and top of the busbars, because those are easily replaced/cleaned. I like the idea that only aluminum touches the battery contacts.

I am a afraid of too much torque on the nuts. It does not feel like the rods can take a lot.

Does anyone have advice?

I can't argue with the logic. The aluminum lock washer probably won't have anywhere near the spring strength of the stainless. I always advocate keeping the dissimilar metals where they can be inspected.
If you're not getting the needed lock with the aluminum lock washer, that might be a good update. Just be sure to keep it lubricated to keep moisture and oxygen out.

 

[johntaves]

I can't argue with the logic. The aluminum lock washer probably won't have anywhere near the spring strength of the stainless. I always advocate keeping the dissimilar metals where they can be inspected.
If you're not getting the needed lock with the aluminum lock washer, that might be a good update. Just be sure to keep it lubricated to keep moisture and oxygen out.

I used normal zinc lock washers because I read that zinc is closer to aluminum than stainless. They certainly feel firmer and I did not strip anything when I torqued to flatten them.

I also realized that I did not read the noalox instructions properly. In my first attempt I sanded the bar and the battery, then smeared noalox on it. Since then, I learned that the oxidation starts within milliseconds, so the idea that you sand then apply the noalox does not make sense. I reread the directions and they say to apply the noalox and then hit it with emery cloth (sand). That makes more sense to me.

 

[SolaroSsaurius]

I may have over-insulated my battery/component compartment in my RV. I was thinking of 10° F camping trips and didn't factor in how well the compartment would hold heat generated from the components - mainly the inverter.

It's a small area, 12"H x 28"D x 35"W under a closet in the bathroom. I haven't seen any high or even moderate temperature warnings from the components, but I haven't stressed the system yet either. It's plenty warm in there. I'm starting to plan for installing a couple of thermostat-based 12v fans. Moving the inverter out of the compartment may be part of the plan, but if it comes to that I may look into upgrading the 20 year old 1000 watt Xantrex MSW inverter.

To add to the thread, I found 6061 Aluminum bolts on Amazon and ordered 15 mm and 20 mm sets. A little bit more than $.50 per bolt.

Hi.

I'm about to build a battery (24v, 8x EVE LF280k, 200A BMS) to be used in a Class B RV (max 130A draw).
I'm thinking about putting the cells and BMS inside a metal box (in the garage, also properly insulated) to mitigate fire risk, but I'm fearing overheating could be prejudicial.
What is your experience given that you are already at it?

Also, I'm afraid that a cell connection may get loose due to road vibrations, hence a bigger heat risk and fire hazard. How have you been dealing with these issues?

Thanks in advance for your thoughts

 

[SolaroSsaurius]

Same question to @Bob B , how are you dealing with these risks...

 

[HRTKD]

Hi.

I'm about to build a battery (24v, 8x EVE LF280k, 200A BMS) to be used in a Class B RV (max 130A draw).
I'm thinking about putting the cells and BMS inside a metal box (in the garage, also properly insulated) to mitigate fire risk, but I'm fearing overheating could be prejudicial.
What is your experience given that you are already at it?

Also, I'm afraid that a cell connection may get loose due to road vibrations, hence a bigger heat risk and fire hazard. How have you been dealing with these issues?

Thanks in advance for your thoughts

I did add a layer of cement board to the top of my battery area, just in case. The connections have been doing remarkably well. Nothing has come loose. I have a reminder on my calendar to check the connections once a year. My RV trailer does see some very rough back country roads (BLM, Forest Service, etc.).

Most of the heating of the compartment is coming from the solar charge controllers and the inverter, not the battery.

 

[kuranaga]

I wasn't familiar with Noalox and just read up on it. This is not a panacea that protects copper to aluminum junctions.
First of all, it introduces two additional metals, zinc and silicon. As the grease dries up, it will exacerbate the galvanic reaction over time. Granted the zinc will corrode away first, but the aluminum will be right behind it.
I would recommended switching to something like Zip-Chem's D-5026NS. It's $18 a can, but a short burst once or twice a year will protect your connections. Use it everywhere.

what about using CRC 06046 ?

 

[kuranaga]

At least you have busbars. I received nothing. I'm not sure what is correct(or good?) busbar for the cells.

I ordered battery with busbars and received only busbars, no battery

 

[SolaroSsaurius]

I did add a layer of cement board to the top of my battery area, just in case. The connections have been doing remarkably well. Nothing has come loose. I have a reminder on my calendar to check the connections once a year. My RV trailer does see some very rough back country roads (BLM, Forest Service, etc.).

Most of the heating of the compartment is coming from the solar charge controllers and the inverter, not the battery.

Thanks for your prompt reply!

IIRC, your setup was alu bar busbars (what type of alu?), alu lock washers, and alu bolts. Is this correct?
How much torque did you use?
Did you use any loctite or similar?
What is your max draw from the batteries and any given time?

Heating sources: top! great piece of information!

Thanks for all your insights!

 

[Ampster]

what about using CRC 06046 ?

It looks like that product is designed for Lead battery posts. It doesn't say anything about aluminum and copper. NoAlox is designed specifically for Aluminum to Copper connections.

 

[HRTKD]

Thanks for your prompt reply!

IIRC, your setup was alu bar busbars (what type of alu?), alu lock washers, and alu bolts. Is this correct?
How much torque did you use?
Did you use any loctite or similar?
What is your max draw from the batteries and any given time?

Heating sources: top! great piece of information!

Thanks for all your insights!

Between the cell terminals I am currently using the tin-plated copper bus bars that were provided with the cells. I may later switch to aluminum bus bars since I have the aluminum stock already on hand for that.

No thread locker. As I recall, the torque was 12 inch pounds. Max continuous draw was about 200 amps, so 100 amps per battery. Surge amps when I fired up the air conditioner were likely higher than that.

 

[kuranaga]

It looks like that product is designed for Lead battery posts. It doesn't say anything about aluminum and copper. NoAlox is designed specifically for Aluminum to Copper connections.

best would be laser welding these terminals, but machine is too expensive for diy. Maybe better consider buying welded packs