preferred battery terminal connectors?

[callmeburton]

Going to be assembling a DIY 48vdc EVE 280 battery here in the next couple of weeks and was looking for passthrough terminal post connectors and insulators. I will admit the ones I have seen on rack mounted units were attractive so it had me hunting for different options.

What are people using and why? I have seen some projects with anderson connectors ( I have experience with those from other projects ) and some just going 100% exposed terminals.

 

[John Frum]

Going to be assembling a DIY 48vdc EVE 280 battery here in the next couple of weeks and was looking for passthrough terminal post connectors and insulators. I will admit the ones I have seen on rack mounted units were attractive so it had me hunting for different options.

What are people using and why? I have seen some projects with anderson connectors ( I have experience with those from other projects ) and some just going 100% exposed terminals.

I've not used the pass through terminals but Bluesea has a good rep.

Feed Through Connectors - Blue Sea Systems

Eliminates charge and provides strain relief when passing high current through hulls, decks and bulkheads.

www.bluesea.com

 

[Steve_S]

I have used these & other similar bulkhead connectors and they work very well for the purpose. Summit-Racing is an AUTO place but a great resource for such parts without the crazy markups with "Solar Suppliers".

The GOTCHA's ! These are most typically BRASS which is likely the most recycled metal in the world. Each recycling process makes the brass get lighter from that deep coppery orange to a pale yellow when high recycled. Brass while a good stable metal, the RESISTANCE increases with reduced purity (more recycled) and one might be surprised at how much resistance can result. "Chrome Plated" is not helpful and is typically camouflage for the yellow brass which is high resistance. In cars with momentary pulls it's not a big deal but for us building ESS systems it adds up fast (contributes to line loss/drop of voltage & amperage.

I have different ones which I have tested, Same Style as #2 shown below in the "set" picture.
Clean "Red Brass" @ 11mOhm resistance
Yellow Brass @ 15mOhm
Chrome Plated 18mOhm




Listing of BulkHead Connectors @ Summit

https://www.summitracing.com/search/part-type/electrical-bulkhead-connectors

 

[callmeburton]

The GOTCHA's ! These are most typically BRASS which is likely the most recycled metal in the world. Each recycling process makes the brass get lighter from that deep coppery orange to a pale yellow when high recycled.

Did not know about this ... this is good info!

I am now thinking of just going with Anderson connectors if I can find the ones I want in stock ... its hard to bridge them when not in use, when they are connected they are "solid," and the amp rating is well known ... I think blue is the color code for 48VDC the downside is typically this is an expensive solution ... for paralleling multiple packs the last connector would need to be a Y which adds extra cable and an extra connector as well as terminals depending how you are doing it.

A lot of these terminal connectors I am finding don't post amp ratings, and if they do it is for 12vdc. 550A @ 12VDC is only ~117A @ 56VDC ... doesn't give me a warm and fuzzy feeling.

 

[John Frum]

550A @ 12VDC is only ~117A @ 56VDC .

How does that work?
I thought amps were amps.

 

[Steve_S]

There is NO problem for using bulkhead connectors but one must be aware of all the little sneakies that get in. Every connection, lug, switch & shunt add resistance & drop. This is typically dealt with when "Calibrating" the system and applying compensation values for the losses.

Anderson Connectors are GREAT but beware of Knock Offs ! The Genuine Article is not really that much more expensive and you can't beat the quality.

 

[callmeburton]

How does that work? I thought amps were amps.

So if something is rated for 550Amps ... then it will do that at say 20kVDC ? I know if something is rated 600v 550A then you can use 12v on it no problem but idk about the reverse.

I was taking 550x12=6.6kw/56vdc=117A assuming there was a limit to the voltage / amp rating since to me it is more about the heat something will generate (or not if within spec)

And yeah, I would only ever by brand name anderson connectors. Use to own an electric motorcycle (119vdc) and used a lot of anderson connectors, with proper crimping (never welded).

Steve_S Do you know of a place which advertises proper ratings for their bulkhead connectors? I feel like if I am going out of my way to make sure everything else I am using is rated for the task the last thing I want to skimp on is the bulkhead connector. This is why I like AL connectors for wire as they provide a torque spec with them to ensure you don't get any heat issues later down the road (assuming you check the torque once in a while)

 

[timselectric]

So if something is rated for 550Amps ... then it will do that at say 20kVDC ?

If it's insulated for that voltage, then yes.

 

[SparkyJJO]

Amps is what the conductor can handle.

Volts is what the insulation can handle.

A wire has a conductor wrapped in the insulation, combined gives you a current (amps) and voltage rating.

Yeah, there's a little more to it (temperature rise and voltage drop due to internal resistance, etc), but this is a very simple way to think about it.

 

[John Frum]

So if something is rated for 550Amps ... then it will do that at say 20kVDC ? I know if something is rated 600v 550A then you can use 12v on it no problem but idk about the reverse.

I was taking 550x12=6.6kw/56vdc=117A assuming there was a limit to the voltage / amp rating since to me it is more about the heat something will generate (or not if within spec)

And yeah, I would only ever by brand name anderson connectors. Use to own an electric motorcycle (119vdc) and used a lot of anderson connectors, with proper crimping (never welded).

To add to what @SparkyJJO said...
To the best of my knowledge as far as conductivity goes DC amps is DC amps regardless of voltage.
Their is a thing called skin effect but it applies to AC current.
If a connector has a voltage rating I would think that is about conductor spacing to prevent arcing.
The higher the voltage rating the the greater the spacing.

 

[timselectric]

To add to what @SparkyJJO said...
To the best of my knowledge as far as conductivity goes DC amps is DC amps regardless of voltage.
Their is a thing called skin effect but it applies to AC current.
If a connector has a voltage rating I would think that is about conductor spacing to prevent arcing.
The higher the voltage rating the the greater the spacing.

Correct
Spacing, is just using air as an insulator.

 

[Steve_S]

Steve_S Do you know of a place which advertises proper ratings for their bulkhead connectors? I

BlueSea does provide info for their bulkhead connectors (they are all made by the same folks BTW) but they only offer a limited set.
This

is rated for 250A @ 48VDC.

Some Solar "Resellers" do provide the additional specs for these but not all. Painless, Moroso, House brands (summit, jegs etc) all use the same stuff. Also check the Marine Sites as they usually note that info as well.

I run a stack of LFP in a Bank (30kWh), all have the unplated bulkhead connectors and never have any issues. I have Thrash Tested the system, meaning each pack being pushed Max Amp charge pushed & Max Discharge rates pulled (280A for 1 Hr pull on 280 packs) and no issues. I mean not even warmer than ambient temp ! I have done the extreme tests because I am very rural & remote and can be Landlocked for up to 5 days in winter and there are NO SUPPLIES within 200km from me.

IF you end up pulling Max C Rate which is 1C for LFP then you are undersized. A Healthy Properly Sized System will never goto High Amp discharge.

Last Point to note: Anderson's will let you disconnect the battery and reconnect it but to what end ? 3 Seconds with a Socket Wrench and same is accomplished. Multiple Packs in Parallel with Andersons start to get complicated (remember they each add their own losses too !) but it is all manageable. It really all depends on teh ultimate design goal. MANY if not most people run Batteries to BUSBAR then to an ON/OFF Switch like one of these BlueSea E-Series (300A rated) switches. Direct Link to BlueSea E-Series. and then to SCC/Inverter or AIO. The ability to SEPARATE SCC/INverter from Batteries for Maintenance is ever important and recently far too many "people" cheap out & skip it till they realize it was idiocy to do so. No Beating Experience ! Some just need to learn the hard way and refuse to admit it to themselves or others.

Hope it helps, Good Luck

 

[callmeburton]

I have Thrash Tested the system, meaning each pack being pushed Max Amp charge pushed & Max Discharge rates pulled (280A for 1 Hr pull on 280 packs) and no issues. I mean not even warmer than ambient temp !

I won't even have the means to pull that much till I get my second leg setup and that likely isn't happening for year >__< But I will have a thermal camera ready to go when I do ... love that thing.

I agree ... being able to disconnect for maintenance is key. I should never have to touch the battery inputs at the inverter, if things are designed right, to move my battery out of the system. I actually prefer something I can torque down like the BlueSea over the Anderson as the Andersons can get dust in them and that can cause serious heat issues if you are not aware of the threat. And ... it is cheaper ... like half the price to do it "right" :D

 

[Steve_S]

Give you a suggestion which is a bit of a twist. Have a look at Andy's efforts for a different way to build a great battery bank system. The 3 latest video's are "quite telling".

https://www.youtube.com/c/OffGridGarageAustralia

 

[callmeburton]

Give you a suggestion which is a bit of a twist. Have a look at Andy's efforts for a different way to build a great battery bank system. The 3 latest video's are "quite telling".

watching the whole playlist now for the battery as it is pretty nicely laid out. The only issue I see so far is the 100A breakers ... with one battery I might push as much as 125A with max load >__<

When I "expand out" to more batteries the configuration he has would be great.

I already have a BlueSea switch you previously linked as well as a T fuse on hand I will likely use for now. But might get this shelf system going knowing I am going to expand out :D

 

[Steve_S]

It's best to look at the "Long View" and build the system foundation with that in mind, then you add in over time to get the end result. But also expect to do a few updates along the way as the wisdom & experience grows ... ;-) When you have multiple packs installed in a balanced bank they share both charge & discharge quite well. In his latest video I think it is, he pulls 6000W from that 48V Bank, pulling about 38-40A from each of the 3 batteries. Note that Temps affect the batteries, if shelf/rack the closest to the floor will be cooler than the one at the top, even 1 Celsius temp difference will affect the way the batteries will charge & discharge.

 

[callmeburton]

Yeah I saw, but if he did that with one battery pack active it likely would have tripped his smaller breakers.
My current layout isolates batteries with a T Fuse and a switch https://diysolarforum.com/threads/batrium-watchmon-install.17539/post-494928 that should allow for my SMA to pull a full load without tripping anything if required. This adds two more connections vs OGG's build per battery I think. Could still build out a shelf busbar system with this layout though and be set for future packs when I can add them.

 

[callmeburton]

Ok so might sound a little odd ... but I came into an empty Outback Radians box which has two sets of through terminals on the box itself. I think it might hold all the batteries and I can make a lexan cover for the top ... might use that for the first battery BUT since my batteries are not here yet I cannot confirm this will work yet.