To Busbar or not to Busbar

[Lizbiebrowne]

Working out my Li battery installation. I’ll be charging it with a 30 A B2B and a 30 A solar panel and I’ll be taking up to 150 A out of it with a 1500 W inverter.

My question: Should I run appropriately fused cables from each of these three devices directly to the Li battery posts or should I connect the devices up to a Busbar and then run a single cable (for each polarity) from the Busbar to the Li battery posts. If the latter, does the Busbar to battery cable need to be capable of carrying 210 A or just 150 A (since the most current that will travel into the battery is 60 A and out of the battery is 150 A)?

 

[LithiumConvert]

Just considering those two options and nothing else, the maximum current in your cable will be 150 Amp.

 

[bigtwin]

Is it a single LiFePO4 battery or a bank?

If the former, whichever option works best, if the latter, I’d opt for a busbar arrangement (this will allow you to cable all of the batteries with equal length cables to the busbar).

In either case, fuse appropriately.

Ian

 

[JimmE]

I still haven’t finished the write up of my upgrade, but I went down the route of a mega/midi fuse box to cover both busbar and fusing.



Here partway through installation I have the main battery feed coming in via the largest fuse, and the B2B/MPPT/Mains chargers connected on smaller (but appropriately sized) fuses. One feed to the main / original Sargent board on a 20A fuse as per the original installation.



Almost finished, ignore the temporary thin wire feed to the smart shunt - that is fused in-line but out of shot, though since moved to another fuse box.

Only the inverter currently connects directly to the battery, due to potential to exceed the 180A limit of this fuse box/busbar.


(There is a negative busbar slightly out of shot behind the smartshunt on the left)

 

[denisejoe]

You may need more solar

^{_{Subscribers  do not see these advertisements}}

 

[Lizbiebrowne]

I still haven’t finished the write up of my upgrade, but I went down the route of a maxi-fuse box to cover both busbar and fusing.

View attachment 867280

Here partway through installation I have the main battery feed coming in via the largest fuse, and the B2B/MPPT/Mains chargers connected on smaller (but appropriately sized) fuses. One feed to the main / original Sargent board on a 20A fuse as per the original installation.

View attachment 867281

Almost finished, ignore the temporary thin wire feed to the smart shunt - that is fused in-line but out of shot, though since moved to another fuse box.

Only the inverter currently connects directly to the battery, due to potential to exceed the 150A limit of this fuse box/busbar.


(There is a negative busbar slightly out of shot behind the smartshunt on the left)

Thanks for the information. Where did you buy the Maxi-fuse from?

 

[Lizbiebrowne]

Is it a single LiFePO4 battery or a bank?

If the former, whichever option works best, if the latter, I’d opt for a busbar arrangement (this will allow you to cable all of the batteries with equal length cables to the busbar).

In either case, fuse appropriately.

Ian

It's a single battery (at the moment), I'm no electrician but I guess from your comment on cable length that the positive and negative cables from each appliance should be the same length?

 

[JimmE]

12voltplanet - I did have to contact them to confirm the maximum rating, but they then shared some documentation from the manufacturer so that’s good enough for me.

It seems like a good quality item, not flimsy, although of course there are bigger/higher rated busbars out available if that’s all you want,

Edited my last post as it seems the correct term is ‘mega’ fuse rather than maxi, and the fuse box is rated at 180A total not 150A.

The fuses themselves were also ordered from them except one I picked up elsewhere as they were out of stock in that size.

Mega & Midi Fuse Power Distribution Box

Compact power distribution & fuse box that distributes power theough a single mega link fuse into 4 midi or strip link fuses.

www.12voltplanet.co.uk

 

[bigtwin]

It's a single battery (at the moment), I'm no electrician but I guess from your comment on cable length that the positive and negative cables from each appliance should be the same length?

No, the reference to cable lengths relates to ensuring that the cables from each battery to the busbar are of equal length (to ensure that they charge/discharge equally). It would be nigh impossible to ensure that the cables from each load were of equal lengths.

With a single battery it doesn’t matter if the positive and negative cables are of different lengths.

Ian

 

[Kannon Fodda]

Despite only a single battery, I found that the post on the battery was of insufficient height to allow the numerous connections from B2B, solar charger, habitation system, inverter, EHU charger, et all. Busbar became the best way to allow all that different wiring.

Cable size from the busbar to battery should be sized for the total current that can flow at once. So add the inverter max, plus other habitation. The solar input or charger inputs would deduct, in some way, from the loads, as they are connected on the same positive / negatives, so size based on the worst case total load drawn from the battery. Of course batteries have a maximum load they can support so you shouldn't be planning to exceed that with your total of inverter plus other habitation.

^{_{Subscribers  do not see these advertisements}}

 

[Raul]

Despite only a single battery, I found that the post on the battery was of insufficient height to allow the numerous connections from B2B, solar charger, habitation system, inverter, EHU charger, et all. Busbar became the best way to allow all that different wiring.

Cable size from the busbar to battery should be sized for the total current that can flow at once. So add the inverter max, plus other habitation. The solar input or charger inputs would deduct, in some way, from the loads, as they are connected on the same positive / negatives, so size based on the worst case total load drawn from the battery. Of course batteries have a maximum load they can support so you shouldn't be planning to exceed that with your total of inverter plus other habitation.

I agree with this, your max continuous load, should be 1/3 of you battery capacity.