Cable Terminations--where to land them on a simple battery bank.

[Goodoz]

Apologies if this has been discussed...(probably a dumb question)

I have a 24V LiFePo4 battery bank with two batts in series. The two posts that are not connected in series will be used for load and connect to a stand alone inverter. I have a stand alone solar charge controller and a stand alone converter/charger that will need to connect. Question: Do I land these three components on the same battery posts? Or should I connect either (or both) SCC and Charger to the posts that are in series? Does it matter?

 

[Ampster]

Does it matter?

Assuming all the devices are 24 volts, they should be connected to 24 volt posts. Nothing should be connected to middle (?series) posts because batteries will become unbalanced.

 

[Goodoz]

Thanks. Yes, everything is 24V. My intended use for the system is back up during grid down. So if solar is active and charging then grid comes back and charger kicks in, the two won't harm each other as they are connected to one another and both sending power?

 

[Bob B]

Most will bring the battery supply power to an external bus bar instead of stacking multiple connections on the battery terminals.

 

[Ampster]

Most will bring the battery supply power to an external bus bar instead of stacking multiple connections on the battery terminals.

I agree and we haven't talked about overcurrent protection and grid interlock if this connected in anyway to circuits that are powered by grid. I suggest the OP review his entire plan.

 

[Ampster]

So if solar is active and charging then grid comes back and charger kicks in, the two won't harm each other as they are connected to one another and both sending power?

It is hard to answer that without knowing how everything is connected. Yes there could be great harm if connected to one another and both sending power. It all depends on what devices are connected and sending what kind of power.
If you are unsure about anything dealing with ekectricity, keep asking questions and be more specific about what is connected to what.

 

[Goodoz]

I've been following this diagram...where the inverter/charger is just a charger. It's a Progressive Dynamics PD9140-24AL.
Input: 105-130 VAC 50/60 Hz. 1,300 Watts
Output: 28.55 Volts VDC 40-Amps

No connection to sub panel...just using plugs for now (Samelex PST-2000-24) and no 12V fuse block.

The SCC is a Victron MPPT 150/85. Shunt is also Victron w/Bluetooth.

Nothing is connected yet...I'm still waiting on some parts.

 

[Ampster]

I've been following this diagram...where the inverter/charger is just a charger. It's a Progressive Dynamics PD9140-24AL.

Follow the diagram and manufacturers instructions. I am confused by your statement about the inverter/charger is just a charger. Ambiguity with electricity is dangerous because of uninteded consequences. Also that shore power connector does not look like anything I have seen for 120 volts. Is this an RV or vessel? North America?

 

[Goodoz]

North America, Alabama...LOL.

The diagram shows an inverter/charger combo unit tied to a 120V breaker box. My setup will differ because I will have a separate inverter (Samelex) and separate charger (PD9140) with zero connection to the 120V breaker box.. The charger has a standard 120VAC plug and will connect to grid via a 20A receptacle in my garage...it outputs a 24V charge with a Lithium profile.

This is a stationary system for my house. Extension cords will be utilized when in use.

 

[Goodoz]

FYI -- I received a reply to this inquiry from AMSolar.

They said "no problem on landing multiple 'active' charging sources on the same bus bars so long as the supplied current from all does not exceed the charge rating of the battery bank..."

These batteries (BMS) are 100A charge/discharge rated and are in series.

In my case, I would exceed by 25A (85+40), but that's at max output for solar and the BMS should catch that anyway (in theory).

Thanks for the replies.

 

[Ampster]

In my case, I would exceed by 25A (85+40),

I did not see what your two sources were that totaled 125 Amps? I see that the charge controller is rated at 85 Amps but do not know anything about the size of the panels powering that. The charge controller could output 40 Amps. You most likely would not run them concurrently?

 

[Goodoz]

Victron MPPT 150/85 (85A)
Progressive Dyn PD9140-24AL (40A)
2xAmpereTime 200AH batteries in series...each with 100A BMS.

I think I read somewhere that the Victron can be adjusted for output. In that case, maybe I can dial it back to 60A...regardless, today y'all convinced me to add kill switches in between the chargers and batteries. If the grid goes down, I'll disconnect the PD9140 until I disconnect solar when the grid comes back.

 

[Goodoz]

Sorry...I was 1/2 working and 1/2 reading your post...

I have six, 24V 200W Rich Solar panels and I'm running them 3 in series/2 groups in parallel...actually, I have 7 with one of them shattered...Rich has a fantastic policy of send us a picture and we'll send you a new panel...keep the broken one. It still makes power, just no good for rain.

I really don't understand how the MPPT works...I'm looking at it as a Watts solution. In that configuration and at the charge controller, I'm at 136.2 VOC and 11.66 ISC (this fits inside of my Bluetti limits, as well).

 

[Larry619]

Sorry...I was 1/2 working and 1/2 reading your post...

I have six, 24V 200W Rich Solar panels and I'm running them 3 in series/2 groups in parallel...actually, I have 7 with one of them shattered...Rich has a fantastic policy of send us a picture and we'll send you a new panel...keep the broken one. It still makes power, just no good for rain.

I really don't understand how the MPPT works...I'm looking at it as a Watts solution. In that configuration and at the charge controller, I'm at 136.2 VOC and 11.66 ISC (this fits inside of my Bluetti limits, as well).

View attachment 33701

Sorry...I was 1/2 working and 1/2 reading your post...

I have six, 24V 200W Rich Solar panels and I'm running them 3 in series/2 groups in parallel...actually, I have 7 with one of them shattered...Rich has a fantastic policy of send us a picture and we'll send you a new panel...keep the broken one. It still makes power, just no good for rain.

I really don't understand how the MPPT works...I'm looking at it as a Watts solution. In that configuration and at the charge controller, I'm at 136.2 VOC and 11.66 ISC (this fits inside of my Bluetti limits, as well).

View attachment 33701

@Goodoz. How are you Rich Solar 200W panels going so far? Do they produce their rated power? I’m about to hit the button on 4 24V panels.