Battery Configuration Question

[mileshanley]

I am getting ready to build a portable hand truck 24v solar system that will primarily serve a shed I'm going to build. I will be using a 24v 3000w hybrid inverter charger from Sungold Power, 4-100 w Solar Panels and 2 PowerUrus 12v batteries I plan to wire in series. I've checked the battery specs and this is permissible. My question: I was going to purchase a 24v Case battery to take with me on travels to use in conjunction with a small 24v inverter. I chose 24v because I assumed I could wire the battery in parallel with my system batteries to maintain the 24v with an increase in current. Wires are oversized to accommodate expansion. I have read somewhere that when tying batteries together they should be very similar in specs (typically the same brand?). My case battery obviously will be a different brand. The specs on the case battery I'm thinking of purchasing is 24v 100ah made by NYDPP. Can I wire this in a 2s1p configuration or is that something I can't or should not do? ?Thanks in advance for your help.

 

[12VoltInstalls]

I'm thinking of purchasing is 24v 100ah made by NYDPP. Can I wire this in a 2s1p configuration or is that something I can't or should not do?

I am not understanding you. 2S would make that 48V….

 

[mileshanley]

The 2-12v batteries in series should be 24v. The single case battery is 24v, I want to parallel that to the 2 in series. That is why I said 2s1p. In total that would be 3 batteries, not 4 as you show.

 

[EastTexCowboy]

I think what you're asking is can you add the 24v single battery parallel to your two 12v in series batteries. If that is correct then you should be able to do so with properly sized bus bars and assuming everything else is correct.

 

[EastTexCowboy]

The 2-12v batteries in series should be 24v. The single case battery is 24v, I want to parallel that to the 2 in series. That is why I said 2s1p.

Terminology can be confusing. 2s1p denotes a configuration like the drawing by @12VoltInstalls. So you would have one string of 2s1p and one single 24v battery connected parallel with the 2s1p string. If you later added another 24v battery you would need to parallel it with the existing24v battery making that string 1s2p.

 

[mileshanley]

I think what you're asking is can you add the 24v single battery parallel to your two 12v in series batteries. If that is correct then you should be able to do so with properly sized bus bars and assuming everything else is correct.

That is what I'm asking. Thanks.

 

[EastTexCowboy]

That is what I'm asking. Thanks.

Cables from each string to the bus bar should be same length and gauge if possible. Cables on the batteries in series should be same length respectively. You may not get perfect balance but there's no reason it shouldn't work. I'm assuming you're covered for BMS.

 

[mileshanley]

Terminology can be confusing. 2s1p denotes a configuration like the drawing by @12VoltInstalls. So you would have one string of 2s1p and one single 24v battery connected parallel with the 2s1p string. If you later added another 24v battery you would need to parallel it with the existing24v battery making that string 1s2p.

Thanks for the correction. As a civil engineer, this electrical stuff is outside of my normal comfort zone.

 

[mileshanley]

Cables from each string to the bus bar should be same length and gauge if possible. Cables on the batteries in series should be same length respectively. You may not get perfect balance but there's no reason it shouldn't work. I'm assuming you're covered for BMS.

I know the BMS for the 2-12v batteries can handle up to 4 batteries in series, so that should be fine. The case battery has its own BMS and I assume that should be fine. Am I correct?

 

[EastTexCowboy]

I know the BMS for the 2-12v batteries can handle up to 4 batteries in series, so that should be fine. The case battery has its own BMS and I assume that should be fine. Am I correct?

That sounds right to me.

 

[EastTexCowboy]

Thanks for the correction. As a civil engineer, this electrical stuff is outside of my normal comfort zone.

Most of this stuff was outside my comfort zone but like so many here I was able to figure it out. Mostly because of the experience, expertise, and willingness to help from the folks on this forum. Youtube videos only go so far.