4x Valence vs EG4

[wittyhome]

I'm on the Growatt 3k ES+ 48v EG4 Server rack battery train, and I love it. I especially love that I can grow the system gradually. I currently (ha!) have one EG4 battery, and I'd like to expand that a bit. I found someone with 4 Valence batteries for sale locally for $150 each. So my options are:

4x Valence U1-12RT batteries in series with each other, tied in parallel with the existing EG4 battery (<~2kWh for $600 local pickup)
1x EG4 LiFePower4 48v battery tied in parallel with the existing EG4 battery (~5kWh for ~$1700 after shipping)

Which is the better choice, and why? I've got a bunch of pros-and-cons and I'm probably missing something that makes the choice obvious. Thanks for the advice!

 

[Solar Guy Richard]

Although you may think I'm biased - if you choose the EG4 you will get communication between batteries (and inverter if you wanted), they are of the exact same chemistry (which is good), they come with a warranty, and the price per watt is extremely close. Also, not sure if the valence batteries are used or not but ours are likely rated for more cycles (7000 DOD~80%) and so in the end you actually get more use out of them. Additionally - no headache in wiring 4 batteries in series with another in parallel. Just easier all around.

 

[wittyhome]

Although you may think I'm biased - if you choose the EG4 you will get communication between batteries (and inverter if you wanted), they are of the exact same chemistry (which is good), they come with a warranty, and the price per watt is extremely close. Also, not sure if the valence batteries are used or not but ours are likely rated for more cycles (7000 DOD~80%) and so in the end you actually get more use out of them. Additionally - no headache in wiring 4 batteries in series with another in parallel. Just easier all around.

Of course you're biased, but that's okay. You led with that. Thanks for being so communicative with the community! Had a great experience with one of your techs by phone as well.

Here's a question for you: I already have one LiFePower4 battery communicating fine with the Growatt. If I parallel the valence batteries, do they not adopt the benefits of this? The Growatt still knows if the battery is at, say, 50% - it's just ...bigger? I believe the Valence RT cells have their own internal BMS so I wouldn't see the individual cell info. But won't the Growatt basically see the SOC of a 140Ah battery instead of a 100Ah battery? If not, why not? Sorry if this a novice assumption, and I'm excited to have it cleared up either way for me.

 

[Solar Guy Richard]

Of course you're biased, but that's okay. You led with that. Thanks for being so communicative with the community! Had a great experience with one of your techs by phone as well.

Here's a question for you: I already have one LiFePower4 battery communicating fine with the Growatt. If I parallel the valence batteries, do they not adopt the benefits of this? The Growatt still knows if the battery is at, say, 50% - it's just ...bigger? I believe the Valence RT cells have their own internal BMS so I wouldn't see the individual cell info. But won't the Growatt basically see the SOC of a 140Ah battery instead of a 100Ah battery? If not, why not? Sorry if this a novice assumption, and I'm excited to have it cleared up either way for me.

Not a problem - So what would happen is it would discharge at the same rate - the EG4 battery and the valence would try to stay balanced. So currently if you use 50% of your battery, it's xx volts. When you add these, it would be at 75% because it's a higher voltage. So technically it would sort of communicate by the fact that the cells from the valence are also being depleted and the EG4 just knows it's own voltage. That being said - voltage is not always the best indicator for SOC in LiFePo batteries - they have a very flat charge/discharge graph to the point of where .1 v can be 10% battery life or it could be 30%. With a BMS and comms - other factors help determine the actual SOC so it's far more accurate. The growatt NEVER sees the actual 'AH' of your battery bank. It either sees voltage and is using that to determine or it sees the SOC from the battery via communications.

So to answer your question - they do SOMEWHAT adopt the comms between the EG4 and Growatt, but it's not going to be nearly as accurate as having 2 batteries that communicate SOC.

 

[wittyhome]

Okay, unfair question: bias me:
Are there any upcoming sales / coupons / incentives on the EG4 battery that will make it a better deal than the current options? Currently they're neck-and-neck. Which I guess means you've priced them well.

 

[Solar Guy Richard]

Okay, unfair question: bias me:
Are there any upcoming sales / coupons / incentives on the EG4 battery that will make it a better deal than the current options? Currently they're neck-and-neck. Which I guess means you've priced them well.

I'm not aware of any but I'll check and see what I can find.

 

[SignatureSolarJames]

Lithium ore is rising, either choice is good compared to waiting a couple months