48V Server Battery Questions

[JeremyN]

We installed grid tie/battery backup solar just over a decade ago and the basic 48V configuration is:
- 18 panels
- 1 6048 (6,000W) Xantrex (220V) inverter
-1 Outback Charger
- and some lead

Well that lead is now dead (gotta give it credit for lasting a decade). Based on the way our system is wired, without the batteries, the solar panels are now offline and idling. I had to hit the bypass switch due to some crazy power fluctuations from the dead batteries. I need to get the system back online at minimal cost while switching over to LiFPo. Questions:

1) Can I get by with a single 48V EG4 or similar for now, just to get the system back online? I know it won't last long in an outage, but that's not my primary concern at the moment, I just want to get my system up and running again. I can expand later as budget allows. About half of our 2000sq/f home is on the solar/battery. So, there'll be a decent continual draw (that'll be continually re-charged via grid and/or solar panels 99.99% of the time - we haven't had a power outage in years). The question is, will that continual draw on a single server battery system be too much? (not unheard of to hit close to the 6KW capability of the inverter).

2) Can I re-configure the Outback charger to work with LiFPo pack, even though it predates that? I've read it's easy, but I want to make sure. Or should I look for a rack that includes a charger?

3) I noticed my outback, and the Xantrex and these server batteries all have CAN bus-like connectivity, can I get them all talking to each other?

4) What kind of software is around for me to monitor the above, we didn't get the Xantrex or Outback monitoring hardware back in the day, as they were expensive and limited.

Many thanks ahead of time.

 

[rmaddy]

A single EG4 48V 100Ah LiFePO₄ battery is rated for a max continuous discharge current of 100A. Assuming the battery is at about 54V that means you can pull roughly about 4600W out of the inverter (taking into account some inefficiencies). So if you can keep your inverter loads under 5000W you can get by with one battery. But the battery will only last 1 hour at that load.

 

[JeremyN]

A single EG4 48V 100Ah LiFePO₄ battery is rated for a max continuous discharge current of 100A. Assuming the battery is at about 54V that means you can pull roughly about 4600W out of the inverter (taking into account some inefficiencies). So if you can keep your inverter loads under 5000W you can get by with one battery. But the battery will only last 1 hour at that load.

Thank you that was super helpful.

 

[JeremyN]

Anyone else got info on my questions 2-4? Thanks!

 

[Abodyofscience]

Anyone else got info on my questions 2-4? Thanks!

If you get the programming wrong, I guess the worst is, it doesn't work. I'd hope these intelligent devices protect themselves from operator error & bad configurations but there is always a "Black Swan event".

And they can't be reduced to some simple equivalent circuit using a voltage source, current source, resistor, switch or diode. Even if you had the source code.

 

[JeremyN]

Makes sense. I had just hoped that in the 10 years since I last looked into it, somebody had come along and built a device that kind of coordinated all the disparate efforts to do CAN bus-y stuff for solar. I recall somebody was working on an open source project way back then, but I lost track of it. In a perfect world there'd be some device listening into the Xantrex inverter, the outback charge Controller and now these new fancy server batteries. A device that can take all that info and feed it into to some online service for monitoring and making adjustments. Maybe that's pie in the sky. Maybe I'll do it myself someday, I did some CAN bus stuff back then for I worked for VIA Motors (Electric Trucks), so maybe I can figure something out.

 

[Mr-Sandman]

1) Can I get by with a single 48V EG4 or similar for now, just to get the system back online? I know it won't last long in an outage, but that's not my primary concern at the moment, I just want to get my system up and running again. I can expand later as budget allows. About half of our 2000sq/f home is on the solar/battery. So, there'll be a decent continual draw (that'll be continually re-charged via grid and/or solar panels 99.99% of the time - we haven't had a power outage in years). The question is, will that continual draw on a single server battery system be too much? (not unheard of to hit close to the 6KW capability of the inverter).

NO, one EG4 battery is NOT enough for a 6000 watt inverter that can surge much more. You need 2 minimum and 3 would be ideal to cover that inverter peak current. Each EG4 can supply 100amps max. Your inverter can pull 125 amps constant and surge up to 200 amps... I have (3) EG4 LL batteries hooked to a Schneider XW Pro 6848.

2) Can I re-configure the Outback charger to work with LiFPo pack, even though it predates that? I've read it's easy, but I want to make sure. Or should I look for a rack that includes a charger?

I have no experience with Outback charge controller, but if you can specify the Bulk/Absorb/Float voltage, you should be fine. Basically you just need Bulk/Absorb set to 55.4v and 54.4 float to get them up to 95% or so and keep them happy.

3) I noticed my outback, and the Xantrex and these server batteries all have CAN bus-like connectivity, can I get them all talking to each other?

No sir unfortunately they cannot. The EG4 batteries currently only talk to GroWatt inverters. That's not a big deal really, especially since the older Xantrex doesn't have closed loop BMS support in it anyway.

I do NOT recommend the EG4 LifePower4 batteries for your inverter. There has been several reports of them not starting large inverters such as yours, that powers up soon as DC power is applied (no on/off). The EG4 LL seem to power them just fine or there are many other rack batteries in that price range showing up now.

 

[JeremyN]

Fantastic feedback. Thank you. Time to save more $$. I refuse to go lead acid again.

 

[JeremyN]

I'm narrowing down on getting two of the SOK server rack batteries when they come out. Crossing my fingers that'll be enough juice to drive my inverter?

 

[Koldsimer]

Those sok batteries look really nice. I'm also impressed with the trophy battery and the standard features it has. If you are going to keep the batteries in an environment that regularly sees temps below 32f , i would seriously consider the trophy battery with its internal heaters.

Keep in mind, some of the rack mount batteries have a recommended discharge of 30a. It may be capable of 100a but if they recommend only discharging 30a i would try to keep it close to that number.

One caveat, neither of these batteries has been on the market for any period of time so first hand accounts of their performance aren't out there yet. That being said, SOK seems to have an excellent reputation for their other lithium batteries and the video Will did shows they are very well made.

 

[Mr-Sandman]

Keep in mind, some of the rack mount batteries have a recommended discharge of 30a. It may be capable of 100a but if they recommend only discharging 30a i would try to keep it close to that number.

if you are referring to EG4 30amp discharge recommendation, I THINK that's a typo and it should be 30amp recommended charge current. I COULD BE WRONG. @RichardfromSignatureSolar could you check into this. The manual and your sales literature states 30 amp recommend discharge current. That seems REALLY low, normally there is a lower recommended charge current, 30 amp seems appropriate for that, was this a typo?

 

[JeremyN]

Those sok batteries look really nice. I'm also impressed with the trophy battery and the standard features it has.

I live in Utah and they will be installed in my garage, which does get cold. So I'm also intrigued by the Trophy batteries as well and their internal heaters, but they are on the wrong side of the country and shipping costs would blow my budget. I'm hoping SOK will allow me to pick up in person as Vegas is a relatively short drive.

This is a grid tie/battery back up system and as such I'll have AC nearby at all times, so I'm going to have to come up with an alternate battery warming strategy. Probably just a couple of these.

I am open to other ideas to get our system up and running again. Our battery budget is no more $3400 including shipping. I considered getting 12 Ampere Time 50Ah batteries and doing 4s3p (I think that's the right way to say that). But that just seems like a lot of wiring and a lot of individual BMS's inside all the batteries, any of which could fail and the overall KWh would be less, but that's not my primary concern at this time.

 

[Koldsimer]

I live in Utah and they will be installed in my garage, which does get cold. So I'm also intrigued by the Trophy batteries as well and their internal heaters, but they are on the wrong side of the country and shipping costs would blow my budget. I'm hoping SOK will allow me to pick up in person as Vegas is a relatively short drive.

This is a grid tie/battery back up system and as such I'll have AC nearby at all times, so I'm going to have to come up with an alternate battery warming strategy. Probably just a couple of these.

I am open to other ideas to get our system up and running again. Our battery budget is no more $3400 including shipping. I considered getting 12 Ampere Time 50Ah batteries and doing 4s3p (I think that's the right way to say that). But that just seems like a lot of wiring and a lot of individual BMS's inside all the batteries, any of which could fail and the overall KWh would be less, but that's not my primary concern at this time.

Looks like the sok is the best option for you. I don't think the ampere time batteries can be run in a series/parallel connection but i could be wrong. Check with mfr. Even if they can be run in that configuration, i'm with you- seems like a lot to go wrong and if one fails, your entire bank is shot. I like the idea of running two battery packs for redundancy in case one fails.

If it stays above 32f in your garage, you will have no problems charging/discharging. If the battery temp falls to 32f or lower, temp protection will not allow battery to charge below 32 but it will still be able to discharge down to 0f.

Check out the Jakiper server rack battery. 51.2v 100ah like most. Very nice build and i believe they are in stock right now. You could get two shipped under your budget. Will did a video review of the jakipers- check it out.

 

[mini4mw]

Amperetime can be be in series/parallel, but there are vendor recommendations for total size (series/parallel connections). The older ones also did not have cold temp cut-off as well in the BMS. I have 2 12v 300amp in series and they are working well and can pull 3000W loads for extended periods of time when needed.

 

[JeremyN]

Pulled the trigger on 2 (for now) SOK server batteries. Those guys have absolutely stellar pre-sales support.