Buy now or wait? (pre-made 24V LFP pack, 100-300AH range)

[AlpineJoe]

TLDR: Should I get a 24V premade LFP now (in the 100-300AH range) or wait for the prices to fall?

Background:
Pretty happy with my solar setup. Have ~ 4 KW of panels in various series/parallel arrangement going into 3 MPPT SCCs and then into a 24V LFP pack made from used CALB 180AH cells and 4 qty Redodo 12V 100AH batteries. I'm not sure the AH capacity remaining in CALB cells. What I do know is reading the graph from my Victron Smart Shunt, my voltage curve starts dropping steeply after~ 300AH of power is drawn during the night. This is with only a 30A draw. Voltage is down in the 25.7V range. I am able to charge the batteries back up to 100% during the day. I'd like to add more battery capacity to capture all that I'm making during the day, especially since I'm already seeing increased solar production from the sun angle changing as the days get longer (my panels are flat mounted). It's really noticeable on the weekend when I can leave my EV plugged in during the day to capture the excess. During the week, I don't have that luxury as my car is parked at work.

I read that LFP prices are supposed to drop, but I'm not seeing it in the packaged batteries. Is it going to trickle down into the pre-built batteries soon?

Thanks

 

[12VoltInstalls]

Batteries are low priced and available- now

If the price goes up will you be more disappointed indulging in that or more disappointed if you buy and the prices go down?

I’d buy now probs

 

[Brucey]

Get pairs of ecoworthy 12V 150Ahs at $250 each.

https://www.amazon.com/ECO-WORTHY-Rechargeable-Phosphate-Protection-Motorhome/dp/B096FGMLNZ

 

[chrisski]

I’d buy now; however, I recommend you figure how much you need to get comfortably through the night.

Do you know how many more kWh you use and how much more you need?

I’m not convinced you only need 300 ah.

I charge about 7 kWh for my commute off my Tesla app. If I wanted to charge the car at night, I’d plan on 8 kWh from the battery, so a pack in the 10 kWh - 15 kWh would cover me.

I’d want a 24 volt battery of at least 420 ah.

 

[AlpineJoe]

I’d buy now; however, I recommend you figure how much you need to get comfortably through the night.

Do you know how many more kWh you use and how much more you need?

I’m not convinced you only need 300 ah.

I charge about 7 kWh for my commute off my Tesla app. If I wanted to charge the car at night, I’d plan on 8 kWh from the battery, so a pack in the 10 kWh - 15 kWh would cover me.

I’d want a 24 volt battery of at least 420 ah.

On paper I should already have 480AH (the original owner of the CALB's said they were in the 140AH range) , but the voltage drop suggests much lower. And yeah, 300AH is not enough. 70AH of that is just running the PCs, internet and networking hardware, ham radio stuff and a bunch of raspberry Pi's when the sun goes down. That leaves 230AH for the car or 5.5 KWh or 22 miles theoretical. I'm only charging the car at 5A rate (I only have the Victron 24/1200) and I'm convinced charging that low is really inefficient as I'm not seeing the range increase to what theoretical calculations say.

I really need to be charging at 10A rate but if my pack is already sagging at only 30A draw, it's going to really drop at 60A draw. So more batteries and I wish Victron had a 1500W 24V inverter. 10KWH into the car at 24V is 412AH / 80% = 520AH. Round up and a solid 600AH would do it.

So the consensus so far is I should go ahead and buy 24V LFP batteries now.

 

[AlpineJoe]

Get pairs of ecoworthy 12V 150Ahs at $250 each.

https://www.amazon.com/ECO-WORTHY-Rechargeable-Phosphate-Protection-Motorhome/dp/B096FGMLNZ

Good price but their other batteries don't get good reviews. I'll have to read up on these.

The DJLBERMPW 24V 100AH was $399 for a few days a week ago but they seem to have 2 versions and I don't know the difference.

 

[12VoltInstalls]

not convinced you only need 300 ah

On paper I should already have 480AH (the original owner of the CALB's said they were in the 140AH range) , but the voltage drop suggests much lower.

a 30A draw

30A over ~10hrs is 300Ah by itself, never mind the weak ‘early’ and ‘late’ production even with 4000W of panels.

The BMS’s are probably going to cut you off for the last 10% of charge I’m guessing, so the actual numbers probably are a bit smaller than your ‘global’ figures.
I’m also not sure about this:

I am able to charge the batteries back up to 100% during the day. I'd like to add more battery capacity to capture all that I'm making during the day, especially since I'm already seeing increased solar production from the sun angle changing as the days get longer (my panels are flat mounted)

This is wildhat guessing exercise cuz I don’t know your region and a coupla things…
Q: Are you married to Victron?

Because before I even get to battery capacity I’m wondering if you would get more out of the system with more inverter. And for dollars there’s MPPSolar 24V 3000W AIO’s around for $500ish. This would give you some (in my opinion: much needed) headroom to use your 4000W of panels, a decent SCC- and the other convenient features of an AIO- for small bucks.

Then batteries: in theory you have ~12kWh on hand. And that’s not quite doing it though you certainly have the panels to support more.
A 200Ah 24V EG4 is ~$1300, which is cost-wise similar to getting two of the Chins (or like) 200Ah 12V batteries, just with less cabling. Either approach is ~5kWh more storage and - again wildhat guessing- if you had 10kWh more you’d be getting somewhere that would should let you do the EV charging at a more optimal rate and improve the underlying weakness you’re experiencing.

My outside observation with no real info other than an opinion is that you are trying to do too much with too little.

If it were me, though, I’d probably be

• calculating the annual cost of charging the EV on grid versus the amortized cost of adding batteries
• planning how to morph to 48V and probably use a 6548 and comparing costs
• figuring out if / how the dead end limits of 24V make any financial sense (ROI) versus a 48V system- because at your usage even a 12V system would do it, but there’s no opportunity to maximize or justify ROI.

If you are wed to Victron, though, you’ll have to decide within that veneration’s limits.

I just wouldn’t plan anything under 2000-3000W output myself, and at about 2500W 48V appears to be the most economically feasible path these days.
So my highly opinionated response to the direct questions is above, while my perspective is to just make a jump and make some serious power to use at 48. The ROI calcs would be my top priority, however.

 

[chrisski]

I'm only charging the car at 5A rate (I only have the Victron 24/1200) and I'm convinced charging that low is really inefficient as I'm not seeing the range increase to what theoretical calculations say.

I found that charging a Tesla is a bit inefficient at lower amps. There’s supposed to be a fixed amperage to condition the battery with heating. Also an idle draw of at least a couple percent a day, which at level 1 charging is close to an hour charging.

I measured level 1 charging a Tesla at 12 amp setting.

Level 1Charging a Tesla Model 3 off grid

I did level 1 charging with my Tesla model 3 with my solar setup, and these are the results: 4.33 miles / hour charged 322 wh/mile from the ac inverter 367 wh/mile from the Batteries to cover AC losses AC draw from inverter while charging 1400 watts +/-2watts. AC Draw from inverter before...

diysolarforum.com

 

[Q-Dog]

If you need them now, buy them now.
Litime.com still has some AmpereTime branded batteries at lower cost. Same thing just with a different name. I have had zero issues with the Amperetime LiFePO4.

 

[Danke]

Battery manufacturing prices are going down and are projected to continue to do so. But shipping is getting more expensive and that will be reflected in prices. Conflicts don’t seem to be going away anytime soon either.

Trump is in the lead, and “unnamed insiders” say he wants to put a large tariff on all Chinese imports. That could be BS, but didn’t he do that before? I think that was the reason many Chinese companies moved their operations to Indo-China countries, etc. And bifacial panels became competitive because they weren’t included in the high tariff.

 

[Aussieguy]

I just bought from amazon yesterday
2 x Elfhub 100ah with bluetooth $189.00 free delivery
I should get them 5th Feb

almost bought some 304ah cells + BMS from Docan
but Docan price was only 520

If the Eldhub goes bad can always open them and possibly fix?
May just open them anyways........... so I can fit / install them in my trailer's double battery box (undecided)

 

[AlpineJoe]

If it were me, though, I’d probably be

• calculating the annual cost of charging the EV on grid versus the amortized cost of adding batteries
• planning how to morph to 48V and probably use a 6548 and comparing costs
• figuring out if / how the dead end limits of 24V make any financial sense (ROI) versus a 48V system- because at your usage even a 12V system would do it, but there’s no opportunity to maximize or justify ROI.

Lots of good points. Edison charges me $0.37 all in per KWh (totally getting reamed). I get 4 miles per KWh, so 100 miles would cost me $9.27. Work has free charging, so in reality I just need to make at most 50 miles of charging in a day, or $5/day if I run the pack down too far.

The reason for more battery is that the car is not home in the daytime Mon-Fri to consume the excess solar production. I'm close, and that's with the Winter sun. I'm going to be very over paneled in the summer time. If I peel off more of the house's power needs to battery, I'll need more battery too to cover overcast days.

Not married to Victron, and 48V system would make sense if I were to start over.

 

[AC/DC]

Get pairs of ecoworthy 12V 150Ahs at $250 each.

https://www.amazon.com/ECO-WORTHY-Rechargeable-Phosphate-Protection-Motorhome/dp/B096FGMLNZ

How often are they discounted to this level? I picked one up off eBay for $240, now I wish I had grabbed two!

 

[Brucey]

Good price but their other batteries don't get good reviews. I'll have to read up on these.

The DJLBERMPW 24V 100AH was $399 for a few days a week ago but they seem to have 2 versions and I don't know the difference.

I picked one up for $360 during a lightning sale. It's massive compared to the ecoworthy 24V 100Ah "mini" but surprisingly easier to carry I think due to more empty space. Mini is slightly taller than the djl

 

[Brucey]

How often are they discounted to this level? I picked one up off eBay for $240, now I wish I had grabbed two!

Last I looked they had $30 off on Amazon and $270, I'm guessing they'll be back on sale at some point, they prob got a fair bit of action from the eBay presidents week 20% coupon.

 

[AlpineJoe]

Eco-Worthy on Ebay has a 20% Springtime coupon. I really want to get their 280AH pack, but the largest is 12V 280AH, they don't offer a 24V 280AH. I could get 3 of the 24V 100AH packs but it isn't as cheap as the 280AH. Still $391 per 24V 100AH battery is pretty good.