Can I use golf cart batteries in parallel for solar/AC power storage?

[ArtieKendall]

Will has a new video out about Epoch 48V 30AH golf cart batteries. He seems impressed with the build quality.

I posted a question a few days ago about the high cost of shipping solar batteries --- $800 for a 5kWh EG4 battery from Signature Solar. I am also very concerned about how much it weighs (around a hundred pounds), because I'm an old guy by myself, and the only way I could get it out of my truck would be to spend another several hundred dollars on a scissor jack table like Will shows in some of his videos.

These golf cart batteries come in kits with all the cables you need to wire them in parallel. Four of them would give you 48V 120AH, and the shipping is only 120 bucks. And they only weigh 30 pounds apiece, so I could easily move them around without special equipment. They cost more per kWh, but I would save about $1500 in shipping and the jack table.

So, could I use three or four of these in parallel in place of one 48V 100AH solar battery? Would the SCC or whatever (I'm brand new to this) in a budget all-in-one converter like the EG4 3000EHV-48 be able to balance the charging and discharging on these?

The other thing that I noticed is that in the specs

48V 90Ah GC2 - Golf Cart LiFePO4 Lithium Battery - Complete Kit

www.epochbatteries.com

it says that not only is the minimum charging temp 32 degrees F (0 degrees C), which I believe is normal for Lifepo batteries, but also the discharge and storage minimums are 32 F, while all the solar batteries I've seen go down to like -4 F. That would be a deal-breaker if true, but why would the same lithium-iron-phosphate chemistry have such a different low storage and discharge temperature?

Thanks for any advice.

 

[OffGridInTheCity]

This kit - https://www.epochbatteries.com/products/48v-90ah-gc2-golf-cart-lifepo4-lithium-battery-complete-kit - says 48v @ 90ah. This is only (48v * 90ah) = 4,320kwh for $2400. 4 of them for $3000 would be 120ah * 48v = 5760kwh.

This is $558/kwh (for 3) or $521/kwh (for 4).


The EG4 (48v * 100ah) 4,800kwh batteries are $1500 - https://signaturesolar.com/eg4-lifepower4-lithium-battery-48v-100ah/


This is $312/kwh.


The golf cart kit has good features to fit into a golf cart and may be worth the $, but in terms of raw kwh / solar battery bank - not sure how you're thinking the golf cart kit is cheaper. Golf cart is $521/kwh and EG4 is $312/kwh.

 

[MichaelK]

Costco has traditional 6V lead-acid golf-cart batteries for 110$ right now. 210Ah at 48V would be eight of those. If you have to pay tax and a core-charge, maybe <135$ out the door cost. 1080$ for 105 USEABLE amphours at48V.

 

[ArtieKendall]

This kit - https://www.epochbatteries.com/products/48v-90ah-gc2-golf-cart-lifepo4-lithium-battery-complete-kit - says 48v @ 90ah. This is only (48v * 90ah) 4,320kwh for $3000.
View attachment 147399

These EG4 (48v * 100ah) 4,800kwh batteries are $1500 - https://signaturesolar.com/eg4-lifepower4-lithium-battery-48v-100ah/
View attachment 147400


The golf cart kit has good features to fit into a golf cart and may be worth the $, but in terms of raw kwh / solar battery bank - not sure how you're thinking the golf cart kit is cheaper. Looks like golf cart is twice as expensive in terms of kwhs.

Thank you for the response, but I'm not understanding you. Your link shows the GC kit costs $2400, not $3000. And if I bought from SS, I would get the LL battery which is $1750, because Will's buyer guide says it is more reliable than the Lifepo you linked to. The shipping cost on the LL is $811 for me, bringing my total cost to $2561. The shipping cost on the GC kit is $110, bringing my total cost to $2509. So the cost per kWh is higher, but with shipping it's not that much higher, and adding a fourth battery would only be $600 more, so I'd have more storage than with the LL battery. I'm willing to pay more per kWh for the convenience of being able to keep running if one of my batteries has a problem, and being able to move them around without special equipment.

But my main concern is whether it would work well, and the storage/discharge minimum temperatures.

 

[ArtieKendall]

Costco has traditional 6V lead-acid golf-cart batteries for 110$ right now. 210Ah at 48V would be eight of those. If you have to pay tax and a core-charge, maybe <135$ out the door cost. 1080$ for 105 USEABLE amphours at48V.

Thank you. I wasn't considering lead-acid, but maybe I should.

 

[MichaelK]

Thank you. I wasn't considering lead-acid, but maybe I should.

One word of caution though. The reason why traditional lead-acid batteries fail is typically from chronic undercharging. A good rule of thumb for traditional lead-acid is they like charging in the 1/10th of C to 1/8th of C range. With the batteries mentioned above, with C being 210A, they would be at their happiest at 210Ah/8 = 26.25 charging amps. To get that level of charging, what you need is.....

26.25A X 50Vcharging X 1.175fudgefactor = 1542W of solar.

Call that six 260W high-voltage residential grid-tie panels. How you wire up those panels is going to be related to what the max incoming solar voltage of your EG4 3000EHV-48 is? BTW, the fudgefactor is a adjustment to compensate for lower than nameplate output, which is the norm. Nameplate specifications are typically met only in a test-chamber, not in your backyard.

Since 48V is normally implemented in whole-house systems, maybe just a single string of those Costco batteries is going to be a bit light. Going 8S2P with a total of sixteen batteries would double your battery capacity, but you would also want to double your input solar also. Never skim on the solar. Your batteries will thank you for it!

 

[OffGridInTheCity]

Thank you for the response, but I'm not understanding you. Your link shows the GC kit costs $2400, not $3000.

The $2400 is for 90ah (3 of the batteries).
The $3000 is for 120ah (4 of the batteries).

And if I bought from SS, I would get the LL battery which is $1750,

OK, $1750 for 100ah Cheaper than either 3 or 4 battery golf cart kits!

because Will's buyer guide says it is more reliable than the Lifepo you linked to.

LifePo4 is LifePo4 - functionally the same. The larger BMS might be due to motor surge which is not a factor for solar battery banks.

The shipping cost on the LL is $811 for me, bringing my total cost to $2561. The shipping cost on the GC kit is $110, bringing my total cost to $2509. So the cost
per kWh is higher, but with shipping it's not that much higher, and adding a fourth battery would only be $600 more, so I'd have more storage than with the LL battery. I'm willing to pay more per kWh for the convenience of being able to keep running if one of my batteries has a problem, and being able to move them around without special equipment.

OK, LL is this (UL listed I guess?) - https://signaturesolar.com/eg4-ll-lithium-battery-48v-100ahd - but $800 shipping? Doesn't sound right. If it's that much why do EG4 / Signature Solar. @Will has done extensive reviews - perhaps take a look at something besides EG4 + $800 shipping (crazy!).

But my main concern is whether it would work well,

BMS is different - but I've not heard that EG4 5kwh batteries have a BMS issue so I don't think this is an issue for solar storage applications.

and the storage/discharge minimum temperatures.

Would be the same as they are both LifePo4 cells.

DIY is DIY and I'm not trying to argue or imply anything negative about you're choices! Just sharing that I think you're paying too much for a solar battery bank if you go with golf cart kit compared to other choices.

 

[Gason]

I think this is feasible, maybe you can consider the competitive finished product as well.

 

[millsan1]

I converted my electric side by side to Lithium, using big battery Eagles (48V golf cart batteries). As an experiment, I hooked them up to a 6048 and wired into my generator input to house. Ran the loads just fine. I used the side by side as my emergency backup for a few months and a few outages, with no issues.

 

[Delmar]

Same here. I still have the [unknown age] lead batteries and plan to replace with lithium when they die. I repurposed an old 48V UPS and backfeed 120V into both sides of my breaker panel via a dedicated pair of breakers. Ran my furnace blower during the 2021 Great Houston Freeze.