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So I just ordered a 14S3P LiFePo4 battery bank, and looking around there aren't a lot of BMS options for 14S LFP, but there are quite a few for 16S LFP banks. I ordered a 36V inverter, but I don't know if changing to a 48V version is an option or not prior to delivery, or if a 36V inverter would work with a 16S LFP bank. I'd have to order more batteries to get a 16S bank anyway, so I'm not really committed to a changeup.
The BMS boards I'm looking at have load leads on the BMS itself, and have potentially higher balance current. I can reuse my two BMSes (SBMS0) for the upper/lower half of the battery bank- the disconnect mechanism would be a Victron Battery Protect (48V/100A) which takes a remote lead from the BMS for low-voltage disconnect. They currently control the remote leads on my MPPT as well.
Thoughts?
I ordered a 36V inverter, but I don't know if changing to a 48V version is an option or not prior to delivery, or if a 36V inverter would work with a 16S LFP bank.
Absolutely you can switch to a 48v before delivery. The inverters arrive completely unwired; they have to be set up and configured for the desired system voltage. You can request a battery voltage change all the way until it's in the box to ship. Technically, they can be changed in the field--but this voids the warranty (as it's really easy to mess things up when rewiring the transformer!)
For a 16S LFP bank, you definitely want the inverter set up for 48v. (I personally have a 16S LFP bank...works great with a 48v inverter.)
14S LFP...that's 44.8v nominal, 50.4v max, 42v min...on the high side for 36v, but definitely on the low side for 48v.
How would I request the change? Btw, the cells I got:
https://www.alibaba.com/product-detail/4pcs-Lifepo4-3-2V-280Ah-Battery_62517113167.html
44 Cells (two extra), 37kWh. $4700 delivered is somewhere around $0.11/Wh if I did my math right.
12 minutes ago, kazetsukai said:How would I request the change? Btw, the cells I got:
https://www.alibaba.com/product-detail/4pcs-Lifepo4-3-2V-280Ah-Battery_62517113167.html
44 Cells (two extra), 37kWh. $4700 delivered is somewhere around $0.11/Wh if I did my math right.
Is that the 280A 4cells? for 344 Bucks? If that is a real cell and not a fake one I would be getting 16 of them in next week when they pass the 1400 bill. that would give me 13kwh at 24vfor only $1376, thats dirt cheap for that would be $106 per KW. Not bad.
Let me know if they are real when you get them.
Is that the 280A 4cells? for 344 Bucks? If that is a real cell and not a fake one I would be getting 16 of them in next week when they pass the 1400 bill. that would give me 13kwh at 24vfor only $1376, thats dirt cheap for that would be $106 per KW. Not bad.
I ordered them because of testing done by Off Grid Garage (YouTube):
How would I request the change?
Probably the best way would be to call Sean during business hours and ask him to adjust your order to 48v. I don't have access to the order list (at least right now!), so it's not like I can adjust the order.
5 hours ago, kazetsukai said:44 Cells (two extra), 37kWh. $4700 delivered is somewhere around $0.11/Wh if I did my math right.
Roughly $127/kwh--really a pretty good price. I thought I did super well making my pack out of 32650 NOS (new old stock) LFP cells for roughly $120/kwh--so that's a really good price.
It's always good to run up the cost calculations on other options and see just how they price per KWH...to see how good a certain price really is.
- Simpliphi 3.8kw cells come out at ($2,525 / 3.8) = $664/kWh. Yeah, ouch.
- DIY with BatteryHookup 6Ah LFP cells works out to roughly $195/kWh. Not too terrible, though they do require a considerable amount of work to assemble...think 1,000 cells for 19kwh.
27 minutes ago, Sid Genetry Solar said:Roughly $127/kwh--really a pretty good price. I thought I did super well making my pack out of 32650 NOS (new old stock) LFP cells for roughly $120/kwh--so that's a really good price.
It's always good to run up the cost calculations on other options and see just how they price per KWH...to see how good a certain price really is.
- Simpliphi 3.8kw cells come out at ($2,525 / 3.8) = $664/kWh. Yeah, ouch.
- DIY with BatteryHookup 6Ah LFP cells works out to roughly $195/kWh. Not too terrible, though they do require a considerable amount of work to assemble...think 1,000 cells for 19kwh.
Yeah, three of my batts 12v are made witht he battery hook up 6ah. and really, if you don't want to assemble them now they offer a 20 cell modual 4 pack to make a 12v for $320, which isn't bad for a 100ah battery. all you got to do is throw on a bms which amazon is the place to go for your dayly bms, so for a 48v 100ah setup thats roughly $1500 for4.8kw bank. just get four cases of those and one 48v 16s bms and your good to go.
I just hate the cost when going to a higher voltage. to me 24v with the 6k GS Inverters is the sweet spot for small to medium house size. If I had a family, then that would be a different story, since I live by my self I can get by with it. The highest I've ever seen my watt usage went up to is 15k, and thats with the whole hose heater and the water heater hitting at the same time. Other then that I hover around 400 watts and with this grow tent setup I got going, its goes up and down with the heaters in the tent from 400 watt to 2000 watts and only for a few mins.
1 hour ago, Sid Genetry Solar said:It's always good to run up the cost calculations on other options and see just how they price per KWH...to see how good a certain price really is.
I can't understand why people don't see how insanely expensive the "drop-in replacement" 12V LFP batteries are...
34 minutes ago, The Blind Wolf said:to me 24v with the 6k GS Inverters is the sweet spot for small to medium house size. If I had a family, then that would be a different story, since I live by my self I can get by with it. The highest I've ever seen my watt usage went up to is 15k, and thats with the whole hose heater and the water heater hitting at the same time. Other then that I hover around 400 watts and with this grow tent setup I got going, its goes up and down with the heaters in the tent from 400 watt to 2000 watts and only for a few mins.
I just checked- sans climate control I'm drawing 421W, 284.5W on the AC side:
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400W is impressive, and I live in a bus, not a house.
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Highest I've seen my draws... heat pump going, a small space heater and the convection oven, around 4000W-5000W.
39 minutes ago, kazetsukai said:I can't understand why people don't see how insanely expensive the "drop-in replacement" 12V LFP batteries are...
I just checked- sans climate control I'm drawing 421W, 284.5W on the AC side:
//content.invisioncic.com/g308908/monthly_2021_03/2104826816_meters_30.thumb.jpg.4cc6d4e1c45efeae0fcdeae367e7ec6a.jpg
(DC side not shown)
400W is impressive, and I live in a bus, not a house.
//content.invisioncic.com/g308908/monthly_2021_03/1444917337_drone_overview_30.thumb.jpg.a55d9d9b9b8f3a85988b97db1a55b94e.jpg
Highest I've seen my draws... heat pump going, a small space heater and the convection oven, around 4000W-5000W.
We draw on average 3kWh an hour during the day and about 2.5kWh an hour at night for an average of 67kWh a day. But then there really isn't much time when the A/C is off. But if I'm doing an hour's worth of welding, that can add 10kWh to the bill right there.
4 hours ago, kazetsukai said:I can't understand why people don't see how insanely expensive the "drop-in replacement" 12V LFP batteries are...
I just checked- sans climate control I'm drawing 421W, 284.5W on the AC side:
(DC side not shown)
400W is impressive, and I live in a bus, not a house.
Highest I've seen my draws... heat pump going, a small space heater and the convection oven, around 4000W-5000W.
You would be better off to do 24v in that case, less chance of something going bad and losing a battery bank cause of one bad battery. Just my thoughts. cause I ran a 24 foot box truck with heat pump AC unit and lights and freezer off of 12v useing 4 led batteries off a 6k go power inverter with no issue for hours before having to crank the truck up. And that was useing a stupid modify sign wave inverter, which is the worse thing for a heat pump or any motor setup.
7 hours ago, The Blind Wolf said:You would be better off to do 24v in that case, less chance of something going bad and losing a battery bank cause of one bad battery. Just my thoughts. cause I ran a 24 foot box truck with heat pump AC unit and lights and freezer off of 12v useing 4 led batteries off a 6k go power inverter with no issue for hours before having to crank the truck up. And that was useing a stupid modify sign wave inverter, which is the worse thing for a heat pump or any motor setup.
Could you clarify- in what case? I'm running a 48V system. I used to run 24V until I did my first solar upgrade (700W -> 3000W of panels). My 150/100A Victron can only handle around 2400W of PV when running 24V, whereas with 48V it can handle 4800W of PV. Now that I'm adding another 3000W of panels to the roof for 6000W total, I can't really escape needing a second controller.
My current batteries (Teslas) have inherent redundancy- they're each an array of 18650s in 6S74P configuration, any one cell going bad would require something rather extreme. My new bank is going to be either 14S3P or 16S3P, with a pair of spares in case any one cell goes bad.
BTW people, you can edit the quote block to reduce the number of lines, you don't have to repost all of the images/etc that a previous commenter made:
13 hours ago, kazetsukai said:Highest I've seen my draws... heat pump going, a small space heater and the convection oven, around 4000W-5000W.
23 minutes ago, kazetsukai said:Could you clarify- in what case? I'm running a 48V system. I used to run 24V until I did my first solar upgrade (700W -> 3000W of panels). My 150/100A Victron can only handle around 2400W of PV when running 24V, whereas with 48V it can handle 4800W of PV. Now that I'm adding another 3000W of panels to the roof for 6000W total, I can't really escape needing a second controller.
I'd say to stay at 48v. Apart from cost of the MPPTs, system voltage doesn't make an extreme difference in cost--but if it costs twice as much in charge controllers to do 24v vs 48v...well, I went 48v 😉 .
Not to mention thinner wires are cheaper, and the system will be more efficient. There's a reason the big power transmission lines run in the KV range.
54 minutes ago, Sid Genetry Solar said:I'd say to stay at 48v. Apart from cost of the MPPTs, system voltage doesn't make an extreme difference in cost--but if it costs twice as much in charge controllers to do 24v vs 48v...well, I went 48v 😉 .
Not to mention thinner wires are cheaper, and the system will be more efficient. There's a reason the big power transmission lines run in the KV range.
This sums up why I moved from 24V to 48V. Those Victrons aren't cheap... Many people on skoolie.net running 12V systems see scenarios where they're well over 200A of charge/draw, I think that's insane. I do more with my system than most and my peak draws are still under 100A.
More or less just trying to understand his rationale than anything.
2 hours ago, kazetsukai said:More or less just trying to understand his rationale than anything.
Sounds like a lead-acid 12v battery setup.
3 hours ago, kazetsukai said:My 150/100A Victron can only handle around 2400W of PV when running 24V, whereas with 48V it can handle 4800W of PV. Now that I'm adding another 3000W of panels to the roof for 6000W total, I can't really escape needing a second controller.
Another option you might consider is the Epever Tracer MPPT series. They're a good bit cheaper--$420 for a 200v input 100A battery output model on eBay right now. I personally have 2 of them (Tracer 8420ANs to be precise, i.e. 80A, 200v max input), and for the price, I really can't complain. Definitely no comparison to the (much more expensive) Morningstar Tristar TS-MPPT-60 that I started out with--but I somehow blew one of those out via MODBUS commands. (Warranty was stellar; they replaced it with very quick shipping.)
The only issue I have had with the Epever Tracers (besides that either a computer cable or their "remote meter" is required for configuration setup--well, same for the Morningstar...), is that the actual voltage regulation is quite slow. Meaning that if you go from a big load to no load, the battery voltage will surge for 15-30 seconds. Same on the other direction: putting a huge load on it, the battery voltage will sag for 15-30 seconds. Obviously, this is a software issue--and probably a band-aid for oscillations or other issues they might have had. (Definitely not an issue on the Morningstar though--I can go from 20W to 3,300W and back in the blink of an eye.)
But for the price...and the 200v max input...not to mention RS-485 MODBUS (@115kbaud though), as well as MODBUS-controllable relay outputs, etc., there's some potential with the Tracers. Not to mention that they don't have a cooling fan--they use a huge heatsink on the back.