Lead carbon and the cycle claims at 50% DOD?

[Snowynorth]

Hi all. I've been here reading various topics for quite some time before signing up. We are building off grid. I am leaning towards lead carbon due to the sometimes extremely cold winter weather here, and the location of my upcoming battery bank. The components and batteries will go into a well insulated 10x10 shed, with a small direct vent propane wall heater. The shed has wiring already trenched to our panel location, and to the cabin. The propane is roughed in from our tank to feed the wall heater and a future propane back up generator. I have a gas inverter gen for now. In case the wall heater fails at some time when we aren't there, which will be most of the winter, lead carbon seems to be the best, for both decent cycle life and ability to sit dormant in the cold for a couple weeks or more without power impute or draw.

Cycles, from 1800 to over 3000 @ 50% dod? (that seems to be a big variation). A few other specs seem to have some large variations. Are some of the suppliers over stating, or being conservative? I'm trying to do some math and come up with the best bang for my bucks.

2 volt narada or sacred sun would be great, but I'm starting with a smaller bank for a few years. 12v, for a 48v system due to part time use, and finances.

Here is a small sample of cycle claims. Most claim discharge as low as-40 c or f. In our area I'm not concerned about any of the high ambient temp ratings I've read.

Sol-ark carbon agm- 3000 cycles @ 50% DOD, max charge 140a 100a recommended, Charge temp -10f -23c 7+ years off grid

Northstar Blue- 2050 cycles @ 50% DOD, max charge current "no limit" ?? nothing on charge temp, just "operating temp" of -40
Northstar claims lower cycles than sol-ark, but 15+ year design life vs sol-ark 7+ years off grid 12 years on grid.
Sol-ark and Northstar sure do look at lot alike, other then color. I think the 210 vs 230 ah rating might explain the slight weight difference.
Enersys makes Northstar, and I'm guessing sol-ark

Canbat 2500+ cycles @ 50% DOD, Max charge 63amps, charge temp 0c 32f

Switch energy- 2800 cycles @50% dod, max charge, 40a, charge temp -20c -4 f

Any experience with lead carbon would be appreciated.

 

[minerva]

I would be interested to hear opinions and experiences as well. Lead carbon certainly seems to be a good choice in subzero temperatures.

 

[SolarTexan]

I have two Outback 1000xlc lead carbon battery banks in parallel. They are rated for 3500 cycles @ 50% DOD. I have only had them installed about three months now in Texas, and my cycles are about 10% DOD. They appear to be working great. and I hope they last a long time. I can't really comment on the cold characteristics when the lowest temperature I have seen in the past few months is 18f/-8c, and my solar room never drops below about 60f.

 

[minerva]

I have two Outback 1000xlc lead carbon battery banks in parallel. They are rated for 3500 cycles @ 50% DOD. I have only had them installed about three months now in Texas, and my cycles are about 10% DOD. They appear to be working great. and I hope they last a long time. I can't really comment on the cold characteristics when the lowest temperature I have seen in the past few months is 18f/-8c, and my solar room never drops below about 60f.

Just curious- why lead-carbon in TX?

 

[codfish]

Probably should add the Kilovault lead carbon to your list as well.

12V PLC 2100 Advanced Pure Lead Carbon Battery - KiloVault

The KiloVault PLC is a 12V 2160kWh deep-cycle AGM battery. Rapid charging & great performance in Partial State of Charge (PSoC) applications.

kilovault.com

 

[Bluedog225]

And where in Texas? Interested in the heat performance.

 

[SolarTexan]

Just curious- why lead-carbon in TX?

I am supplying 100 amp service to my house, and will be adding another home to the same system in the next year or so. My batteries need to supply 500+ amps at 48v whenever it is necessary, and I did not want any BMS to get in the way and limit my power. The other issue is longevity of the lithium BMS controller boards. A quick peek inside some of the lithium batteries shows several small cells and multiple BMS boards. I have doubts about the reliability of some of these BMS boards over time. I design electronics and have seen numerous shortcuts in circuit design that will lead to failures of circuit boards. I have not evaluated the actually BMS boards in the lithium batteries, but am hesitant to believe that "all is well" with their designs that they will last 10 years or more. I needed a battery that is rock solid and absolutely has to work. I was on the fence about AGM lead carbon or lithium, but eventually decided to go with the lead carbons up front on the main solar system.

My entire setup has 3 separate solar systems, and I will be adding some lithium later this year...stay tuned.

 

[SolarTexan]

And where in Texas? Interested in the heat performance.

Johnson County Texas. The batteries are in a temperature controlled room that we affectionately call "the solar room".

 

[Snowynorth]

Probably should add the Kilovault lead carbon to your list as well.

12V PLC 2100 Advanced Pure Lead Carbon Battery - KiloVault

The KiloVault PLC is a 12V 2160kWh deep-cycle AGM battery. Rapid charging & great performance in Partial State of Charge (PSoC) applications.

kilovault.com

The kilovault had my interest. It looks a lot like Northstar and sol-ark as well, probably another enersys rebrand. Problem again is the low temp charging. There has to be something other than terrible performance lead acid that can charge in cold weather. I think I have the heat issue for the inverter figured out with a plate behind, and heat pad, with a preset sealed solid state thermostat. That wiil use very little power. Electric battery heat will use a lot more, and not great for those times with no sun for 4 or 5 days. Uncommon but it dipped below -45 here numerous days in December this year.-4f charging won't quite cut it. Everything is going into a well insulated with rockwool shed that will be boarded ceiling, walls, and floor with cement board, and have a direct vent propane wall heater. The problem is that it's a rec property for the next 5 years, with maybe 2-3 weeks winter use total, and Murphy's law dictates that the wall heater will quit for some reason some time when it's very cold. I was hoping to not shut the system down when we're not there but that could be a pipe dream.

 

[Bluedog225]

Johnson County Texas. The batteries are in a temperature controlled room that we affectionately call "the solar room".

Quite the batteries. I agree on the that the longevity of a bms for 10 years may be fantasy. But replacement wouldn’t be too bad.

Would like to see your setup. I need to do something similar in Smithville. I’m trying to plan on failover cooling for those 115 F days. Or a root cellar….

Welcome and I hope you stick around.

 

[Snowynorth]

I have two Outback 1000xlc lead carbon battery banks in parallel. They are rated for 3500 cycles @ 50% DOD. I have only had them installed about three months now in Texas, and my cycles are about 10% DOD. They appear to be working great. and I hope they last a long time. I can't really comment on the cold characteristics when the lowest temperature I have seen in the past few months is 18f/-8c, and my solar room never drops below about 60f.

I think they might be out of the budget. Nice tho.

 

[Kornbread]

What about the carbon/foam batteries? Supposed to have advantages over the carbon fortified batteries. carbon foam

 

[SolarTexan]

What about the carbon/foam batteries? Supposed to have advantages over the carbon fortified batteries. carbon foam

I considered the Firefly batteries. Their specs are comparable, but more pricey than the Outback 1000xlc that I ended up with. Now if Firefly sold a 48v bank of 2v batteries, complete with rack and all the interconnects, then I may have gone with them over the Outbacks.

 

[Snowynorth]

I'm going with Lithium, "I think". My 10x10 component shed is well insulated. I'm roughed in to it for a propane direct vent wall heater, and back up generator. I'm also going to build an insulated battery box with heat pads, and thermostat. If the wall heater ever craps out it has back up.
A couple extra panels will keep the power up. We don't use much in winter. Wood stove supplies the heat. Fridge will be unplugged, as we have a free fridge called winter weather when we are out there. Lights are all high efficient, and we know how to use only the light needed. We have lived with a 3500w inverter generator for 5 years. Without spending well beyond our budget on 2 volt lead carbon cells, I can get the same ah with more cycles at a deeper dod then lead carbon for the same money or less. My only extra cost is a couple of panels. I was going to build a box anyway. Lower long term cost. Does this sound reasonable?

 

[minerva]

I'm going with Lithium, "I think". My 10x10 component shed is well insulated. I'm roughed in to it for a propane direct vent wall heater, and back up generator. I'm also going to build an insulated battery box with heat pads, and thermostat. If the wall heater ever craps out it has back up.
A couple extra panels will keep the power up. We don't use much in winter. Wood stove supplies the heat. Fridge will be unplugged, as we have a free fridge called winter weather when we are out there. Lights are all high efficient, and we know how to use only the light needed. We have lived with a 3500w inverter generator for 5 years. Without spending well beyond our budget on 2 volt lead carbon cells, I can get the same ah with more cycles at a deeper dod then lead carbon for the same money or less. My only extra cost is a couple of panels. I was going to build a box anyway. Lower long term cost. Does this sound reasonable?

There are also the lifepo ytrium batteries that work to -20c or something but are expensive.

 

[Snowynorth]

There are also the lifepo ytrium batteries that work to -20c or something but are expensive.

Yes Lithioncs is one heated lithium. I spoke to a guy at another maker, not sure which one anymore. He told me they do consume a fair amount of their own power when it's real cold. I think just slightly less than external heat pads will, and still advised to have an insulated box to hold the heat. They are quite pricey. - 40 is -40 anyway you look at it f or c. I can get a 48v 280 ah lithium for about $4k Canadian, about $3100 usd. That will be more than we need out there, even if we are there and keeping the batteries, and inverter warm. Add in the box and some heat pads, and I am way under on cost, apples to apples. I've got 2x8, and 8" rockwool insulation. I'm paneling the whole inside of the shed with cement board, and will add a piece to do the inside of the box for extra protection. I hope I'm good with wall heater and back up. Not much more I can think of.

 

[minerva]

I recently got 16 280ah for about $2000 all included. Grade A

 

[solarsimon]

I'm going with Lithium, "I think". My 10x10 component shed is well insulated. I'm roughed in to it for a propane direct vent wall heater, and back up generator. I'm also going to build an insulated battery box with heat pads, and thermostat. If the wall heater ever craps out it has back up.
A couple extra panels will keep the power up. We don't use much in winter. Wood stove supplies the heat. Fridge will be unplugged, as we have a free fridge called winter weather when we are out there. Lights are all high efficient, and we know how to use only the light needed. We have lived with a 3500w inverter generator for 5 years. Without spending well beyond our budget on 2 volt lead carbon cells, I can get the same ah with more cycles at a deeper dod then lead carbon for the same money or less. My only extra cost is a couple of panels. I was going to build a box anyway. Lower long term cost. Does this sound reasonable?

I'm in the UK, so long term sub zero temps aren't relevant, but I'm a little perplexed by this issue, almost regardless of how cold it might get.

Firstly, some maths: For a 1m x 1m x 1m battery compartment with 100mm thick foil lined PIR insulation. (Kingspan/Celotex/Recticel in UK.)
0.023/0.1=0.23 W/m2.k So for every degree of temp change you need 0.23 Watts of heating per square meter of 'wall.'

For a cube with 6 x 0.3 sq.m sides at -20 dec C: 0.23*6*0.3x20= 8.3 Watts for a battery box operating at - 20 deg C when surrounded by 100mm of PIR insulation, perfectly sealed. Then add the heat loss from the copper cabling - I calculate it to be maybe another 1W.

So to maintain equilibrium we need under 10W of heating in a well designed compartment to sit 20 deg C above ambient.
Or 0.24kWh per day. Double the thickness of insulation to halve it.

Am I missing something? Are my sums wrong?

 

[Pukehūrepo]

There's a lot of confusion around lead-carbon. The biggest reason is that carbon is used in different ways, with different results. I'm no expert, but as I understand it has uses of at least:

1) as an additive in various forms to the electrolyte.

2) as a kind of shield over the cathode plate, providing a physical matrix.

3) as a separate, secondary cathode. This configuration seems the most interesting. It results in the battery taking on significant super-capacitor characteristics, with some tremendous and well independently tested advantages.

This third type was developed at CSIRO, the Australian Governments science research agency.

It was then spun off as a business entity, branded as 'UltraBattery' (/eyeroll) and they went about finding national licensees to manufacture the technology.

And tried to convince the world that PbC ultra batteries were the obvious replacement for NiCd batteries in electric cars. (/facepalm)

And around then of course Lithium 'happened'. And later the business was sold cheap, then the purchaser effectively shut it down completely a couple of years after that.

It appears that the situation now is that there are a few licencees still ticking over, who obviously want to protect their patch, but with no licensor enforcing the IP rights globally, the legal situation is murky.

Step up a few competent Chinese manufacturers who have realised that there is an opportunity here

And many many many Chinese battery manufacturers who use the words 'lead carbon' in their product descriptions and titles for regular AGM/VRLA because SEO.

Anyhow, that's enough for one post. My advice when searching for lead-carbon is to look for references to 'ultra-battery' or ultra- or super-capacitor in searches and on sites.

After a ton of research, I recently purchased 8x 200Ah 12v PbC at about US$350 per battery FOB Qingdao.
Datasheet: https://drive.google.com/file/d/1MerAE4sKDNURqRWWMckT9Vfi57UReP_m/view?usp=drivesdk

 

[Pukehūrepo]

... of PIR insulation, perfectly sealed.

Am I missing something?

Only that if overcharged sealed batteries will pop their valves and vent hydrogen gas and oxygen gas into that perfectly sealed chamber full of sparky things... ?

But you're right, min temps shouldn't be a significant problem, just add a small amount of ventilation and a bit more heating.