Replacing lead acid batteries. Same thing or going with other type of batteries.

[Kanada North of 50]

Hello all,

I have 4 6volts 6CRP525 Crown flooded lead acid batteries that will need replacing next summer. when replacing them I would like to double my actual capacity (525 AH@100 HR to 1050 AH@100 HR) .

In my part of Canada temperatures are ranging from -30 Celcius to +37 Celcius. Batteries are in an insulated/ventilated battery box (they for sure exposed to -20 C to +37). I have no space problem. I have a solar array and also a wind turbine.

I would like to have advices on what type of batteries (also which make) should I go with that are the most cost effective solution and the best solution without money in the way.

Flooded batteries from my experience behave better in the cold than AGM and Gel cells. I have seen hundreds of Gel bursting in the cold deforming and craking the plastic case beyond safe use.

I dont know if LiFePO4, LTO and other new types of batteries can be of interrest for my system.

Big thanks for your advices and help.

PL

 

[Samsonite801]

Yeah, I suppose lots of factors come into play in deciding for new batteries... Do you have any more detail on why you think maybe LiFePO4 wouldn't be of particular interest for your system? (just curious is all)

Me personally, I am all over the LiFePO4 technology for a handful of my own reasons, but I understand there are a lot of people who would not prefer them.

If I wasn't going to use lithium battery solution in my system, my second choice for batteries would most likely be the Sol-Ark PCC-230 Batteries, as they tout those for their EMP hardened systems, and claim even longer overall life than lithium...

Most of the shareholders in our coop ranch are going with Sol-Ark 12k EMP hardened systems, and they all chose the PCC-230 AGM's, since they want to be fully certified EMP hardened (there aren't any BMS's on the market that are EMP hardened at this time).

I'm sure there may be other companies who make comparable AGM batteries, I haven't really looked into the various brands out there. Perhaps others have more ideas on this, but I've heard these ones are pretty good, not sure how much they cost though in comparison to other AGM options out there.

Sol-Ark PCC-230 Batteries | Sol-Ark Solar Systems

Sol-Ark PCC-230 Batteries for energy independence. Partial Charge Carbon AGM PCC-230 have the lowest cost per cycle of any commercially available battery.

www.sol-ark.com

 

[Samsonite801]

Price looks like around $3600 for 11kW/h: Example here:

11 kWh Sol-Ark Carbon AGM Battery PCC230

The Sol-Ark SA-PCC230 is an 11 kWh, 48 volt partial charge carbon sealed AGM battery designed for affordable residential or light-commercial grid-tied backup storage or off-grid renewable energy power demands. With 3,000 cycles at 50% DOD for 7+ years off-grid use or 12 years grid-assisted...

sunwatts.com

More info about them from Practical Preppers website:

Sol-Ark PCC230 Batteries - Practical Preppers

Sol-Ark PCC230 batteries boast excellent energy efficiency ratings, optimal partial state of charge. No watering or off-gassing maintenance required!

practicalpreppers.com

 

[Kanada North of 50]

I'm not saying LiFePO4 wouldn't be of particular interest for my system. I'm saying that I dont know if they can be of interest since I dont know much about them.

Maybe my phrasing is confusing (I'm a francophone so English is my second language, sorry...)

So your input is very welcomed about LiFePO4.

 

[Hedges]

I don't have the extreme cold experience with batteries you do.
Here's what I'm using, in a very mild climate. SunXtender AGM. Chart page 26 says 50% state of charge for -25C freezing point. If you limited DoD to that maybe you'd be fine. But I'm not sure if that is 50% DoD based on 25C capacity, or based on -25C capacity. It's obviously electrolyte concentration that matters, but don't know if that is uniform in the cold or not.

http://sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf

They're certainly not the cheapest per cycle. A quality wet-cell like Rolls, or a forklift battery, is better in that regard.
In comparison to the Sol-Ark AGM battery, 1/3 as many cycles but same purchase price. What SunXtender has as an advantage is high discharge rate (which only matters if you use a small battery bank as I use for grid-backup with PV)

As for lithium, generally can't be recharged below freezing without ruining them. A solution to that of course is to first use electricity to heat them, then to charge them.

New BattleBorn Heated batteries

In case you haven’t heard, BattleBorn just came out with a new ‘heated’ battery that includes a built in thermostat and heater that allows the battery to be charge in sub-zero temperatures. You can find the video and info about it on their website.

diysolarforum.com

 

[Kanada North of 50]

I don't have the extreme cold experience with batteries you do.
Here's what I'm using, in a very mild climate. SunXtender AGM. Chart page 26 says 50% state of charge for -25C freezing point. If you limited DoD to that maybe you'd be fine. But I'm not sure if that is 50% DoD based on 25C capacity, or based on -25C capacity. It's obviously electrolyte concentration that matters, but don't know if that is uniform in the cold or not.

http://sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf

They're certainly not the cheapest per cycle. A quality wet-cell like Rolls, or a forklift battery, is better in that regard.

As for lithium, generally can't be recharged below freezing without ruining them. A solution to that of course is to first use electricity to heat them, then to charge them.

New BattleBorn Heated batteries

In case you haven’t heard, BattleBorn just came out with a new ‘heated’ battery that includes a built in thermostat and heater that allows the battery to be charge in sub-zero temperatures. You can find the video and info about it on their website.

diysolarforum.com

That was my understanding for lithium, I can't put them at a temperature in winter that will enable their recharge (except if I start the generator for a day to heat the battery room... which is not very ecofriendly).

Wet-cells are the best regarding price per cycle but some stuff come with it like the size, the weight, the liquid, etc. Is it still true today?

In regard of AGM, I know there is diffenrent kind of technology regarding them such as standard AGM, carbon AGM, other?

Recommeded Dod of wet cells is 50% and for AGM it is about 80%. Factoring this in the calculation I need less batteries to obtain the same capacity? So maybe this way AGM becomes a serious contender for price over wet cells?

thanks for your help.

 

[Kanada North of 50]

I don't have the extreme cold experience with batteries you do.
Here's what I'm using, in a very mild climate. SunXtender AGM. Chart page 26 says 50% state of charge for -25C freezing point. If you limited DoD to that maybe you'd be fine. But I'm not sure if that is 50% DoD based on 25C capacity, or based on -25C capacity. It's obviously electrolyte concentration that matters, but don't know if that is uniform in the cold or not.

http://sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf

They're certainly not the cheapest per cycle. A quality wet-cell like Rolls, or a forklift battery, is better in that regard.
In comparison to the Sol-Ark AGM battery, 1/3 as many cycles but same purchase price. What SunXtender has as an advantage is high discharge rate (which only matters if you use a small battery bank as I use for grid-backup with PV)

As for lithium, generally can't be recharged below freezing without ruining them. A solution to that of course is to first use electricity to heat them, then to charge them.

New BattleBorn Heated batteries

In case you haven’t heard, BattleBorn just came out with a new ‘heated’ battery that includes a built in thermostat and heater that allows the battery to be charge in sub-zero temperatures. You can find the video and info about it on their website.

diysolarforum.com

The problem I had with GEL batteries was 20 years ago with SONNENSCHEIN 2V gel cell we installed where I work and almost all of craked under cold condition.

So my 2 countenders so far are wet cells and AGM? Am I right?

 

[Hedges]

You wouldn't want to heat the entire battery room, just the batteries, pretty much sealed in insulation so no draft. But they have to be able to get rid of heat when necessary. Greenhouse window automatic opening struts? Thermostatic fan and baffled vent? Heating either takes the power to heat the mass (looks similar to heating same mass of water, I think). Or continuously supply as much heat as escapes through the insulation.

Guess your frost line is fairly deep, can't easily put it far enough underground?

I went with AGM for a moderately small bank (405 Ah 48V) so no maintenance. Others use wet sell because cheaper, could be 1/2 or 1/4 the price per Wh, sigificant for a large bank.

You can drain AGM 100% occasionally (at least some models) for a moderate penalty in life span.
Forklift batteries may be OK discharged 80% if quickly recharged after that. But I'm not sure that means 80% depth of discharge over 4 days without sun then recharged would be fine; normal usage would be discharged during an 8 hour shift in a warehouse then recharged.

I'm just going by SunXtender's data sheet on cold tolerance. I think the key is if you can keep state of charge high enough in cold weather, which may mean backup generator when necessary. Maybe your inverter can auto-start it for you. Otherwise, should set up to shut off all loads at 50% DoD. My inverter uses its default 70% DoD for that.

AGM is also getting popular for automotive starting batteries, indicating extreme cold is OK at least charged. And of course people do leave their lights on, although not as often as before (automatic or warning buzzer.)

 

[Kanada North of 50]

You wouldn't want to heat the entire battery room, just the batteries, pretty much sealed in insulation so no draft. But they have to be able to get rid of heat when necessary. Greenhouse window automatic opening struts? Thermostatic fan and baffled vent? Heating either takes the power to heat the mass (looks similar to heating same mass of water, I think). Or continuously supply as much heat as escapes through the insulation.

Guess your frost line is fairly deep, can't easily put it far enough underground?

I went with AGM for a moderately small bank (405 Ah 48V) so no maintenance. Others use wet sell because cheaper, could be 1/2 or 1/4 the price per Wh, sigificant for a large bank.

You can drain AGM 100% occasionally (at least some models) for a moderate penalty in life span.
Forklift batteries may be OK discharged 80% if quickly recharged after that. But I'm not sure that means 80% depth of discharge over 4 days without sun then recharged would be fine; normal usage would be discharged during an 8 hour shift in a warehouse then recharged.

I'm just going by SunXtender's data sheet on cold tolerance. I think the key is if you can keep state of charge high enough in cold weather, which may mean backup generator when necessary. Maybe your inverter can auto-start it for you. Otherwise, should set up to shut off all loads at 50% DoD. My inverter uses its default 70% DoD for that.

AGM is also getting popular for automotive starting batteries, indicating extreme cold is OK at least charged. And of course people do leave their lights on, although not as often as before (automatic or warning buzzer.)

Frost line is between 4 to 6 feet deep depending on the hardness of the winter.

It is no problem to mantain the charge of the batteries in winter since I only use them on week-ends. Most of the time, on average there is enough sun in a 5 days period to maintain them.

Knowing that, I'll surely look to what is available in Canada as AGM.

 

[Deleted member 9967]

Lifepo can discharge down to minus 20 Celsius.
BUT, can only charge at 5% when at least zero Celsius out.
So somehow they need to be warmed up before being charged.
Another factor is that Lifepo do not like to be floated.
So some of us get more than we need and only use down to 10% and up to 80 or 90%.
IF you get lifepo and do not want to bother with a BMS etc etc. The only charge to 80 or90 % and only go down to 10% ALL the time and you could be fine. I switched over to lifepo for my vehicle and love it. They are 50 % larger and heavier but I get 280 Ah as opposed to 25 usable Ah.

My AGM's were 50 Ah but you can only use 50% safely. Where as lifepo you can use 80% all the time and it will almost double the life of the batteries if you only use 80%. So they could last as long as 20 years before they lose to 80% capacity.
I do not know of any AGM that can do this.
But I am sure some one here did it once. But with Lifepo you can do it all of the time.

Lastly, Lifepo do not catch fire even if shot etc.

 

[Gazoo]

Where as lifepo you can use 80% all the time and it will almost double the life of the batteries if you only use 80%. So they could last as long as 20 years before they lose to 80% capacity.

It would be nice to know how many years one looses by using 80% capacity compared to how many years one gains. There are many things to consider. For me to calculate it all out is above the wattage of the bulb in my brain.

 

[Deleted member 9967]

It would be nice to know how many years one looses by using 80% capacity compared to how many years one gains. There are many things to consider. For me to calculate it all out is above the wattage of the bulb in my brain.

It is cycles actually. Not years. However considering most people here do NOT discharge fully and charge fully every single day I see it like this.
3,000 cycles if you treat them nicely.
Double that if you compress them and only use 80% per cycle.
So now you have 6,000 cycles.
So say you do a full discharge recharge cycle 300 times a year.
That is 20 years.

Does this help more Gazoo?

 

[Gazoo]

It is cycles actually. Not years. However considering most people here do NOT discharge fully and charge fully every single day I see it like this.
3,000 cycles if you treat them nicely.
Double that if you compress them and only use 80% per cycle.
So now you have 6,000 cycles.
So say you do a full discharge recharge cycle 300 times a year.
That is 20 years.

Does this help more Gazoo?

In a perfect world with prefect compression and perfect temps. and perfect SOC's.......and besides, does anyone know how aging effects the cells? I don't have a clue.

 

[Deleted member 9967]

In a perfect world with prefect compression and perfect temps. and perfect SOC's.......and besides, does anyone know how aging effects the cells? I don't have a clue.

Read the forums Gazoo. The answers are in there.
And it doesn't have to be perfect by the way.
Close enough is good enough.

 

[Gazoo]

And it doesn't have to be perfect by the way.
Close enough is good enough.

I definitely do agree with you on that point. Are you going to use springs or bladders to compress your cells? No? Neither am I...lol. Not that I am knocking it.

 

[the_colorist]

Double that if you compress them and only use 80% per cycle.

Compression is something to consider for sure. I have seen the lab tests. Depending on the chemistry, a person can easily looking at the difference between 500 cycles to 80% vs 3500 cycles to 80%. This depends on the temp, C-rates etc of course.

I'm sure this is covered elsewhere on the forum but the cells expand and contract in every cycle. It's a by-product of the chemistry. And any time you have movement you can have mechanical failure. For those interested one of the issues is connected to the anode and cathode. It's been a while since I read the white papers and tests on this but as I recall you're physically moving them in every cycle if they are not under compression. Over time they slowly come loose and separate. Before it gets there though you could have high temps due to the resistance rise from bad internal connections.