Something that’s been bugging me recently and I can’t seem to find the answer for it anywhere.  Hoping someone here has the answer.

Why do lead acid replacement 12v lithium iron batteries seem to always be advertised as having much less cycles than larger 24v and 48v batteries?

initially thought it was just that batteries advertised as such just used cheaper, B Grade cells but I can’t seem to find any 12v lead acid replacement batteries that are 6k cycles.  All the manufacturers can’t be using B Grade cells?

34 minutes ago, PhatJoe said:

Something that’s been bugging me recently and I can’t seem to find the answer for it anywhere.  Hoping someone here has the answer.

Why do lead acid replacement 12v lithium iron batteries seem to always be advertised as having much less cycles than larger 24v and 48v batteries?

initially thought it was just that batteries advertised as such just used cheaper, B Grade cells but I can’t seem to find any 12v lead acid replacement batteries that are 6k cycles.  All the manufacturers can’t be using B Grade cells?

For some i can say they do indicated they use 2nd life cells that have already done 1000 or more cycles. 

What is strange is one of the makes that in fact use new cells also give the same cycles as 2nd life. 

I think those used with comms may in fact give more cycles but it is early days for us to know out of experience how many cycle we are going to get. 

We also see some counters counting 1 cycle when only 50% of storage has been used. 

Edited January 8, 20232 yr by Scorp007

That makes sense! Did think of that but then it occurred to me that the good lead replacements do still have a BMS which provide a decent level of protection in terms of over voltage, under voltage etc etc.  I guess they still don’t enforce perfect conditions though.

Maybe it’s because using a lead acid charge and discharge profile against these lithium lead acid replacements is ok but not perfect.

I’m trying to source a 12v lead acid replacement lifepo4 battery for someone who is really going to be stretching themselves financially in purchasing it. As such, really wanting to make sure they get one which is most likely to provide max cycles.

Any suggestions as to which brand to choose?  I imagine FreedomWon would be 1st prize but at R11k per battery for 100ah it’s a little steep. Especially as they needing two (24v inverter).

I'd assume it has something to do with the DoD and the speed at which it is discharged. So, with a 48V battery you will notice the the voltage drops slower on a 20A load when compared to a 12V. I assume something about the speed of discharge and the DoD levels that leads to reduced cycles on the 12V variant, the nature of the electrolyte means faster discharge should reduce cycles.

Look, if they are on a tight budget, there isn't anything wrong with deep cycle gel batteries. You can get 2x 12V batteries for like 5k each and they should last a couple years as long as they are maintained and taken care of properly. I couldn't afford lithium so I have deep cycle gels installed and I am slowly saving up to drop the huge amount it costs for lithium replacements, they've been in for a year and haven't had I can still run my essentials right through loadshedding. I'll probably be able to afford a lithium in the next couple months but I'll probably run off gels until they are completely dead...

Observing the 50% discharge level on lead acid and much better to install a battery protector to cut the inverter off than asking you to switch off the TV when watching a great movie or a goal in sports. 

Yes most will disagree but still a place for cheaper lead acid if just for LS power and not cycling during the night and trying to save. 

The intension is for these batteries to be used in a Smart Power Systems SPS-1000 (https://www.smartpowersystems.co.za/).  It's a power trolley style inverter.  It's being used by our domestics elderly mother in Zimbabwe in an entirely off grid scenario with a single 400w solar panel feeding it during the day.  She has been struggling continuously with batteries dying prematurely for obvious reasons in this environment and I suggested lithium is (as I can see it) their best option and their current use case isnt suitable for other battery types (no grid present - entirely off grid and cycling batteries daily).  I'm going to be assisting to finance the purchase and just want to make sure we got with the right batteries considering the use case and the distance we will need to transport them once purchased.

I would stay with Blue Nova and Freedom Won.

Those are both (Freedom & BlueNova) around R10k each when compared with Hubble selling for around R7k each for comparable battery.  Would you say they are worth the extra R3k per battery?

Ive been happy with is one. It's outperforming, by a long way, the 200 amp hour Gel it replaced in a 12 volt setup I look after. Suitable for series connection.    https://www.communica.co.za/collections/loadshedding/products/batt-12-8v100-scp

Thanks for sharing that.  I like that they clearly state that new cells are used in the batteries construction!  Do you know what the warranty / guarantee is on it?

41 minutes ago, Mako said:

Ive been happy with is one. It's outperforming, by a long way, the 200 amp hour Gel it replaced in a 12 volt setup I look after. Suitable for series connection.    https://www.communica.co.za/collections/loadshedding/products/batt-12-8v100-scp

This is of great interest to me. You're running that 100ah Li battery in place of 200ah gel? I had figured that a 100aH Li was actually an adequate replacement for 2 x 105aH SLA.

54 minutes ago, Bobster. said:

This is of great interest to me. You're running that 100ah Li battery in place of 200ah gel? I had figured that a 100aH Li was actually an adequate replacement for 2 x 105aH SLA.

You might be right depending on the load. Starting of a fridge from 1x12V 100Ah means exceeding 1C many times per 24hrs. Lead acid it is no sweat for the few seconds. 

The common reply when drawing down to when the inverter switches off at 10.5V is the manufacturer designed it to be fine. Then after less than 18months they wonder why the battery is done. 

Now in the link placed earlier the life is given as less than 3000 to 80%. Does it imply even 100 cycles is meeting the spec? 

@PhatJoe

Depending on which Hubble some of the 12V units use 2nd life cells. I find mine very good after a year. 

Edited January 9, 20232 yr by Scorp007

1 hour ago, Scorp007 said:

You might be right depending on the load. Starting of a fridge from 1x12V 100Ah means exceeding 1C many times per 24hrs. Lead acid it is no sweat for the few seconds.

This inverter is backing up a TV, a DSTV decoder and maybe there'll be a cell phone on charge. So my thinking is that the extra DOD and greater life of the lithium will trump the 2 (in parallel) SLAs. It will also mean that I don't have to bother with one of those balancer thingies (you should note my mastery of technical jargon).

Edited January 9, 20232 yr by Bobster.

5 hours ago, Scorp007 said:

You might be right depending on the load. Starting of a fridge from 1x12V 100Ah means exceeding 1C many times per 24hrs. Lead acid it is no sweat for the few seconds. 

The common reply when drawing down to when the inverter switches off at 10.5V is the manufacturer designed it to be fine. Then after less than 18months they wonder why the battery is done. 

Now in the link placed earlier the life is given as less than 3000 to 80%. Does it imply even 100 cycles is meeting the spec? 

@PhatJoe

Depending on which Hubble some of the 12V units use 2nd life cells. I find mine very good after a year. 

Is there any reason why it would be a bad idea to use a 24v BMS based battery such as the Hubble AM4 in the SPS-1000?  Asked in a different way - is the label of ‘lead acid replacement’ nothing other than marketing or does it mean there is a level of BMS control that ensures the battery will work well in a system that doesn’t support lithium iron batteries and only officially supports lead acid?  The SPS-1000 for example has no lithium iron profile and is rather configured for lead-acid as a profile when installing lead acid replacement batteries.