Gel/AGM vs Lithium batteries comparison

[RhysMcW]

I currently have 4 x 12v 250AH Gel/AGM batteries that are now coming up on 4 years old and are not performing as they did when new (not really unexpected)...
I'm running an Infinisolar 3kPlus and 2 arrays each with 8 x 250w panels.
The load circuit on the inverter draws between 500w and 900w, depending on what is powered when, with an overall average of around 750w.
I only use the batteries when grid power is unavailable and the PV is not producing enough to supply the load circuit.
My main aim for battery power is to be able to provide way more than enough to get through load shedding as both myself and my wife work from home so we need our offices powered at all times...

With my current AGM batteries performance degrading I've been looking at the possibility of getting Lithium batteries and have been fairly impress with the reviews, this forum and elsewhere, of the PylonTech units.
My question is, how do I compare my current batteries with something like the PylonTech's with regard to their kW ratings as compared to what I have (48v 250AH)???
I do understand that the DoD of the Lithium batteries are significantly better than the AGM so my guess is that I could ultimately go with a "lower" kW rating that my AGM's are "rated"???

[DeepBass9]

If your load drawn from the Lithiums is not too high (there is a limit and its lower than for AGM batteries), it should be fine if you are just using it for running computers etc. I recently compared lithiums and AGMS and eventually went with a bank of 8 x 375Ah trojans, mainly because the capacity was similar, and the cost slightly less for the AGMs than for lithiums, but the main reason was that my inverter was not guaranteed for use with Pylons, or any other type of lithium battery for that matter. 

[Jaws]

20 hours ago, RhysMcW said:

I currently have 4 x 12v 250AH Gel/AGM batteries that are now coming up on 4 years old and are not performing as they did when new (not really unexpected)...
I'm running an Infinisolar 3kPlus and 2 arrays each with 8 x 250w panels.
The load circuit on the inverter draws between 500w and 900w, depending on what is powered when, with an overall average of around 750w.
I only use the batteries when grid power is unavailable and the PV is not producing enough to supply the load circuit.
My main aim for battery power is to be able to provide way more than enough to get through load shedding as both myself and my wife work from home so we need our offices powered at all times...

With my current AGM batteries performance degrading I've been looking at the possibility of getting Lithium batteries and have been fairly impress with the reviews, this forum and elsewhere, of the PylonTech units.
My question is, how do I compare my current batteries with something like the PylonTech's with regard to their kW ratings as compared to what I have (48v 250AH)???
I do understand that the DoD of the Lithium batteries are significantly better than the AGM so my guess is that I could ultimately go with a "lower" kW rating that my AGM's are "rated"???

Currently you have 48 V x 250 Ah = 12 kWh rated

12 000 kWh x 50 % = 6 kWh usable

 

Polyntech has two models

US2000 = 2.2 kWh usasble ( 6000 cycles)

US3000 = 3.2 kWh usable (6000 cycles)

 

So you will need either 3 x US2000  (R45k) for 6.6 kWh    (R15k per battery|)

Or 2 x US3000  (R40k) for 6.4 kWh    (R20k per battery)

 

 

Priced based on based advertised price I could find locally but exludeds brackets and cables)

Edited March 26, 2019 by Jaws

[Dean]

What do you recommend as the best Deep Cycle battery, I am using Omni Power but would like a battery that offer more cycles at 50% DoD

[DeepBass9]

Trojan T105RE (6V 225Ah) is fairly widely used, or Trojan SAGM375 (6V 375 Ah). Google for the data sheets.

If you find them could you post the links here for future reference.

Edited March 26, 2019 by DeepBass9

[Guest]

10 minutes ago, DeepBass9 said:

Trojan T105RE (6V 225Ah) is fairly widely used, or Trojan SAGM375 (6V 375 Ah). Google for the data sheets.

8 x 375Ah Trojans have better cycles like 1700 tot 50% DOD, no need to water and can be installed inside.

T105RE's may have a shortage, Trojan SA seems to be in a mess, they need water, have to be well ventilated and have 1600 cycles to 50% DOD.

Personally I'm waiting on Trojan Lithiums ... they are out, not yet in SA.

[DeepBass9]

I'm hoping to get 3000 cycles out of mine by being nice to them. I just looked at the data sheet and saw the short circuit current on the battery is 3650A. That will make you hair stand on end!

[RhysMcW]

1 hour ago, Jaws said:

Currently you have 48 V x 250 Ah = 12 kWh rated
12 000 kWh x 50 % = 6 kWh usable

Polyntech has two models
US2000 = 2.2 kWh usasble ( 6000 cycles)
US3000 = 3.2 kWh usable (6000 cycles)

 

Thanks @Jaws, that's pretty much what I was after.
Currently my AGM's show, via ICC, as 100% SOC while there is PV supplying charge/float but they drop to <80% within minutes of the sun going down and no PV any more and if grid power fails they drop fairly rapidly to <70% with the load at around 750W and then the batteries SOC slowly drops and typically reach about 63%-65% by the end of a typical just over 2 hour load shed...
This is quite a bit worse than when they were new, hence me starting to look at lithium's... I'm not in a major rush to replace my batteries just yet as they're still supplying the load during a load shedding but I'll probably replace them by the end of the year...
6000 cycles is quite attractive, I'd then enable the options to use battery in the evenings until the SOC reached about 75% thereby still leaving plenty battery for the middle of the night load shedding, at which point we're typically only drawing around 500W...

[Zombie]

12 hours ago, The Terrible Triplett said:

8 x 375Ah Trojans have better cycles like 1700 tot 50% DOD, no need to water and can be installed inside.

T105RE's may have a shortage, Trojan SA seems to be in a mess, they need water, have to be well ventilated and have 1600 cycles to 50% DOD.

Personally I'm waiting on Trojan Lithiums ... they are out, not yet in SA.

Good day master Triplett

If I may ask, what's your reason for waiting on the trojan lithiums as opposed to going for the pylontechs ?

 

[Guest]

Good day Sir Zombie, and welcome.

1 hour ago, Zombie said:

If I may ask, what's your reason for waiting on the trojan lithiums as opposed to going for the pylontechs ?

Because I trust the brand. 

What they advertise is what they deliver and they back their warranties.

The batts are out but not yet generally available, models are coming in 12v and 24v ranges, which I prefer.

10 000 cycles at 40% DOD or 6000 at 70% DOD: https://www.trojanbattery.com/trillium/

But not cheap.
Trojan Trillium TR 12.8 110Ah Li-Ion for like +R 18 888.71 - 12.8V 110Ah
Trojan Trillium TR 25.6-25 25Ah Li-Ion for like +R 15 616.60 - 25.6v 25Ah

https://www.trojanbattery.com/product/tr-12-8-110-li-ion/

https://www.trojanbattery.com/product/tr-12-8-92-li-ion/

https://www.trojanbattery.com/product/tr-25-6-25-li-ion/

[DeepBass9]

Once my AGMs have expired in about 2025 I'll get these Trojan lithium and those will probably be the last batteries I'll ever buy.

[Guest]

2 hours ago, DeepBass9 said:

Once my AGMs have expired in about 2025 I'll get these Trojan lithium and those will probably be the last batteries I'll ever buy.

I like your 2025 - 6 years - that is now what I call being a realist.

And if they last longer, that would just be a nice cherry on the cake.

[DeepBass9]

Generally I only run them down to about 80% (not bad for off grid!) and they have been below 70% once in the 3 months I have had them, so I think 2000+ cycles is achievable.

[LivSol]

On 2019/03/26 at 9:41 AM, The Terrible Triplett said:

8 x 375Ah Trojans have better cycles like 1700 tot 50% DOD, no need to water and can be installed inside.

T105RE's may have a shortage, Trojan SA seems to be in a mess, they need water, have to be well ventilated and have 1600 cycles to 50% DOD.

Personally I'm waiting on Trojan Lithiums ... they are out, not yet in SA.

T105RE is discontinued. Trojan current line and spec sheets here. http://livingsolar.co.za/batteries/

 

[Jaws]

On ‎2019‎/‎03‎/‎27 at 6:21 AM, DeepBass9 said:

Once my AGMs have expired in about 2025 I'll get these Trojan lithium and those will probably be the last batteries I'll ever buy.

How old are you 75 ?

[Guest]

2 hours ago, LivSol said:

T105RE is discontinued. Trojan current line and spec sheets here. http://livingsolar.co.za/batteries/

 

T105RE's has been renamed to SPRE_06_225, as has all the ranges.

Am not aware of them being discontinued.

[SilverNodashi]

On 2019/03/26 at 9:41 AM, The Terrible Triplett said:

8 x 375Ah Trojans have better cycles like 1700 tot 50% DOD, no need to water and can be installed inside.

T105RE's may have a shortage, Trojan SA seems to be in a mess, they need water, have to be well ventilated and have 1600 cycles to 50% DOD.

Personally I'm waiting on Trojan Lithiums ... they are out, not yet in SA.

@RhysMcW Just keep in mind that these batteries need maintenance in order to perform well over a long period of time. They need to be monitored (preferably daily) and topped up whenever necessary. 

[georgelza]

anyone use / can it be done, run 2 banks, with dedicated MPPT's.

One say AGM based, one Lithium based ? - both 48Volt,

... can imagine it won't work as the PylonTech has a data cable going from the battery to the VenusGX to align the numbers used to manage the battery bank, so a dumb  AGM/Gel won't "gel" well int he solution.

G

[DeepBass9]

11 hours ago, Jaws said:

How old are you 75 ?

10000 cycles is a loooooooooooong time. By that time 'll be 75!

[SilverNodashi]

11 minutes ago, georgelza said:

anyone use / can it be done, run 2 banks, with dedicated MPPT's.

One say AGM based, one Lithium based ? - both 48Volt,

... can imagine it won't work as the PylonTech has a data cable going from the battery to the VenusGX to align the numbers used to manage the battery bank, so a dumb  AGM/Gel won't "gel" well int he solution.

G

Yes, you can do this, but don't connect them to the same inverter, cause there's where the battery banks will try and equalize each other. 

[georgelza]

1 minute ago, SilverNodashi said:

Yes, you can do this, but don't connect them to the same inverter, cause there's where the battery banks will try and equalize each other. 

so different banks would require different MPPT's and inverters... aka a "expensive" parallel system, that then joins on the output side/bus bar/isolator.

G 

[SilverNodashi]

20 minutes ago, georgelza said:

so different banks would require different MPPT's and inverters... aka a "expensive" parallel system, that then joins on the output side/bus bar/isolator.

G 

Don't do that. Generally, inverters which can be paralleled, have communications between them to keep the grid in sync, but it also keep the battery statuses in sync. If you want to run two seperate banks, you would need to MPPT's, two individual inverters and split your DB into 3 individual phases. My neighbor does it this way. He has 2x 5Kw Microcare inverters, one with Poly and the other with Mono panels. The one has a 1070Ah battery bank and the other has a 520A battery bank, and his DB is split into 3. One phase for lights, the 2nd for plugs and the 3rd for eskom loads. 

Unless you have inverters which can run independent battery banks. 

[georgelza]

Just asking... to build up understanding what can and what can't be done.

G

[Coulomb]

Axperts that can be paralleled (3-phase, actual parallel, or both) must be powered from the same battery. I think most parallelable inverters have that restriction. I've speculated elsewhere that this is mainly to simplify the firmware, but I could be wrong.

[Guest]

1 hour ago, georgelza said:

Just asking... to build up understanding what can and what can't be done.

Inverter / inverterS can share the same battery bank.
One battery bank can be charged by Multiple MPPT's:
If they are set identically or MPPT's can be "connected" to share all the salient data when charging to be seen as "one".
Or you use different arrays, like positioned for morning / afternoon or different sized arrays, on different MPPT's provided you can program them to the same settings.

But you can never have multiple battery banks on the same inverter as Silver explained.

So rule of thumb:
One battery bank = one system.
Two battery banks = two totally separate systems.
Can have multiple MPPT's (programmable ones) on the same bank but you don't want the MPPT's to "fool / fight" each other when they are working.