Hi Guys..

I currently run a small 3KVA Growatt inverter (24v). this was installed quite a few years ago, mainly to keep my son studying from home to have  break-free power supply during the load shedding period and during Covid years when all classes / exams were on-line.

The batteries then bought, is reaching their end of life!!!

I am looking to upgrade from 24v to 48v in the years to come.

Is there a 48v (52v) battery out there 100Ah that I can configure as a 24v 200Ah battery whilst the 24v system is still working?

I prefer LiFePO4!

 

Cheers

Z

 

I don't believe this would work. Your inverter would try to charge the battery at 24V, which is not much good to a 48V battery.

Tell us more. Is this a trolley inverter (plugs into a wall socket rather than wired into the DB). Do you have panels or this just inverter and battery? What battery do you have at present? What's the maximum charge and discharge current for the inverter?

You can get 24V 100-ish Ah Li batteries. EG https://www.maidenelectronics.co.za/enertec-24v-105ah-lithium-ion-drop-in-lead-replacement-battery

 

only 2 solutions I can think of now,

buy 2x 12v lifepo4 batteries now, connected in series its a 24v battery,

buy 2 more when you switch to 48v, 4 in series is 48v,

the best practise in this scenario will be to add a balancer to the series connected batteries.

or 

 

buy 16x 100ah  lifpo4 cells and a BMS that can operate with anything from 4 to 17 cells.(or 20) JK bms is a popular brand.

8 of these 100ah cells in series will make a 100ah 24v battery, to make a 200ah 24v battery, take 2 cells and connect them in parallel with each other, and connect 8 of these 2 cell packs in series with each other, now you have 24v 200ah battery.

and when you switch to 48v, connect all 16 in series for a 100ah 48v battery. 

1 hour ago, Z Ga said:

Hi Guys..

I currently run a small 3KVA Growatt inverter (24v). this was installed quite a few years ago, mainly to keep my son studying from home to have  break-free power supply during the load shedding period and during Covid years when all classes / exams were on-line.

The batteries then bought, is reaching their end of life!!!

I am looking to upgrade from 24v to 48v in the years to come.

Is there a 48v (52v) battery out there 100Ah that I can configure as a 24v 200Ah battery whilst the 24v system is still working?

I prefer LiFePO4!

 

Cheers

Z

 

Due to pricing 2x24V cost more than 1x48V same AH rating. 

If you want to buy batteries once then go the DIY way with external BMS that can for not support 2 banks of 8S for 24V. Later the same BMS can be used for 16S when going to 48V.

A BMS like JK can support 20cells in series from 8 or more cells.. That is the BMS I am using. 

Again DIY with BMS seems to cost more than a complete battery. 

@stefan44 sorry you type faster than me. 2x24V drop in could also work where each has it's own BMS. This is problematic when one wants to later use them in series (48V) as not many if any balances between 24V batteries AFAIK. 

Edited November 15, 20241 yr by Scorp007

2 hours ago, Z Ga said:

Hi Guys..

I currently run a small 3KVA Growatt inverter (24v). this was installed quite a few years ago, mainly to keep my son studying from home to have  break-free power supply during the load shedding period and during Covid years when all classes / exams were on-line.

The batteries then bought, is reaching their end of life!!!

I am looking to upgrade from 24v to 48v in the years to come.

Is there a 48v (52v) battery out there 100Ah that I can configure as a 24v 200Ah battery whilst the 24v system is still working?

I prefer LiFePO4!

 

Cheers

Z

 

For the amount of battery capacity you want, I'd consider just to make the jump straight to a 48V system and shop around for the best offers for a 5kWh battery and 5kW offgrid inverters around.

45 minutes ago, GreenFields said:

For the amount of battery capacity you want, I'd consider just to make the jump straight to a 48V system and shop around for the best offers for a 5kWh battery and 5kW offgrid inverters around.

I have to fully agree with @GreenFields now that a 5kW inverter sells for R5000 and battery at R15000 it just makes sense than to battle with a 24V 3kW that needs lithium batteries if budget allows it. 

8 hours ago, Scorp007 said:

I have to fully agree with @GreenFields now that a 5kW inverter sells for R5000 and battery at R15000 it just makes sense than to battle with a 24V 3kW that needs lithium batteries if budget allows it. 

Thanks = I knew that was going to be the conclusion - jump directly to 48v with a 5kW inverter -

Yes, connected to solar panels - 4 x Vision 6Fm100Z 100AH batteries - 2 in series with the other two in parallel. 

Currently - I run the inverter from 8am to about 5pm without any problems up in Pretoria. I even run the pool pump during the hottest part of the day.

3Kw Geyser connected to a 20 tube solar collector. In the past 3 years, had to use mains on only 4 occasions! A massive saving! At least R1500 per month.

Over the last 3 years, my electricity use (Eskom) was under R400 per month.

4 plate gas stove does the bulk of the cooking!

Thanks for the info.

 

Regards

Z