Gamatronic G Net UPS battery replacement

[ryan10]

Hey guys,

Does anyone know if it is possible to replace the 7.5Ah 12V batteries with LiFePo4 batteries or any other type of bigger batteries?
The unit has 8x 7.5Ah 12V lead acid batteries.

Thanks

 

[leon.davibe]

Technically you could

The potential problems
1 the bms in these batteries means that you would only be able to use bout 768w load max if 7.5a bms

2 not sure if the bms of these small batteries are ok with series setups have seen some listings of small lifepo4 with warnings of not suitable for series setup

The other problem is price ie the smaller batteries price per kw tends to be higher so buying 8x 7.5ah batteries means you are buying just 0.768 kwh while you can buy a 12.8v 1.28kwh battery for under 5k + a cheap inverter may still work out cheaper/same as 8 lifepo4 7.5ah batteries

 

[wingnut771]

Technically you could

The potential problems
1 the bms in these batteries means that you would only be able to use bout 768w load max if 7.5a bms

2 not sure if the bms of these small batteries are ok with series setups have seen some listings of small lifepo4 with warnings of not suitable for series setup

The other problem is price ie the smaller batteries price per kw tends to be higher so buying 8x 7.5ah batteries means you are buying just 0.768 kwh while you can buy a 12.8v 1.28kwh battery for under 5k + a cheap inverter may still work out cheaper/same as 8 lifepo4 7.5ah batteries

8 batteries, I wonder what the pack voltage is? Do these small things support more than 24V?

Edit: I see it’s 96V, so not possible afaik. Anyway, this type of inverter is not meant to run for long duration. Better to get a R4k 100Ah LFP from geewiz and a 12V PSW inverter.

 

[ryan10]

Thanks for the info.
I will look into other options.

 

[leon.davibe]

8 batteries, I wonder what the pack voltage is? Do these small things support more than 24V?

Edit: I see it’s 96V, so not possible afaik. Anyway, this type of inverter is not meant to run for long duration. Better to get a R4k 100Ah LFP from geewiz and a 12V PSW inverter.

The beauty of lifepo4 is the charge voltage of one lead acid matches 4 cells of lifepo4 rather perfect so all you need to be sure of is that you have the right cell count by using 8 12.8v lifepo4 you know it will match

Or if you build a custom battery with 32 cells ie 8*4 cells

Don't think you can get a 32s bms so two 16S 48v ones will give you the 96v

The problem is price of the small cells are overpriced for what you get

When i got my cells i bought for something like R60 each which would mean you could buy 32/R1920/ 576wh
or double up 64/R3840/1152wh but with the extra cost even at those lower prices you would pay the same as 12v 100ah lifepo4 with the extra bms and balancer costs a 12v battery and a cheap inverter may match price

But since the cheapest cells i see is double that now custom is out of the question

That leaves 8x 7.5ah batteries
Which will most likely work, but can't guarantee the cheaper build of these batteries won't cause a problem
But again overpriced by kwh

 

[wingnut771]

The beauty of lifepo4 is the charge voltage of one lead acid matches 4 cells of lifepo4 rather perfect so all you need to be sure of is that you have the right cell count by using 8 12.8v lifepo4 you know it will match

Or if you build a custom battery with 32 cells ie 8*4 cells

Don't think you can get a 32s bms so two 16S 48v ones will give you the 96v

The problem is price of the small cells are overpriced for what you get

When i got my cells i bought for something like R60 each which would mean you could buy 32/R1920/ 576wh
or double up 64/R3840/1152wh but with the extra cost even at those lower prices you would pay the same as 12v 100ah lifepo4 with the extra bms and balancer costs a 12v battery and a cheap inverter may match price

But since the cheapest cells i see is double that now custom is out of the question

That leaves 8x 7.5ah batteries
Which will most likely work, but can't guarantee the cheaper build of these batteries won't cause a problem
But again overpriced by kwh

8 small batteries is the same price as one 12V 100Ah. Note sure how you will custom a battery to fit in the ups. Seems like a lot of work for very little gain not to mention finding a 96V bms.