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DIY Lithium Ion UPS questions


Bl4d3
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Hey all

So I've built a 3s13p 18650 battery packing using 39 x Panasonic NCR18650PF 2800mah batteries.
They are connected to a BMS.
Technically the pack should have 36AH of capacity

The intention is for it to run a router and tv at the S/O place.

I am currently testing the pack by running it through a few charge and discharge using a small Turnigy Accucell 6 charger.


Now, I would like to build a system so that it functions similar to a UPS, just with a lithium ion battery pack. I've seen a few videos of this being done but there are a few problems with just a direct swap.
A UPS is not designed to charge lithium ion cells and the transformers aren't made to run for extended periods of time.

 

Can anyone point me in right direction on how to go about this? It would be ideal to have it in a single unit where it is plugged into mains, will maintain charge and power an output at 220v AC but will maintain the output even when the mains are unplugged (pretty much like a UPS).

 

Thanks

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Tried something similar a few years back with a normal UPS and large battery and my UPS did overheat and shut down.

Depending on budget, and as a suggestion, you could perhaps consider getting a low cost or used hybrid inverter e.g. something like this?

https://www.victronenergy.com/inverters-chargers/multi-500-va

or perhaps slightly larger depending on the consumption of the TV which most probably uses most of the energy

https://www.dixonbatteries.co.za/multiplus-c-12-800-35-16

One of these may be another option, not too familiar with them however:

https://mustek.co.za/mecer-axpert-family/

 

 

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7 hours ago, Bl4d3 said:

Now, I would like to build a system so that it functions similar to a UPS, just with a lithium ion battery pack. I've seen a few videos of this being done but there are a few problems with just a direct swap.
A UPS is not designed to charge lithium ion cells and the transformers aren't made to run for extended periods of time.

It will depend on the UPS that you are using. Yes, the voltage of the Li-ion batteries is lower than the equivalent lead acid 12V battery.

I wouldn't rely on the charging circuit of the UPS. Rather charge the Li-Ion batteries with its own charger.

But rather do not use a 12V UPS. A better option are 24V or 48V UPSs..  

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