# Interest group forums > Energy and Resource Conservation Forum > [Question] Drop in Hubble Lifep04

## Alfred M

Hi all has anybody used this specific drop in replacement i would appreciate any feedback on performance. I need to replace 22 Gel batteries that reached end of life with Lifep04 and had these units in mind.

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## GCE

Not sure if you mean 22 individual units or 22 feeding one UPS/Inverter 

Most of the drop in replacement type batteries have limitations with regards to connecting in parallel and also max voltage when connecting in series

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## Alfred M

> Not sure if you mean 22 individual units or 22 feeding one UPS/Inverter 
> 
> Most of the drop in replacement type batteries have limitations with regards to connecting in parallel and also max voltage when connecting in series


Sorry it is actually 24 100ah gel batteries 8 batteries per bank and 3 banks parallel to a Microcare 8kw bi- directional inverter. 3 banks as illustrated in drawing below that has a class t primary fuse at inverter positive. Sorry i cant take pictures the client dont allow pictures taken in his plant. I got the picture below on the internet as explanation picture below x 3 to the inverter.The wiring is not very neat they are using 16mm welding cable with 16x8 crimped lugs on the battery terminals.

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## Isetech

Why not install batteries designed for that application with a built in BMS, which can communicate with inverter.

You need to understand the inverter specs and only then choose a battery suitable for the inverter. I would strongly advise against just dropping in replacement batteries.

Something I see a lot while doing inverter audits for customers, general and battery setting not suitable for the type of batteries, like charge/discharge rates, battery cutout settings etc etc. Leaving an inverter in default setting, could destroy the batteries in a matter of months.

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Cyon (26-May-22)

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## Alfred M

> Why not install batteries designed for that application with a built in BMS, which can communicate with inverter.
> 
> You need to understand the inverter specs and only then choose a battery suitable for the inverter. I would strongly advise against just dropping in replacement batteries.
> 
> Something I see a lot while doing inverter audits for customers, general and battery setting not suitable for the type of batteries, like charge/discharge rates, battery cutout settings etc etc. Leaving an inverter in default setting, could destroy the batteries in a matter of months.


Thanks for the advice i did manage to find a manual for the Microcare inverter and did speak to the technical guys at Microcare in PE. The parameters could be set up for Lifep04.The main challenge in charging a Li-Ion battery is to realize the battery's full capacity without overcharging it. Constant current constant voltage (CCCV) I will set the inverter cut off voltage at 40% dod.

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## Justloadit

> Thanks for the advice i did manage to find a manual for the Microcare inverter and did speak to the technical guys at Microcare in PE. The parameters could be set up for Lifep04.The main challenge in charging a Li-Ion battery is to realize the battery's full capacity without overcharging it. Constant current constant voltage (CCCV) I will set the inverter cut off voltage at 40% dod.


LiFePO4 batteries can go down to 10% DOD as per your chart or minimum of 12V.
Voltage per cell, I think your battery has 4 cells in series
Minimum discharge voltage = 2.5 V = 10V
Working voltage = 3.0 to 3.2 V = 12V to 12.8V
Maximum charge voltage = 3.65 V = 14.6V

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## Alfred M

> LiFePO4 batteries can go down to 10% DOD as per your chart or minimum of 12V.
> Voltage per cell, I think your battery has 4 cells in series
> Minimum discharge voltage = 2.5 V = 10V
> Working voltage = 3.0 to 3.2 V = 12V to 12.8V
> Maximum charge voltage = 3.65 V = 14.6V


Thanks guys i appreciate the guidance and info. The ac load is 25amps single phase on inverter output and these new Lifep04 will be much more efficient than the 120ah deep cycle gel batteries so my thinking was to discharge only to 40% dod for the longevity of the battery bank as the client is paying R160k for the new batteries i have enough capacity to run down to 40% dod (24 batteries@120ah/battery) series/ parallel for 24v dc inverter input. I see on the existing installation there is 1x class T 30 fuse installed as primary disconnector on the positive side at the inverter or would it be better to put fuse protection between every bank and leave the class t fuse as main interrupter. I also see that this inverter can run at 200% 16kw if mains is present. There is also a ats changeover switch installed for a 30 kva diesel generator with one fase and neutral feeding the inverter. I was also thinking of using copper busbar with short leads to the battery terminals and get rid of the 16mm welding cable making the installation looking very untidy or am i overthinking the setup.

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## Alfred M

> LiFePO4 batteries can go down to 10% DOD as per your chart or minimum of 12V.
> Voltage per cell, I think your battery has 4 cells in series
> Minimum discharge voltage = 2.5 V = 10V
> Working voltage = 3.0 to 3.2 V = 12V to 12.8V
> Maximum charge voltage = 3.65 V = 14.6V


Thanks guys i appreciate the guidance and info. The ac load is 25amps single phase on inverter output and these new Lifep04 will be much more efficient than the 120ah deep cycle gel batteries so my thinking was to discharge only to 40% dod for the longevity of the battery bank as the client is paying R160k for the new batteries i have enough capacity to run down to 40% dod (24 batteries@120ah/battery) series/ parallel for 24v dc inverter input. I see on the existing installation there is 1x class T 300 fuse installed as primary disconnector on the positive side at the inverter or would it be better to put fuse protection between every bank and leave the class t fuse as main interrupter. I also see that this inverter can run at 200% 16kw if mains is present. There is also a ats changeover switch installed for a 30 kva diesel generator with one fase and neutral feeding the inverter. I was also thinking of using copper busbar with short leads to the battery terminals and get rid of the 16mm welding cable making the installation looking very untidy or am i overthinking the setup.

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## Justloadit

LiFePO4 have life cycles from 2,700 to over 10,000 cycles depending on conditions, so there is no advantage making the DOD at 40%.

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## Isetech

One of the common battery failures or reduction in cycles in SA, high temperature.

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## Isetech

> LiFePO4 have life cycles from 2,700 to over 10,000 cycles depending on conditions, so there is no advantage making the DOD at 40%.


Not lower than 10 % and not higher than 90 charge is a good average ? I am told some batteries have built in 10 % compensation, so going from 100 % to 0 % is not an issue.

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## Isetech

If you are looking for a money saving solution, I would be using the batteries to the max. J

Something to note there is already talk of better battery technology in pipe line, would you need your batteries to last 10 years? 

This whole backup trend is going break people, especially the ones who are taking second bonds to pay off large installs over 25 year bond terms  :Frown:  

I have seen how some of these replacement batteries have cleaned out customer life savings. Repo rate expected to hit 6 % by the end of the year. Fuel price to go up over R3 next week and expected to hit R30 by the end of the year. Only the rich and smart are going to survive.

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## Justloadit

A good time to make the decision on Quality over Price!

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