EG4 LiFePOWER4 48v, 100 AH, 5.12kWh Startup Questions

[Michaells]

@Will Prowse (and others)

I am almost ready to power up my new off-grid system. I have 4 of the EG4 LifePower4 48v 100AH, 5.12 kWh batteries in the rack. And I have a couple of questions before I start her up.

• In this video
  Will Prowse demonstrates a pre-charge procedure that is baked into the battery and that I was unaware of. I can’t find any documentation of this and wanted to check if anyone else has. I had been planning on using a resistor and doing the precharge the old fashioned way.
• Will seems to follow the procedure with the inverter off, and then turns the inverter on after the precharge. Did I get this right?
• One of the reasons I put in this off-grid system is to have backup power in case of an outage, which happens often here. Given that, I would like to set the inverter to only allow the batteries to discharge as much as necessary before charging. The default for LiFEPo4 on the Growatt SPF 6000T DVM-MPV inverter seems to be discharge to 40% and then charge to 80%. Can I discharge and charge to a higher level without adversely affecting the health and longevity of the battery? If so, how high is recommended?

Thanks in advance to all for your advice!

 

[Will Prowse]

I still prefer manually charging with a resistor. If you feel comfortable with that method, use that instead. Either method works.

Yes, inverter off first. Only turn on after the capacitors are charged up and the batteries are on and connected.

Yes charge to 100%. Discharge down to 10%. It will not hurt them.

 

[Michaells]

I still prefer manually charging with a resistor. If you feel comfortable with that method, use that instead. Either method works.

Yes, inverter off first. Only turn on after the capacitors are charged up and the batteries are on and connected.

Yes charge to 100%. Discharge down to 10%. It will not hurt them.

Thanks @Will Prowse. My question about charging is do I have to discharge that low, or even as low as 40%? Again, I don’t want to get caught with low battery power during a power outage. So how low do I have to discharge and still keep the batteries in good shape?

 

[Michaells]

@RichardfromEG4 Can you advise on my question above re the EG4 LifePower4 48v 100AH, 5.12 kWh batteries? (I have 4 of these in a rack.) Do I have to discharge as low as 40% each cycle to maintain the health and longevity of the battery? I don’t want to get caught with low battery power during a power outage. How low do I have to discharge and still keep the batteries in good shape before charging?

 

[Solar Guy Richard]

There should be no issues at discharging or charging to any percentage. LiPo batteries measure cycles by AH discharge and charge through the BMS. If you want to get the full use out of batteries, feel free to discharge to 10% but if you are worried about getting caught at low charge - set it higher (or the best answer is to honestly add another battery).

 

[Michaells]

Thanks @RichardfromEG4. I will see how it goes and how well my system gets me through the night (or a couple of cloudy days) at the inverter default (40% discharge triggers utility source and 80% charge triggers battery source) then go from there. It appears as though my inverter allows me to set the discharge point to 5-50% and charge point to 51-100% when in Li mode.

 

[MikeSC]

New to solar here and putting together my first system. I just purchased three of these batteries from Signature Solar along with two of their 6500 watt inverters. How critical is it that the batteries are charged to 100% prior to initial startup? I would prefer not purchasing a 48 vdc portable charger for a one-time charge.

Also - what size resistor is used for the pre-charge.

 

[Michaells]

I received conflicting information about the charging except to say that it is important that each battery is within 0.1 volts of the others. I would charge to full. One user suggested using your inverter in utility mode to do this, one battery at a time.

The resistor can be almost anything, it seems. I used one of the attached, from Walmart.

My system is now up and running with a single, split phase 6K inverter and I already wish I had more batteries. I bought 4 and wonder if I might not get two more to fill the rack. But maybe that depends on your location and setting. I am in the northeast with an imperfectly oriented roof mount. Maybe if I lived in a sunnier state with a perfectly oriented rig, I might feel differently about that.

 

[Solar Guy Richard]

I received conflicting information about the charging exempt to say that it is important that each battery is within 0.1 volts of the others. I would charge to full. One user suggested using your inverter in utility mode to do this, one battery at a time.

The resistor can be almost anything, it seems. I used one of the attached, from Walmart.

My system is now up and running with a single, split phase 6K inverter and I already wish I had more batteries. I bought 4 and wonder if I might not get two more to fill the rack. But maybe that depends on your location and setting. I am in the northeast with an imperfectly oriented roof mount. Maybe if I lived in a sunnier state with a perfectly oriented rig, I might feel differently about that.

Awesome man!

 

[Lilikoi_Heavy_Industries]

New to solar here and putting together my first system. I just purchased three of these batteries from Signature Solar along with two of their 6500 watt inverters. How critical is it that the batteries are charged to 100% prior to initial startup? I would prefer not purchasing a 48 vdc portable charger for a one-time charge.

Also - what size resistor is used for the pre-charge.

You wire your entire system together and then only turn the batteries on one at a time until they're all 100%.

You don't need an external charger, you'll use the hybrid inverter to charge the batteries one at a time by only turning one circuit breaker on at a time... The hybrid inverter can charge it from sun or AC (grid/generator).