Trying to decide on a 48V 100ah Battery with max discharge of 50amps

[Gairyc]

Newbie here. I am trying to purchase a battery. It's 5kwh. 48v 100ah but with only 50amp max discharge and 25amp standard charge/discharge. Is this a good battery? A so called Powerwall. Seems like many of the ones here in Jamaica have this rating. I I notice rack batteries like EG4 will do 100amps, but not here unless you spend a lot more for someone to import. Any advice?
It's gonna be paired with a 4000 watt inverter, and 2700w of Solar. Will be doing a separate load panel to keep within the battery capacity.
Advice appreciated.

Battery on vendor site
or File with specs attached.

 

[Millennium]

Really depends on how long you want your batteries to last and what you are powering.

 

[BentleyJ]

50A discharge limit on a 48V nominal battery is only 2,400W which is undersized if its a true 4,000W inverter. You would never be able to use the full capacity of the inverter.
Is the inverter rated at 4,000W continuous or is that that the peak output?

Ultimately it depends on what your loads are. If you only need to keep the refrigerator, couple of lights and maybe a TV or computer running then the battery will work.

You really need to specify the load and how many hours of run time on battery is needed. Without this info we can't help.

 

[OffGridForGood]

Newbie here.

Welcome to the DIY Solar Forum @Gairyc

I am trying to purchase a battery. It's 5kwh. 48v 100ah but with only 50amp max discharge and 25amp standard charge/discharge. Is this a good battery? A so called Powerwall. Seems like many of the ones here in Jamaica have this rating. I I notice rack batteries like EG4 will do 100amps, but not here unless you spend a lot more for someone to import. Any advice?

The specs read like a typical 100Ah pack, 50kg is right for a battery of this capacity. No "alarm bells" jump out at me from what I see in the specs. IP-20 so be sure you put it in a protected area away from weather. Is there a brand-name associated with the battery you are interested in?

It's gonna be paired with a 4000 watt inverter, and 2700w of Solar. Will be doing a separate load panel to keep within the battery capacity.
Advice appreciated.

2700W of solar, at 48vDC = 56Amps in good Jamaican-sunshine. If your charging is limited to 25A your system will be clipping and you will lose about half of the available power of the array. You will want at least two batteries when you can, to make use of the full PV potential you have.
Once the sun goes down, if you ran 50A via your inverter this would be about 2.5kw, and the battery would last about 2 hrs. If you run 1kW of loads your battery will have up to 5-hours.

Assuming you already have the 2700W of solar panels, and the 4kW inverter, the battery is likely too small for this system, unless you just run some lights after sundown, or use the battery just for back up if grid is offline. Not a problem if your just starting out and plan to add more battery as you can later, or you use most of the solar during the day and don't need much storage, just enough to get through the night. Adding a second battery in parallel later will allow you to use the full 2700 of incoming solar for charging, and the full capacity of your inverter output.

 

[Gairyc]

50A discharge limit on a 48V nominal battery is only 2,400W which is undersized if its a true 4,000W inverter. You would never be able to use the full capacity of the inverter.
Is the inverter rated at 4,000W continuous or is that that the peak output?

Ultimately it depends on what your loads are. If you only need to keep the refrigerator, couple of lights and maybe a TV or computer running then the battery will work.

You really need to specify the load and how many hours of run time on battery is needed. Without this info we can't help.

Thanks for the response BentleyJ. Yes, true 4000w. I know the battery is undersized. Just a fridge, a few leds and 2 tvs for now.

 

[Gairyc]

Welcome to the DIY Solar Forum @Gairyc

The specs read like a typical 100Ah pack, 50kg is right for a battery of this capacity. No "alarm bells" jump out at me from what I see in the specs. IP-20 so be sure you put it in a protected area away from weather. Is there a brand-name associated with the battery you are interested in?

2700W of solar, at 48vDC = 56Amps in good Jamaican-sunshine. If your charging is limited to 25A your system will be clipping and you will lose about half of the available power of the array. You will want at least two batteries when you can, to make use of the full PV potential you have.
Once the sun goes down, if you ran 50A via your inverter this would be about 2.5kw, and the battery would last about 2 hrs. If you run 1kW of loads your battery will have up to 5-hours.

Assuming you already have the 2700W of solar panels, and the 4kW inverter, the battery is likely too small for this system, unless you just run some lights after sundown, or use the battery just for back up if grid is offline. Not a problem if your just starting out and plan to add more battery as you can later, or you use most of the solar during the day and don't need much storage, just enough to get through the night. Adding a second battery in parallel later will allow you to use the full 2700 of incoming solar for charging, and the full capacity of your inverter output.

Thanks for the welcome very good info @OffGridForGood. Panels are actually out of stock. I can get 1800 watts worth, is that a better wattage? Just starting. I will try to add more battery capacity as soon as possible. And yes at times the grid goes down like 4 times in a 30 min period then stabilizes. Mainly during the day.
Would a 6.9kwh 51.2v @135ah with 135 amp max charge/discharge be much of an improvement?

 

[OffGridForGood]

Just a fridge, a few leds and 2 tvs for now.

Short outages mean low total energy needed, just back up power.
Watch out for the idle consumption of the inverter you choose - some (like mine!) chew up quite a lot of energy just to be on.

Thanks for the welcome very good info @OffGridForGood. Panels are actually out of stock. I can get 1800 watts worth, is that a better wattage? Just starting. I will try to add more battery capacity as soon as possible. And yes at times the grid goes down like 4 times in a 30 min period then stabilizes. Mainly during the day.
Would a 6.9kwh 51.2v @135ah with 135 amp max charge/discharge be much of an improvement?

I don't want to say it is better to have 1800 W of PV instead of 2700, it depends on your use, and plans for the future. If you can start with 1800W PV and add later when stock becomes available, this will mean your PV is more in line with your available battery storage. The 25A charging limit of the first battery you noted, would pair best with about 1400W of PV - so the 25A charging limit is more closely matched to the output of the PV on a sunny day.
If you have access to 135Ah cells - and could charge at 135A (ie 135A x 51.2v = 6900W) meaning the battery charging is not limiting your PV and will not be clipping during full sun. With the 135Ah battery, a full charge of 6.9kW using 1800W PV array would take about 4 hours. Typically you will have more then 4 hours of daylight and this would work quite well.

For your use case, the smaller battery may work fine, since it seems you are mostly interested to have a back up for frequent utility interruptions.
If the costs are similar the bigger capacity battery is always better (in my opinion) but your earlier comments lead me to think the bigger battery is much more expensive in your market. For just the fridge/TV/lights I would consider the smaller battery (if price difference is significant) and just try it out. Add a second one if you find you need it after running the system for awhile. Consider how much PV makes sense for you - if you have plans to expand the system going with 1800W PV may be the right thing to do. If no plans for expansion, I would target about 1400W PV knowing you live in a sunny place, with very little seasonal differences.
Try to find the idle consumption power for your inverter, typically this is not shown up front on entry level equipment (they don't want to scare you off) but in a small system idle consumption is a significant load on the battery.
Hope this helps.

 

[MisterSandals]

48v 100ah but with only 50amp max discharge and 25amp standard charge/discharge.

As discussed above this will only provide 2700W to your 4000W inverter if needed.
If you exceed the 25A, the battery BMS protection will shut down the battery to protect itself.

You could easily connect 2 of these batteries in parallel to double the capacity and output.

Just an option in case you had a deal on these or were otherwise interested in them.

 

[hwy17]

Even with the 100A rating of the Lifepower4 with a single battery mine trips on much lighter loads due to inrush current. Can't for example even power up my mini split in standby. This may be due to the characteristics of my 6.8kw inverter.

If 50A is the actual rating I would be concerned. That sounds like a straight telecom battery without any of the upgrades that make them barely work as a house battery.

You could possibly buy a separate BMS with a higher rating to install on the cells in that battery.

 

[Gairyc]

Thanks for all your responses. Got a different 100ah battery. Full access to the entire amount, albeit for short bursts.

 

[Gairyc]

Another question. Can you run a split phase 120/240 inverter from 120v temporarily? The label says N Hot 1 Hot 2. Output says the same but it has a plug that is 120v separate from the hardwire outputs.
Can't find a manual for this anywhere.
Thanks.

 

[hwy17]

Another question. Can you run a split phase 120/240 inverter from 120v temporarily? The label says N Hot 1 Hot 2. Output says the same but it has a plug that is 120v separate from the hardwire outputs.
Can't find a manual for this anywhere.
Thanks.

Yes it's perfectly fine to run one leg as long as it's below the 1 leg rating. That outlet is surely wired that way and ready to use.

 

[Gairyc]

Yes it's perfectly fine to run one leg as long as it's below the 1 leg rating. That outlet is surely wired that way and ready to use.

Not sure you understand. Just to clarify. I want to use a 120v input Hot on Hot 1 and N on hot 2.

 

[hwy17]

Not sure you understand. Just to clarify. I want to use a 120v input Hot on Hot 1 and N on hot 2.

That would make 240v unless I misunderstand your inverter. You want Hot on Hot 1 and N on N.

 

[OffGridForGood]

Not sure you understand. Just to clarify. I want to use a 120v input Hot on Hot 1 and N on hot 2.

It depends on the inverter.
My own MPP 6048's let me do this - charge with just 120v - however this was discribed in the manual.
In my case they showed L1 jumpered to L2, N to N.
I know you have a 4kW inverter - what brand is it?

 

[Gairyc]

It depends on the inverter.
My own MPP 6048's let me do this - charge with just 120v - however this was discribed in the manual.
In my case they showed L1 jumpered to L2, N to N.
I know you have a 4kW inverter - what brand is it?

 

[Gairyc]

It depends on the inverter.
My own MPP 6048's let me do this - charge with just 120v - however this was discribed in the manual.
In my case they showed L1 jumpered to L2, N to N.
I know you have a 4kW inverter - what brand is it?

 

[OffGridForGood]

I tried to find Pegpower - several similar companies in TX and CA but they don't sell inverters. I wasn't able to locate a manual for your make and model. (I tried!)
From the label - looks like you need 240 AC in. I wouldn't try 120 myself without finding the manual or verification by someone else with the same model. Did you find the inverter on Amazon or Aliexpress? maybe we can track down the manual that way?

 

[Gairyc]

I tried to find Pegpower - several similar companies in TX and CA but they don't sell inverters. I wasn't able to locate a manual for your make and model. (I tried!)
From the label - looks like you need 240 AC in. I wouldn't try 120 myself without finding the manual or verification by someone else with the same model. Did you find the inverter on Amazon or Aliexpress? maybe we can track down the manual that way?

No, this inverter is from a previous install. Can't find the previous installer. No manual was given to the owner. Thanks for trying. I will have do the 240. As the label doesn't state 120/240 input. Thanks again.

 

[OffGridForGood]

Try an image search of the Pegpower logo?