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Adding cheaper LFP to existing Battle Born array

Radagast

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Joined
Mar 5, 2022
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I installed 2 Battle Born 100ah 12v batteries, ~Aug, 2018, wired in series for 100ah 24v system. In Jan, 2020, I added 2 more batteries in a 2s2p config for 200ah 24v system. Last summer I added 2 more [2s3p] for 300ah 24v. I'm still running out of power when I watch movies all day [HD projector system], so I want to add more. However, I can't afford any more Battle Born batteries! They are down to $799 at Amazon [from the $949 I paid], but there are several brands offered now that are much cheaper, such as Ampere Time, for $374 [less than 1/2 price!].

Can I safely add these batteries to my system as a new 24v 100ah "segment" to get a 24v 400ah system? Would it be better to get a single 24v 100ah battery [$819], or stick with two 12v 100ah batteries [2x$374=$748] wired in series, then add whichever to system in parallel?

Is there a better brand that is still significantly cheaper than BattleBorn?
 
Yes. I have 280ah in parallel with Battleborn, I would add a mid pack jumper to help them stay balanced.
 
Sounds like you need more charging power so that your batteries get charged as well as your daytime loads are being covered. 300 ah @ 24 volts is quite a bit of power.

What is your charging source?
I have 2x250w panels wired in series, and 2x160w panels also wired in series. All wired in parallel for 820w @ 24v. I usually hit my max of 26.1v charge ~midday if it's sunny. I had to set a overvoltage cutoff of 26.1v on my controller because otherwise my inverter would shutdown with an overvoltage error. I usually drop ~0.5v while watching movies, or as soon as the sun goes down. Most sunny days, while watching movies, the system hovers between 25.6v down to 25.4v. It's when it drops to 25.3v or lower that I know I better stop watching after the current movie or I might not last through the night. Of course, if it's cloudy out, I usually don't watch any movies [or maybe just 1], because the system rarely gets above 25.4v. Thanks for your reply. Let me know what you think.
 
I have my lifepo battery charging set for 28.2 volts . I had set it for a low voltage like you have and was dropping down to 25.2 overnight. The problem was I wasn't getting a full charge with my settings set so low. I went back to 28.2 (3.52 volts per cell) and everything went back to normal and I only draw down my bank 20 % overnight.
 
That sounds great! It would be nice to not need another bank of batteries. What can I do about my inverter ["Reliable" brand] shutting down with an overcharge error?
 
I installed 2 Battle Born 100ah 12v batteries, ~Aug, 2018, wired in series for 100ah 24v system. In Jan, 2020, I added 2 more batteries in a 2s2p config for 200ah 24v system. Last summer I added 2 more [2s3p] for 300ah 24v. I'm still running out of power when I watch movies all day [HD projector system], so I want to add more. However, I can't afford any more Battle Born batteries! They are down to $799 at Amazon [from the $949 I paid], but there are several brands offered now that are much cheaper, such as Ampere Time, for $374 [less than 1/2 price!].

Can I safely add these batteries to my system as a new 24v 100ah "segment" to get a 24v 400ah system? Would it be better to get a single 24v 100ah battery [$819], or stick with two 12v 100ah batteries [2x$374=$748] wired in series, then add whichever to system in parallel?

Is there a better brand that is still significantly cheaper than BattleBorn?

You don't need new batteries. You are using too much energy for the amount of charging available.

Are you regularly breaking your bank down and individually charging the 12V like Battleborn recommends?

I have 2x250w panels wired in series, and 2x160w panels also wired in series. All wired in parallel for 820w @ 24v. I usually hit my max of 26.1v charge ~midday if it's sunny. I had to set a overvoltage cutoff of 26.1v on my controller because otherwise my inverter would shutdown with an overvoltage error. I usually drop ~0.5v while watching movies, or as soon as the sun goes down. Most sunny days, while watching movies, the system hovers between 25.6v down to 25.4v. It's when it drops to 25.3v or lower that I know I better stop watching after the current movie or I might not last through the night. Of course, if it's cloudy out, I usually don't watch any movies [or maybe just 1], because the system rarely gets above 25.4v. Thanks for your reply. Let me know what you think.

Using mismatched panels requires following some rules. Did you do that?

If your charge/inverter is cutting off at 26.1V, you have an inverter problem. You're not getting your batteries charged anywhere to full - likely not even close to 50%.

As you've discovered, it might be called "Reliable," but it ain't. I have that brand in a 2000W/24V model, and I have no complaints, but it handled > 28V without any issue whatsoever. IIRC, cut off is 32V.

Replace your inverter as you likely should have done so before ever adding any batteries. Small fraction of the cost of new batteries.

Add a battery monitor to it, so you actually know how much charge you have.
 
@Radagast Look at the link at the bottom of @sunshine_eggo 's link the one called oh no its smoke! that's your inverter and that's your problem...not all inverters are the same, especially when you are dealing with the lower tier units.

that link still makes me giggle like a 5 year old every time I watch it!
 
You don't need new batteries. You are using too much energy for the amount of charging available.

Are you regularly breaking your bank down and individually charging the 12V like Battleborn recommends?



Using mismatched panels requires following some rules. Did you do that?

If your charge/inverter is cutting off at 26.1V, you have an inverter problem. You're not getting your batteries charged anywhere to full - likely not even close to 50%.

As you've discovered, it might be called "Reliable," but it ain't. I have that brand in a 2000W/24V model, and I have no complaints, but it handled > 28V without any issue whatsoever. IIRC, cut off is 32V.

Replace your inverter as you likely should have done so before ever adding any batteries. Small fraction of the cost of new batteries.

Add a battery monitor to it, so you actually know how much charge you have.
I forgot to mention that the 26.1v max I was experiencing was as displayed on the inverter display. My EPever charge controller usually displays a battery voltage about 1.0 to 1.2 volts above what the inverter displays. When I put a voltmeter across the batteries [while still connected - too much trouble to disconnect them], it always seems to read 30v, regardless of inverter or controller displays. Anyway, it was about 2 years ago [shortly after I changed to 4 batteries] that I changed the controller settings to avoid the high voltage disconnect by the inverter that I started experiencing. Fortunately I wrote down the changes in the EPever user manual. I changed: "Over Voltage Disconnect" from 29.4v to 28.0v; "Charge Limit Voltage" from 29.2v to 27.7v; "Over Voltage Reconnect" from 29.2v to 27.7v; "Equalize Charging Voltage" from 28.8v to 27.5v; & "Boost Charging Voltage" from 28.8v to 27.5v. All other settings were left as recommended by Battle Born when I set up my 2 battery system [as well as the "from" values in the settings described above].

As to "regularly breaking your bank down and individually charging the 12V like Battleborn recommends", I never saw that recommendation. Breaking my battery system down is a major project that I try to avoid at all costs. <sigh>

As to "mismatched panels requires following some rules", as I indicated above, "I have 2x250w panels wired in series, and 2x160w panels also wired in series. All wired in parallel for 820w @ 24v." This follows the rules as I understood.

What kind of "battery monitor" do you recommend? Thank you very much for your detailed reply!
 
I forgot to mention that the 26.1v max I was experiencing was as displayed on the inverter display. My EPever charge controller usually displays a battery voltage about 1.0 to 1.2 volts above what the inverter displays. When I put a voltmeter across the batteries [while still connected - too much trouble to disconnect them], it always seems to read 30v, regardless of inverter or controller displays. Anyway, it was about 2 years ago [shortly after I changed to 4 batteries] that I changed the controller settings to avoid the high voltage disconnect by the inverter that I started experiencing. Fortunately I wrote down the changes in the EPever user manual. I changed: "Over Voltage Disconnect" from 29.4v to 28.0v; "Charge Limit Voltage" from 29.2v to 27.7v; "Over Voltage Reconnect" from 29.2v to 27.7v; "Equalize Charging Voltage" from 28.8v to 27.5v; & "Boost Charging Voltage" from 28.8v to 27.5v. All other settings were left as recommended by Battle Born when I set up my 2 battery system [as well as the "from" values in the settings described above].

Still likely need to replace your inverter. Should also confirm all measurements with a separate meter.

As to "regularly breaking your bank down and individually charging the 12V like Battleborn recommends", I never saw that recommendation. Breaking my battery system down is a major project that I try to avoid at all costs. <sigh>

It's in the Battleborn battery manual.


How to Maintain the Batteries
Battle Born Batteries require very little maintenance. If your batteries are in series and not being charged by a multi-bank charger it is recommended that you fully charge the batteries individually once a month if the system is used frequently. This will internally balance your batteries to ensure that they will reach their expected life span and allow you to get the full power out of them with each use.

You should now go and check that all of your 12V are at nearly identical voltages throughout the operational range.

As to "mismatched panels requires following some rules", as I indicated above, "I have 2x250w panels wired in series, and 2x160w panels also wired in series. All wired in parallel for 820w @ 24v." This follows the rules as I understood.

The 250W and 160W panels must be very nearly the same Vmp for proper performance.

What kind of "battery monitor" do you recommend? Thank you very much for your detailed reply!

Will recommends several:

 
I installed 2 Battle Born 100ah 12v batteries, ~Aug, 2018, wired in series for 100ah 24v system. In Jan, 2020, I added 2 more batteries in a 2s2p config for 200ah 24v system. Last summer I added 2 more [2s3p] for 300ah 24v. I'm still running out of power when I watch movies all day [HD projector system], so I want to add more. However, I can't afford any more Battle Born batteries! They are down to $799 at Amazon [from the $949 I paid], but there are several brands offered now that are much cheaper, such as Ampere Time, for $374 [less than 1/2 price!].

Can I safely add these batteries to my system as a new 24v 100ah "segment" to get a 24v 400ah system? Would it be better to get a single 24v 100ah battery [$819], or stick with two 12v 100ah batteries [2x$374=$748] wired in series, then add whichever to system in parallel?

Is there a better brand that is still significantly cheaper than BattleBorn?
Lots of great info here about things to consider when adding capacity to an existing system. Assuming appropriate, adequate charging capacity is available, temperature is within appropriate ranges, series/parallel constraints are adhered to, is anyone aware of any substantial 'study' about combining batteries from different manufacturers or can share/discuss other concerns regarding mismatches between different manufacturer's BMS, charging/maintenance parameters or other characteristics?
 
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