LifePo4 battery for Sump Pump Backup

[bedpan]

Hey folks. Not quite solar but mostly kinda related ;-)

I have a sump pump that runs quite a bit through Fall to Spring. 5 Years ago when I bought the house I put in a 12V battery backed up pump. This has worked quite good but I need a new battery for it. I have some Renogy 100Ah batteries (borrowed for now) so I put one in. It runs the pump fine but I get zero charging out of it. So I put a Renogy 20A charger on it. All said this works fine. The battery sits at 100% waiting on the pump to kick in should there be a power outage.

This led me to thinking.. I know its not great to leave LifePo4 at 100% all the time which is what will happen with the current setup. Is there a charger around that will maintain say 50%? I am ok giving up 50% of the capacity as its still functionally the same amount of pumping power as the old Lead Acid that was in there. If I can make the battery last long though I would like to do that.

So I guess 2 questions really;
1) How bad it is for LifePo4 to sit at 100%? Is there a measurable decline in capacity or not enough to worry about?
2) Is there a better charger, or some other means to keep the battery at 50%ish that is ideally automatic? I have pondered just unplug the charger when not in use and plug back in after a power outage.

Cheers and much thanks for the input!

 

[bedpan]

Anyone?

I did find Some Victron Chargers have a storage mode. I am finding some literature say its for lead acid only but one website says it drops the voltage so that the battery is not held at 100%. Also no clear literature which charger support it.
Could be I am just miss-reading it as well

NEW STORAGE MODE IN SMART BATTERY CHARGERS EXTENDS LITHIUM BATTERY LIFE – Safiery

www.safiery.com

Thoughts anyone?

 

[MiSh]

Anyone?

I did find Some Victron Chargers have a storage mode. I am finding some literature say its for lead acid only but one website says it drops the voltage so that the battery is not held at 100%. Also no clear literature which charger support it.
Could be I am just miss-reading it as well

NEW STORAGE MODE IN SMART BATTERY CHARGERS EXTENDS LITHIUM BATTERY LIFE – Safiery

www.safiery.com

Thoughts anyone?

I have an Aims 1500w inverter, Relion 12v lifepo4 battery, and a Victron blue smart charger connected to a small Xantrex transfer switch that I use for my sump pump backup system. The charger does have a storage mode that you can adjust via their bluetooth app. I don't leave my charger plugged in 24/7 either for the reasons you cite above even though it has a storage mode. Not sure it's the best for battery longevity.

 

[bedpan]

I have an Aims 1500w inverter, Relion 12v lifepo4 battery, and a Victron blue smart charger connected to a small Xantrex transfer switch that I use for my sump pump backup system. The charger does have a storage mode that you can adjust via their bluetooth app. I don't leave my charger plugged in 24/7 either for the reasons you cite above even though it has a storage mode. Not sure it's the best for battery longevity.

Thanks Mik..

I would be running a 12V pump so I can skip the inverter in my application and my floats on the 12V pump is set higher then the 120V pump so it only comes on in the event that the 120V pump does not run (power out, pump failure or super high flow rate).

Any idea how the storage mode works on the Victron with Lithium batteries? I think i will have to email them to ask. I am doing the same right now and just unplugging but I would prefer to automate the process and keep the battery at 50%ish.

Cheers!

Mike

 

[MiSh]

Thanks Mik..

I would be running a 12V pump so I can skip the inverter in my application and my floats on the 12V pump is set higher then the 120V pump so it only comes on in the event that the 120V pump does not run (power out, pump failure or super high flow rate).

Any idea how the storage mode works on the Victron with Lithium batteries? I think i will have to email them to ask. I am doing the same right now and just unplugging but I would prefer to automate the process and keep the battery at 50%ish.

Cheers!

Mike

The storage mode is adjusted by voltage. There's an adjustable scale you can slide back and forth to whatever voltage you want storage set at. I'm pretty sure it has to be the 'smart' charger model though.

 

[jvin248]

.

Non-solar related, sump pump info, since I have an active pumper too.

-Make sure all roof downspouts have kicks at the base to get water away from the house. When I bought this house they ran them into the footing drains and a 'dry well' so all that water needed to get constantly pumped out. Every seven minutes in the Spring.

-Make sure your driveway is not pooling water run off and transporting it back at the house. My current house driveway slopes up from the house and water likes to run through the gravel and sand under the slabs perfectly aimed at the basement sump. I've re-routed yard run off through a separate french drain to the ditch, skipping the sump now.

-Make sure the grade around the house is not aimed 'in' but out and away to shed surface water.

-Look at making a larger sump for the pump to sit in. This will reduce the frequency of on/off cycles favoring longer run times. On/off cycles reduce sump pump lifespans.

Then your sump pump running frequency is much reduced.

.

 

[K8MEJ]

So I guess 2 questions really;
1) How bad it is for LifePo4 to sit at 100%? Is there a measurable decline in capacity or not enough to worry about?
2) Is there a better charger, or some other means to keep the battery at 50%ish that is ideally automatic? I have pondered just unplug the charger when not in use and plug back in after a power outage.

Cheers and much thanks for the input!

Theoretically, you will degrade your LFP battery if you leave it sit at 100% for long periods of time. However, I think practically it doesn't matter much so long as you don't keep it at 14 plus volts constantly. I'm fairly conservative with my charging profile for LFP batteries. I set a bulk/absorption voltage of 14.1V (for 12v batteries) and a float voltage of just 13.5V. Once the battery is charged and absorbed, the charger switches to 13.5V and holds there.

And, if you're using Renogy gear, I wouldn't worry too much about it. The equipment is likely to fail before you do anything to damage it.

Seriously, though, so long as you keep your charging voltages lowish and your charger either has storage mode or float mode, I don't think you need to worry about it.

 

[bedpan]

The storage mode is adjusted by voltage. There's an adjustable scale you can slide back and forth to whatever voltage you want storage set at. I'm pretty sure it has to be the 'smart' charger model though.

Thanks Mik. Turns out it was just a fundamental miss understanding on my side. I was thinking that the storage mode would drop the battery to say 50%.. It just drops the voltage and stops pushing amps.. Don't mind me. I am new..

Cheers!

 

[bedpan]

.

Non-solar related, sump pump info, since I have an active pumper too.

-Make sure all roof downspouts have kicks at the base to get water away from the house. When I bought this house they ran them into the footing drains and a 'dry well' so all that water needed to get constantly pumped out. Every seven minutes in the Spring.

-Make sure your driveway is not pooling water run off and transporting it back at the house. My current house driveway slopes up from the house and water likes to run through the gravel and sand under the slabs perfectly aimed at the basement sump. I've re-routed yard run off through a separate french drain to the ditch, skipping the sump now.

-Make sure the grade around the house is not aimed 'in' but out and away to shed surface water.

-Look at making a larger sump for the pump to sit in. This will reduce the frequency of on/off cycles favoring longer run times. On/off cycles reduce sump pump lifespans.

Then your sump pump running frequency is much reduced.

.

Thanks Jvin for taking the time to respond.

Your on point for all your suggestions.. I have gone through most of them. The largest issue is grading around the house. The backyard is a large hill with several houses up hill from us with all the water running downhill to us. The builder did not do a great job of moving the water around the house.

Long term I need to get a excavator in and re-grade a large chunk of our back yard... In the mean time I just make sure the sump keeps pumping!

Cheers and thanks!

 

[bedpan]

Theoretically, you will degrade your LFP battery if you leave it sit at 100% for long periods of time. However, I think practically it doesn't matter much so long as you don't keep it at 14 plus volts constantly. I'm fairly conservative with my charging profile for LFP batteries. I set a bulk/absorption voltage of 14.1V (for 12v batteries) and a float voltage of just 13.5V. Once the battery is charged and absorbed, the charger switches to 13.5V and holds there.

And, if you're using Renogy gear, I wouldn't worry too much about it. The equipment is likely to fail before you do anything to damage it.

Seriously, though, so long as you keep your charging voltages lowish and your charger either has storage mode or float mode, I don't think you need to worry about it.

Thanks K8MEJ.

As a new guy to solar, Renogy seemed the way to go....... I find myself slowly moving away Case and point. I have opened support tickets with Renogy and heard nothing back from them. I emailed Victron with some questions about their charger last night and had a response this morning. Hard to beat.

From Victron

Hello,
Storage mode just means that if the battery has been connected to a charger continuously and fully charged and sitting in Float for 24hrs, it will reduce the output voltage to prevent corrosion on the positive plate.
This is for the health of lead-acid battery types, not lithium.
In our opinion, there is no problem leaving a LiFePO4 battery connected at Float level, assuming this is not set too high (13.5V is our recommendation)
Usually people want the full capacity of their battery when power goes out.
If you want to stop charging at 50%, you would need to set the charge profile to a lower voltage range, or use a battery monitor with a relay set to turn a charger off at at particular SOC%. The BMV712 has such a programmable relay.
Th charger you use would need a remote port to connect to the relay.
Our Phoenix IP43 chargers are the smallest ones with such a remote on/off port.

So a key point from Victron - "no problem leaving a LiFePO4 battery connected at Float level" which is exactly what your said.

Sooo I think I am just over-engineering the problem. I miss-understood how the charger works with float mode and how that can be used to achieve what I want.

I am going to order an IP65 Victron charger. I think it will work just fine.

Thanks kindly!

Mike

 

[MiSh]

.

Non-solar related, sump pump info, since I have an active pumper too.

-Make sure all roof downspouts have kicks at the base to get water away from the house. When I bought this house they ran them into the footing drains and a 'dry well' so all that water needed to get constantly pumped out. Every seven minutes in the Spring.

-Make sure your driveway is not pooling water run off and transporting it back at the house. My current house driveway slopes up from the house and water likes to run through the gravel and sand under the slabs perfectly aimed at the basement sump. I've re-routed yard run off through a separate french drain to the ditch, skipping the sump now.

-Make sure the grade around the house is not aimed 'in' but out and away to shed surface water.

-Look at making a larger sump for the pump to sit in. This will reduce the frequency of on/off cycles favoring longer run times. On/off cycles reduce sump pump lifespans.

Then your sump pump running frequency is much reduced.

.

Excellent points, especially the first one. There are basement waterproofing companies that thrive on homeowners not discharging thier downspout water far enough away from the foundation.

 

[French_guy]

Thanks K8MEJ.

As a new guy to solar, Renogy seemed the way to go....... I find myself slowly moving away Case and point. I have opened support tickets with Renogy and heard nothing back from them. I emailed Victron with some questions about their charger last night and had a response this morning. Hard to beat.

From Victron


So a key point from Victron - "no problem leaving a LiFePO4 battery connected at Float level" which is exactly what your said.

Sooo I think I am just over-engineering the problem. I miss-understood how the charger works with float mode and how that can be used to achieve what I want.

I am going to order an IP65 Victron charger. I think it will work just fine.

Thanks kindly!

Mike

How is your system working for you? I'm in the exact same boat: 12VDC backup sump pump, with VRLA batteries that need to be replaced.
I'm thinking going LiFePO4 with Victron Blue smart charger, but some people mentioned AGM are ideal for standby application.....So now making a decision is even more difficult...

 

[bedpan]

How is your system working for you? I'm in the exact same boat: 12VDC backup sump pump, with VRLA batteries that need to be replaced.
I'm thinking going LiFePO4 with Victron Blue smart charger, but some people mentioned AGM are ideal for standby application.....So now making a decision is even more difficult...

Sorry for the delay in responding. I don't get notified of new posts for some reason.. I need to figure that out.

Short answer is it works great.

Long answer.. It has been problem free since install and does what its suppose to. One long power outage and the Renogy 100Ah battery I have on it carried for about 9 hours and still over 50%. Power came back on and it charged back up and is ready to go again. The Victron charger keeps it about 97%. Its not ideal for LiFePo4 but nor is it terrible. If it drops down to 80% capacity over 5 years so be it.

Here are a few photos from the Victron App and Renogy App



I need to clean up the wiring and make it pretty but its a super easy install and having twice the capacity of Lead Acid is nice.

 

[French_guy]

Sorry for the delay in responding. I don't get notified of new posts for some reason.. I need to figure that out.

Short answer is it works great.

Long answer.. It has been problem free since install and does what its suppose to. One long power outage and the Renogy 100Ah battery I have on it carried for about 9 hours and still over 50%. Power came back on and it charged back up and is ready to go again. The Victron charger keeps it about 97%. Its not ideal for LiFePo4 but nor is it terrible. If it drops down to 80% capacity over 5 years so be it.

Here are a few photos from the Victron App and Renogy App

View attachment 143706View attachment 143707View attachment 143708

I need to clean up the wiring and make it pretty but its a super easy install and having twice the capacity of Lead Acid is nice.

So what battery are you using now?

 

[DIYrich]

Sorry for the delay in responding. I don't get notified of new posts for some reason.. I need to figure that out.

Don't. Will is trying to reduce the number of emails going out.

 

[bedpan]

So what battery are you using now?

I have a Renogy 100AH battery. I was using a cheap Deep Cycle battery before. It only lasted about 4 years.

Any half decent LiFePo4 battery should do. Prowse just updated his guide and recommends the Roypow "Power Urus". They are only $400 USD. You likely don't need the low temp protection though so could go with the LiTime/AmpreTime at $350.

 

[bedpan]

Don't. Will is trying to reduce the number of emails going out.

Has he post why out of curiosity?

 

[French_guy]

I have a Renogy 100AH battery. I was using a cheap Deep Cycle battery before. It only lasted about 4 years.

Any half decent LiFePo4 battery should do. Prowse just updated his guide and recommends the Roypow "Power Urus". They are only $400 USD. You likely don't need the low temp protection though so could go with the LiTime/AmpreTime at $350.

What do you think about Redodo batteries?
By the way, I won't need low temp cutoff....will never be exposed to low temperatures in my basement

 

[time2roll]

Has he post why out of curiosity?

Not sure it is the emails going out so much as infrequent users now tend to report email as spam rather than unsubscribe and delete. This gets legit simpler systems to be wholly blocked from sending.
Going to a commercial email system is going to cost a bundle.

There is a thread on it to explain.

Glad to hear the sump is working.

 

[bedpan]

What do you think about Redodo batteries?
By the way, I won't need low temp cutoff....will never be exposed to low temperatures in my basement

Not an expert here.. I would buy them if the price were right. They appear to be built well.