Renogy Lithium at 14.4 volts?

[Deleted member 783]

That is what they spec for the limit. I'm starting to think they are smoking the wacky weed at Renogy. Sorry for the terrible pic.

 

[Ped]

14.4 +/- .2

Standard. 14.6v is generally max and they do need max like lead.

 

[Justin Laureltec]

I'm more surprised to see their float voltage at the same... charge voltage isn't surprising, Battle Born says the same as do a few other well-known brands (14.2-14.6) but float voltage is usually backed off a bit. This is odd...
...then again, we all know Renogy isn't a manufacturer to begin with, so they're likely just pulling voltage values more or less out of their arse and trusting the batteries will hold up to the abuse.

 

[Sojourner1]

Renogy only needs the batteries to last 5 years in warranty then they're prorated according to their website.

Definitely better warranties on lfp batteries if longterm ownership is a factor.

 

[mnsprinter170]

This is what Renogy emailed me:


Over voltage disconnect voltage 16.0v
Charging limit voltage 16.0v
Over voltage reconnect voltage 15.0v
Equalize charging voltage 14.4v
Boost charging voltage 14.4v
Float charging voltage 14.4v
Boost reconnect charging voltage 13.2v
Equalize duration 0 minutes
Boost duration 120 minutes

 

[MrNatural22]

Wow! Wouldn't that mean the battery stays in a constant boost/equalize charge situation (Though they say equalize time 000)?? But float at 14.4v?? No resting. I'm not that experienced but that doesn't sound healthy for the life of a battery? Maybe only LA, SLA and gel can benifit from this?

 

[Sojourner1]

Renogy doesn't care about longevity of lfp batteries if that's what they're telling customers. They want those customers to buy more after cooking the cells. ? ? ??

 

[Will Prowse]

That is strange.

Renogy has a team of engineers that are qualified and very helpful. But the marketing team that designs manuals/product descriptions will copy/paste without understanding what it says. I have seen this a few times. When there are enough complaints (such as with the dc dc mppt), then the engineering team will step in and rewrite the whole thing.

A lot of people are scared of keeping lfp at high soc for prolonged duration (especially in hot environments), and you will have some capacity loss, but I have never found actual data to back this up. The marine lfp battery builders say to avoid keeping lfp at high soc like the plague, but never have shown proof of it:

Here is a marine guy talking about this (source: https://marinehowto.com/lifepo4-batteries-on-boats/)

DURATION AT TARGET VOLTAGE (Over-Absorbing):

One area folks often misconstrue is thinking a lower charge voltage means it’s 100% safe for the LFP battery. It may not be. If your charge sources are not suitable they can still potentially over-charge by holding the constant-voltage stage (absorption) for too long. Over absorbing, even at pack voltages as low as 13.68V, can result in charging to 100% SOC. Continuing to charge beyond the point where the Li-Ions have stopped moving, from the cathode to the anode, would be considered charging more than is necessary. Charging at high voltages, beyond when the bank is full, can lead to a phenomenon known as lithium plating. If the CV (constant voltage) stage of the charger is held long enough an LFP cell can be fully charged at voltages as low as 3.42VPC.

Most lead acid designed charge sources can hold the absorption voltage stage more than long enough to cause long term damage or eat into some cycle life capacity of your expensive LFP cells. Some LFP manufacturers are now starting to understand this point, when selling into a lead-acid charger environment, and have reduced recommended max charging voltages accordingly, though some others have not. The quality of the cells used inside the battery also play a role as to how well they deal with constant voltage being held longer than is necessary.

I recently had four prismatic cells in the shop, sent to me by a gentleman who assumed a GEL setting on his charger was safe. He decided this based on Winston’s voltage specifications. He assumed, seeing as it was only 14.2V or 3.55VPC, and well within the spec, that 14.2V was safe for a nominal 12V bank. However, as I mentioned earlier, voltage is not the only factor to consider. You have voltage, duration at target voltage, and charge rate to also consider.

LiFePO4 cells are optimally charged to 100% SOC, then charging is terminated, stopped or dropped to a voltage level that will not cause major harm. This was the original design of the chemistry. This does not happen with far too many lead-acid designed chargers so you as an owner will need to chose charge sources that can be carefully programmed..

The problem the GEL setting installation was the absorption DURATION, not the voltage. At 14.2V the absorption duration was 4 hours long with no way to change the length of the absorption cycle-timer. On top of a 4 hour absorption the chargers charge rate, which was very low in comparison to the banks Ah capacity, his cells were actually hitting 100% SOC before the voltage even got to 14.2V. Continuing to charge beyond the 100% SOC point can lead to lithium plating.

In other words he was technically over-charging his bank before he even got to 14.2V because charge rate also plays a role. Once his bank hit 14.2V the charger then continued to charge them for four more hours each time he went to 100% SOC. On top of all this his so called “smart charger” was actually really quite dumb and could reset the absorption timer when ever a large load kicked in and momentarily dropped the sensed voltage below the re-absorb trigger. he also still had the temp compensation circuit active, something that is not good for LFP.

In just 150 +/- cycles his 180Ah cells could barely deliver 96Ah’s and they were puffed up like balloons. 2000 cycles? His expensive Winston LFP cells were severely diminished in less than 150 cycles while using the GEL setting we so often read about as being “safe” for LFP. If his charger had stopped charging when the cells actually hit 100% SOC, it would have been much better for the cells, 14.2V or even 14.6V is a safe “stop-charge” point, but instead it kept charging for 4+ hours after the bank was full. It could also, too easily, be re-triggered back into another 4-hour absorption cycle when a house load kicked on. Considering the boat spent much time at a dock, it is impossible to say how many hours they were maintained at 14.2V/3.55VPC.

Contrast the real world scenario above to a study conducted at a University using the same exact prismatic cells. They charged the cells to 4.0V then discharged to 0% then repeated this for 950 cycles. The cells survived 950 complete 100% discharge & recharge cycles. The difference here being the charging was 100% terminated/stopped when 4.00VPC was reached and the discharge current automatically turned on. This means the cells were only above 3.45VPC for a very, very brief period on each cycle and were never held continuously at 100% SOC..

The relationship between target voltage, duration at target voltage + charge current is where damage can occur.. When setting up an LFP system these three factors can’t be ignored;

Target Charge Voltage

Duration the Charge Source Maintains/Holds Target Voltage

Charge Rate

These three items go hand in hand with LFP.

Charging LFP is simple – Charge to target voltage then stop charging.

So there are a few stories where people had loss of capacity. and he shows that the university study, and many other studies, hold the lfp cells at 100% for a brief instance. But what I do know is that lfp can handle higher voltages nicely, and some people even quote 4.2v per cell as max before electrolyte degradation. I would personally charge to 14.0v for a 12v lfp because you will get the majority of the capacity without shooting any of the cells voltages up too much (of course I imply that the cells are matched), and a float of 13.6 because the voltage settles so quickly after charging.

I dont know. lots of opinions on this topic...

 

[Sojourner1]

Could fall in the category of when a company is so big that front end doesn't communicate with the back end. Or some cases of just growing faster than they can handle.

The data shows one thing with personal saying something else. College education at it's best, all book smarts and no common sense. Or would this be just poor management/ supervision.

 

[letsrig]

I just purchased a Renogy 100ah LiFePo4 battery and would like to know if anything new has been learned (in this community) about Renogy's LiFePo4 voltage settings because their documentation is still 'recommending' 14.4v float.

 

[letsrig]

I just purchased a Renogy 100ah LiFePo4 battery and would like to know if anything new has been learned (in this community) about Renogy's LiFePo4 voltage settings because their documentation is still 'recommending' 14.4v float.

I'm not getting any replies from Renogy on this question. Has anyone else received clarification from Renogy on this issue? I will likely go with @Will Prowse recommendations in post #8 above.

 

[Sojourner1]

Error on the side of caution. There is plenty of data out that shows Renogy settings are "aggressive ". Bulk 14.4v, balancing of cells "should" happen in this voltage range. Float 13.6v if in daily use and you should be good to go.

Floating at 14.4v will eventually shorten the life of the cells inside.

 

[letsrig]

A follow up. Renogy finally replied to my question regarding the float setting and i was sent the image attached. The float setting has simply been removed - which is the complete opposite of the 14.4v 'recommended' in the manual that came with the battery.

 

[Substrate]

Well, what's supposed to happen is that Renogy's BMS will disconnect the charge source when it thinks it is full, so even if you do have "float" set for 14.4, it isn't actually connected and floating!

If this were a bare DIY battery, then maybe the long term float at 14.4v would be very bad. I certainly never held my bms-less batts that way for long periods.

From a manufacturer's standpoint, they have no idea what the end user is *really* going to use to charge. For instance:

A solar controller for lead-acid that has a "timed" absorb, say of only 2 hours reaching 14.4v, and then automatically dropping back to a 13.6 float. Mostly to ensure that they don't overcharge lead-acid in non-cyclic applications. That would result in a less than full charge on the LFP batt.

So to ensure that the LFP batt will actually get charged to full, and let the BMS decide when to pull the plug, to prevent an early termination of CV with "timed" solar charge controllers, they recommend having "float" at the same setting to ensure that charge continues until the bms decides it's time to disconnect.

My best theory anyway...

 

[trevor.the.van]

Well, what's supposed to happen is that Renogy's BMS will disconnect the charge source when it thinks it is full, so even if you do have "float" set for 14.4, it isn't actually connected and floating!

If this were a bare DIY battery, then maybe the long term float at 14.4v would be very bad. I certainly never held my bms-less batts that way for long periods.

From a manufacturer's standpoint, they have no idea what the end user is *really* going to use to charge. For instance:

A solar controller for lead-acid that has a "timed" absorb, say of only 2 hours reaching 14.4v, and then automatically dropping back to a 13.6 float. Mostly to ensure that they don't overcharge lead-acid in non-cyclic applications. That would result in a less than full charge on the LFP batt.

So to ensure that the LFP batt will actually get charged to full, and let the BMS decide when to pull the plug, to prevent an early termination of CV with "timed" solar charge controllers, they recommend having "float" at the same setting to ensure that charge continues until the bms decides it's time to disconnect.

My best theory anyway...

Sounds like a good theory. When Will did the tear down of the Renogy battery, the BMS was very advanced so its quite likely this could be the reasoning.

I just picked up 3 of the Renogy batteries for a new van build - and from experience, it's rare to be bringing batteries up to 100% charge on a daily basis anyway. Travelling in the van rarely gives ideal conditions all the time. However, giving the batteries a proper 100% charge once a month or so should help to keep them balanced and working for a long time.

 

[4kSecuritySolutions]

That company renogy, I don't trust their batteries agm line, I've ordered 6 of the 200ah, the 1st 4 arrived, it's when the second 2 arrived and I started testing I got pissed. These batteries would not even hold a charge over 12.85. ?.. I was really hoping to see 13.8 or even 14v

2 out of the 6 batteries didn't even work

Ordered on Amazon from their store

 

[MrNatural22]

That company renogy, I don't trust their batteries agm line, I've ordered 6 of the 200ah, the 1st 4 arrived, it's when the second 2 arrived and I started testing I got pissed. These batteries would not even hold a charge over 12.85. ?.. I was really hoping to see 13.8 or even 14v

2 out of the 6 batteries didn't even work

Ordered on Amazon from their store

12.85v resting is considered a full charge for agm batteries

 

[Substrate]

Yep - and even brand new conventional agm's that have actually been charged properly, will rest at 12.8 to 13.1v.

Sadly, when reading some reviews, one never knows if the end user has charged with an arc-welder, or a wall-wart for a baby swing. Ya' just don't know the whole story that prompts the returns.

 

[teddysx3]

So, bringing this thread back to life.

Any new news from Renogy from anybody here?

I just picked up a 100ah battery, because of the 1/3 price here in Europe, compared to some of the other brands.

From the people that are actually using this battery, what are your setting in the SCC? I might just go with Will's advice in post #8, but curious to see why settings you guys went for.

 

[Jamie Marshall]

I found this thread while doing reasurch, like most people i thought Wills comment 8 sounded sensible.
This weekend I enacted that advise but found the results unsatisfactory.

I Set the bulk charge to 14v on my 30Amp Renogy MPPT DC DC.
This immediately reduced the charge from my alternator from about 18amps down to 9.
I wasn't actually getting 14v, it seems to leave a safety margin.
I tried a few different settings but in the end any less that 14.4 had a detrimental effect on my charge current.
Not that the battery was seeing 14.4v in the process.

My SOC was about 50% at the beginning of the jurney and 100% towards the end.
I monitored it the whole time and decided to stick with the recomended 14.4v.
I want good battery life so I'll reduce this to 14v for any periods that I don't need allot of power.

I hope this helps. Sorry I haven't got any Solar data, I'm in England.