Are Renogy 170Ah LI batteries as good an idea as they seem?

[markopolo]

Originally Posted by @Michael

Here's a couple of Renogy docs with temp ratings:

https://www.renogy.com/content/files...anual_V1.0.pdf
https://www.renogy.com/content/files...LFP-12-170.pdf

The 170ah is rated at -10c, the 50 and 100ah are rated at -20c.

The 3.8V over voltage protection from the PDF's is kind of like closing the barn door after the horse has run off.

3.7 VPC is already overcharge territory.

[booster]

Originally Posted by markopolo

Some of the AGM related info on their site must be very wrong. No charging at 32F & below seems/is preposterous. That makes every other bit of info suspect.

Yep, and this is one of the things that has always bothered/worried me about some of the drop in battery manufacturers and sellers, as it has seems to have become the norm. Battleborn has also had grossly exaggerated claims of weaknesses of AGM batteries and lot of conflicts about temp ratings, charger rates, etc in their literature too.

If they are willing to mislead about this kind of stuff, can you really believe the number for cycle life or allowable discharge depth or the high float and charge voltages because they are "deigned to handle it"?
What the Renology sheet doesn't show is a low temp cutoff, which is probably one of the more important things to have. Perhaps, it is because if they do, they would have to make heater and a recovery process available, most likely, and that would make "drop in" a lot tougher sell.
I guess I am one that gets very skeptical, very quickly, if there appears to be a effort to mislead in stuff like this, probably from too many years of dealing with industrial sales reps during my working days, as most of them were chronically "truth impaired".

[Davydd]

Originally Posted by markopolo

Some of the AGM related info on their site must be very wrong. No charging at 32F & below seems/is preposterous. That makes every other bit of info suspect.

The 170ah lithium ion data sheet seems to correlate with LiFePO4 information from other companies. That's what this thread is about.

Charging lithium ion below freezing doesn't kill the batteries dead as storing batteries getting down to -4F does, but it incrementally damages them. A good BMS should prevent charging, but no BMS can prevent -4F in storage.

Lots of things came out on lithium ion batteries temperature wise long after they had been installed in RVs. Could it be people are taking second looks at AGMs? Charging frozen batteries regardless of chemistry may not be a good idea.

[markopolo]

Water freezes at 32F.

Progressive Dynamics has this to say about electrolyte in lead acid batteries and freezing:

If your battery is partially discharged, the electrolyte in a lead acid battery may freeze. At a 40% state of charge, electrolyte will freeze if the temperature drops to approximately -16 degrees F. When a battery is fully charged the electrolyte will not freeze until the temperature drops to approximately -92 degrees F.

I think the advice to not charge an AGM at or below 32F is preposterous. You would not be able to drive your Sprinter or your car during the winter in many places if you had to worry about AGM's at 32F for example. A lead acid battery might have to be down to 9V to worry about electrolyte freezing at 32F.

[markopolo]

Originally Posted by Davydd

The 170ah lithium ion data sheet seems to correlate with LiFePO4 information from other companies. That's what this thread is about.....................

Getting back to the Renogy 170Ah LFP battery.

Booster already pointed out that there is no Under-temperature Protection temp listed in those documents. Is it more likely that they forgot to list that critical specification or that it does not have that feature?

Another curiosity from the LFP datasheets is the charge until "charging current has tapered to a 0.02C". Do any/many other LFP battery vendors recommend that?

Also the "effect of temperature on cycle charge voltage: -4 mV / °C / Cell" seems unusual. To me, it implies temperature compensation. Again, do any/many other LFP battery vendors recommend that?

Over-voltage protection at 3.80±0.05V is higher than what I'd use.

Similarly, under-voltage protection at 2.30±0.05V is lower than what I'd use.

I just booted up a programmable BMS on my work bench. I think there are more than 50 settings that can be adjusted. It also has two stored profiles you can use. They label the profiles Normal LiFePO4 and Light LiFePO4.

The profile Normal LiFePO4 has Over-voltage Protection at 3.65V and Under-Voltage Protection at 2.5V.

The profile Light LiFePO4 has Over-voltage Protection at 3.60V and Under-Voltage Protection at 2.75V.

Those are very different than Renogy's Over-voltage Protection at 3.8V and Under-Voltage protection at 2.3V.

I think of the BMS as being the last line of defense. If you have a charger go berserk the BMS needs to be set with protection set points that will save the battery cells.

[booster]

In some of the tech papers we have seen over the years, I do recall seeing the charging to an amp reading based on capacity on some of the charge profiles given during their testing. I can't say if it just was for test consistency or if it was also based on what they thought was good for the batteries. I do think it went to a lower percent than the 2% Renogy listed.


I think these manufacturers and sellers are cherry picking range ends and the very most favorable to selling that they can find. In the real world, they are probably very willing to accept the fairly small percent of users that will be operating in areas that might be problems so they can claim more impressive specs. Will they get more failures, most likely, but the trade off for sales is worth it to them and they hope the warranty and reputation costs of that strategy doesn't hurt them too much. Roadtrek is probably the poster child for that strategy, coupled with a less the truthful defense of their actual problems.

[rowiebowie]

Originally Posted by markopolo

Some of the AGM related info on their site must be very wrong. No charging at 32F & below seems/is preposterous. That makes every other bit of info suspect.

I agree that information can't be right. But I'm sure I translated the information from Celsius correctly as I recall the charge range being the same as the lithiums (just didn't dawn on me at the time).

I think Renogy offers too many products and it wouldn't be the first time they can't keep their information accurate. For example, my Renogy inverter/charger was over 1" wider than their posted dimensions because they didn't include the mouning flange. It barely fit in the small space I had available, literally scraping the sides of my compartment to get it in.

They need to do a better job.

[BigFatGuy]

I sent them some questions via their website contact-us page. It took them quite a while to reply, and, if i'm reading right, their batteries shut themselves off at 32F!

(I've since come up with a better plan than a high-output 12V charger, btw)

My Questions:

I'm looking to upgrade my RV from a pair of AGM batteries to lithium, and I like your 170ah product very much.

I do have a question: as part of this eventual overhaul of my RV's electric system, I plan to replace the 120v generator with a high-ouput alternator attached to the engine... 200A, 280A, something like that.

However, 2 batteries with a 280A alternator means the charging current could be absurdly high.

So, I have some questions:

1: do you have some kind of "best practices" guidance for wiring up an RV with your batteries?

2: does your BMS meter the charging current, or otherwise self-protect the battery? Or, is my only real defense to limit the alternator size to be no greater than 50A * # of batteries? (I'd like to be able to run my AC off this alternator and an inverter, so the overhead may be important)

3: How compatible is your battery with other vendor's "good quality" chargers? My RV came with a Zampf solar system (500W) and a Progressive Dynamics battery charger. Is your battery likely to do well in a "drop in replacement" type situation, or should I plan on replacing with your chargers and solar controllers upfront?

4: there is apparently a "safe mode" that requires a special charger to recover from in your BMS. How often does this happen?

Thanks for your help!

Their reply

Thank you for reaching out to Renogy.

​1- We do not have a guide for hooking up the batteries to the RV
2- The BMS of the battery will not limit the current. If the maximum current is exceeded, the BMs of the battery will be locked it out and would need to be reactivated. In the event that this happened, you will a Renogy charge controller with a Lithium reactivation feature or a smart charger like the NOCO Genius.
3- unfortunately, I am familiar with these other companies, but I do know how the Their systems operate. So long as they can be configured to charge the battery at a constant 14.4v for both the boost and float stage. IF they can not accommodate for that value, I would recommend a Renogy charge controller and an inverter charger.
4- The "safe mode" only occurs when the battery exceeds any of its rated values. For example, More than the 50a for charging, the temperatures rise or drop past 32F-113F, Under voltage <10, or over voltage 14.6<.

[booster]

Originally Posted by BigFatGuy

I sent them some questions via their website contact-us page. It took them quite a while to reply, and, if i'm reading right, their batteries shut themselves off at 32F!

(I've since come up with a better plan than a high-output 12V charger, btw)

My Questions:


Their reply

I think I would certainly pursue what the the necessary equipment and procedure are to "unlock" their BMS protections. AFAIK, it is very unusual for some product to lock a system then rely on other vendor's systems to be able to unlock it. Sounds like a recipe for finger pointing and problems.

[BigFatGuy]

Originally Posted by booster

I think I would certainly pursue what the the necessary equipment and procedure are to "unlock" their BMS protections. AFAIK, it is very unusual for some product to lock a system then rely on other vendor's systems to be able to unlock it. Sounds like a recipe for finger pointing and problems.

I suspect it's to force one to use their charger.

I find myself talking myself out of these batteries.

[rowiebowie]

I don't know the proper terms behind it and don't fully comprehend it, but here's what I researched when checking into it a few months ago.

It seems when the Renogy Lithium BMS shuts down; to protect itself from say low voltage condition; some chargers will not produce charge the they sense no charge is being accepted.

You need a charger that will continue to put out low charge until the BMS awakens. As I understand it, my Renogy 3000W Inverter/Charger won't even do the job. I will need a separate NOCO model charger. Reading the NOCO site I came away confused as to what specific feature to look for. I'm hoping I'll never need it, and if I do, will have to find out more at that time.

So there you have it, clear as mud.

[BigFatGuy]

Yeah... I can't have my hardware refusing to do it's job in 32F, or if it runs down a bit to low.

Thanks, all, for a rousing discussion.

[markopolo]

The 32F and 113F in Renogy's reply to BFG is the same as the recommended operating temperature range in the manual and differs from the over-temperature information in the same manual.

When asked about under-temperature cutoff protection Renogy's reply should always include four temperatures.

1. low temp charge cutoff temperature
2. low temp charge recovery temperature
3. low temp discharge cutoff temperature
4. low temp discharge recovery temperature

If the battery has under-temperature protection they should just post that temperature info on their website.

They do provide that info for over-temperature:

1. high temp charge cutoff temperature: 60 Celsius (140F)
2. high temp charge recovery temperature 50 Celsius (122F)
3. high temp discharge cutoff temperature 65 Celsius (149F)
4. high temp discharge recovery temperature 55 Celsius (131F)

I kind of / sort of doubt it has built-in under-temperature protection because it is not listed in the manual or specifications.

Similarly, when the subject of LFP reactivation comes up then Renogy should include what voltage is required in their answer. Chargers that need to sense battery voltage before initiating charging won't work.

Rowie might just have to start his van's engine to reactivate his LFP batteries if his Renogy DC to DC charger can output charging voltage and current without a battery on the output end.

BFG's Progressive Dynamics unit will output charging voltage and current without needing to see a battery on the output so almost certainly would reactivate a shutoff LFP battery.

[MarCorpsMustang]

Originally Posted by @Michael

The 170ah is interesting, but seems to have some caveats:

Maximum Charge Current:50A

.

Maybe I'm misunderstanding, but doesn't "maximum charge current" mean you can't charge the battery at anything *greater than* 50A. Anything less than a 50A charger would be fine; right?

[MarCorpsMustang]

The 170Ah Renogy LFP battery is selling for $1,225 on Amazon. Free delivery.

[BigFatGuy]

Originally Posted by MarCorpsMustang

The 170Ah Renogy LFP battery is selling for $1,225 on Amazon. Free delivery.

You're killing me, Smalls...

[@Michael]

Originally Posted by MarCorpsMustang

Maybe I'm misunderstanding, but doesn't "maximum charge current" mean you can't charge the battery at anything *greater than* 50A. Anything less than a 50A charger would be fine; right?

Yes, that's how I read the spec. No more than 50A rate of charge.

That's a minor limitation, and only for those who have the capability of charging at a rate >50A. For example - my Transit has the heavy duty alternator and appears to be able to supply at least 100A over what the van needs to run. So if I wanted to charge at that rate, I'd be better off with two 100AH batteries that can each be charged at a 50A rate. Vans with a second alternator would also be limited by the 50A rate limit on these batteries.

For most uses though, they seem like a heck of a deal.

[Sprinter Lex]

Looks like Renogy did some kind of updating

Here is there 170 Lithium webpage link. (Go to the downloads tab a bit down to see the specs sheet, in case it was updated again)
https://www.renogy.com/lithium-iron-...12-volt-170ah/

Here is the specs sheet:
https://www.renogy.com/content/RNG-B...170-Manual.pdf

Charging amps may have been upgraded- The sheet says 85A for the 170AH and 50A for the 100AH/50ah batteries.

BMS may of been upgraded- Charge/disconnect voltage cut-off is 14.6V and 10V

Cycle life is now (0.2C, 20±5℃) 2000 Cycles @ 80% DOD.

Also, Over-charge`Protection now says 3.9±0.05V/Cell. So no longer 3.8.... the wrong direction perhaps... Or is tech knowledge advancing faster than our knowledge. Can't advance faster than my knowledge, I don't have any haha.

I didn't really check to see if there were any other differences. I just noticed these numbers didn't match in my head when reading.