Renogy Batteries

[artfulltune]

Hello James, the Balmar regulator displayed immediate charge rate with the batts at 40-50% are @14.4 bulk, about equal to lower helm console mounted Xantrex & Renogy remote displays when I am on shore power AC.

 

[ranger58sb]

I understand 50% discharge is FLA. If it is also the same for AGM, as far as Odyssey goes, why spend the extra money if you don't need to store them on their side?

Also. what is used to measure SOC as far as capacity left or used?

The positioning is one advantage, not one we've needed.

Two other AGM advantages are reduced off-gassing (more important if batteries are in living spaces), and the whole maintenance-free thing (especially if access is difficult). These two are part of the reason we usually gravitate toward AGMs, but I don't mean these as valid reasons for everyone.

We tend to choose either Odyssey or Lifeline (depending) because we've had good service from those... nicely longer than what I often read other folks reporting about their brands. This one can also be unimportant for some... who might prefer to spend less now and are OK with replacing batteries more often.

There's a bit of equivocal "advertising" language, though, in some cases. Some FLA (or SLA, not AGM) makers say to not discharge below 50% -- for longest life -- and I think some makers say that discharge below 80% will actually damage their battery. Whereas Odyssey does say you can discharge their batteries to 80% without damage. Which is not much different in language... and is also not a recommendation to do that all the time.... and it's also not the same as a comparison of life-cycles. Odyssey and Lifeline both mention their milspec-hood-ness, though... and I don't remember seeing other brands do that. (Haven't really looked, though.)

There's a test for capacity. Basically it needs powering a specific load with your battery bank and recording how long that lasts. There are devices to keep track of discharge rates versus recharge rates, but I think they all need to start with some ground truth (that basic test).

-Chris

 

[ranger58sb]

I understand 50% discharge is FLA. If it is also the same for AGM, as far as Odyssey goes, why spend the extra money if you don't need to store them on their side?

The positioning is one advantage, not one we've needed.

Two other AGM advantages are reduced off-gassing (more important if batteries are in living spaces), and the whole maintenance-free thing (especially if access is difficult). These two are part of the reason we usually gravitate toward AGMs, but I don't mean these as valid reasons for everyone.

If it matters, there's another advantage, for some, that I forgot to include. That's the one about a higher charge acceptance rate, which in turn can (might) mean faster charging.

Isn't perfect for everyone. For instance, if you have a couple large banks on a small multi-bank charger... then charger limitations probably negate the AGM fast charging advantage.

OTOH, if you have bank with it's own dedicated, relatively high-amp charger, then AGMs can accept a more significant bulk charge and a higher absorption voltage even as amperage begins it's decline. (Compared to FLAs/SLAs.)

In our case now, we would generally run the generator at anchor twice/day, to coincide with (electric) cooking times. That means heating water and charging batteries at the same time. A relatively short 2-hour genset session can cram a decent recharge into our AGMs... so our AC-only freezer and fridges (powered by an inverter/charger bank) can stay happy...

On the last boat, we eventually had a 60A charger on one main bank, a 50A inverter/charger on the other main bank, and an older 40A multi-bank charger that I could select for either or both of those banks too. A couple hour-long genset sessions per day at anchor kept our AGM banks relatively highly charged.

BTW, I'm not really trying to sell AGMs. They work for us, but they're not the right solution for everyone in every situation. I think FLAs still have a solid place in the line-up, as do gels probably (no experience with those), and of course the newer LFP solutions so far seem nifty for house loads. In our case, I just juggle ease of use versus effectiveness versus cost... to arrive at what works for us so far.

-Chris

 

[catalinajack]

If it matters, there's another advantage, for some, that I forgot to include. That's the one about a higher charge acceptance rate, which in turn can (might) mean faster charging.

Isn't perfect for everyone. For instance, if you have a couple large banks on a small multi-bank charger... then charger limitations probably negate the AGM fast charging advantage.

OTOH, if you have bank with it's own dedicated, relatively high-amp charger, then AGMs can accept a more significant bulk charge and a higher absorption voltage even as amperage begins it's decline. (Compared to FLAs/SLAs.)

In our case now, we would generally run the generator at anchor twice/day, to coincide with (electric) cooking times. That means heating water and charging batteries at the same time. A relatively short 2-hour genset session can cram a decent recharge into our AGMs... so our AC-only freezer and fridges (powered by an inverter/charger bank) can stay happy...

On the last boat, we eventually had a 60A charger on one main bank, a 50A inverter/charger on the other main bank, and an older 40A multi-bank charger that I could select for either or both of those banks too. A couple hour-long genset sessions per day at anchor kept our AGM banks relatively highly charged.

BTW, I'm not really trying to sell AGMs. They work for us, but they're not the right solution for everyone in every situation. I think FLAs still have a solid place in the line-up, as do gels probably (no experience with those), and of course the newer LFP solutions so far seem nifty for house loads. In our case, I just juggle ease of use versus effectiveness versus cost... to arrive at what works for us so far.

-Chris

Yes, AGMs have a higher charge acceptance rate but the amount of time they are accepting a higher rate of charge does not lead to anything but a marginal decrease in charging time. Furthermore, you need an alternator(s) that put out enough juice to take advantage of that acceptance rate.

 

[ranger58sb]

Yes, AGMs have a higher charge acceptance rate but the amount of time they are accepting a higher rate of charge does not lead to anything but a marginal decrease in charging time. Furthermore, you need an alternator(s) that put out enough juice to take advantage of that acceptance rate.

I've not timed it... nor done the math to compare times... just accept that "faster" is a good idea for our situation.

And I'm not at all considering alternator charging; instead I'm using the generator and a high-amp battery charger.

-Chris

 

[ranger58sb]

Just happened across this, Rod Collins commentary relevant to Renogy (see post 30):

https://www.cruisersforum.com/forums/f14/multiple-charging-sources-273428.html

-Chris

 

[catalinajack]

I've not timed it... nor done the math to compare times... just accept that "faster" is a good idea for our situation.



And I'm not at all considering alternator charging; instead I'm using the generator and a high-amp battery charger.



-Chris

Chris, I have timed how long it takes to charge my flooded batteries on alternators and on shore power with a 125-amp charger. From a 50% depth of discharge, it takes about 5.5 hours by either method (920-amphour bank). Regardless of the charging method, AGMs simply do not charge appreciably faster than flooded batteries. There are other good reasons for AGMs to be a better choice in some use cases, but speed of recharging is not one.

 

[Iggy]

I agree on the charging.

I know I am a pain on this, but. Kilovault just had another price drop! https://www.altestore.com/store/dee...-lithium-solar-battery-p41627/#KLV2400HLXPLUL

Panbo did two write ups on them. Built in auto heater, Bluetooth, 7.5 year warranty.

 

[ranger58sb]

Chris, I have timed how long it takes to charge my flooded batteries on alternators and on shore power with a 125-amp charger. From a 50% depth of discharge, it takes about 5.5 hours by either method (920-amphour bank). Regardless of the charging method, AGMs simply do not charge appreciably faster than flooded batteries. There are other good reasons for AGMs to be a better choice in some use cases, but speed of recharging is not one.

Have you compared your charging times against a 920-Ah bank of AGMs?

Using Trojan's info for reference (first that came to hand easily), their flooded batteries have a charge acceptance rate of 13% of C20, whereas their AGMs (aka one of their VRLA options) says 20% of C20. (Lifeline says ours can tolerate up to 5C, although our chargers can get there from here.)

https://www.trojanbattery.com/resources/battery-maintenance

If I did the math right and assuming nominal temps, that would mean your set-up would take approx 3.84 hours to replenish 50% of 920 flooded.

Or it would take 2.5 hours to replenish 50% of 920 of their AGMs. (Maybe would need a 185A charger to do that?)

Allowing for minor real-world details, that whole long slow tail for finish charging, temp differences, etc etc etc.

Is my math wrong?

-Chris

 

[Don L]

I agree on the charging.

I know I am a pain on this, but. Kilovault just had another price drop! https://www.altestore.com/store/dee...-lithium-solar-battery-p41627/#KLV2400HLXPLUL

Panbo did two write ups on them. Built in auto heater, Bluetooth, 7.5 year warranty.

$880/200ah sale price with a $1995 list price. Seems insulting doesn't it?

Guess all the inexpensive drop-ins are starting to drive the overpriced guys down. There are lots of choices in 200ah LFP right off Amazon for $600-650

 

[Iggy]

$880/200ah sale price with a $1995 list price. Seems insulting doesn't it?

Guess all the inexpensive drop-ins are starting to drive the overpriced guys down. There are lots of choices in 200ah LFP right off Amazon for $600-650

For something like that, I don't think Amazon is the place. Have you ever tried calling them for tech support on a product like that? I would rather deal with a dealer or the manufacture. Alt-e from that link is the manufacturer of the Kilovault battery.

As to price, I think its more like DVD players when the first come out. Two years later they were more than half price off. The more they make the cheaper they can be produced.

I also take it that you have not read the write ups from Panbo.

 

[mvweebles]

I believe Panbo generally liked Kilovault. Will Prowse hasn't done a tear-down on Kilovault, but has on other batteries such as Ampere Time, one of the low cost Amazon batteries.

Folks, regardless of where these LFP are assembled, they are built from Chinese components with minerals (Lithhium, cobalt, etc) mined in SE Asia and Australia. Build quality is improving rapidly. There is absolutely junk in the marketplace, but the gap between known hi-quality such as Battle Born and their low cost competitors is shrinking.

Peter

 

[Iggy]

I believe Panbo generally liked Kilovault. Will Prowse hasn't done a tear-down on Kilovault, but has on other batteries such as Ampere Time, one of the low cost Amazon batteries.

Folks, regardless of where these LFP are assembled, they are built from Chinese components with minerals (Lithhium, cobalt, etc) mined in SE Asia and Australia. Build quality is improving rapidly. There is absolutely junk in the marketplace, but the gap between known hi-quality such as Battle Born and their low cost competitors is shrinking.

Peter

But I think, and this is me. That the BMS units separate them apart. Battle Born does make a great battery. But there heater is not automatic and no Bluetooth. Other wise I would have bought them being 2nd on my list. Victron was first choice, but they were just too much money at the time. Their integration with battery, shuts, chargers and more take it to a new level.

 

[ranger58sb]

If I did the math right and assuming nominal temps, that would mean your set-up would take approx 3.84 hours to replenish 50% of 920 flooded.

Or it would take 2.5 hours to replenish 50% of 920 of their AGMs. (Maybe would need a 185A charger to do that?)

Is my math wrong?

Yep, initial math incomplete, sorry. I suspect I should have added another 3-4 hours to each for absorption time.

Using Lifeline's formula:

[(DoD / 100) x Rated Capacity] / Charger Output + Absorption Time = Charge Time

920 Rated Capacity
120A charger output
3 hours = Absorb time (from table)

Their table suggests 3 hours of absorption time for DoD between 30-50%, and then 4 hours for above 50%. I've used 3 hours.

Your bank size, 50% DoD, at your charge rate of almost exactly .13C:

[(50/100) * 920] / 125A + 3 = 6.68 hours @ charge rate of .13C

If you were capable of charging at .2C (Trojan's recommendation for their AGMs, and Lifeline's minimum recommendation), then it might look like:

[(50/100) * 920] / 184A + 3 = 5.5 hours @ charge rate of .20C

If I were to use your bank size and my theoretically-achievable charge rate (.27C):

[(50/100) * 920] / 248A + 3 = 4.85 hours @ charge rate of .20C

I think.

And I suspect at least one and maybe 2 or more of those theoretical hours in each formula outcome might be about the final .05C tail, but I don't know that for sure.

I've been focused on one of our 3 banks, the one that powers the inverter and therefore keeps the AC-only freezer and fridge powered up... and for now, that's our only bank we can charge at that .27C rate. So that's why we have AGMs on that bank.

I suspect we can all quibble about how much "faster" is really useful. For us, more charge "faster" is good enough.

DC loads on the two main banks are comparatively miniscule, and our charging capacity for those isn't as tall anyway... so AGMs for "faster charging" isn't really necessary. OTOH, I can't easily get there from here to water one of those banks, and AGMs make that whole service thing easier for me.

-Chris

 

[twistedtree]

Yep, initial math incomplete, sorry. I suspect I should have added another 3-4 hours to each for absorption time.

Using Lifeline's formula:

[(DoD / 100) x Rated Capacity] / Charger Output + Absorption Time = Charge Time

920 Rated Capacity
120A charger output
3 hours = Absorb time (from table)

Their table suggests 3 hours of absorption time for DoD between 30-50%, and then 4 hours for above 50%. I've used 3 hours.

Your bank size, 50% DoD, at your charge rate of almost exactly .13C:

[(50/100) * 920] / 125A + 3 = 6.68 hours @ charge rate of .13C

If you were capable of charging at .2C (Trojan's recommendation for their AGMs), then it might look like:

[(50/100) * 920] / 184A + 3 = 5.5 hours @ charge rate of .20C

If I were to use your bank size and my theoretically-achievable charge rate (.27C):

[(50/100) * 920] / 248A + 3 = 4.85 hours @ charge rate of .20C

I think.

And I suspect at least one and maybe 2 or more of those theoretical hours in each formula outcome might be about the final .05C tail, but I don't know that for sure.

I've been focused on one of our 3 banks, the one that powers the inverter and therefore keeps the AC-only freezer and fridge powered up... and for now, that's our only bank we can charge at that .27C rate. So that's why we have AGMs on that bank.

I suspect we can all quibble about how much "faster" is really useful. For us, more charge "faster" is good enough.

DC loads on the two main banks are comparatively miniscule, and our charging capacity for those isn't as tall anyway... so AGMs for "faster charging" isn't really necessary. OTOH, I can't easily get there from here to water one of those banks, and AGMs make that whole service thing easier for me.

-Chris

I just started to point out that you missed the absorption cycle, but see you caught the omission. But there is another thing that happens that reduces the effectiveness of higher charge current. The higher the bulk current, the sooner you get to absorb, which would seem like a win. But it's only a partial win because the higher bulk current causes you hit the absorb voltage at a lower SOC. That leaves more of the charge cycle handled by absorb, which is slower. These are made up numbers, but an example would be that at a lower bulk current the transition from bulk to absorb happens at 80% SOC, leaving 20% to be finished in absorb. But with a higher current the transition happens at 75% SOC, leaving 25% to be finished in absorb. So with a higher bulk current, you shorten bulk, but lengthen absorb. The net does get shorter, but not by the amount you shortened bulk, and it's a diminishing return as you add more and more bulk current.

 

[Mambo42]

@NMT

Going back to your original question, whether you can or cannot use the same AGM for housebank and bow thruster ?
In my opinion that should be possible, after all that was the set up I had in the beginning and it never was a problem.................however......

Usually you use the bow thruster right before docking and that thing draws a hell of a lot of amps. And most people immediately shut down the engines right after docking, which means you took a lot of Ah out of your battery and don't put them back in before turning those batteries into a housebank. So your housebank actually holds a lot less Ah when you are done sailing for the day. Now, of course that does not happen when you go on anchor, since you won't use the bowthruster when you anchor, however..............does the windlass use the same batteries or do you draw that from the start batteries ?
I stated that I had the same set up, but I decided to change it. I did not want to end up in a situation where I had depleted the housebank overnight and then needing the bow thruster in an emergency. I would be sitting with empty batteries and that means no bow thruster. So in the end I changed to a dedicated battery for the bow thruster and the windlass. The housebank is now just what it should be, a housebank.


As for the quality of those batteries I can't help you with that. Have never used them, don't know how they really are.

 

[SteveK]

another opinion on renogy
Youtube

 

[ranger58sb]

But there is another thing that happens that reduces the effectiveness of higher charge current. The higher the bulk current, the sooner you get to absorb, which would seem like a win. But it's only a partial win because the higher bulk current causes you hit the absorb voltage at a lower SOC. That leaves more of the charge cycle handled by absorb, which is slower. These are made up numbers, but an example would be that at a lower bulk current the transition from bulk to absorb happens at 80% SOC, leaving 20% to be finished in absorb. But with a higher current the transition happens at 75% SOC, leaving 25% to be finished in absorb. So with a higher bulk current, you shorten bulk, but lengthen absorb. The net does get shorter, but not by the amount you shortened bulk, and it's a diminishing return as you add more and more bulk current.

Thanks, didn't know all that.

FWIW, our situation is not usually about long-term anchoring. We seldom anchor out for more than a week at a time, only very rarely for 2 straight weeks. Also, this current set-up is new to us (and we've not had AC-only refrigeration before) and semi-wishful, since I don't have any ground truth about our consumption pattern yet.

So I'm just hoping to cram as many more amps as I can back into the batteries in short probably twice-daily 1- or 2-hour shots of generator + chargers.

I do realize that the calculations are not only theoretical... and that I also haven't taken into account our inverter loss and VDC being diverted to run AC loads...

Although I guess all that would likely be approx the same no matter whether our batteries were flooded or AGMs.

-Chris

 

[Don L]

For something like that, I don't think Amazon is the place. Have you ever tried calling them for tech support on a product like that? I would rather deal with a dealer or the manufacture..

Well my house LFP batteries I got off Amazon and when I have a question I ask the manufacturer who has always responded.

My houee LFP has never been on shorepower and are operating great.

 

[Mambo42]

Damn, already bought Renogy AGM 12V 100 Ah battery and 100W solar panel kit (which includes 30A PWM Battery Solar Charge Controller). Hope I have better luck with Renogy than mvweebles did!
I Also have the Vevor 2.500 kW pure sinewave inverter (fridge, microwave) , and Jupiter 2kW quasi sinewave inverter (lights, heater).
I was (maybe naively) wondering if anyone had run the two inverters in parallel with success off the common 100Ah battery (low enough battery impedance).
For emergency use only in kitchen of house
Thanks, Terry

With running two inverters in parallel I guess you would like to increase the total available Kw of AC power. Am afraid that a set up like that will only work if the inverters can communicate and can be programmed to supply to each other. I have Victron and wanted to do the same, but they advised against it. It means 2 times stanby power and it won't prevent a tripped fuse due to drawing too much.
So I would advise to check with a specialist and figure out if this can be done with your inverters in an easy way. If not i would simply dedicate equipment to each inverter and have both inverters connected to both generator, shore power and battery.

However, I read you have 1 x 100 Ah battery, a 100 Wp solar panel and a 30 A solar charger ? As for the charging an AGM (or any lead battery) can charge quickly to about 80 - 85 %, but the remainder takes a very long time. And am not sure your solar panel of 100 Wp will be able to help a lot. I calculate with about 50 % efficiency (at best) which means 50 Wp and at 33 V that means about 1.5 A that the panel can put back into your batteries. However, there is a loss due to equipment that is just in st by mode, so in reality I don't see that 1 panel recharge your battery when you are on anchor.
For that reason I installed 3.2 kwp of solar panels and am even thinking of ways to expand it.

Another thing I don't understand is why you have 2 inverters of 2.5 Kw, when you only have 50 Ah available from your battery ? Did you calculate your total Ah for the night and for the day ?
Easiest way is to take an Excel sheet, write down all the equipment you have, what the Voltage is, what the amps are and how long that piece of equipment is in use.
E.g. the compressor of a fridge will probably run 8 -12 hours out of the 24 hours in a day. A coffeemachine perhaps a couple of minutes each time you make coffee, so the total Ah is not that high.
Once you know how many Ah you actually use each day it becomes very easy to figure out how many batteries you need and after that you can also figure out how many solar panels you need in order to charge them to 100 %.
As a benefit you can then also plan your use of the boat accordingly. Sounds strange, but let's say you use the boat each day for a few hours (e.g. during the Great Loop). That means the alternators will charge the batteries to a certain level. Once you see the Amps drop you know you have reached the absorption phase of the charge. If you can do that part with the solar panels you have optimized the use of all available power and you could shut down the engines, in other words you can plan your routes to be around that length of charging. E.g. 3 hours to get to the absorption phase, then the daily trip average can be a 3 hour trip..
If you ever think of changing to Lithium you will be happy to find out that lithium can accept a fully charge until the batteries are completely full. That makes the calculation even easier. And, lithium can indeed be discharged to 20 %, which means you have 80 % of capacity available. That means that a 100 Ah lithium can deliver almost double the Ah of a 100 Ah AGM battery. Yes, lithium is more expensive, but the price per Ah is actually lower than that of an AGM battery. Reason is simple, a lithium battery will last much longer than an AGM.

 

[foxbat67]

Renogy batt.

Hey all, anyone have experience with Renogy batteries? Thinking of getting these https://www.renogy.com/deep-cycle-agm-battery-12-volt-200ah/ for house bank and bow thruster. Could I also use one for a starting battery for a Lehman 120? They seem to be the most affordable AGMs I’ve found. Want AGMs because batteries are right under salon in engine room.

Yes I have used the D size in my boat one forward for the bowthruster and anchor winch it has been charged with its own batt charger. Used it now for over 2 years, working great.
I am considering setting up a 3D size 2nd battery bank for 120vac only(with same batt.) and using solar charging.

Dont use them for start battery, they are not designed for that.

My boat single 120 HP Lehman alternators are used for main bank and start battery.

 

[TTrep]

I purchased the exact battery you asked about thru Home Depot in Sept 2020. They arrived faster than expected in perfect condition.

I have a GB 36 with 3160 Cat and bow thruster. Installed 2 for the house (including thruster) and 1 as a starter. I'm not an electrical expert but they have worked great for me to this point. I have an inverter, no generator, and meets all my needs.

Regards,
Ted
GB 36-301 Classic

 

[Capt Dan]

How do you quantify "safe"?
Do you have some kind of monitoring system to test the air you are breathing, or are you saying they are safe just because you are still alive?
Just curious.

 

[RickyD]

No experience with their batteries, but had stupendously awful experience with them as a company. Inverter arrived clearly DOA (throwing over-temp error in 50-degree ambient temps). You have no idea the hoops they sent me through to RMA. Ultimately required a BBB complaint and credit card dispute. Still had to dog them for 2 months to actually pay

If you buy, do it via Amazon. But seriously, in a world of poor customer service and tech support, they really stand out in my mind. Waste of time.

Peter

Beware ording a big battery on Amazon. I thought my old Odyssey group 31 had died so I ordered a new one $600+ from Amazon. Hours later I was back to my boat and found that the old one had returned from the dead so I tried to cancel the order. No dice. So after it arrived I asked for return authorization and they said this item can not be returned. Luckily my boat neighbor happened to need one and I sold it to him at a discount.

 

[ranger58sb]

How do you quantify "safe"?
Do you have some kind of monitoring system to test the air you are breathing, or are you saying they are safe just because you are still alive?
Just curious.

To whom is your question directed?

-Chris

 

[C lectric]

FROM MAMBO'42s comment, Post #50
+++++With running two inverters in parallel I guess you would like to increase the total available Kw of AC power. Am afraid that a set up like that will only work if the inverters can communicate and can be programmed to supply to each other. I have Victron and wanted to do the same, but they advised against it. It means 2 times stanby power and it won't prevent a tripped fuse due to drawing too much.
So I would advise to check with a specialist and figure out if this can be done with your inverters in an easy way. If not i would simply dedicate equipment to each inverter and have both inverters connected to both generator, shore power and battery.+++++++

Does not matter the AC source. Generators, inverters or large scale power plants. The AC waves must be in perfect synchronization and voltage with each other or the result will be one source will become a load to the other and if out of synch enough it will become an out right short circuit. Voltage peaks and lows MUST match exactly and stay in synch.
THus the comment from MAMBO 42's electrician and installer. The two units to operate in parallel they must be able to commumincate with each other.

THe only way you could use two inverters is if each unit had specific loads connected to them but not to the other inverter. NO CROSSCONNECTIONS or one or both can be damaged or destroyed.

 

[twistedtree]

I agree that paralleling inverters absolutely requires communications between them, and that is clearly shown in all their installation manuals. It's typically a Cat 5 cable linking the devices.



That said, paralleling inverters is VERY common, and fully supported by any and all reputable manufacturers. A single, larger inverter typically has lower idle power consumption vs two smaller inverters, but check the data sheets. All specify idle power consumption.


If paralleling, keep in mind that it probably does NOT add redundancy, and in fact actually reduces MTBF (mean time between failure). That's because one of the inverters is set up to be the master, and the others are slaves. In all cases, if the master fails, all the slaves stop working too. You could probably get the survivor(s) back on line, but it would require reprogramming one of them to be the new master.


With some products, a slave failure shuts down everything as well, so in that case you actually cut the MTBF in half by paralleling two inverters. I know at least one product line where if a slave fails, the master and any other slaves keep running, so that increases MTBF a bit as long as it's a slave that fails. But if the master fails, everything shuts down.

 

[CMS]

Hey all, anyone have experience with Renogy batteries? Thinking of getting these https://www.renogy.com/deep-cycle-agm-battery-12-volt-200ah/ for house bank and bow thruster. Could I also use one for a starting battery for a Lehman 120? They seem to be the most affordable AGMs I’ve found. Want AGMs because batteries are right under salon in engine room.

Absolute Junk. And Renogy is a despicable company not honoring warranties and the worst customer service I have ever experienced.

This was a brand spanking new Renogy 100Ah AGM, less than 4 very shallow cycles. It could barely deliver 72Ah. Renogy gave the customer a run around for months and he finally gave up. I got $10.00 for it at the scrap metal yard... Yet another very unhappy Renogy customer..

 

[CMS]

I just started to point out that you missed the absorption cycle, but see you caught the omission. But there is another thing that happens that reduces the effectiveness of higher charge current. The higher the bulk current, the sooner you get to absorb, which would seem like a win. But it's only a partial win because the higher bulk current causes you hit the absorb voltage at a lower SOC. That leaves more of the charge cycle handled by absorb, which is slower. These are made up numbers, but an example would be that at a lower bulk current the transition from bulk to absorb happens at 80% SOC, leaving 20% to be finished in absorb. But with a higher current the transition happens at 75% SOC, leaving 25% to be finished in absorb. So with a higher bulk current, you shorten bulk, but lengthen absorb. The net does get shorter, but not by the amount you shortened bulk, and it's a diminishing return as you add more and more bulk current.

This article illustrates just that.. but with AGM so expensive compared to LFP it makes zero sense buying them for house bank use...

https://marinehowto.com/how-fast-can-an-agm-battery-be-charged/


Difference between .2C & .4C

 

[mvweebles]

Absolute Junk. And Renogy is a despicable company not honoring warranties and the worst customer service I have ever experienced.

This was a brand spanking new Renogy 100Ah AGM, less than 4 very shallow cycles. It could barely deliver 72Ah. Renogy gave the customer a run around for months and he finally gave up. I got $10.00 for it at the scrap metal yard... Yet another very unhappy Renogy customer..

Mirrors my experience with Renogy with a DOA 12v>>2000w inverter. They wanted me to replace a nearly new battery bank that was showing 12.4v at rest saying it was dead. And that was only the beginning.

Terrible company.

Peter