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Old 25-06-2019, 17:01   #6646
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by sparrowhawk1 View Post
First -closing a thread because it's too big doesn't make any sense to me.if you want to start another thread on particulars cool. Of course on a thread this long you're going to have repeating so here I go.On this YouTube Will says that hooking up his ($200+)controller to the BMS can harm it if the BMS disconnects it. which I pointed out before and that's why drop-ins make no sense to me especially if you're using an alternator to charge.he also shows hooking up the BMS for low-voltage to a separate switch that can handle high amperage. My question is why not attach that switch before the solar controller and have the BMS set to cut it off at a set voltage (measured at the highest cell). This way I can use my existing $200 plus mppt controller and have my batteries stop charging at a voltage of my choice. Also in the future I can charge my electric dinghy with solar panels with just the BMS and the switch https://youtu.be/_PgthByAYz4

I think the issue with damaging the Victron MPPT is because the BMS opens the MPPT's ground when is disconnects. I remember (I think) reading a caution in the Victron manual about always grounding it first to prevent damage.



I haven't looked at many BMSes, but is it common for them to open the ground rather than the positive side? The few I have looked at open the positive.
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Old 25-06-2019, 20:42   #6647
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by tanglewood View Post
I haven't looked at many BMSes, but is it common for them to open the ground rather than the positive side? The few I have looked at open the positive.
Only Victron and junk Chinese ones on Alibaba as far as I have seen. From a BMS electronics point of view, it is much easier and cheaper to switch the ground because you do it using N-channel MOSFET transistors and these can be turned on with a gate voltage that is less than the battery voltage, so readily available.
To be fair, this can be fine if the installation is dead simple.

P-channel FETs to switch the positive side require more silicon to carry the same current, or they have higher "on" resistance and it makes them more costly to use. You turn them on by pulling the gate voltage down.

The best solution is switching the positive using N-channel FETs and it is possible, but it requires generating a gate voltage several volts above the battery voltage and adds circuitry and complexity for driving the FETs.

However, most BMS don't integrate solid-state switching of the battery current. This is done by an external device that can be sized for the installation.
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Old 11-07-2019, 05:51   #6648
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

STRAW POLL ! Which would you buy ?
I have to choose between these two options for my new 800Ah LiFePo4 bank….

1/ Winston 8 x 400 Ah discounted to $3,200
WB-LYP400AHA direct from Winston with 1 year warranty

2/ CALB 16 x 200 Ah from AliBaba agent for $1,900
the new blue SE200FI - CALB don't manufacture a 400Ah cell any more
who promises to match cells within 200-204 Ah capacity and 0.2-0.3 mOhm resistance
offering 1 year warranty, but the batteries do not have original CALB manufacturing labels
he has 20+ 5-star reviews from USA / Canada / Aus authentic buyers
I believe the cells are a part batch manufactured some 2 years ago, but stored carefully

Winston
  • most USA seem to go for the yellow batteries, but are they really any better?
  • yttrium seems nice but I am cruising in the tropics so not a big issue
  • 400Ah units are easier to install, and less stress with getting cells in right configuration 2p4s
  • Number of life cycles is tempting, at 3 days for a cycle that is >> 20 years

CALB
  • risky but I feel I can nearly trust the agent - he answers direct questions honestly but you have to ask the right questions!
  • some the smaller 200Ah cells are more robust, although my Hylas 44 will give them a fairly smooth ride
  • stress of 'which cell to put where?' in 4p4s with differing capacities and impedances? This is a concern
  • at this price, I would buy 20 and configure the 'spare four' as a portable battery bank for hookah / electric bike / emergency engine start, etc - and still $700 in cash leftover
  • if they 'only last 10 years', I will have the money I saved to buy the fancy current thing at the time

I have already decided upon
  • Victron MultiPlus 12/3000/120, CCGX and 2x SmartSolar 100/50 - one 48V series, one 12V parallel.
  • REC Active BMS for Victron CCGX / VE-Can
  • Blue Sea 7700 bi-stable 500A contactors with CatNewBee's latching / LED circuit
  • 850W solar which will mean a cycle should generally take 3 days between engine charging
  • planning to add CMI's 200A large frame alternator to my 30 year old Yanmar 4JH-TE's fly wheel
  • full time liveaboard, so extensive time at anchor, with watermaker, washing machine, movie projector and aircon to suck up excess power (!)

I have read everything I can find on the internet and now my brain is overflowing
Please help me decide….
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Old 11-07-2019, 08:15   #6649
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

That "agent" is a huge unknown, I do not trust reviews through any selling platform. If you could actually make use of the warranty, local return **and** were set up to test thoroughly on arrival

or if fellow skeptical forum members without any self-interest vouch for a seller maybe I'd be more receptive the the CALBs.

Fewer cells and direct from factory are big pluses for the Winstons. Only downside is money, that's your call.

Have you tried to get CALBs direct or from a source located on the same continent as you?
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Old 11-07-2019, 08:36   #6650
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REC BMS - so far great experience

For those who have seen my previous post, I have been working on finishing my LiFePO4 battery installation for a long time (due to a lot of issues not related to this installation). I have 16 100ah Sinopoly cells in a 4P4S configuration for 400ah at 13.2v.

This has been a slog, which, a lot can be attributed to the wide range of opinions and changes to the products available along with the costs of all. I decided to go with a BMS to help protect the batteries due to user errors (not uncommon), potential charger regulation failures and lack of features for LFP, not being a liveaboard to constantly monitor the system, etc. I know there are many on here who thing BMS's are not necessary. More power to you.
Others are going to batteries with integrated BMS capabilities. There has been rapid development in this area which will continue. It is all very expensive and as of right now, to my knowledge, does not have a long track record.
I initially planned to use a "BMS" from a vendor which has gone out of business. It required substantial wiring to a little circuit board, which I went through (and is for sell if anyone wants it - I'll post it later) and didn't strike me as a durable/stable product. This has turned out to be true.
I finally found the REC ABMS (BMS) product. It seems to be widely used in Europe and is sold by reputable LFP system vendors over there. It is made in Slovenia. Slovenia? Well, my experience with European vendors has been very positive over the years and much of the best equipment comes from there, e.g. Victron, Mastervolt, many others.
I have had a fantastic experience with REC. There customer service is responsive and patient which has been very important to me. The product looks ans seems commercially and industrial ready. I have taken the case of of the it and it seems to me (amateur that I am) to be built to the highest standards. They are very eager to develop a market to the marine trade.

Due to time zone issues communications have all been by email, so it takes a couple of days for the back and forth but that has not been a problem. They have always gotten back to me with the answers I needed in a timely manner. They did not get upset with all the questions I had. They understood that mistakes happen with installations at times (I blew the fuses inside their box twice due to incorrect installation on my part with my relays). The fuses protected the unit and I have not had any problems since. They replaced the fuses the first time and then gave me the specs to buy and replace them myself for the second.
You can buy a preprogrammed unit with the minimum and maximum voltages that you cannot change. I went with that as the voltages were in the range I wanted. You can buy a unit that is completely programmable via a RS-485 connection to a PC. They have a really nice touchscreen display with optional displays showing individual "cell" voltages - the 4S part of my configuration. It is actively balances the cells which not all on here believe is necessary or good. I decided it was OK and time will tell. I top balanced mine carefully before the installation.
The installation was straightforward with a reasonably good manual. It took this amateur a bit of work to understand all the values given but the wiring was easy with the optional wiring harness(necessary unless you want to build a custom one like for car builders). The unit is waterproof/resistant to IP something which I forget right now (IP6 ?). Everything has heat shrink on the terminals. It has an on/off switch, temp sensor, and leads for the relays/contactors to turn them on if the voltages are within range or off if not. There are delays to prevent short spike changes. It takes minimal current when operating or in "sleep" mode.

The current available for the on/off leads was not adequate for my big contactor relays so I put in intermediate small relays to drive them (where I mixed up my wiring the first go). I had to build a housing out of teak for the little display and have suggested to them that they make it easier for an owner to install. The BMS was easy to mount with the included mount hardware. There are two serial pigtails - one for the remote display (they will put any length lead on the display that you specify). I am not using the PC connection right now. I sealed the pins with a high-quality compound to protect the pins (and the other one too).

The unit, after I changed the fuses as noted above, fired up and turned on my relays and contactors. No errors or issues yet.
Note: I have not tested the upper voltage limit for shutting off the charge contactor or the lower voltage limit for the discharge side. Since I would normally be on the boat if my inverter/charger is charging the battery I had to put it on the discharge contactor as a compromise.

I am attaching my system diagrams and a picture of the installation.
All in all, until I experience a problem with the unit doing what I bought it for, I would recommend the company for their customer service, credible distributor base, professional design and build. Others on here will test the limits I am sure. I may do so myself in the near term but have not as yet.

So this is a shout out for a BMS that any one doing a new installation should consider. Mine cost a little under US$485. I paid via PayPal so I had some protection financially. The shipping/customs was seamless and the unit came as fast as anything I have ever had shipped from Europe.
I had very little space to jam everything in (under my nav seat) so it looks a little jumbled. The main contactors have the yellow tops. The BMS is at the upper right. The "baby" relays are at the top middle/left. I have an acrylic cover for the cells not shown to protect from shorts by dropping items on the battery terminals. The discharge contactor is behind the top edge of the cells. I made a thick copper strap to connect the contactors to the House Battery Switch output side.
Attached Thumbnails
Click image for larger version

Name:	R-BMS Display.jpg
Views:	55
Size:	162.0 KB
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ID:	195760  

Attached Files
File Type: pdf Argonauta Battery Loads and Charger Wiring Diagram.pdf (150.2 KB, 15 views)
File Type: pdf Argonauta Battery REC BMS Wiring Diagram.pdf (122.0 KB, 22 views)
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Old 11-07-2019, 09:17   #6651
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by yachtshah View Post
STRAW POLL ! Which would you buy ?
I have to choose between these two options for my new 800Ah LiFePo4 bank….

1/ Winston 8 x 400 Ah discounted to $3,200
WB-LYP400AHA direct from Winston with 1 year warranty

2/ CALB 16 x 200 Ah from AliBaba agent for $1,900
the new blue SE200FI - CALB don't manufacture a 400Ah cell any more
who promises to match cells within 200-204 Ah capacity and 0.2-0.3 mOhm resistance
offering 1 year warranty, but the batteries do not have original CALB manufacturing labels
he has 20+ 5-star reviews from USA / Canada / Aus authentic buyers
I believe the cells are a part batch manufactured some 2 years ago, but stored carefully

Winston
  • most USA seem to go for the yellow batteries, but are they really any better?
  • yttrium seems nice but I am cruising in the tropics so not a big issue
  • 400Ah units are easier to install, and less stress with getting cells in right configuration 2p4s
  • Number of life cycles is tempting, at 3 days for a cycle that is >> 20 years

CALB
  • risky but I feel I can nearly trust the agent - he answers direct questions honestly but you have to ask the right questions!
  • some the smaller 200Ah cells are more robust, although my Hylas 44 will give them a fairly smooth ride
  • stress of 'which cell to put where?' in 4p4s with differing capacities and impedances? This is a concern
  • at this price, I would buy 20 and configure the 'spare four' as a portable battery bank for hookah / electric bike / emergency engine start, etc - and still $700 in cash leftover
  • if they 'only last 10 years', I will have the money I saved to buy the fancy current thing at the time

I have already decided upon
  • Victron MultiPlus 12/3000/120, CCGX and 2x SmartSolar 100/50 - one 48V series, one 12V parallel.
  • REC Active BMS for Victron CCGX / VE-Can
  • Blue Sea 7700 bi-stable 500A contactors with CatNewBee's latching / LED circuit
  • 850W solar which will mean a cycle should generally take 3 days between engine charging
  • planning to add CMI's 200A large frame alternator to my 30 year old Yanmar 4JH-TE's fly wheel
  • full time liveaboard, so extensive time at anchor, with watermaker, washing machine, movie projector and aircon to suck up excess power (!)

I have read everything I can find on the internet and now my brain is overflowing
Please help me decide….
Both configs have the same issue I personally would try to avoid, it is paralleling cells. Most of the time it is just fine, but if one cell has a serious issue there is danger. If one cell gets high resistive, the other cells will take the load, you will only experience a lower capacity and the remaining cells will have a tougher time, if one cell gets low resistance, means an internal shortcut, then the remaining cells will discharge all their energy on the paralleled cell. This can cause an overheating and blow of the cell. In both cases it is very likely all paralleled cells will have a shorter life and need to be replaced when this happens, so no cost advantage.

I prefer installations with serial only configs.

I do like the Winston LiFeYPO4 batteries, so I would probably cough up more money for them. I cannot say if this is justified ot not, but I personally like the Winston range.

My bet would either had been for a bank with 4x700Ah or 4x1000Ah instead of the 8x400Ah.

I know many happy owners with 2p4s or 4p4s configurations with 100Ah or 130Ah cells in RV's due to space constrains. So it is doable and may work a long time. It is just my preference to avoid the in my opinion unnecessary risk.

You can mitigate the issue by cell fuses, but it makes installations more complicated and adds resistances on the connections that may cause trouble too...

Whatever you decide, good luck. The REC ABMS is really a great product, you will enjoy it.
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Old 11-07-2019, 10:31   #6652
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by CatNewBee View Post
Both configs have the same issue I personally would try to avoid, it is paralleling cells. Most of the time it is just fine, but if one cell has a serious issue there is danger. If one cell gets high resistive, the other cells will take the load, you will only experience a lower capacity and the remaining cells will have a tougher time, if one cell gets low resistance, means an internal shortcut, then the remaining cells will discharge all their energy on the paralleled cell. This can cause an overheating and blow of the cell. In both cases it is very likely all paralleled cells will have a shorter life and need to be replaced when this happens, so no cost advantage.

I prefer installations with serial only configs.

I do like the Winston LiFeYPO4 batteries, so I would probably cough up more money for them. I cannot say if this is justified ot not, but I personally like the Winston range.

My bet would either had been for a bank with 4x700Ah or 4x1000Ah instead of the 8x400Ah.

I know many happy owners with 2p4s or 4p4s configurations with 100Ah or 130Ah cells in RV's due to space constrains. So it is doable and may work a long time. It is just my preference to avoid the in my opinion unnecessary risk.

You can mitigate the issue by cell fuses, but it makes installations more complicated and adds resistances on the connections that may cause trouble too...

Whatever you decide, good luck. The REC ABMS is really a great product, you will enjoy it.

I agree with you on the number of cells. I would have much preferred 4 100ah cells rather than 16 smaller ones. The issue was indeed space. I wanted to have the system somewhere easy to get to and monitor and this was it. There used to be one of three AGM 8D's in this spot. I would have had to move all the big cables the previous owner had routed there. As it was I replaced several anyway but not the ones that were the hardest to do so with. I spent weeks and weeks trying to find cells that would fit and the Sinopoly's were the only ones which would have fit with an inch to spare on top and one side. And putting them in on their sides was not an option. I actually (at the time) wanted Winston's.
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Old 11-07-2019, 17:19   #6653
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by CatNewBee View Post
Both configs have the same issue I personally would try to avoid, it is paralleling cells. Most of the time it is just fine, but if one cell has a serious issue there is danger. If one cell gets high resistive, the other cells will take the load, you will only experience a lower capacity and the remaining cells will have a tougher time, if one cell gets low resistance, means an internal shortcut, then the remaining cells will discharge all their energy on the paralleled cell. This can cause an overheating and blow of the cell. In both cases it is very likely all paralleled cells will have a shorter life and need to be replaced when this happens, so no cost advantage.

I prefer installations with serial only configs.

I do like the Winston LiFeYPO4 batteries, so I would probably cough up more money for them. I cannot say if this is justified ot not, but I personally like the Winston range.

My bet would either had been for a bank with 4x700Ah or 4x1000Ah instead of the 8x400Ah.

I know many happy owners with 2p4s or 4p4s configurations with 100Ah or 130Ah cells in RV's due to space constrains. So it is doable and may work a long time. It is just my preference to avoid the in my opinion unnecessary risk.

You can mitigate the issue by cell fuses, but it makes installations more complicated and adds resistances on the connections that may cause trouble too...

Whatever you decide, good luck. The REC ABMS is really a great product, you will enjoy it.

Thanks for your reply, and I hope you don't mind me 'nicking' your circuit diagram for the latching relays!!


I know from reading your fantastically helpful posts that you have managed to make it through this entire forum - I have only managed about half so far! Though I have read Eric's articles more than once ...Assembling a Lithium Iron Phosphate Marine House Bank

Eric says that some on this forum have had physical failures with larger cells. I guess a Lagoon is a smooth ride, and even though my Hylas 44 only have one hull and likes leaning over to windward, the boat is 15 tonnes so she doesn't often 'fall off waves.'

So, I'll get the tape measure out and see how I can squeeze in the larger cells! I'm tempted towards the form factor of the 1000 rather than the 700 - I guess you thought the same. Though I guess with the compression plates on the 700, they should be ok.

One final point, I'm getting no replies from REC-BMS on info@rec-bms.com do you have another contact for them?

Thanks, Andy
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Old 11-07-2019, 18:09   #6654
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by john61ct View Post
That "agent" is a huge unknown, I do not trust reviews through any selling platform. If you could actually make use of the warranty, local return **and** were set up to test thoroughly on arrival

or if fellow skeptical forum members without any self-interest vouch for a seller maybe I'd be more receptive the the CALBs.

Fewer cells and direct from factory are big pluses for the Winstons. Only downside is money, that's your call.

Have you tried to get CALBs direct or from a source located on the same continent as you?
with all due to you and your theoretical knoweledge
You have 0 none nada zilch actual practical experience so I feel that you are not the person or persons that yachtshah is asking for information from . Recommend you get some of that experience before rendering an opinion in this
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Old 11-07-2019, 23:59   #6655
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by yachtshah View Post
Thanks for your reply, and I hope you don't mind me 'nicking' your circuit diagram for the latching relays!!


I know from reading your fantastically helpful posts that you have managed to make it through this entire forum - I have only managed about half so far! Though I have read Eric's articles more than once ...Assembling a Lithium Iron Phosphate Marine House Bank

Eric says that some on this forum have had physical failures with larger cells. I guess a Lagoon is a smooth ride, and even though my Hylas 44 only have one hull and likes leaning over to windward, the boat is 15 tonnes so she doesn't often 'fall off waves.'

So, I'll get the tape measure out and see how I can squeeze in the larger cells! I'm tempted towards the form factor of the 1000 rather than the 700 - I guess you thought the same. Though I guess with the compression plates on the 700, they should be ok.

One final point, I'm getting no replies from REC-BMS on info@rec-bms.com do you have another contact for them?

Thanks, Andy
Usually they are very responsive on e-mail requests on this address. I bought mine almost 3 years ago, and do not needed to contact them after the system was working to my specifications (custom programming of the digital outputs).

Tine Andrejasic was the chief developer if I recall and Maja Pozar at the sales department. Not sure if it has changed since.

Try maja@rec-bms.com for a quote.

They use their first mames in the mailing scheme.
Nice people and very helpful.
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Old 12-07-2019, 00:37   #6656
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Regarding Eric's statements to cell sizes. Sinopoly does not produce large cells, so easy for the sales guys to recommend the small ones from their range and make the lack of capacity they are able to provide to a competitive advantage.

I know some off road expedition RV DIY projects using 400Ah cells with no issues. The batteries from Winston are used stationary and in vehicles, like busses etc. I am not saying, they cannot fail, but they are quite robust inside.

I have fitted my battery in place of the original 4x130Ah Excide Equipment Gel battery compartment under the guest bunk aft, I have removed the battery containers and needed a small cut out on the ply wood of the bed structure to allow space for a slightly larger battery. For the compression I have used multilayered rigid plywood plates which are used for trailer applications and are water resistant, bolted with 12mm stainless steel threaded rods. The plates are fix screwed to the boat structure too, so no movements whatsoever.

This is the place with least movement underway too. I do not expect any issues there.
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Old 12-07-2019, 02:15   #6657
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by CatNewBee View Post
I do like the Winston LiFeYPO4 batteries, so I would probably cough up more money for them. I cannot say if this is justified or not, but I personally like the Winston range.

My bet would either had been for a bank with 4x700Ah or 4x1000Ah instead of the 8x400Ah.

I know many happy owners with 2p4s or 4p4s configurations with 100Ah or 130Ah cells in RV's due to space constrains. So it is doable and may work a long time. It is just my preference to avoid the in my opinion unnecessary risk.

You can mitigate the issue by cell fuses, but it makes installations more complicated and adds resistances on the connections that may cause trouble too...
Yes, I think I might have gone with the 1000Ah if I needed that much capacity. But they really are too large to find a space in a 44 foot yacht. And too much weight to put on one side.

I did some measuring and found a place that I could squeeze in 4x 700Ah Winston cells. They are a cumbersome form factor though! At 627 long and each cell 67 wide (305 high.) A lot of weight to support in a long thin plastic case.

Then I found these 2 people with one cell out of four turning weak. Both trying to sell their remaining 3 cells. Not very encouraging (!)
Winston 700Ah lithium cells

So I am pushed back towards the 8x400Ah. If I were to follow Eric's logic, then I could arrange these as two banks with separate BMS's. But I don't think REC have planned for that in their VE.CAN interface to Victron. And it starts to sound way too complicated.

So that means that I must have paralleled cells, and I agree that fuses are a bit of a troublesome idea, potentially adding more problems than they might solve. I wonder if the REC BMS would diagnose a gradual cell degradation with the change in resistance, or a peak in cell temperature (although REC only supports two cell thermostats.) So like most others, I will probably chose fixed copper links, and promise myself that I will disassemble and test the bank in some future 'free time.' Something that only Maine Sail seems to find the time to do...

I agree about Eric's conversation with the Synopoly rep, justifying a lack of large cells. But also I notice that CALB were making 400Ah cells in their old beige casing until 5 years ago, and now the largest cells they make is 200Ah in their new blue casings. I think their main market is electric buses, which must use a lot of cells.

Finally I think of that graph that was published here on the falling price of Lithium batteries, and wondering if I should pay premium price now… or by instalments...

+ $4/Ah for Winston 8x400Ah that justify their cost by offering a lifetime of 16++ years or

+ $2.4/Ah for CALB 16x200Ah that only need to last for 6 years, and may well last a lot longer

And if I go for the CALB, I save so much money, I can buy an extra 4 for my own personal insurance policy and a portable power bank in the meantime.
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Old 12-07-2019, 03:04   #6658
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

No problem, there is no right nor wrong. Either way it can work a long time. Just make your choice.
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Old 12-07-2019, 04:20   #6659
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Testing my small 125AH dropin, it appears a typical voltage drop of 0.3V between charger & batt terminals makes almost no real difference in charging speed time, vs no voltage drop.
From 20%Soc to full (taper current 5%) at 14V, 37A rate: only 16minutes extra with the voltage drop compared to no voltage drop.
And if you charge up to just 80-90%Soc then its virtually no difference in charge time. All this voltage drop does on my sterling pro is cause the absorption led light to come on alot earlier at around 40-45%Soc, but the battery still takes alot of current up to full, only limited by the charge voltage.

Amazing batteries.

Few questions:

Does this fast/high charge acceptance rate diminish over the life of the battery? Say if the battery has lost 20% capacity?

Can the internal bms shunt balancer on these dropins re-balance if the cells are out by ~200mV? Or is that too much?
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Old 12-07-2019, 05:17   #6660
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Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

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Originally Posted by JmanC View Post
Testing my small 125AH dropin, it appears a typical voltage drop of 0.3V between charger & batt terminals makes almost no real difference in charging speed time, vs no voltage drop.
From 20%Soc to full (taper current 5%) at 14V, 37A rate: only 16minutes extra with the voltage drop compared to no voltage drop.
And if you charge up to just 80-90%Soc then its virtually no difference in charge time. All this voltage drop does on my sterling pro is cause the absorption led light to come on alot earlier at around 40-45%Soc, but the battery still takes alot of current up to full, only limited by the charge voltage.

Amazing batteries.

Few questions:

Does this fast/high charge acceptance rate diminish over the life of the battery? Say if the battery has lost 20% capacity?

Can the internal bms shunt balancer on these dropins re-balance if the cells are out by ~200mV? Or is that too much?
Batteries retain their high acceptance rates over the lifetime, they have a low inner resistance, that allows high currents in both directions with very little voltage drop on the battery.

What you measure is the voltage drop along the connection wiring.

The balancers usually kick in at 3.55 to 3.6V cell voltage, they work then all the time, they are not meant to do a radical burning of excess charge energy, rather they constantly burn some current and gradually balance the cell. Because the cells do drift slowly, low current balancing is absolutely sufficient to keep the pack balanced all the time.

They work all the time when charging.
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