LiFePO4 for House bank final designs

[PacificGreen]

Originally Posted by offpist

Thanks.. yeah we charge close to 250A continuous from two Balmar AT200 and external Mastervolt MBII regulators. When the solar is also putting out 40A+ we are getting close to 300A. Still we are under 0,3C..

I still don't understand the mindset of others in this thread specifically regarding the top balancing procedure some have gone through. I would only ever have to want to reproduce that once for a bank and to do it in the smartest way possible i.e.: with the smallest amount of cells that match your desired AH rating and voltage needed.

The simple reality is that if you ever have to repeat this procedure again on a boat they will be disassembling in some cases up to 32 or more of these small cells. What they fail to realize is when in a 4P4S type configurations is they just made much work out of something that could have been simple. Then they are thrown back to the brutal reality of having to go through the process of once again top balancing their bank again on the vessel.

[PacificGreen]

I have:
1. Size of Bank, cell type and how its connected (3P4S or 4S4P etc)
400ah Winston, 16S
2. How long have you had the system, what is your use and have you noticed any capacity loss.
I have had my system installed on my boat for the last 9 months. We used it for four months outfitting on the hard and two in the water. It sat for six months before that on my test bench disconnected for the most part. I have noticed no capacity loss but I'm due back out to the boat in less than a month and will see if I have suffered capacity loss from letting them sit with small parasitc draw on them over the 9 month period.
3. BMS approach, LVD, HVD, Alarms, Cell Ballance or none of the above
BMS is basically HousePower BMS with HVD, LVD. Big orange light.
4. If you do have a BMS with LVD and HVD how do you manage the alternator/wind gen spikes and what do you use for the relay's/contactors. Have you measured the parasitic loads for this gear? Does your HVD kill power to the boat? Does a HVD shunt high voltage to your house electrics.
No alternator purely solar electric. I use only one big contactor on the main disconnect switch. The parasitic drain for a house power bms is roughly At 5 miliamps it will draw down my batteries at a rate of 1 amp-hr for every 200 hours (8 days). A 100 amp-hr bank should be good for about 80 days at that rate. The HVD will stop the boat. No my HVD simply disconnects the battery.
5. How did you deal with the start battery and windlass/thruster battery now that ACR's, echo chargers etc are not usable.
No start battery see above. Using a trolling motor for bow thruster, gps anchor and autopilot that is ran from inverter driven 36v lestronic charger to 36v 72ah calb battery bank.
6. How do you keep your charging equipment happy given the extra duty they now perform. What are the settings you use for this equipment especially if its meant for old school LA.
My portable Alphagen DCX 3000 generators I like to keep dry and empty of fuel when not in use. My Lestronic II chargers love to run so they like to be plugged in. These chargers do it all magically on a timer. They charge to 53.3v and usually shut off thereafter after trickling down to 8 amps.
7. Other thoughts and considerations you feel are important to highlight in the system design?
Selecting the biggest amp hour battery to obtain my desired results. Augment the system with 2160W of solar panels.

https://www.youtube.com/watch?v=Z5PNYUXa-eE

[SV THIRD DAY]

Originally Posted by PacificGreen

I still don't understand the mindset of others in this thread....

I think we should snip the comment right there be happy.....
There is a lot I don't understand with the mindset of others, but that's what you get with cruisers/boaters/new technology adapters. Tweakers like to tweak.

[PacificGreen]

Originally Posted by SV THIRD DAY

I think we should snip the comment right there be happy.....
There is a lot I don't understand with the mindset of others, but that's what you get with cruisers/boaters/new technology adapters. Tweakers like to tweak.

I would disagree with you about the snip..... Simply restating the obvious that has been stated before that for whatever reason (mindset) the others had to go parallel and series is beyond me and that I don't understand each individual case without getting into the specific merits of each one be it space or economic because there are reasons for sure.

They all did their research and many have read:

There are many ways to configure LiFePO4 Cells in series or in parallel/series. I tend to prefer the simplicity of a 4S configuration when that size bank/cells works. It requires less overall connections and less work when doing cell balancing etc.... Some argue that if a cell is ruined with a 2P4S bank you could re-wire it and use the remaining cells.. I much prefer the simplicity of a redundant lead acid reserve bank. Rewiring an LFP bank at sea is not a task you want to undertake... Source: LiFePO4 Batteries - Thoughts & Musings Photo Gallery by Compass Marine How To at pbase.com

What I know is that they will never want to have to tweak away for days at a time twerking over their bank to get it top balanced. For sure they will be tweaking when lithium shorts sound like little whispers in their ears. Not a fun process for any of them. I dread the day I have to go through that again and especially on a boat.....
Incidentally what I found worked well for top balance was X4 AC Plus 4 Port AC/DC Multi-Charger | HITEC RCD USA I used one to balance a 16S calb72ah pack in four days. If I would have just used 3 more of them the process would have been simple as I could have done all the cells at once instead of rotating 4 one day four the next. I found that is what worked for me on a couple of occasions and if it helps others that what this is all about.

[toddedger]

It's been stated several times that larger prismatic cells are not as physical stable as smaller cells. When the volvo 60 ran aground it was theorized that the impact caused those batteries to short out and start smoking. There have been a few reports of cell failures and they were all larger cells. I don't expect to have to fool around with re balancing my 4P4S 400 Ah pack, but I could if needed. If I had gone with 4S 400 ah cells there would be a much greater chance of cell failure, and if I did have a cell fail I wouldn't have much to work with. One scenario leaves me with 300ah @ 12v the other leaves me with 400ah @ 9 volts.

[Maine Sail]

Originally Posted by toddedger

It's been stated several times that larger prismatic cells are not as physical stable as smaller cells. When the volvo 60 ran aground it was theorized that the impact caused those batteries to short out and start smoking. There have been a few reports of cell failures and they were all larger cells. I don't expect to have to fool around with re balancing my 4P4S 400 Ah pack, but I could if needed. If I had gone with 4S 400 ah cells there would be a much greater chance of cell failure, and if I did have a cell fail I wouldn't have much to work with. One scenario leaves me with 300ah @ 12v the other leaves me with 400ah @ 9 volts.

The 700Ah and up cells have been most prevalent in "odd" failures for unknown reasons.

Sinopoly suggests not using cells larger than 200Ah IIRC and Winston & CALB both claim they are all tested to the same standards.

What I do know is that none of the commercially available cells from the likes of Winston, CALB, Sinopoly, Hi-Power, GBS etc. are tested to any industry standardized or Mil-Spec vibration testing. All vibration testing is done in-house to their own in-house standards. Getting a straight answer on vibration testing from any of the Chinese manufacturers is like walking up hill on ice with leather sole shoes... I have tried and their info is non-existent on this subject..

While my 400Ah cells are only 8 years old, and on a vessel with a very clam motion, she does not slam, I think any owner would be best to consider Sinopoly's point. I would not personally use any cell over 400Ah but that's me. If I needed more capacity than 400Ah I might build paralleled pairs of banks or I might just build a series/parallel pack.

When you use smaller cells you have no choice but to put LFP cells in parallel and this could present a potential safety issue, if one cell were to internally short or fail. Course series only simply does not work for all applications.

Most commercial LFP batteries out there are made up of a series/parallel configuration.

The only company I know of building house banks with what I would consider adequate industry level vibration testing is Lithionics. Their batteries are tested to 40G's....

Bottom line? No single right answer..

[toddedger]

I don't understand, how is one smaller cell in parallel shorting out (4 100ah p) more dangerous than a larger cell (400 ah) shorting out?

By dividing that 400 ah into smaller 100 ah unites you give it much more case support and therefore less chance of shorting out due to vibration or impact.

[SV THIRD DAY]

Originally Posted by toddedger

It's been stated several times that larger prismatic cells are not as physical stable as smaller cells.

Yes but as we have learned in this thread is something True because it has been stated?

Someone says it and then it gets repeated over and over and becomes "truth" but where is the real data...I don't see any and since the manufactures of the batteries told me it wasn't true...well I'm voting for internet rumor.

The LiFePO4 battery manufactures I've spoken to and raised this issue of larger cells being more susceptible to physical damage laughed at my question and said there just wasn't any truth behind it. I think it's one of those Chat Room/Internet Rumors that pops up to explain an unknown cell death or to justify "the way I did it".

[exMaggieDrum]

I chose 16 100Ah Sinopoly cells because:

a) good reputation on the manufacturer
b) size - There was no way I could fit larger cells, or even some other manufacturers 100Ah cells in the only spot I had. I would have to have done some significant structural work to do otherwise. I still have pages of the drawings I made for each size cell offered for each manufacturer. It was one of the most time consuming parts of my selection.

I am totally happy with my choice. It will work for me. And, from what I have been told (repeatedly) is that I could have top balanced mine in parallel rather than individually or in sets of 4 in parallel, so if I though I would need to do it on the boat it would only be three bus bars to take off.

[Maine Sail]

Originally Posted by toddedger

I don't understand, how is one smaller cell in parallel shorting out (4 100ah p) more dangerous than a larger cell (400 ah) shorting out?

By dividing that 400 ah into smaller 100 ah unites you give it much more case support and therefore less chance of shorting out due to vibration or impact.

This is not about external shorts it is about internal failure or shorts.

There are no "parallel" connections in a series bank thus a fault in one cell only brings the voltage of the entire bank down.

In a parallel configuration if one cell shorts internally the other cell, or multiple parallel cells, will be discharging into it until both cells are at the same voltage or one cell thermally runs away. The same thing can happen in lead acid parallel banks.

These occurrences are rare but can happen.

I have no qualms with parallel then series LFP, to build capacity, so long as the system is built and designed well. I just have a 4S bank because that's what worked and kept it pretty simple...

[alctel]

My dealer (Sinopoly) refused to sell me cells larger than 200AH when he found they were going on a boat, so my 400AH bank will be 2P4S which goes along with what Sinopoly are apparently saying

[PacificGreen]

Over the course of years of researching what would work for my solar boat batteries I frequently would visit a very informative blog. One thing I find amusing about the fud is that large prismatic and even monolithic cells have been used as traction batteries for big trucks and even submarines.

To note in my recent reading of same blog I found this:
lithium & solar power LiFePO4
lithium & solar power LiFePO4, Fake battery warning* We keep receiving emails...

I find this blog very informative and I am waiting for the day when larger LTO cells are readily available for the consumer market to upgrade. They currently can only be had at a 55ah rating. On a side note I have an old small calb 72ah cell that I might decide to have an inside look at.

[Typhoon]

Originally Posted by alctel

My dealer (Sinopoly) refused to sell me cells larger than 200AH when he found they were going on a boat, so my 400AH bank will be 2P4S which goes along with what Sinopoly are apparently saying

Was that Randy at CanEv ?

I got 8x 300 amp hour sinopoly's from him and he knew they were going into my boat.

Quick edit , to add my cells have been fine and running for almost three years steady.

Regards John.

[alctel]

Originally Posted by ColdEh Marine

Was that Randy at CanEv ?

I got 8x 300 amp hour sinopoly's from him and he knew they were going into my boat.

Quick edit , to add my cells have been fine and running for almost three years steady.

Regards John.

It was, yeah. He said Sinopoly had discontinued larger than 200AH - this was a recent thing, a few months ago.

I think after 3 years you are probably fine!

[Typhoon]

Originally Posted by alctel

It was, yeah. He said Sinopoly had discontinued larger than 200AH - this was a recent thing, a few months ago.

I think after 3 years you are probably fine!

Yes, I wasn't really worried about my cells failing due to vibration . I my actually build another bank, just for back up .

Regards John