LiFePo Batteries: Build or Buy?

[Singularity]

Originally Posted by Moontide

Singularity, as I understand it your comment about a external voltage cutoff working as well is not accurate. With LiFePo batteries one cell can go too low and the BMS will shut off teh battery. Without a BMS the total voltage will be higher. Depending on the external setting it might still be above that overall.

As far as balancing, you would have to measure each cell individually to know if out of balance. Most recommend running a balancing procedure with new cells since they may be out of balance when put into a DIY "pack". Some BMS's have data connections where you can see if any cells are out of balance. They also will re-balance them.

You are very correct that I'm gambling that the cells won't go out of balance.

I started with a bottom balance (indeed adds time to the initial install, such that my citied 30 minutes didn't account for this, though balancing is more babysitting than work), and, instead of rechecking individual cells every 6 months (as another prominent ~no BMS person suggested) I waiting nearly a year, all good.

To emphasize you're point, indeed if a cell drops low, any low voltage cut device won't help. All things considered, I'm comfortable with the risk of this approach vs the risks/benefits/hassle (to me at least) of incorporating a BMS. Horses for courses, and I'm not suggesting that my path is correct, but it is an option that people smarter than me have deemed reasonable, with the above caveats.

Addendum: when I bought my (Calb) cells, the individual cells were less than half the cost of a commercial drop-in battery, such that if my system failed, I could replace the bank and still break even vs come out ahead. If/when commercial battery costs reach parity with DIY prismatics, and if the BMS vs alternator issue doesn't require anything fancy, I'd go with the commercial. But it still seems that commercial batteries are ~twice the price of DIY prismatics.

[apirate]

Lifepo4 drop-in’s are getting so cheap that it’s almost not worth building your own anymore. Unless of course, you just like playing with this sort of thing.

I have enough on the boat to obsess about. I’m not adding batteries to the list. For that reason we bought them ready to go from the electric car parts company. At $1745 for 8D sized 400ah lifepo4 batteries, it’s hard to pass up. So far ours are performing very well.

[Latecomer]

Originally Posted by newhaul

A few issues .
1) no need for a bms ? While correct why would you not want to protect a very expensive boat with a simple piece of electronics.
My 200amp bms was 150 USD
A 300 would have cost me 250 but 200 amp is plenty for my needs

You need to really research that renogy 50 amp b2b unit its not as good as you think . It maxes at 25 amps from either source.
Much better off with the 60 amp b2b they make

https://www.renogy.com/12v-60a-dc-to...ttery-charger/

With the balmar I would recommend just get the balmar regulator.

https://balmar.net/balmar-announces-...ium-batteries/

please provide a link to your 200 amp bms, I need to see if it is suitable for my application.

George

[newhaul]

Originally Posted by Latecomer

please provide a link to your 200 amp bms, I need to see if it is suitable for my application.

George

I went direct to the manufacturer i posted the specs uptrend as to the bms units . The company has an eBay site that has smaller units listed . Contacting them about your needs they will be more than happy to assist you.

https://www.ebay.com/str/shenzhenefiretechnology

And they accept PayPal

[Singularity]

Suppose there's a spectrum of DIY cell options out of China...
On one end there's tiny cells (as in the original post here), and on the other end, tried/true Winston/Calb types; in the middle there are these newer very low cost cells (e.g. blue cells as newhaul has) that are half the cost of Winston/Calbs for some reason.

I suspect those deliberating about going lithium vs new AGMs/flooded are looking at commercial LFP options, or Winston/Calb types (+/- BMS).
I think it'd be helpful when tossing out DIY cost numbers to designate which cells are used. I'm personally shy about these new low cost options for no reason other than why so cheap; while I assume that the commercial battery offerings are not using the newer less-expensive LFPs on the market, but maybe they are.

Just checking Aliexpress now, Calb 12v/400ah from China to US with 4 month delay is ~$1,950. I must assume that if a commercial battery is sold at $1750 with a BMS that this is constructed with blue-case type LFPs, where those currently run ~$1,375 (no BMS) including shipping China-US.

[rgleason]

Read back in the thread. Newhaul's BMS is an Shenzen E-Fire but the Daly is the same and relabled by a reseller.

Shenzhen E-fire BMS and many good parts to build all kinds of batteries

https://cl-rd.en.alibaba.com/
4S Common BMS

4S-200a https://cl-rd.en.alibaba.com/product/62494030106-806708074/4S_12V_200A_250A_li_ion_lipo_bms_with_thermal_sens or.html?spm=a2700.icbuShop.41413.25.1b9358b5UG4ohE

4S-250ahttps://www.alibaba.com/product-deta...1b9358b5UG4ohE

I have not yet found the waterproof one on their Alibaba website, it does seem to be available through Daly (see my link below).
Search for the Waterproof 4S 200ah version, they now have a newer version with "Smart" in the name with some waterproof features.

Singularity wrote:

"newer very low cost cells (e.g. blue cells as newhaul has) that are half the cost of Winston/Calbs"
I have seen a video when these were torn apart by someone and they were favorably impressed. Will try to find it.

[rgleason]

Waterproof for 18650 batteries Smart BMS 4S 12V 80A 100A 120A 200A PCB BMS for 3.2V LiFePO4 battery pack 18650 Lithium Battery Pack


Not Waterproof 200a 4s lifepo4 bms 4s 12v battery management system for solar energy system



Not Waterproof, cheap 4s 12v lifepo4 pcb pcm bms 100a 200a


Not Waterproof 12v lifepo4 bms 4s 200a 100a

[rgleason]

Daly 4S BMS 12V 200A Lifepo4 BMS Lithium Battery Protection Board with Balance Function 4 Cell BMS for Lifepo4 Battery Pack

Deligreen hot sale LifePO4 Lithium battery bms 4S 12V 200A high current bms

Here is a 200ah box with BMS

GTK Waterproof Lifepo4 12V 200AH lithium battery capacity 100A BMS 4S for 1200W inverter EV Fishing boat propeller +10A Charger for $624

16cm high x 18.5 wide x 40cm deep (6.3" x 7.3" x 15.7" )

[newhaul]

Originally Posted by Singularity

Suppose there's a spectrum of DIY cell options out of China...
On one end there's tiny cells (as in the original post here), and on the other end, tried/true Winston/Calb types; in the middle there are these newer very low cost cells (e.g. blue cells as newhaul has) that are half the cost of Winston/Calbs for some reason.

I suspect those deliberating about going lithium vs new AGMs/flooded are looking at commercial LFP options, or Winston/Calb types (+/- BMS).
I think it'd be helpful when tossing out DIY cost numbers to designate which cells are used. I'm personally shy about these new low cost options for no reason other than why so cheap; while I assume that the commercial battery offerings are not using the newer less-expensive LFPs on the market, but maybe they are.

Just checking Aliexpress now, Calb 12v/400ah from China to US with 4 month delay is ~$1,950. I must assume that if a commercial battery is sold at $1750 with a BMS that this is constructed with blue-case type LFPs, where those currently run ~$1,375 (no BMS) including shipping China-US.

You might want to give Rachel a pm she is a member here and also a sales rep for ruixu which is the synopoly parent. Iirc

https://www.cruisersforum.com/forums...o4-211966.html

[newhaul]

Originally Posted by rgleason

Read back in the thread. Newhaul's BMS is an Shenzen E-Fire but the Daly is the same and relabled by a reseller.

Shenzhen E-fire BMS and many good parts to build all kinds of batteries

https://cl-rd.en.alibaba.com/
4S Common BMS

4S-200a https://cl-rd.en.alibaba.com/product/62494030106-806708074/4S_12V_200A_250A_li_ion_lipo_bms_with_thermal_sens or.html?spm=a2700.icbuShop.41413.25.1b9358b5UG4ohE

4S-250ahttps://www.alibaba.com/product-deta...1b9358b5UG4ohE

I have not yet found the waterproof one on their Alibaba website, it does seem to be available through Daly (see my link below).
Search for the Waterproof 4S 200ah version, they now have a newer version with "Smart" in the name with some waterproof features.

Singularity wrote:

"newer very low cost cells (e.g. blue cells as newhaul has) that are half the cost of Winston/Calbs"
I have seen a video when these were torn apart by someone and they were favorably impressed. Will try to find it.

Unfortunately the link you posted to the 200amp unit is for lipo not lfp .
Also a low temp cutout is a nice thing but really not necessary for 99% of boat installs.
If the boat is out for the winter usually you just disconnect the bank somewhere between 70% and 35% charge . The self discharge is less than 1% per month so no need to have active charging for the 4 to 5 months you are not using the boat.
If using year round or living aboard the batteries will not see any sub freezing temperatures.
The lowest mine see when I'm not on board is 42°f due to water temperatures.

[Singularity]

Originally Posted by newhaul

You might want to give Rachel a pm she is a member here and also a sales rep for ruixu which is the synopoly parent. Iirc

https://www.cruisersforum.com/forums...o4-211966.html

-I'm not in the market to buy, but the Ruixu website shows x4 100ah 3.2v Sinopoly cells priced at $559.

-How do you BMS guys deal with the alternator if/when the BMS decides no more charging? Certainly some communication between the BMS and alternator regulator, no? Is that simple with say a Balmar regulator?

-A couple minute web search on the ~newer low-cost blue cased LFP cells found references to them having an aluminum case (vs plastic for Sinopoly/Winston/Calb), where the case has a thin plastic covering, maybe not covering the bottom, where additional protection is necessary in a marine environment given corrosion. Otherwise the lower-cost large LFP cells are lighter weight for some reason, while I assume the traditional S/W/C cells aren't given extra weight for no good purpose. So why are your cells less expensive than the previously more common plastic-cased cells??

[rgleason]

These are very nice more expensive cells.

Fortune LiFePO4 Battery Cells: I love them!

2V Raw Cell LiFePO4 Bus bar Stacking Tutorial for Current Sharing

https://www.electriccarpartscompany....ncased-Battery


Will Prowse at the end of the second video says if you just want some cheaper cells he suggests Winston or Calb.

Cheapest Aliexpress LiFePO4 CALB Cell Reviewed (Not Sponsored)

Calb cells 4 x 100ah $423 shipping and taxes, just add BMS
name branch, charge cycles good, packaging good, cheap, brand new, matched, with bus bars, for houses or use in winter, need a low temp cutoff.


I couldn't find the video with Newhaul's type simple blue encased cells yet.

[Culwatty]

Originally Posted by newhaul

Read the manual again paying special attention to section 3.3 on page 13 of the renogy manual.
Hence my recommendation for the straight 60 amp b2b
As to my bms well it is not a cheap unit . I just happen to be a company that can order factory direct.
BTW ( you like Wil Prowse) he actually agrees with me on BMS. I have been using this model for a couple years now . About a year ago he did a video on the same unit.

Don't worry I'm a retired ( like that will ever actually happen) shipwright. I don't take offense to much. YBYC.

Ah I see what you are pointing too, i would not call that "limiting" to 25a per source as its only in certain circumstance but this in my situation is perfectly acceptable as I do not plan on charging from my alternator often. And cost for cost works for me horses for courses and all that

This discussion could go on for a while about balancing etc, I will be running passive balance boards.

Haha yep retirement, its a pipe dream for all but the 1% (i hope i make it to that 1% before I "retire" hahaha )

Atb

[newhaul]

Originally Posted by Singularity

-I'm not in the market to buy, but the Ruixu website shows x4 100ah 3.2v Sinopoly cells priced at $559.

-How do you BMS guys deal with the alternator if/when the BMS decides no more charging? Certainly some communication between the BMS and alternator regulator, no? Is that simple with say a Balmar regulator?

-A couple minute web search on the ~newer low-cost blue cased LFP cells found references to them having an aluminum case (vs plastic for Sinopoly/Winston/Calb), where the case has a thin plastic covering, maybe not covering the bottom, where additional protection is necessary in a marine environment given corrosion. Otherwise the lower-cost large LFP cells are lighter weight for some reason, while I assume the traditional S/W/C cells aren't given extra weight for no good purpose. So why are your cells less expensive than the previously more common plastic-cased cells??

Alternator
Me personally I have a small FLA battery inline with the lfp bank to continue to provide a buffer for any unforseen disconnect of the bms
I have installed a manual switch in the alternator exciter wire to shut the alternator off when it reaches the voltage point I want my bank to be maxed at (13.8v ) on a regular basis . That's what a battery monitor gauge is for.

Perhaps you should look deeper into the bank and housings . I have sections of horse stall paddock pads to place under the bank .

As to my cost well thats what I get as a business purchasing from a business. Also the pricing was before the new price structures when everything was on mid winter sale .

[newhaul]

Originally Posted by Culwatty

Ah I see what you are pointing too, i would not call that "limiting" to 25a per source as its only in certain circumstance but this in my situation is perfectly acceptable as I do not plan on charging from my alternator often. And cost for cost works for me horses for courses and all that

This discussion could go on for a while about balancing etc, I will be running passive balance boards.

Haha yep retirement, its a pipe dream for all but the 1% (i hope i make it to that 1% before I "retire" hahaha )

Atb

Not that as to retirement I tried but customers keep calling me and basically begging me to do work for them . Like a fool I said sure now 3 years on I can't get away from them