Starting my LFP build.

[Hayden Watson]

Well i finally did it. My LFP build is underway.

• (8) EVE 280K (560A @ 12v)
• 4s JK BMS with 2-amp active balance and 200-A charge/discharge capacity (350-A surge for 5 minutes)
• Flexible multiply buss bars for 2p4s configuration
• 3d printed corner pieces to create 2mm space and secure the four corners from moving. (fixture, not compression)
• The bits and bobs to create the "a simple DIY alternator charge system for lifepo4 batteries (12v system) on boats" from Wout Beekhuizen.
  • PWM controller to limit output
  • Voltage switch to turn on and off as needed.
  • Thermostat to shut down alternator if it gets too hot.

I ordered the cells on Monday and they showed up on Friday and appear to be in excellent condition. No dings, no scratches, no swelling, no marks on the posts and all voltages are at 3.32v. Thanks Docan Power!

Now I just need to wait for the slow boat from China!

 

[FastOlson]

For those of us with traditional charging and storage systems, your images remind me of the scene in Star Trek 4, where Scotty casually reveals the formula for "transparent aluminum"....

 

[Hayden Watson]

I have been working on the research and design of this system for over three years, so it is even looking normal to my wife!

 

[shemandr]

... no swelling, ...

I have a portable li battery pack in my car to jump start it and it has swollen. What does that mean?

 

[kappykaplan]

As the battery ages, the chemical reaction that creates electricity no longer completes perfectly, which can result in the creation of gas (called outgassing), leading to a swollen battery. Time to recycle it.

 

[jssailem]

What does that mean?

I believe it may be pregnant. Likely will give birth to a litter of double A batteries. If the pedigree is right they may all be lithium. Then again it has been sleeping in the garage so you never know. For sure.

 

[Hayden Watson]

I do not know much about the makeup of the LI jump packs. On LFP, swelling is an indication of being over or under discharged at some point.

 

[shemandr]

Sorry, I didn't mean to hijack the thread. I just had this swollen battery. Now back to our regularly scheduled program, which is about Hayden's battery conversion.

 

[Hayden Watson]

Sorry, I didn't mean to hijack the thread. I just had this swollen battery. Now back to our regularly scheduled program, which is about Hayden's battery conversion.

I always wanted to use this emoji! Thanks!

 

[edwardc]

Hayden,
Your build parallels my own 18 month LiFePo4 saga (still in progress). Eight EVE LF280K cells from Docan, and a REC Active BMS from REC. Docan is a pleasure to deal with, and the cells tested well for capacity and balance after top-balancing. Still working on the fixture design. I chose Docan because they have a USA distribution warehouse in Houston, and the REC Active BMS because it can communicate with alternator controllers and solar chargers in case of a BMS disconnect, and uses high current contactors instead of MOSFETs for charge and load disconnects.. REC has also been very prompt in answering questions.

I've decided to do the system in phases. For the initial phase, i will keep my Balmar 612 regulator on a lead-acit batt (used for starter), and use a Victron DC-to-DC charger from the lead-acid to the LiFePo4. This is a little inefficient, but avoids the potential of a BMS disconnect from killing the alternator (and more). Once I have some experience with this system, the next step will be to switch to a Wakespeed 500 alternator controller (which the REC Active can talk to) and use it to charge the LiFePO4 bank directly. The DC-to-DC converter will get repurposed and reprogrammed to charge the lead-acid from the LiFePo4, and a new shore charger to charge the LiFePO4 directly.. In both phases, my existing solar (Midnite Solar KID) will get reprogrammed to charge the LiFePO4 directly.

By the way, in another random parallel, for the last 12+ years, I've been at Oak Harbor in Maryland!

 

[jviss]

Well i finally did it. My LFP build is underway.

Great!
@edwardc yours is cool, too, but I think it would be a "cleaner" thread for Hayden's bu8ild if we don't hijack it. It would be awesome if you'd start a new thread for your build!

Watching this with great interest.

Cheers,

jv

 

[Hayden Watson]

Some more bits and bobs showing up.
A bag with (16) of these two-hole buss bars showed up the other day. The odd thing is that I never ordered them and have no record of paying for them. I did order two of them plus (3) 4-hole bars, but they are still showing as delivery in July. I will use these for my parallel / series connection in the configuration shown until my 4-hole bars show up. I plan to add the sense wires to drilled and tapped holes seperate from the slotted hole so that the thin ring terminal is not under the nuts. The terminals will just have the buss bars and serrated nuts.
These bars are made from 28 layers of bare 100% copper with a cover layer of 100% nickel. They are bent to shape and the ends compression welded together with a shrink tubing wrap over the loose center section. With this construction, they flex very easily and can but pushed to a shorter length and pulled to be longer by hand with maybe 5-lbs of force.
Still waiting for the BMS so cannot really get much done yet.

 

[jssailem]

The excitement builds....

 

[Hayden Watson]

Given all of the extra power we will have on our July cruise with our daughter's family, she sent us this little gem to add to the ship's stores. With two kiddo's (3 & 7) it will be nice to have frozen treats on board. Of course, I don't need ice cream myself.

 

[Hayden Watson]

This portable cooler will fit perfectly behind the companionway on my C30 Mk2. The quarter berth has four cushions and by removing one of them, this unit will just fit under the cockpit sole with an inch clearance. We will need to slide it out sideways to open the top but that isn't a problem.
From a warm start, it dropped to 32º in about 15 minutes and was at -4 in about 45 minutes. The plan is for this to be a deep freeze to supplement the icebox conversion we already have.

 

[Hayden Watson]

My BMS came in yesterday but the packaging was just a single ply bubble wrap bag in an oversized weak cardboard box which was placed inside of a shipping bag so it was tossed, stuffed and otherwise abused for the bast month. The box was hammered and the heat-sink / cover plates were bent badly on one end.



My BMS was badly bent but not broken. It is still working for the time being, but I will be getting a replacement due to concerns about hidden damage. Here is the mockup build getting its first charge. At 8:00 this morning I got the BMS working, and the battery resting voltage as shipped fresh from the boxes was 3.315v with delta-v = 0.000v. After about fifteen minutes of charging at 15A the charging voltage was 13.33v (3.333v per cell and they were exactly the same with 0.000v difference across the pack.

I have been charging the pack for the past 14 hours at close to 25A and have added 340Ah to it and now it is all the way up to 13.55v (3.388v per cell and now the voltage difference is 0.002v difference across the pack. This is without any top balancing and the cells were just taken from the shipping box and put together.

This BMS will do an active top balance with 2A current for any difference greater than 0.005v after the cells get to 3.45v. I then need to keep charging until all cells get to 3.65v (14.6V) so I still have a long way to go.

Here is the mockup. I will get the corner spacers tomorrow so that I can put the finishing touches on it. I also still need to cut, and heat bend the acrylic cover for it and build the pairs of 2-AWG wires from the battery and the 2/O cables for the shunt.


Readout after 1-hour of charge at 15A. Switched to 25A charger just after screenshot.

Readout after 13 additional hours of charge at 24A

 

[JamesG161]

Time to recycle it. [LiPO batteries]

opps! No one is recycling Lithium batteries yet.

Several Companies are trying to do that now, but not yet shown $$ profits.
Jim..

 

[kappykaplan]

@JamesG161 , tks for the clarification. I wasn't aware.

 

[Hayden Watson]

Given that they are rated to do 7,000 cycles at a charge / discharge rate of 560A I am hopeful to not need to recycle them for a while.

 

[Hayden Watson]

I shut off charging at 10:00 last night because I wanted to monitor it as it went into the upper knee. This morning with 24a charging, cell #3 was the first one there and its voltage started climbing and I got a an OVP disconnect when #3 hit the setpoint of3.55v with delta-v = 0.256v. I then reduced the charge rate to 2A and continued charging. #3 stayed at 3.45 for several more hours while the rest of the cells caught up. Given that the active balancing was preventing #3 from running away, I changed the OVP to 3.65 and let it run. The cheap a$$ charger I am using for this initial charge turned itself off when it hit a pack voltage of 14.0v with a cell average of 3.98v and delta-v of 0.003v. I would call that pretty darn top balanced. Pretty good for a first charge out of the box with no conditioning of any kind.
Love this JK BMS! It was fascinating to watch it show -2A for several seconds while it charged the super-caps from the high sell and then +2A as it dumped it into the low cells. All the while the delta kept getting smaller and smaller.