LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[john61ct]

Not LFP but interesting reading. https://www.maximintegrated.com/en/d...echnology.html
I'm sure these will be professionally built into TMS-engineered packs, safe enough for House bank use on boats, one day even becoming affordable.

But OT here, start a new thread if you want to discuss other LI chemistries, in this case pretty sure "lithium nickel cobalt aluminum oxide", aka LiNiCoAlO2, aka NCA.

[john61ct]

Originally Posted by evm1024

I'm using an Ideal BHW windless that typically pulls 90 to 120 amps while pulling up my chain and anchor. It is rarely run for more than 60 seconds which works out to about 2 AH.



One reason I am considering 50 AH of 10 AH 38120 Cylindrical cells is due to their 3C continuous discharge spec with 10C for 30 seconds. That works out to 150 amp (3C) for the 60 second anchor pull with plenty of headroom for peak loads lasting a few seconds. Total discharge is around 4% of capacity

Yes, the Headways should be "fine" for that use case, certainly not optimal, IMO not good value, the bank will last a fraction of A123's lifespan, or the others I listed, everything else being equal.

Of course keeping the C-rate under 2C will be better for longevity.

But "fine" either way, who knows will certainly get 5 years I think, maybe even over 10.

[john61ct]

Li Ping makes some very excellent smaller LFP packs, been highly regarded in the ebike community for very many years, even though they've since mostly moved on to the higher power-density chemistries.

Built up from 5A pouch cells, dunno if A123 or not.

usually 16S for 48V best as 2x 8S in series

and 4P for 20Ah, so if he'll make a custom wiring for you the same size and similar price should yield 12V @80A

I would ask for balance leads brought out to be accessible from the outside, and BMS installed so easily replaceable without disrupting the cell wiring, maybe do that part yourself with waterproof connectors like TE/Deutsche

Also sells chargers

https://www.pingbattery.com/lifepo4-lithium-batteries

pingping227@hotmail.com

[evm1024]

Originally Posted by john61ct

Yes, the Headways should be "fine" for that use case, certainly not optimal, IMO not good value, the bank will last a fraction of A123's lifespan, or the others I listed, everything else being equal.

Of course keeping the C-rate under 2C will be better for longevity.

But "fine" either way, who knows will certainly get 5 years I think, maybe even over 10.

Nice that I have your approval but I am a bit confused.

You state that Headways should be fine but not optimal. How did you come to this conclusion? Also that they were not a good value. Ditto.

You state that they will have a fraction of the lifespan of A123 cells but then state that they (the headways) should last 5 or perhaps even 10 years.

What do you base that opinion on? Is it a wag or do you expect the A123 to last 40 years? That would make the headways last 1/4 the life of A123.

I'm sorry, I had really hoped that this conversation would be a respectful conversation between equals.

[CatNewBee]

Originally Posted by newhaul

Ok guys for those that are actually using Lfp and a shunt type battery monitor I need input.
I'm thinking of adding one but most are to expensive to be considered by me
So I need opinions on this monitor
https://www.aliexpress.com/item/3294...7764499cqd2JU0

There is no description nor a manual available. It is cheap and I assume it will count Ah corectly, but I do not expect much of it, like programmable Peukert, charge efficiency factor, settings for Absorption Voltage to callibrate 100% SOC or a programmable output for alarms. They claim it worksfor different chemistries, so maybe there are preset values for this, it can handle different pack voltages and comes with 3 sizes shunts up to 350A, usually you can short time overpower a shunt for a few seconds to the double, but with chinese cheap products I would rather stay below 50% nominal. There are no higher Amp shunts available nor is there a description for custom shunt callibrations. Maybe they have it, maybe not. But it is dirt cheap, so buy one and play around with the menus and settings, maybe you can replace the shunt by something bigger, and keep / attach the shunt PCB to the new one, as you can do with Victron BMV's and callibrate it accordingly, who knows. The loss is 20$, you can stil use it for a smaller circuit area where you not exceed 350A.

[CatNewBee]

Originally Posted by SweareDeep

REC-BMS sell a Bistable Latching Relay Driver which, I think, does what you want. It's listed under Accessories on their website.

Not suitable for ML-RBS solenoids, they need positive signals and common ground, not common plus and switched ground. What is so complicated in attaching a capacitor, resistor and optionaly a led as impulse interface?

[newhaul]

Originally Posted by CatNewBee

There is no description nor a manual available. It is cheap and I assume it will count Ah corectly, but I do not expect much of it, like programmable Peukert, charge efficiency factor, settings for Absorption Voltage to callibrate 100% SOC or a programmable output for alarms. They claim it worksfor different chemistries, so maybe there are preset values for this, it can handle different pack voltages and comes with 3 sizes shunts up to 350A, usually you can short time overpower a shunt for a few seconds to the double, but with chinese cheap products I would rather stay below 50% nominal. There are no higher Amp shunts available nor is there a description for custom shunt callibrations. Maybe they have it, maybe not. But it is dirt cheap, so buy one and play around with the menus and settings, maybe you can replace the shunt by something bigger, and keep / attach the shunt PCB to the new one, as you can do with Victron BMV's and callibrate it accordingly, who knows. The loss is 20$, you can stil use it for a smaller circuit area where you not exceed 350A.

I ordered one with the 350 amp shunt . Will post a quick review after I play with it for a while.
The 350 is plenty big for my use case I will only have 240ah so 350 amp is well above anything I will be drawing on my boat . Heck even my anchor windlass is manual .

[gscriba]

Originally Posted by CatNewBee

Not suitable for ML-RBS solenoids, they need positive signals and common ground, not common plus and switched ground. What is so complicated in attaching a capacitor, resistor and optionaly a led as impulse interface?

I'm sure it's not complicated at all. But I've never had any exposure/experience with gathering those parts, soldering them together somehow and then containing/mounting said interface. Like I said, ZERO experience with small electronics and their assembly. I'll keep digging.

[SweareDeep]

Originally Posted by CatNewBee

Not suitable for ML-RBS solenoids, they need positive signals and common ground, not common plus and switched ground. What is so complicated in attaching a capacitor, resistor and optionaly a led as impulse interface?

Sorry for the false lead.

However, Gigavac have both high-side and low-side switching options for their latching contractors so there might be a possible solution for the OP to be found there.

Nothing intrinsically complicated in doing as you did (and yours is a very simple, elegant solution), but if I were in the OP's position I'm not sure I would want to trust such a critical function to never-before exercised soldering skills. His caution is commendable.

[CatNewBee]

Originally Posted by SweareDeep

Sorry for the false lead.

However, Gigavac have both high-side and low-side switching options for their latching contractors so there might be a possible solution for the OP to be found there.

Nothing intrinsically complicated in doing as you did (and yours is a very simple, elegant solution), but if I were in the OP's position I'm not sure I would want to trust such a critical function to never-before exercised soldering skills. His caution is commendable.

I understand this. But if you want plug and play or even someone to do it for you, you better go with a solution provider the expensive and not the DIY path.

If you install anything yourself, you need some basic skills and knowledge, this applies not only to electric systems.

I am not aware of the product range from Gigawac, the ML-RBS has the RS logic already inside and does not need an additional external logic interface.

[gscriba]

Originally Posted by SweareDeep

Sorry for the false lead.

However, Gigavac have both high-side and low-side switching options for their latching contractors so there might be a possible solution for the OP to be found there.

Nothing intrinsically complicated in doing as you did (and yours is a very simple, elegant solution), but if I were in the OP's position I'm not sure I would want to trust such a critical function to never-before exercised soldering skills. His caution is commendable.

No need to apologize, SweareDeep. Very much appreciate the thought/suggestion. Re: my caution...commendable or not, I will continue to learn and ask. I've been boning up on circuit board building and soldering. I'm starting to look forward to my next project/skill set.
Thanks!

[gscriba]

Originally Posted by CatNewBee

I understand this. But if you want plug and play or even someone to do it for you, you better go with a solution provider the expensive and not the DIY path.

If you install anything yourself, you need some basic skills and knowledge, this applies not only to electric systems.

I am not aware of the product range from Gigawac, the ML-RBS has the RS logic already inside and does not need an additional external logic interface.

As always, CNB I appreciate your input.
To be clear, I am not interested in a plug and play, nor anyone to do anything FOR me. I was not born with knowledge and skill, but have gained plenty along the way and will continue to do so.

My basic skills and knowledge can and has helped save lives. But quite honestly, I am thrilled to learn new things. I have you and others to thank along the way.

Happy New Year to you, and all those here whose imagination and determination compel them to expand their skill and knowledge. All the best in 2020!

[john61ct]

Originally Posted by gscriba

I am not interested in a plug and play, nor anyone to do anything FOR me.

Why not? Make teaching you hands-on part of the deal.

[newhaul]

Apparently charging our lfp banks at sub freezing temps is not a problem when charging at sub.3C rates.
At least according to battleborn CEO Denis Phares.
https://youtu.be/ywn-vBjKblI

[evm1024]

Originally Posted by newhaul

Apparently charging our lfp banks at sub freezing temps is not a problem when charging at sub.3C rates.
At least according to battleborn CEO Denis Phares.
https://youtu.be/ywn-vBjKblI

Very good find - Dogma replaced by knowledge and experience.

It would be well worth writing up the points made and making them a LiFePO4 sticky.