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

[botanybay]

Originally Posted by OceanSeaSpray

DNV-GL released guidelines for marine Li-ion systems long ago, no big deal in there. I had to request the document via e-mail, but it is otherwise free. I have uploaded it here for now and will leave it for a few weeks.

Thank you VERY much, looks like a good read

[nebster]

Originally Posted by GRIT

Wow, 112 cells...

I’ll say. I would’ve loved to have fewer, larger cells, but they weren’t available in a shape that I could fit into my space.

[tanglewood]

Originally Posted by newhaul

Ok need input . I just got offered a zantrex prosine 2.0 for 300 bucks untested .
It has a 100 amp charger built in I looked at the manuals online and can't find the information .
Is it programmable for use with my Lfp bank ( its way to big but can't pass up the deal . )

So they are paying you $300 to take it? That I might do, depending on what I felt my time was worth.

[GRIT]

Originally Posted by nebster

I’ll say. I would’ve loved to have fewer, larger cells, but they weren’t available in a shape that I could fit into my space.

Well, you gotta do what you gotta do. I'm glad you were able to accomplish your goal.

And here I am, complaining about having 16 cells!

Cheers.
Paul.

[newhaul]

Originally Posted by tanglewood

So they are paying you $300 to take it? That I might do, depending on what I felt my time was worth.

no I'm not getting paid to take it and with just a 100 ah Lfp bank I really don't need a 100amp charger. But if it were worth it I would have doubled my capacity.
As of now I'm running a 1500 watt harbor freight inverter to run my coffee maker and a 4o0 watt one to run the rice cooker . My current charger is only a 10 amp 3 stage so about useless . It would be worth 50 bucks for it if the charger side worked .

My question was answered its not worth a second look.

[senormechanico]

Rather than starting a new lithium thread, I thought I'd just drop this video in here.
It's a very interesting and informative about a 100% electric ferry running between Denmark and Sweden.


https://www.youtube.com/watch?time&v=rE_M1n-ClOA

[newhaul]

Originally Posted by senormechanico

Rather than starting a new lithium thread, I thought I'd just drop this video in here.
It's a very interesting and informative about a 100% electric ferry running between Denmark and Sweden.


https://www.youtube.com/watch?time&v=rE_M1n-ClOA

cool video .
I read the full technical article in one of the trade magazines a few months ago it is a great idea for short running with the ability to rapidly recharge at both ends .

[newhaul]

Here's an interesting study Lfp graphene battery seems to have the safety of good old Lfp but better power density and faster charge characterises
https://www.graphene-info.com/graphene-batteries
Worth keeping an eye on for next battery upgrade.
Should be a mature tech by then :-):-)

[Carl1956]

Anybody has some experience with this latching relay, battery switch?


https://www.axoncontrol.co.uk/remote...battery-switch


any feedback would be appreciated.
cheers Harald

[CharlieJ]

Carl1956 #6444
I don't have any experience about the referenced switch but I recommend you look at Blue Sea Systems 77xx series of latching relays. They are robust, 500A continuous contactors. Here is a link to a 12VDC model: https://www.bluesea.com/products/770...enoid_-_12V_DC

[mike_kelly]

Just need to get some of the jargon straight. I am interested in building my own system.



1. BMS. It seems there is some confusion because this term has been used for a simple voltage-current-power monitor in the past but now might be used to indicate, for LiFEPo4's a simple current-voltage monitor with a charge balancer? Maybe because people add them to older chargers that don't have balancers built- in? I am used to using balancing chargers with Li-po and Li-ion but the chargers have balancers built-in and charge in cycles of charge-balance-charge-balance. They don't try and balance after the fact.



2. There are inexpensive high amp balancers on the market with no displays or apparent data ports so there appears that there is no way to determine if they are doing anything at all? My lipo chargers show me the cell voltages as they charge and balance showing me exactly what is going on. But mine are designed to charge 10amp batteries not 100amp batteries.


I know this is old hat to those involved with these large capacity battery packs but I just need to understand what the common practice is with LiFEPo4 house batteries and what the jargon means to you.


Thanks

[john61ct]

A "BMS" has many different meanings. There are cheap-Chinese boards for $20, and units designed for huge sophisticated systems that cost more than I have to spend on a whole setup.

Best to see it as a collection of protective functionality, both cell-level and overall bank or sub-pack. LVC, HVC, maybe temperature and OCP.

For the most critical functions there should be redundancy, multiple layers. And adjustable setpoints are for me a must.

Some would like to have the BMS actually control charging, in which case a dumb PSU maybe with CAN-control or I2C is enough

Not all use cases require all possible levels of protection.

I've yet to see a reasonably priced all-in-one solution, and wish more were based on FOSS / open-hardware.

[john61ct]

Originally Posted by mike_kelly

I am used to using balancing chargers with Li-po and Li-ion but the chargers have balancers built-in and charge in cycles of charge-balance-charge-balance. They don't try and balance after the fact.

Very rare in marine House banks, and IMO few are high enough balance current.

If BMS doesn't take care of the balancing, a few hobby balancing chargers run manually after Bulk pack-level charging is done, as a maintenance process when needed would work well, but only for those not requiring automation.

Most LFP prismatic banks don't even expose balancing wires to the charger, would need to custom wire the harness for that.

[mike_kelly]

That is what I was afraid of... Lack of clear standards is typical of the wild west stage or I suppose the other end of the lifecycle where corporations all have their own proprietary implementations and have put allt he garage operations out of business.



CANbus is not standard either and would lead to traps of proprietary protocols.


I was hoping to find some good open source or other DIY projects but it looks like even though the batteries have been around for a while they still have not been used much in real life.


It does make it quite difficult to jump in.

[mike_kelly]

Originally Posted by john61ct

Very rare in marine House banks, and IMO few are high enough balance current.

If BMS doesn't take care of the balancing, a few hobby balancing chargers run manually after Bulk pack-level charging is done, as a maintenance process when needed would work well, but only for those not requiring automation.

Most LFP prismatic banks don't even expose balancing wires to the charger, would need to custom wire the harness for that.

I am certainly not going to baby-sit my battery banks. So I am not going to be doing any manual balancing. That seems like dark-ages to me. So time to go to work.


Thanks