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

[caipirinha]

Originally Posted by ebaugh

Whoops! I confused the CellLog with the PowerLab....too many Labor Day (USA) beers today.

I hope you had a good La Beer day...

[bill good]

Originally Posted by vturbo

I have thought of another issue regarding charging LiFePo4 batteries noone seems to have covered.

There is potential for the ripple voltage and maybe ripple current from an alternator to heat up and damage the battery banks.

Has anyone had an issue with this or is it still too early to tell? It is a fact that voltage ripple can and eventually will cause damage to a battery if it is above the batteries spec on ripple.

Is there any cheap way to smooth or remove the AC ripple voltage from a charging line? I have seen VW use big capacitors on their alternator lines when the battery is remote e.g. in the boot of a car in order to help protect the ECU and radios etc.

VTURBO, I am using a small 24A/H as a starting battery on one motor & run the alternator thru a 70A diode to drop the voltage & use a timer to disconnect the alternator after 20 mins. which should be enough time to put any power used for starting back. It is necessary to put a small diode in the reverse across the 70A diode to allow the alternator to start charging. (Standard unmodified auto type) The aditional capacitors used was 4X 4400uf with no ripple when on load but off load the ripple is 2V on top of the DC at the alternator O/P which in my case goes to no other circuits. The radio & others are all on the house bank. Super caps were too expensive for my job. The other engine has a 40 A/H made for dropin auto replacement & it is only feed by the same diode setup & no timer. (As yet)

Regards Bill

[ColdEH]

Wooo Hooo !!!

Just got my batteries 8x Sinopoly 300ah batteries .

Makes two 300ah 12 volt banks. Got them from Canadian Electric Vehicles Ltd. - Batteries

They came boxed and strapped, with all connectors for two 12volt banks.

All 8 Batteries are at 3.29 volts .

Regards

[deckofficer]

Originally Posted by typhoon

Wooo Hooo !!!

Just got my batteries 8x Sinopoly 300ah batteries .

Makes two 300ah 12 volt banks. Got them from Canadian Electric Vehicles Ltd. - Batteries

They came boxed and strapped, with all connectors for two 12volt banks.

All 8 Batteries are at 3.29 volts .

Regards

Welcome to the Lead is Dead club. How much from your source? I paid $1.10 per a-hr per cell.

[ColdEH]

This is from Canev.com

"We sell our lithium for $1.35/ahr ($405 per cell) but this includes the import charges, aluminum end plates, stainless straps, copper interconnects and stainless fasteners.
Shipping to the closest trucking depot is usually about $125 but we would have to get a quote to be sure.
We don't normally stock much lithium with so many cell sizes available and the upfront cost to stock them.
We order about 4 times a year and should be ordering again in April and then its about 4 weeks to get her"

Thats what I paid , Canadian$ done.

Regards

[ColdEH]

Originally Posted by T1 Terry

13.8v will be fine, 13.75v will give you a small reduction in capacity as it won't quite reach fully recharged each cycle, it's not an issue with these type batteries as 100% recharged is not necessary to avoid sulphation like lead acid batteries, there is no acids in these batteries, a different format for energy storage, I won't go into it here as your eyes will roll and you'll fall off your chair :lol:

Grab a coffee, this bit will send you to sleep -There is a theory doing the rounds based on some strong logic that says avoiding fully charging and fully discharging these cells keeps them out of the danger zones and their life could be extended indefinite.... within reason, nothing lasts for ever other than a woman's memory. I tend to believe their theory is based on the old 4v per cell fully charged and 2v fully discharged and these are not actually voltage figures that can be used on their own, there are a lot of other things like charging rate/discharge rate etc connected with the formulae where the 4v and 2v figures were plucked from. I think it dated back to when all the information relating to these batteries was in Chinese, the numbers where the only universally understood language... a little information is just as bad as a little knowledge sometimes and the fact these figures remain on some of the manufacturers data sheets doesn't help, you need to know where the figures fit in.
These cells are fully charged at 3.4v, the extra 0.05v is to ensure even charge distribution throughout all the cells within the pack, low enough to produce even charge distribution without creating heat build up within the cells. Internal heat is what kills these batteries, internal heat generation within a cell happens when the voltages go outside the safety zone, it boils off the electrolyte causing either cathode or anode coating first then loss of conducting fluid, the lithium plates out on which ever electrode and the cell is finished. Damage or destruction of these cells is not instant like some BMS makes claim, it's an accumulative thing, they die slowly when outside their safety zone of 2.8v at the bottom and 3.5v at the top, all the time they are outside these zones they are getting damaged so a short trip outside the zone does little damage, a long stay out there will finally kill them.

Ok, time to wake up again :lol:

T1 Terry

Ok so I have my new cells in the crate (8 x sinoploly 300ah cells making two 12 volt cells totalling 600 Ah ), I havn't really been keeping up on this thread so would anyone want to give me the readers digest version. T1 Terry gave me great advice as to how to charge my cells with my Echo-Tec alternator that has been modified to cut out at 13.8 volts . They actually put a potentiometer on the output so I do have a little bit of adjustment.

Should I balance these cells or just put them into service. They are all at 3.29 V. right now .

Regards .

[deckofficer]

Balance them first. I did a bottom to top balance and they have stayed tight ever since. Since your cells are already banded like mine, you lose the option of just using extra cell jumper bars to put them all in parallel, but no harm, just make up some heavy gauge short jumper leads. Run the batteries down in their 12 volt configuration, remove the series bars and hook up (4) cells in parallel and use an adjustable power supply to bring them back up. For my little 100 a-hr cells that took just under a week, so you have at least a month of balancing but it is worth it.

[ColdEH]

Ok I will have to get an adjustable power supply and some cables made up .

I should run them down to 2 volts per cell and then up to 4v ?

Regards

[Lagoon4us]

Originally Posted by typhoon

Ok so I have my new cells in the crate (8 x sinoploly 300ah cells making two 12 volt cells totalling 600 Ah ), I havn't really been keeping up on this thread so would anyone want to give me the readers digest version. T1 Terry gave me great advice as to how to charge my cells with my Echo-Tec alternator that has been modified to cut out at 13.8 volts . They actually put a potentiometer on the output so I do have a little bit of adjustment.

Should I balance these cells or just put them into service. They are all at 3.29 V. right now .

Regards .

Under direct advisement from the Chinese supplier i put mine into service immediately, balancing is only required to correct an event.

Mine are running fine.

[deckofficer]

Originally Posted by typhoon

Ok I will have to get an adjustable power supply and some cables made up .

I should run them down to 2 volts per cell and then up to 4v ?

Regards

I did mine down to 2.7 volts and up to 3.7 volts. The reading of 3.9 volts on the PS was to speed things up a bit.

[deckofficer]

Originally Posted by Lagoon4us

Under direct advisement from the Chinese supplier i put mine into service immediately, balancing is only required to correct an event.

Mine are running fine.

This is probably true. My new cells were from old stock and the voltages were not tight in the beginning.

So to see how tight your cells are to each other, just cycle a couple of times in the 12 volt configuration and check cell voltages. If they remain tight, as Lagoon4us said, your good to go.

[Lagoon4us]

Agree,
All the documentation they gave me stated that balancing is only required should a voltage event occur OR if cell volts do not match, they see it as a remedy.
To manually start fiddling with balancing perfectly charged cells is akin to chasing cats and that aint fun.
Cheers

[deckofficer]

Lagoon4us, I'm glad you got new stock, nicely balanced cells. That does make them plug and play. If you remember a year back on this thread I wasn't so lucky, getting 3 year old cells. They are tight now though.

[ColdEH]

All my cells are spot on but I only have a volt meter that goes to two decimal points . All eight 3.29 v . They came in a Sinopoly crate wiith instructions. LoL so I take it they are brand new cells .

Regards

[deckofficer]

Originally Posted by typhoon

All my cells are spot on but I only have a volt meter that goes to two decimal points . All eight 3.29 v . They came in a Sinopoly crate wiith instructions. LoL so I take it they are brand new cells .

Regards

Really

They have a date stamp.