#158624  by Nut17
 Thu Feb 06, 2020 7:47 am
We have a reputation of being excessive users of our electrical energy and lived full time with 600 AH LiFePO4 and could easily have survived with half that. Having sufficient solar generation to keep them topped up is the key, and we did have 1200 watts powering an 80 Amp MPPT controller in conjunction with a 50 Amp charger powered separately by the Jeep when driving.
My concern Mike, is that you will be woefully short of solar to refill your 600 AH battery - On a good day at this time of the year you might average 20 Amps over about 6 hours = 120 Ah less what you actually draw down during the day. I reckon that a good balanced system for a high user with a LiFePO4 battery is 4 watts solar for each AH battery capacity. Our current setup has 800 watts and 300 AH - Roof space limited the solar and I had intended purchasing a 200 AH battery but chanced on the used 300 AH bank at a good price.
 #158626  by divxmaster
 Thu Feb 06, 2020 8:28 am
Hi Chris,
We will have a lot of mitigating factors, so we should be ok for now, looking at running 780w solar, and will add 300w or so solar blanket if necessary. Only travelling in the summer months for quite a few years yet. We have had 4.5kw solar on our roof for 11 years, and at this time of year we are generating 541AH per kilowatt (higher on a peak day). so with 780w of solar thats 422AH per day! yes our solar is angled, but 400w of our hiace solar will be able to be angled, if my plans work out.

We will be away from a campsite for a maximum of three days, and even with only a little solar the batteries should last about that long down to 20% SOC. Also will be running alternator dcdc as an addition.
If its forecast heavy rain for three days, we will drive to where the sun is or stay in the campground!

Cheers,
Mike
 #158630  by DarrenM
 Thu Feb 06, 2020 10:51 am
Sure the voltages can add confusion but since a deep cycle battery is bought entirely for its capacity, the fact that the cell has 80Ah stamped on the side (yes those ones you linked appear to be the exact cell), they should be sold as 240Ah not 270

But that said, I'm still really happy with the purchase, we all knew the advert was sketchy with conflicting info and specs and generally some quite bad advice
I had already seen inside yours Mike so the only real surprise was that the cells turned out smaller than I was expecting.

And while thats 10% less capacity than hoped, like you I got 2 and so I still have, theoretically, over 6kWh of lifepo4, for a couple grand and thats pretty cool.

Now the excitement of testing, balancing and building my own battery, and maybe a video or two :)
 #158634  by DarrenM
 Thu Feb 06, 2020 9:00 pm
Nomadic wrote:Interesting do the cells have the serial numbers on the top or have they been removed?
Yep they all have them. not consecutive though, thousands apart in fact. Some were dusty and looked older, no sign of a manufacture date
DSC00074.JPG
Some also have a sticker on the side
DSC00082.JPG
 #158690  by Nut17
 Sat Feb 08, 2020 3:23 pm
I did not realise that T1 Terry's link could not be viewed. Better late than never !! :oops:

This sounds way too good to be true. I will be interested in your comments Terry.

https://www.trademe.co.nz/a.asp?id=2458 ... ec607c017e

This auction will expire tomorrow so have copied the text from the auction site below. This is the second unit this seller has listed over the last month. There has been some discussion on my NZ forum https://nzmotorhome.co.nz/forum/viewtop ... 50&t=19884

"Buy Now" price is NZ$988.00

Description
Questions & answers
This is the latest generation of 12v 270ah lithium iron phosphate battery(liFePO4). The latest catl cell is used. This is also the safest lithium iron phosphate battery in the world.
5 years warranty.
This deep cycle liFePO4 battery is 12v 270ah. Up to 3kw output.
Deep cycle next generation lithium battery in conventional sizes is finally here! Providing higher energy density than their lead acid counterparts with an added bonus of massive weight saving.
Suitable for RVs, solar energy storage, yachts, automobiles, water pumps. this liFePO4 battery can be replaced directly with the original battery. The circuit does not need to be modified.

This battery is resistant to low temperatures and can work normally in - 37 C.

Our LiFePO4 deep cycle batteries offer high cycle life, higher max discharge rate and can be recharged much faster than lead acid batteries. This range of LiFePO4 deep cycle all include built in battery management system (BMS). The BMS will protect the internal cells from over discharge, over charge and short circuit protection. Providing much higher level of protection around thermal runaway as well as increasing the overall life of the battery.

This liFePO4 battery uses a stainless steel case, which is sturdy and waterproof. This battery is highly safe and supports high-current charging without thermal runaway and fire. It is particularly safe.

reach 80% 80,000 deep cycles times.
bms protection system.
Built-in voltmeter can display voltage at any time.
Automatic overload protection.
Install independent 3A equalizer to support high current automatic equalization.
short circuit protection.
Continuous discharge current reaches 180 amps. Can be used for car, truck engine start, discharge CCA up to 2000cca
over-discharge protection
overcharge protection


Voltage: 12V
Capacity: 270Ah
Charge voltage: 13.6-14.9V
Float voltage: 13.6-13.8V
Cut-Off Voltage: 10.8V.
LiFePO4 (LFP) chemistry
Discharge operating Temp : -37 to 65 C
weight:28kg
Please click here to ask a question
Shipping options
Auckland (Excl Waiheke Island & Others)$20.00
Outer Auckland$20.00
North island NON RURAL$20.00
North island RURAL$30.00
South island NON RURAL$30.00
South island RURAL$35.00
Store allows pick-ups
Store location: Auckland City, Auckland, NZ


Cheers and "Merry Christmas" Chris

Reply by T1Terry !!!
A couple of things say this is B/S wrapped in technospeak. 100Ah @ 0.5CA discharge rate weighs min of 16kg. These batteries claim to have a stainless steel case so that would make them even heavier. This means a genuine 250Ah LiFePo4 battery would weigh at least 40kg, this thing weighs 28kg.
The claim is the battery can handle -37*C and still operate as normal ... this is total B/S unless it was built with a special electrolyte mix, but then it wouldn't be able to handle the 65*C. At house battery discharge rates of 50 amps per 100Ah capacity, the operating range is 0*C to 60*C for LiFeP04 chemistry and -20*C to 65*C for LYP chemistry cells. The cell won't be destroyed at -37*C, but you can't attempt to discharge or recharge at anything more than a trickle rate at those temperatures, maybe 10 amps per 100Ah max, so not a normal LiFeP04 charge or discharge rate.
The cases are claimed to be stainless steel, this one is a real scary item. The metal cases develop a voltage and this needs to be isolated from any other metal surface that could also have a voltage or tied to the battery negative. A member of the local AEVA had his Prius burn to the ground due to the insulation between the cells and the body failing. The arc produced burnt a hole through the aluminium battery tray, it was that much of a short circuit.
The charging upper voltage of 14.9v is to make it look like they are lead acid drop in replacements, but 14.9v would equal 3.75v per cell in a perfectly balanced 12v battery. Anyone who is experienced with using lithium batteries knows as soon as the cell voltage goes over 3.6v it starts to rapidly run away. All the cells reaching 3.6v at the same time, every time, is just never going to happen, to reach 3.75v all at the same time, yeah right .... The claim it can shift 3 amps from cell to cell isn't much use if the charge rate is higher than 3 amps, one cell will run away to the point of destruction.

Simply by weight, this battery would be less than a genuine 170Ah @ 12v, probably more likely a 150Ah battery. The continuous 180 amp discharge would be a little more than a 1C discharge rate if it was a 170Ah battery, a 1.2CA discharge rate for a 150Ah battery, both well within the capabilities of any decent LiFeP04 cell or battery.

In reality, this battery is $6.50 per AH @ 12v, can not have any of the cell links cleaned during its service life, nor can it have any individual cell replaced if needed. A replacement 160Ah Winston cell would be about $320, not $988 if a cell failed resulting in the whole battery headed for the rubbish bin.

Cheers
Terry
 #158795  by johnny
 Wed Feb 12, 2020 12:38 pm
re - this battery;

I am about to replace some 12v Gell batteries with this unit using a 600 w array.

I note the solar controllers 2/30A. does not support Lithium .
The equalisation setting for Gell is 14.2v

'Micromall ' claim just drop in replacement, no mention about the need/must be a lithium
compatible controller.

The info provided by 'experts'?[you tube etc.] that 15V will kill this Battery.

Any opinions on the equalisation voltage of 14.2v will do damage.
[how often time wise this equalisation occurs at present ,I have no previous facts.]

Others also maybe thinking of doing this but when you add another $500+ for lithium friendly controllers if you existing setup is not suitable ?

This is a stand alone hunting hut some led lights , phone chargers , Sky if needed & 2 Game freezers and a beer fridge.
Some call it our Man Cave used most weekends etc.
 #158797  by scubadoo
 Wed Feb 12, 2020 1:33 pm
johnny wrote:
Wed Feb 12, 2020 12:38 pm
...Any opinions on the equalisation voltage of 14.2v will do damage....
Model of your solar controller(s)? Are you sure any equalization setting can not be turned off?

My opinions based on 5 years of fulltime travel with our 300Ah Sinopoly bank and no significant capacity loss so far.
Occasional 14.2V short term equalisation will not harm a 4 cell LiFePO4 battery bank. I would avoid 15V.

The Victron solar controller (self modified lithium setting) charges our battery to 14.20V and holds that voltage for 20 minutes or charge current =<1A onetime each and every day prior to settling at 13.40V. Absorption and float in lead acid jargon.
Once our battery is full the truck alternator will maintain it at 14.2V while driving. No harm yet.
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