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paulz
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# Posted: 21 Dec 2020 08:40
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These came up on a pop up last night. Looks about the same price as an equal lead acid battery, and much less than a power tool battery. Might be good for something, maybe just learning about Li batteries. If they are any good.
https://tinyurl.com/y9ry6cna
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Nobadays
Member
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# Posted: 21 Dec 2020 09:25
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I don't know about the quality but an 8ah/102wh battery isn't going to power much... for very long. Didn't read that it had a BMS.
THIS ONE has caught my attention. I've read good things about it and it includes not only a BMS but a low temp disconnect so you don't ruin your battery charging at low temps. At $570 for a 100ah Li battery, that's pretty good.
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Steve_S
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# Posted: 21 Dec 2020 09:40
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SOK are Good Quality pre-builts. They will NOT be shipping till January as they oversold and stock is back-ordered.
If you look at Building your own, you might be surprised at the cost differences.
4x120AH cells = $335 USD DDP (Delivered duty taxes incl to USA)
Plus a 120A-4S BMS ($75 USD) with cold temp cutoff & Bluetooth interface
CELLS: https://www.alibaba.com/product-detail/3-2V-120Ah-Li-ion-Lithium_62585331091.html?spm =a2700.shop_pl.41413.10.2ada3239UppUsp
Value Added JBD 12V BMS, US Vendor. ($115 USD)
https://overkillsolar.com/product/bms-120a-4s-lifepo4/
* Can be purchased for 2/3 from China
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paulz
Member
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# Posted: 21 Dec 2020 09:48 - Edited by: paulz
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Quoting: Nobadays I don't know about the quality but an 8ah/102wh battery isn't going to power much... for very long. Didn't read that it had a BMS.
In the comments, one or two guys said they are using 6 of them in parallel in their RVs, fwiw. Also one of the answers says it does have a BMS.
I have several things I power off small batteries at the cabin, a 12v hand held vacuum cleaner, a little circular saw and some other things I can't think of right now that had cigarette lighter plugs. This battery would work for that, and it's double or triple the AH of a tool battery. But, as I posted on the Craigslist thread, last week I bought this battery for the same purpose. Used it yesterday. Light as a feather, ion, not iron.
Lot of negative reviews on the battery in the link I posted though. More positives of course, but I read most of those are fakes. 
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paulz
Member
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# Posted: 21 Dec 2020 10:01 - Edited by: paulz
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Quoting: Steve_S Charging LFP is 2-stage CC/CV there is no need for float, no equalisation / desulphation either. Ending Amps for charging is also tricky which is a percentage of actual charging amps.
Thanks Steve. I am quoting you from the thread on panels since it's straying off topic. I understand the charging stages, although I've never understood how current can be varied.
Anyway, I bought a typical 4 amp lithium power tool 'fast charger' to charge the battery in the photo above. Do those have the proper characteristics to charge both Li ion and LifePO4 properly?
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gcrank1
Member
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# Posted: 21 Dec 2020 11:41 - Edited by: gcrank1
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If Im getting this Lith thing figured right that 8ah bat should give you some 6ah usable at the 80% rate. That equates to 50% on a 12ah lead/acid. That is a pretty small lead/acid bat, as is.
This Lith is small and light, but so is the 12ah lead/acid (ie, for me, if the bat-bank fits in a small plastic ammo can with room for some wires and clamps it is fine).
The spec page on your link says this one will charge off a reg lead/acid charger....hmmmm
Im used to using and maintaining my lead/acid bats.
So, looking at this little Lith it isnt calling my name. What will is when the price point drops on the 100ah, or more, 'big ones' from a reputable seller with all the built in trick stuff. Think I'll save up the $30 here/$30 there for the big boy.
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Steve_S
Member
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# Posted: 21 Dec 2020 13:04
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Well, I can't speak to a 4A charger... I run pair of 24V/175AH & and a pair of 24V/280AH packs and just building a 12V/280AH pack for my Powerhouse Furnace power (only thing left on AGM).
LiFePO4 (LFP) & Li-Ion NMC, NCA etc all have different voltage profiles and as such their charging requirements are different. LFP is the chemistry which is the closest to Lead Acid battery profile.
For the 12V pack, I am also doing Capacity & IR (Internal Resistance) tests using a Yaorea YP1835+. This means emptying each cell to 2.60V and then charging to 3.55. I will be charging that at 3.60V/40A, yes forty, which means 7 hrs charge per cell. As the cell hit's 3.60V (limited) the 40A will be pushed to that cell but as it reaches full the amps will drop which I will end at 3A. As Internal Resistance Increases (as cells reach full) they will take less & less amperage.
Once all cells are @ 3.60V, I will then TOP balance by setting the cells in Parallel and applying 3.65V/40A and allow that to drop to 3A again. After this the pack should be ready for final assembly into a 4S pack and then attach the 120A BMS with Low Temp cutoff & PC-RS485 Interface.
Now to be clear, I am using Lab Bench Power supply for Bottom to Top Balancing linked below.
Lab Power Supply:
https://tekpower.us/power-supply/digital-powersupply/tp1540e.html
8 In 1 150W 180W Digital Battery Capacity Tester Voltmeter Adjustable Constant Current Electronic Load Charger Meter Indicator I have the 180W.
https://www.alibaba.com/product-detail/8-In-1-150W-180W-Digital_62090055059.html?
Alternative Testers with logging:
CBA IV - Computerized Battery Analyzer: http://www.westmountainradio.com/product_info.php?products_id=cba4
DL24/P Color 2.4" DC USB tester electronic load lithium battery capacity monitor discharge charge power meter supply checker APP:
https://www.aliexpress.com/item/4000479624068.html
Video Teardown of the Miady Batteries:
https://www.youtube.com/watch?v=Wm3Bnpjohhk
Hope it helps
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