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slaz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Topic: LiFePO4
    Posted: 05 February 2021 at 8:38pm
There seems to have been a bit of an upsurge in folk using/considering  this chemistry recently - not surprising as the prices are coming down somewhat.

I've had LiPO for quite a while (RC style ones) and a few bodged up DIY packs from 18650 cells. Mostly quite happy with em .... but never used LiFePO4.

So I'm looking around at them - all seem to come in with strong sealed ABS(ish) industrial-style cases - with built-in BMS. The form factors seem to pretty much ape the standard lead-acid sizes/shapes - which makes sense.

But reading around a bit, I've seen quite some folk having trouble with the BMS's .... and with the buit-in BMS's, any trouble would seem to imply the whole pack would be a write-off ... no ?
Guessing a simple feckin passive component failure would brick the sealed pack wouldn't it ? Don't fancy a 1p R or C or whatever trashing a 200-300 quid battery.

Any experiences in here with that ? Anyone know of batteries that use/can use external BMS ?

Also - I'm assuming these batteries are pretty much designed for use with various types of bike/scooter/golf trolley or whatever - with very different current deliver patterns. Is there any reason to think there'd be issues with sound system use where the current draw will be very intermittent and peaky ?

The folks doing the soundboks (Saturnus) has been supplying them for a while now - would be good to hear his experiences over time ...

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Post Options Post Options   Thanks (0) Thanks(0)   Quote bass*en*mass Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2021 at 9:20pm
lifepo4 is much safer than those 18650 li-ion cells, no fire risks etc..!
the bms is never really built in, its a module that often includes the required balancers to level the typically 4 cells voltage, 3.2-3.3v each, for a 12v norminal battery..
4x 100Ah lifepo4 cells could be had for about 100quid, add the balancers/BMS and a shunt with bluetooth connectivity for convenience..

the discharge/charge currents are about the same as the capacity, the bigger the cells, the larger the currents - i see no problem there re. soundstuff..!


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slaz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 06 February 2021 at 1:22am
Erm yeah - I understand what a BMS does .... what I was getting at is ... the BMS must be pysically mounted inside the battery casing - yes ? By the look of them, those casings look designed to never be opened up, so if the BMS fails the battery fails unless you dremel open the casing and replace (and probably re-calibrate) the BMS.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 06 February 2021 at 2:04pm
I guess it is a risk that lead-acid batteries don't have yes, but personally I've never had a BMS fail (apart from a Bosch one, but they are *unnecessarily* complicated and if I had a Bosch dealer laptop I could probably have unbricked it!)
I mean if you are really concerned about it you could just buy 4x 100Ah prismatic cells and a seperate BMS and put them together, it's easy enough with square batteries. 
I've been using a set of LiFePO4 10Ah pouch cells for about 7 years now, they came with a BeBike setup from Decathlon. Only one cell out of 8 has gone duff, and if I get around to taking the pack apart and re-balancing it, it may well come back to life. They are a really great technology. Plus I can charge the 4s packs from a "5 amp" car charger without any apparent problems. Get about 2.5 amps initial current which tapers naturally to about 100mA, then the BMS just cuts the current off when the voltage is 14.4v.
Studio45 - Box Builder Commotion Soundsystem -Mobile PA
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bass*en*mass Quote  Post ReplyReply Direct Link To This Post Posted: 06 February 2021 at 10:10pm
"the BMS must be pysically mounted inside the battery casing - yes ?"

- no, it doesnt, diy, for convenience its included in the available `all in packages`though..
diy i would rather get individual parts and put them together as required!


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Post Options Post Options   Thanks (0) Thanks(0)   Quote eshroom Quote  Post ReplyReply Direct Link To This Post Posted: 15 February 2021 at 9:21pm
FWIW I build my own pack out of individual lifepo4 cells. 32700 and 18650. I wire in BMS and balance boards as required.

Found Liitokala cells on AliExpress very cheap and while the figures are exaggerated a bit, they still represent excellent value for money. about 6ah per 32700 cell. My 12ah 19.6v pack keeps my halfinator going for days and set me back about £40.
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slaz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 04 March 2021 at 11:08am
Moann' all ...

Well I'm looking at getting a LiFePo4 pack now (a ready-made one with internal BMS).

Has anyone used Ultramax ones ? Is that a brand that can be trusted ? Looking at the 12V 36Ah one.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 05 March 2021 at 5:31pm
No-0ne ?

Well - as there's a published UK phone contact for Ultramax, thought I'd give em a call to (with a tech question) to sound em out a bit.

Well its sold by an actual UK company with UK staff etc. (the brand seems to belong to Barusch - which also disributes other battery-related stuff including Yuasa).

I was told on the phone that the Ultramax LiFePo4 packs have a 2 year warranty - not great, but better than 1 year !
The accompanying chargers on;y have a 1 year warranty :-)

They have a promotion up until March 12 ... 10% off Ultramax LiFePo4 .... so I think I'm gonna go for either a 12V 36Ah or a 12V 50Ah.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 05 March 2021 at 11:52pm
Originally posted by slaz slaz wrote:

No-0ne ?

Well - as there's a published UK phone contact for Ultramax, thought I'd give em a call to (with a tech question) to sound em out a bit.

Well its sold by an actual UK company with UK staff etc. (the brand seems to belong to Barusch - which also disributes other battery-related stuff including Yuasa).

I was told on the phone that the Ultramax LiFePo4 packs have a 2 year warranty - not great, but better than 1 year !
The accompanying chargers on;y have a 1 year warranty :-)

They have a promotion up until March 12 ... 10% off Ultramax LiFePo4 .... so I think I'm gonna go for either a 12V 36Ah or a 12V 50Ah.


I've spent so long looking at batteries I have bored myself so I ordered one of the 36Ah ones last night. Should be here on Monday so will let you know how it looks. Might be able to set up a crude capacity test.
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slaz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 07 March 2021 at 11:37pm
Originally posted by snowflake snowflake wrote:


I've spent so long looking at batteries I have bored myself


:-) Yeah know what yiou mean ...

Check the warranty when you get it .... I was told (on the phone) that their LiFePo4 packs carry a 2 year warranty, not 12 months like in the ebay listing.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 08 March 2021 at 10:01am
Originally posted by slaz slaz wrote:

Originally posted by snowflake snowflake wrote:


I've spent so long looking at batteries I have bored myself


:-) Yeah know what yiou mean ...

Check the warranty when you get it .... I was told (on the phone) that their LiFePo4 packs carry a 2 year warranty, not 12 months like in the ebay listing.



everything is covered for at least two years guarantee (EU minimum - I assume carried over to UK law post-Brexit). up to six years if you can prove failure was due to poor design/manufacture rather than mis-use (UK law). manufacturer warranties for less than two years are meaningless except that if the seller goes bust you can go to the manufacturer instead.

Edited by snowflake - 08 March 2021 at 10:15am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote opus jody Quote  Post ReplyReply Direct Link To This Post Posted: 09 March 2021 at 9:34am
I built precisely this, for my GF's sprinter conversion.



(except with a different inverter, and no DC isolator)

it's awesome!

One on/off switch, & everything else is automated.

Normally it would have been really expensive, but I figured the best way to avoid any F-ups would be to get matched equipment that's designed to work together, so over a fairly long period of time, I was collecting the bits.
One battery (normally £700 odd) I got for £200, un-used, & bought for a never finished robotic project.
The 2nd battery was a bit more, £300 odd iirc
BMS - £200 odd.
800w inverter - £200 odd

Having all the sensor cables, for balance charging, over-temp cutoff etc seemed like a damn good idea.
It'll run all my power tools easily.
Should last 10x longer life span than other systems.
Safer.
Solid voltage.
Ran all lights & fridge & computer for over 2 weeks before I was driving (charging) again, & felt like there was plenty more to go. I still haven't reached cutoff point yet.
It's been sat for 6 months, and I actually left it turned on by accident, but it's all fine, and was still working. (the fridge was off)
And it all fits into the box under the passenger seat :D ideal !

You probably know this, but paralleling batteries, it's best to have the positive connection on one batery, and the negative on the other end of the chain, so both (or more) of the batteries are working equally, otherwise the single connected battery gets hammered more than the parallel connected one(s)

Like this:


Expensive outlay, but probably the cheapest system in the long run.




Edited by opus jody - 09 March 2021 at 9:48am
Improvised Hardware Music http://vimeo.com/user9389813/videos
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