LiFePO4 |
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slaz
Old Croc Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2713 |
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Posted: 18 March 2021 at 1:27pm |
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Assume your battery showed .... did you get around to putting it thru its paces in any way yet ?
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slaz
Old Croc Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2713 |
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Snap. Well I ordered a 50Ah one yesterday. Compare notes maybe ... ? The 50Ah one - their ebay listing had the weight wrong. They listed as 7.5Kg - which didn't sound right to me when the 36Ah was listed as 4.3Kg .... so I got em to go down to the warehouse and stick one on the scales - and lo and behold, the 50Ah was 6.4Kg with its packaging, so guessing 6Kg or just over :-) |
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opus jody
Young Croc Joined: 06 June 2006 Location: United Kingdom Status: Offline Points: 1246 |
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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 |
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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3118 |
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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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slaz
Old Croc Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2713 |
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:-) 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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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3118 |
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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
Old Croc Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2713 |
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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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slaz
Old Croc Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2713 |
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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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eshroom
Registered User Joined: 26 August 2020 Status: Offline Points: 15 |
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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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bass*en*mass
Old Croc Joined: 03 September 2009 Location: "unknown" Status: Offline Points: 4009 |
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"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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studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3863 |
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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.
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slaz
Old Croc Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2713 |
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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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