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LiFePo Battery Packs - My little Yoda


Bash

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So, Stuart and I have been making things again (well, in truth, mostly I make the phone calls, Stuart does the actual 'making') and this time we have made some LiFePo battery packs.

Stuart has managed to shoehorn into a Peli Storm 2100 case, 70AHr worth of LiFePo cells, a 5 amp charger, all of the balancing and monitoring stuff, 6 x XLR4 OP sockets...

You can only use the LiFePo cells at 80% of their capacity, so we now have a 56AHr battery, that can be plugged in and charging whilst the battery is in use. We have included a battery monitoring system, that looks at current going into, and out of, the battery. If it works out then it will give us an indication of remaining power, at whatever current is being used. I am about to start testing that part of the system next week. I was going to try and test it this week, but my cart only draws about 2.5amps, so in fact so far I have hardly touched the available capacity in the battery.

Here are pictures of the 'front' and 'back'.

It is surprisingly small, and half the weight of the battery that it is intended to replace.

I have nicknamed mine 'Yoda' as it is small but has unbelieveable power ;-))

If there is interest, then I may well have a few made up and sell them. I think they will be circa £1250 plus any taxes, ex UK.

Kindest regards to all,

Simon B

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post-346-0-09511700-1354919509_thumb.jpg

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Looking good, Simon! Interesting use of the inverted Pelican case --- is that the way it is to be used or is it just sitting that way during testing? Also, really like the BM-1 Compact monitor --- looked that up and it seems to be only available in the UK. I will continue to look for a source here in the US.

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Looks terrific. I'm interested in seeing how it performs.

A couple of thoughts.

What is the total weight?

I see a lot of screws, instead of rivets - will they begin to loosen over time through normal transport?

is the power switch inset enough to avoid accidental shut off? Or could it have been placed on the front handle side?

Why is the case (Pelican?) set up in an upside down arrangement?

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That is a really neat battery you guys came up with. I have had several customers ask for something just like that, but I had to decline their requests to build it. I am not trying to discourage you, but I would caution you to check into the shipping limitations on Lithium batteries before you decide to ship or sell these. You have a 70 amp/hour 12.8 volt pack there..........896 watt hours worth! Any lithium battery of 300 watts or greater is forbiden to ship on any comercial airline. Lithium is considered a Class 9 Hazard shipment. Shipping any battery of 300 watts or greater can result in fines of $250,000 and six months in prision. We all know that the newer LiFE technology is a much safer than the older Lithium technology, but the TSA and others do not yet understand the difference. This is why you see our LiFE battery products and others only have a 20 amp battery at 12.8V (256 watts) Good luck and be carefull.

Ron Meyer

PSC

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I am one of the lucky testers of Simon and Stuarts Yoda. Four of us chipped in to build the first batch and we are putting them through their paces. Jeff: the battery monitor is a yacht system. The works are in the Peli and the display is remote. Richard: Stuart Ebbs who built the batteries suggests that they be inverted so that we can see the LEDs when the battery is mounted low but the battery can be used in any orientation and I use mine upright as I get all the info that I need from the remote display mounted so I can see it easily. Ron: Your worries about air transportation whilst entirely valid are not so much of a problem to us in Europe. Whenever I am travelling with my main cart - which is now powered by this beast the production would truck the tech equipment. About the furthest we go in Europe from the UK is Turkey (OK technically Europe / Asia) and that is within a couple of days trucking range. My other filming locations (with tax breaks) Latvia, Lithuania and Hungary well within 30 hours - I know, I have done London to Hungary. Justin: It can be charged and used simultaneously and that does create a UPS. With my tests so far I have been impressed. Particularly, when you are used to the fact that a lead gel battery rating is rarely achieved and usable capacity is greatly reduced when the batteries are really cold. I ran between 4.5 and 5A for 12 hours and only just dipped below 12v (10.6v being their end voltage) indicating that 70ah is a modest rating. Also with these LiFe batteries, if kept within the 80% range, they should take 2000 charge cycles before they loose capacity to 80% of their original rating - compared with 300 for a LiIon.

Tim

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Justin: It can be charged and used simultaneously and that does create a UPS. With my tests so far I have been impressed.

Tim

Is this circuitry something you guys designed or bought pre-fab? I have a lifepo4 battery that runs total-loss (charge, drain to empty, charge again etc) and I'm interested in working with a system like this quasi UPS you have created...

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Prefab circuitry Justin. Stuart did most of the research. I will check what came from where, but we had stuff shipped in from amongst other places Hungary and Australia!!!

Justin, our research came up with that you can greatly improve the battery's life and loss of capacity by only cycling the cells within the 89% range.

Interesting aside - we were looking at smaller capacity cells, but the dimesions didnt fit so easily into the box (they were smaller, but a different shape) and it worked out that the larger capacity cells (and larger physically) actually left us more useable space within the box!!!

Kindest regards to all,

Simon B

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Prefab circuitry Justin. Stuart did most of the research. I will check what came from where, but we had stuff shipped in from amongst other places Hungary and Australia!!!

Justin, our research came up with that you can greatly improve the battery's life and loss of capacity by only cycling the cells within the 89% range.

Interesting aside - we were looking at smaller capacity cells, but the dimesions didnt fit so easily into the box (they were smaller, but a different shape) and it worked out that the larger capacity cells (and larger physically) actually left us more useable space within the box!!!

Kindest regards to all,

Simon B

Oh yeah, I didn't mean FLAT flat. I swap out well before 11.5v if I even have to. I can usually go a whole day with my low-power rig if I turn off at lunch etc. (2Aish draw).

Good to know you got some stuff from here in Aus - electric bikes and lifepo4 backup systems are growing in use.

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You mentioned the battery was able to be used while charging...Is this system float charging like a SLA setup or UPS style?

If your load is low - such as your 2A system - the internal 5A would do it - but this system is about 3x what you would need for a day's work. My system is a Sonosax ST which is max 2.2A (all channels and AD converters on), Lectro Field 1.5A, Cantar 0.9A (digital power on) and if I have Blackmagic Design Duo screens on, that is another 1A. So with all blazing I would exceed the 5A internal charger and there would be a small battery discharge. I have used it on my 10A linear PSU (set to 13.8v) and according to Stuart who has done his homework, it is a good float solution. Plenty of capacity to power and charge but if you need absolutely full capacity the next day, an hour of so on the charger will bring it up to maximum (which 13.8v will not do).

Tim

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If your load is low - such as your 2A system - the internal 5A would do it - but this system is about 3x what you would need for a day's work. My system is a Sonosax ST which is max 2.2A (all channels and AD converters on), Lectro Field 1.5A, Cantar 0.9A (digital power on) and if I have Blackmagic Design Duo screens on, that is another 1A. So with all blazing I would exceed the 5A internal charger and there would be a small battery discharge. I have used it on my 10A linear PSU (set to 13.8v) and according to Stuart who has done his homework, it is a good float solution. Plenty of capacity to power and charge but if you need absolutely full capacity the next day, an hour of so on the charger will bring it up to maximum (which 13.8v will not do).

Tim

I'm not 100% sure what you're doing here: Are you feeding 13.8V (from your 10A PSU) to the battery like a normal float system and then top-off charging the battery if needed in the evening? Is this different/instead of using the 5A inbuilt charger due to the high power demands of your cart?

I just think it's convenient to have the charger inside the body of the battery. I'd be happy to have the piece of mind of having the 5A charger floating over the battery, and then use battery juice alone for kick-outs and moves. It's like a Meon in a box!

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Looking good, Simon! Interesting use of the inverted Pelican case --- is that the way it is to be used or is it just sitting that way during testing? Also, really like the BM-1 Compact monitor --- looked that up and it seems to be only available in the UK. I will continue to look for a source here in the US.

Jeff!

One of the main suppliers is in fact in New Jersey.

The item number on UK E-Bay is 400337052112.

Malcolm Davies. A.m.p.s.

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I'm not 100% sure what you're doing here: Are you feeding 13.8V (from your 10A PSU) to the battery like a normal float system and then top-off charging the battery if needed in the evening? Is this different/instead of using the 5A inbuilt charger due to the high power demands of your cart?

I just think it's convenient to have the charger inside the body of the battery. I'd be happy to have the piece of mind of having the 5A charger floating over the battery, and then use battery juice alone for kick-outs and moves. It's like a Meon in a box!

You have it exactly. The 10A PSU is already fitted to my cart so I might as well use it. If my consumption is 6A, then with the 5A internal charger, the battery would discharge at 1A. Might as well keep the 10A linear PSU on all day and the internal charger to get the extra 10% or so in the evening if needeed. In reality, unless I know I am without power the whole of the next day, I am unlikely ever to top it up. Ideally a slightly bigger internal charger would be good but then we are getting into size, heat and fan considerations. So far and it is early days, this is working really well.

Tim

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You have it exactly. The 10A PSU is already fitted to my cart so I might as well use it. If my consumption is 6A, then with the 5A internal charger, the battery would discharge at 1A. Might as well keep the 10A linear PSU on all day and the internal charger to get the extra 10% or so in the evening if needeed. In reality, unless I know I am without power the whole of the next day, I am unlikely ever to top it up. Ideally a slightly bigger internal charger would be good but then we are getting into size, heat and fan considerations. So far and it is early days, this is working really well.

Tim

Cool. I'm assuming you disconnect the internal charger and attach your 10A supply, or can you / do you just feed through one of the XLR's? Or some sort of quick connection swap over...?

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  • 3 years later...

So.... Stuart and I just managed to make a hybrid Mk6 EasyLiFe battery. We used 100AHr 'pouch' cells, which save massively on weight and size. We also used a new BMS (Battery Management System) which utilizes a Bluetooth connection to a smart phone. I can now monitor the state of my cart battery by wireless on my iPhone!!!!!

Here's a pic of my phone balanced over the battery, showing the app. The top third shows power coming in to the system. The middle shows the state of the battery, and the bottom third shows what is happening at the OP of the battery. Its quite cool, and a free app.

The 100AHr battery fits into the smaller peli case that we used to use for the 70AHr batteries. So far it is working out well in every way!!!

 

 

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  • 2 years later...

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