LiFePo4 for Permobil C500S

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Re: LiFePo4 for Permobil C500S

Postby ex-Gooserider » 19 Mar 2019, 03:10

A PROPERLY done crimp connection is sufficiently good that it is what most military specs require for use on 'life sensitive' weapons systems - where if it doesn't work, soldiers die.... and do NOT allow soldered connections.... However at a minimum it needs good ratchet crimpers to make that sort of connection on all but the smallest of pins...

A proper crimp does a sort of 'pressure weld' between the wires and the connector body, such that it is 'gas-tight' and the joint will not move or corrode (though the wire and connector themselves will...) If you cut a properly made crimp in half it will still be hard to pull the wire out of the connection without breaking wire strands as the connector metal will actually have penetrated into the spaces between the strands and wrapped around them...

I have a pair of plier crimpers from Japan (I think 'Engineer' tools brand) that is amazingly good at JST / Molex size pins, but is a bit of a pain to use - otherwise I have ratchet crimpers that I use for larger wires

However BM is right if talking about the sort of crimps made by the cheap 'Plier' style crimpers that one finds at the average hardware / auto store..... Those are not capable of making a good crimp as they don't have enough leverage to apply sufficient pressure....

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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 19 Mar 2019, 06:21

Its not just the crimp tool. Its the stupid cheap soft copper terminals made from copper tube and tinned that you see almost everytwhere for the last 2 decades. They are too thin walled, and too soft to ever crimp to any kind of degree that is either secure or capable of keeping out oxides. You make em, and I will pull the wires out.

Meaning that almost all crimps done at home are completely useless. And the larger the cable size the worse it is. And theres no such thing as a pressure weld. Its just squeezed together tight enough to keep oxygen out in theory. Requiring thick walled terminals, not the crap seen 99 percent of the time. It also means PROPER selection of cable size, terminal quality size and type, as well as tooling and technique. The sort of thing you may find on a production line with quality control testing and fine tuning.
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Re: LiFePo4 for Permobil C500S

Postby Scooterman » 19 Mar 2019, 09:41

I've crimped up to 120mm^ using hydraulic crimpers. They're good, they come with a complete set hexagonal jaws different sizes (two halves) and crimp the terminal evenly on all sides. But we never worried about a few volts here or there, whereas I've learnt from this forum mV count when talking of cell voltages.
As far as electrical components go, you get what you pay for. I always reckon you can't go wrong with 3M. :thumbup:

EDIT: In large installations there was so much 'induced current/voltage' that you couldn't rely on a multimeter, it wasn't safe (false readings). The old fashion mains test probe with a small tungsten filament pigmy bulb was better, as it collapsed false voltages that were trying to deceive me hanged
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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 19 Mar 2019, 10:11

Burgerman wrote:Almost. You still need the 36 inch extentions for balance wires. You will likely use 4.

Please explain why do I need 4 36 inch extentions?
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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 19 Mar 2019, 10:26

Because you need 1 for charger side. 1 for battery side, to make your new loom. And extra 1 for charging or testing batteries on the bench. And 1 spare for when you muck up a cable or something. Because nothing else fits the pl8 and they are cheap if ordered at the same time! If you figure out I am right later on carriage is very expensive... And theres nowhere else to get those cables at least in the UK.

You can get away with just 2 but then no spare, and no cables to charge any other battery or to test or balance the one you own/build on the bench. I think expresso and others will likely tell you the same. Same with the safe 4mm connectors. Dont buy those from revolectrix. Get 10 at a time loose, no too short cables, oneBay. Because you will want to charge other cells, on the bench or other batteries like lead, or whatever at a later date. Remember this charger can test and charge anything. Your cars battery, your tools or mower, hobby stuff, AAs etc.
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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 19 Mar 2019, 10:34

EDIT: In large installations there was so much 'induced current/voltage' that you couldn't rely on a multimeter, it wasn't safe (false readings). The old fashion mains test probe with a small tungsten filament pigmy bulb was better, as it collapsed false voltages that were trying to deceive me hanged


In the modern world, good multimeters like my fluke have 2 differrent AC voltage settings. One is called LOW IMPEDANCE and it is basically the same, other than there's a resistor across the input to remove induced "ghost" voltages. So you can read almost no volts, or anything from 100 to 240V on a wire depending on which option you use. So if you see a voltage where you dont expect one, switch to LOW and its gone. If its real, then it still reads obviously...

The Fluke 289 digital multimeter is designed to solve complex problems in electronics, plant automation, power distribution, and electro-mechanical equipment.

Low impedance voltage function for eliminating ghost voltages.
Low Pass filter for accurate voltage and frequency measurements.
Two terminal 50 ohm range with 1 milliohm resolution, 10 mA source current.
https://www.fluke.com/en-gb/product/ele ... /fluke-289
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Re: LiFePo4 for Permobil C500S

Postby Scooterman » 19 Mar 2019, 11:25

Burgerman wrote:
In the modern world, good multimeters like my fluke have 2 differrent AC voltage settings. One is called LOW IMPEDANCE and it is basically the same, other than there's a resistor across the input to remove induced "ghost" voltages. So you can read almost no volts, or anything from 100 to 240V on a wire depending on which option you use. So if you see a voltage where you dont expect one, switch to LOW and its gone. If its real, then it still reads obviously...

The Fluke 289 digital multimeter is designed to solve complex problems in electronics, plant automation, power distribution, and electro-mechanical equipment.

Low impedance voltage function for eliminating ghost voltages.
Low Pass filter for accurate voltage and frequency measurements.
Two terminal 50 ohm range with 1 milliohm resolution, 10 mA source current.
https://www.fluke.com/en-gb/product/ele ... /fluke-289

Oh, I never knew that thank you :thumbup:

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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 19 Mar 2019, 13:46

Burgerman wrote:Because you need 1 for charger side. 1 for battery side, to make your new loom. And extra 1 for charging or testing batteries on the bench. And 1 spare for when you muck up a cable or something. Because nothing else fits the pl8 and they are cheap if ordered at the same time! If you figure out I am right later on carriage is very expensive... And theres nowhere else to get those cables at least in the UK.

Sorry, not clear for me.
I use one on the charger side. On the battery side I use JST pigtail. Then I connect them. Right?
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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 19 Mar 2019, 13:52

Why JST?

The PL8 isnt using that. I have non of those on my chairs. The PL8 connectors and cables are also very well made compared to the mass of JST ones you generally find. I do use those on hobby stuff only because thats what those batteries come with.

You need a subD 40A connector in the middle too. But you can do it however you want.

I have
two halves like this:
http://www.wheelchairdriver.com/BM3-con ... le-40A.jpg 36 inches long...
http://www.wheelchairdriver.com/BM3-con ... DCABLE.jpg

And the chair half has a PL8 style connector in between the SUB-D and the battery. And for the sake of convinience I have 2 of those charge cables. In case one fails and because thares a charger next to my PC and another next to my bed.

http://www.wheelchairdriver.com/BM3-con ... -pl8v2.jpg
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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 21 Mar 2019, 11:18

I still don't understand.
Here's expresso's 30Ah pack:
30Ah.jpg
30Ah pack

It has 3 wire parts. How they can be made from this:
Cellpro36CutOff.jpg
Cellpro 36 in

Do I need to cut off one side?
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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 21 Mar 2019, 12:00

Yes.

In expressos pic above, 1, 2 and 3 all use that cable with 1 end or the other cut off. And eiither a connector or ring terminal used in place.

4 leaves 1 spare for when you f**k up or wish to charge or extend another cable or battery. They are good quality, cheap, long, and heavy on carriage. So I usually get 5 or 6 since I charge many packs. Theres one on my mower for e.g...

Did you know that for hobby packs, mower, tools, camera batteries etc you can charge up to 3 Amps with NO 4mm connectors? Balance tabs only. As long as you use FMA wiring mode. I use that on my bot, quadcopter, its rc transmitter and its FPV screen, as well too.
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Re: LiFePo4 for Permobil C500S

Postby expresso » 21 Mar 2019, 14:30

those 36 inch balance cables - they show the picture like above with a board on one End - but they are not like that - so far i mush have purchased a dozen or more of those cables and never received one with the board on the end - which is good - i didnt want the board

i even called to make sure i dont get the cable with the board - - i be very surprised if someone gets one with a board on one end -

either way you have to cut one end off - but just make sure you match the other end up correctly so they both connect -

i have made mistakes where i put the rings on the wrong end - then i was left with two ends male or two ends female - that didnt connect to each other

so i am sure i have at least one charge cable made with the wrong end and works only on the pack with the right end - :D

i have another balance cable made that can fit in between to work if needed for testing etc.
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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 21 Mar 2019, 20:30

I prefer the ones with board. More secure. And I have both types. But all work the same and are decent quality unlike the typical cheapo xh style ones you see everywhere.
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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 22 Mar 2019, 13:24

Ok, thanks for explain.
I'll order 5 of them.
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Re: LiFePo4 for Permobil C500S

Postby Scooterman » 31 Mar 2019, 13:17

Burgerman wrote:PER CHANNEL. Or PER MOTOR.

Your motors take around 100A each on a zero turn or climbing a ramp. Thats 200A for a pair. Intermittently. The motors take only around 5A each running at constant speed with no load. Maybe 30A as you drive up a very slight hill.

The permobil guy has no clue. I actually MEASURED this on many chairs.

Theres a complication here thou to muddy the waters.
The motor Amps is not always the same as battery Amps. With high impedance motors, the motors may be drawing 100A at stall each, but still only show say 100 Battery Amps. As speed increases, the motor Amp level stays the same if load stays the same. But battery Amps increase along with the pulsewidth. With high impedance motors MORE battery amps are used.


So yes your chair can take 200A . If its a 120A R-Net system, it can actually take 240A for up to 10 seconds. Measured on my Salsa chair.

I worked out very roughly that my scooter draws about 15A continuous from the lithium cells on a long run, i.e. 15Ah per hour if that makes sense? But it's all straight ahead riding with pumped up tyres and me about 50kg.
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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 08 Apr 2019, 09:04

Got my charger.
IMG_20190407_115819_small.jpg
Revolectrix Cellpro PowerLab 8

Waiting for batteries.
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Re: LiFePo4 for Permobil C500S

Postby c500user » 08 Apr 2019, 17:34

Would this be an idea to have an idea of charge? A friend on mine uses it for a solar hot water system. The main unit could be placed near the batteries. The display can be used wirelessly.
http://s.aliexpress.com/yAnUf6ru
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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 08 Apr 2019, 17:43

Depends on what you are trying to measure and why.
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Re: LiFePo4 for Permobil C500S

Postby c500user » 08 Apr 2019, 17:46

It would be useful to know how many Ah are used to estimate how much remains.
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Re: LiFePo4 for Permobil C500S

Postby Burgerman » 08 Apr 2019, 22:16

That wont help with lead. It will be useful with lithium. But theres a lot of wires and a current sensor to add into the battery cables. If you fit a big enough battery you wont need it. So I would see how you get on for a month or two first. I still have no monitor!
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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 11 Apr 2019, 12:14

What cable should I use for wires?
10AWG or 12AWG?
(I ordered 176Ah batteries)
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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 11 Apr 2019, 12:31

Why 2 pairs of power cables are used here?
80ah length .jpg
80Ah pack
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Re: LiFePo4 for Permobil C500S

Postby Scooterman » 11 Apr 2019, 13:42

Looks like the thicker b&r cable goes to chair and thinner b&r cable to the charger?
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Re: LiFePo4 for Permobil C500S

Postby expresso » 11 Apr 2019, 16:18

Yes Scooterman - thats correct - i used two sets of cable on one ring lug - one set of cable is 10AWG with the fuse - thats going to the ADD ON Cable going to the Chair using 8AWG

the other set is 12AWG and for charging only - this is an ADD ON -

if your doing a 176ah pack for inside the chair - i woulnt use anything less than 8 AWG - if you can use 6awg even better - if you find 6 awg is too hard to make short cables for the connections instead of buss bars - then use 8AWG at least - nothing less - and if you can use 6 awg for the power cables

as i move forward with more future packs - i will start using 8awg mostly if i can instead of 10awg if room allows etc, - i have had no issues with any of my packs using 10awg - and i have a few of them now in use - 3 ADD ONs all in use on each chair - 4th is in use on a friends chair -

thicker wire cables never hurt - but dont go less than 8 AWG at least -
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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 15 Apr 2019, 14:20

swalker used 10 AWG as main charging wire and 6 AWG for battery interconnect cables.
I understand that thicker is better but what is min allowed?
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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 15 Apr 2019, 14:22

expresso wrote:Yes Scooterman - thats correct - i used two sets of cable on one ring lug - one set of cable is 10AWG with the fuse - thats going to the ADD ON Cable going to the Chair using 8AWG

So I don't need this second pair going to chair.
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Re: LiFePo4 for Permobil C500S

Postby expresso » 15 Apr 2019, 17:45

quadcopter wrote:swalker used 10 AWG as main charging wire and 6 AWG for battery interconnect cables.
I understand that thicker is better but what is min allowed?



I would say 8 AWG is min for the chair power cables and interconnects - i have done them with 10 AWG before interconnects - but 8 AWG works fine -
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Re: LiFePo4 for Permobil C500S

Postby quadcopter » 15 Apr 2019, 19:21

Is 8 AWG enough for interconnects?
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Re: LiFePo4 for Permobil C500S

Postby swalker » 15 Apr 2019, 19:23

There are many online sources that can help you decide the appropriate size wire to use in various situations. I recommend that anyone embarking on building a lithium battery pack research the power needs for the various wires that are necessary and then decide for themselves what wire sizes are appropriate.

I will share what I Learned, but I encourage you to do your own research so you are comfortable with the wire sizes you select.

I think 10mm2 is the appropriate size for the cables that provide power from the batteries to the wheelchair and for the interconnects between cells. 10mm2 is about 7 AWG. In the US, I have not found a practical way to buy small quantities of 7 AWG. For folks in the US, I suggest using 6 AWG, which is one size larger, to connect from the battery to the wheelchair power module and for the interconnects between the battery's cells.

I think it is fine to use thinner wire for the main charging cables (the ones that go from the charger's banana plugs to the battery). I chose 10 AWG for that. I used the Revolectrix fused banana plug leads for the first part of that run. They are 12 AWG (which is what is listed on their website). They get too hot for my tastes when charging at 35 amps. Charging at 25 amps keep them cool enough for my tastes.

I used 22 AWG for the ballance wires and for the wires that go to the cell monitor.

Be sure to use an appropriate fuse or circuit breaker.

I used tinned copper wire with silicone insulation where practical. I could not find a practical way to buy 6 AWG tinned copper wire with silicone insulation, so settled on 6 AWG tinned copper wire with PVC insulation.

Steve
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Re: LiFePo4 for Permobil C500S

Postby shirley_hkg » 16 Apr 2019, 00:46

Wonder how you insert 6awg cable in an Anderson SB50 pin. czy
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