PINNED - Lithium battery conversion/info

[FJC10]

Thank you very much!

I have a problem with buzzer. Why is this happening?

https://youtu.be/Cg6IaxEcHyY

Apparently, everything's okay, I think...

https://youtu.be/RYrYOOYwykw

https://youtu.be/t6jNdButIkE

[shirley_hkg]

It is better to have multiple connections than just one . I use 3 to 4 smaller wires to join two blocks .

You need to set the alarm voltage lower , eg 2.85V .

BTW , your alarm is a fake 8S . It just do 6S .

[FJC10]

It is better to have multiple connections than just one . I use 3 to 4 smaller wires to join two blocks .

Wouldn't that complicate it too much?

Can you put a photo of your battery with those multiple connections to put the two blocks together?

You need to set the alarm voltage lower , eg 2.85V .

Yes, but first it should work properly, and it doesn't.

BTW , your alarm is a fake 8S . It just do 6S .

Which one do you use? Where can I buy a REAL 8S buzzer?

[Burgerman]

https://www.amazon.com/iSDT-BG-8S-Smart ... 8s+balance

https://www.ebay.co.uk/itm/ISDT-BattGo- ... 2809031926

?
2 of them. The small one and the bigger one. You want the bigger one!!


youtu.be/x9KOrWcEQtc

[shirley_hkg]

Wouldn't that complicate it too much?

Can you put a photo of your battery with those multiple connections to put the two blocks together?
?

It's simple . Just replace it with 3 smaller cables for your single thick one , so you can bend them easier .

Exprience told me that a single directly connected cell gets weak sooner than the others .

I'll put them in a way that no cell is far away from the 3 connections . You may use 4 , depends on your cable available .

[FJC10]

You want the bigger one!!

Great! Right now I buy it at Hobbyking. Thank you!

https://hobbyking.com/es_es/bg-8s-smart ... ecker.html

By the way, what would you buy in hobbyking? It's to get to the free shipping costs.

[FJC10]

It's simple . Just replace it with 3 smaller cables for your single thick one , so you can bend them easier .

Maybe a 16mm2 cable is too much to join both batteries together. A cable of 10mm2 (or less) should be enough, right?

If to put several small cables I need to change the batteries position, I better not complicate myself. If a cable of 10 mm2 (or less) is enough, it will help me to put the batteries together as much as possible.

My chair has an 80 amp fuse which means it won't consume more than 80 amps of peak, right? So, an 8" 10mm2 cable to connect both batteries should be more than enough, right?

[steves1977uk]

I removed my cell voltage checker years ago as it causes cell balance problems when charging. By all means plug it in temporary, but don't leave it connected 24/7.

Steve

[LROBBINS]

An 80 Amp fuse will pass 80 A forever. It will open if over 80 A, but the amount it takes to do that depends on how much over. Some fuses are fast blow, but those are mostly small ones for electronics. Most 80 A fuses will blow after 1 second at something like 160 A. It's there to protect your wiring from catching fire or melting if there's a short circuit. What limits current during normal operation is the current limit of your controller and the strongest commercially available controllers are limited to at most 120 A per motor for one or a few seconds. 10mm2 wire should really be sufficient.

[Burgerman]

And larger than stock.

[expresso]

10mm2 - - would that be a 8 AWG wire more or less ?

[LROBBINS]

10mm2 is AWG 7 (which you won't actually find)

[expresso]

thats right - i did a search and found a conversion Chart - 6 AWG would be about 13mm2 - - we either have to use 6 AWG or 8 AWG -

i actually just got some 6 AWG to see how hard it is to work with if making cables -

[steves1977uk]

Here's a good size conversion calculator... https://www.rapidtables.com/calc/wire/w ... chart.html

Steve

[FJC10]

I removed my cell voltage checker years ago as it causes cell balance problems when charging. By all means plug it in temporary, but don't leave it connected 24/7.

Steve

I would only use it when using the wheelchair. Most of the time I use a manual wheelchair indoors, the electric wheelchair is for outdoor use only.

Although I think that with 108 Ah will be quite unnecessary because I do not think that consumes all the battery any day, but I suppose that in addition to low battery warning will warn if you ever have any problems, bad contact or defective cell.

[FJC10]

An 80 Amp fuse will pass 80 A forever. It will open if over 80 A, but the amount it takes to do that depends on how much over. Some fuses are fast blow, but those are mostly small ones for electronics. Most 80 A fuses will blow after 1 second at something like 160 A. It's there to protect your wiring from catching fire or melting if there's a short circuit. What limits current during normal operation is the current limit of your controller and the strongest commercially available controllers are limited to at most 120 A per motor for one or a few seconds. 10mm2 wire should really be sufficient.

10 mm2 cable to join both 12 v batteries? How much is the maximum number of amps that will circulate through the cable that will join both 12 v batteries? In addition, I think that, because the cable is so short, approx. 20 cm maximum, it can still be thinner and hold more amps than if the cable were longer, am I right?

[FJC10]

10mm2 - - would that be a 8 AWG wire more or less ?

[Burgerman]

6MM square is often used by manufacturers because your 80A fuse blows first. You can use 10mm as it IS available in the US, and then use a 120A fuse so it will never blow in normal use with some better reliability. Or you can connect two smaller cables into 1 ring connector... So its more flexible.

[steves1977uk]

Here's what happens when a cell voltage checker is left connected 24/7...

Steve

[Burgerman]

And many BMS take power all the time from 1 cell group, or several. So same thing, only you cant see it happening and 100mA balance takes 50 hours rather than 5...

[LROBBINS]

I think that, because the cable is so short, approx. 20 cm maximum, it can still be thinner and hold more amps than if the cable were longer, am I right?

Yes

[Gnomatic]

Here's what happens when a cell voltage checker is left connected 24/7...

ccs3 Volts.GIF

Steve

Yikes! That doesn't look so hot.

[Burgerman]

Many BMS do the same, they are powered from 1 or 2 cells.

[shirley_hkg]

This pair are meant for a friend's INVACARE ARROW .

The 112 cells I purchased earlier have been in the bathroom , only 24 of them are used . 72 left for spare .
( See page 82 .)

My current pack is 216Ah with 72P8S of SONY 26650cells @3000mAH . Very stable & conform .

See I put 148Ah back to it, when cells were discharged to 3.235V ( Page 152 )


I have 2 add-ons :
53Ah @SAMSUNG 2600mAH cells , ( See page 21 & 36 )
45Ah @15Ah 40152 cells . ( See page 92 , 97 , 105 .)

They can be ALL mounted on my chair, though I haven't tried yet .

They will be a total of 314ah then .
@26.2V average , it's 8.23 KWH .

Added that , , , ,
My first self assembled 10P8S A123 20Ah pouch in 2012 , still takes back 160Ah when drained to 3.0V .

Tried putting all 314Ah on chair but can't see a significant gain in mileage . Chair is too heavy ! ! !

[ex-Gooserider]

In the perfect world of electronic theory, all points along a bus that connects a group of cells are the same, so you can connect two groups by hooking the connecting link to any points on the two bus bars....

(We make our packs in groups of parallel cells connected in series, the bars that tie all the ends of a given group together is a 'bus')

In practice, all wire has resistance and so do the bars, so if you connect two groups of cells with a single wire, the cells next to the connection point will have less resistance across the point than the cells that are far away. This means that the cells that are close will supply more current and discharge more than the ones that are distant. The amount of difference will be fairly small, but it is significant.

Rather than using one large connection, you are better off to use several smaller ones of the same length attaching to different points on each bus, as that way there will be less difference in the distance between any two cells, so they will discharge more evenly... As others have mentioned, 3-4 connections in AWG 10 or the metric equivalent will be about right...

As a second comment, I have found that welding cable seems to be a good choice when looking for flexible wire in larger sizes.... It is very flexible, and the insulation is pretty robust - as it needs to withstand all the abuse that a welding shop environment subjects it to...

ex-Gooserider

[Burgerman]

The amount of difference will be fairly small, but it is significant.

True, very small. But the moment you let go of the joystick, that difference is negated as the fullest cells charge up the lowest cells fast. And they do do all day long, and while charging during CV. So the difference it actually makes is somewhat minute! If even measurable.

[FJC10]

Rather than using one large connection, you are better off to use several smaller ones of the same length attaching to different points on each bus, as that way there will be less difference in the distance between any two cells, so they will discharge more evenly... As others have mentioned, 3-4 connections in AWG 10 or the metric equivalent will be about right...

like this?



Isn't AWG 10 too much if I use 6 cables? If I use six cables can't I reduce its size by 6? 6 wires, AWG 16 or 17 would be enough?

As a second comment, I have found that welding cable seems to be a good choice when looking for flexible wire in larger sizes.... It is very flexible, and the insulation is pretty robust - as it needs to withstand all the abuse that a welding shop environment subjects it to...

If I put 6 wires awg 16 or 17 I think I can put them of pvc and copper because so thin I would have no trouble bending them...

[FJC10]

Well, hello world of my battery :



What does it look like?

What should I do now? Charge them fully? And then? Maybe discharge them with PL8?

[FJC10]

By the way, what's the point of making the loading/balancing cable with D-Sub connectors if I find more easy to connect the balancing cable and the positive and negative banana cable directly from the baterie to PL8?

I have already made the cable on the side of the PL8. I still have to solder the D-SUB connector to the positive and negative + balancing cables on the battery side.

The cable on the side of the PL8 that I made seems too short to me, only 21", 1.8 ft or 57 centimeters. Is that right or what did I do wrong? The silicone cable with bananas for the PL8 I bought from revolectix is no longer than about 19". Do they sell a longer one maybe?

[Burgerman]

Yes charge fully. It may take a while... They wont be balanced at all.

The purpose of the charge cable? So you can connect one connector to a socket mounted on the chair, then press charge!