80Ah ADD ON build

[ex-Gooserider]

I suspect that the newer units are less power hungry - I get at least a couple months out of a cell on mine, using it daily... The big thing is remembering to turn it off when not in use... I notice that the one Expresso linked to is supposed to have an auto-off feature...

I'll admit to a preference for the feel of a metal caliper, but the plastic ones I've used on occasion have been OK, and are supposedly as good for accuracy. Definitely looked like the one Expresso got was a reasonable choice for the kind of stuff he does... I use my cheapo "eBay special" caliper for 99% of the stuff I do, and only occasionally feel the need to break out my fancy Starrett dial caliper or micrometers...

ex-Gooserider

I've been using one like that almost daily for at least 10 years now. The only shortcoming is that the button cells don't last long with this heavy use. Once I got fed up with that, I soldered in a couple wires to connect an AA battery (taped to the caliper) which lasts a loooong time compared to the button.

[ex-Gooserider]

Looks like a reasonable choice for a caliper - isn't it nice to be able to do precision measuring?

0.3mm x 20mm = 6mm^2 cross section as BM said... Per my favorite chart, that is between AWG 9 and 10.... There is some electrical theory that says you'll get a capacity bonus because of the increased surface area due to 'skin effect' but that is pretty minor... More significantly, one of the bigger concerns when looking at current capacity is the DISTANCE involved, as a wire's resistance is directly related to it's length.... Given the 40mm length, you have a LOT more capacity than most charts will say you have since the charts are usually based on several meters of length, and are also highly conservative...

I would not want to use 6mm^2 for the main wiring on my chair - although AWG 10 (only 5.25mm^2) is what I see many chair manufacturers using. However for the under 2" length of those bars, it would be plenty... Bottom line is that I don't see any reason you NEED to use two bars per connection, one is plenty for the currents you'd see... However it won't hurt anything to double up...

ex-Gooserider

Ok i finally got a digital Caliper and i love it already came with an extra battery also -
this is the connectors i have to use - you cant see the readout from the pictures but the thickness is about 0.3mm
20mm width and 40mm long -
can one of these handle the job alone ? just to know - but i will use two anything to fill the gap

[expresso]

i decided to use two connectors for each connection - reason being is the screws they sent were too long and i have a gap - i then checked the screws i have plenty of from the headway cells - they work and are a bit shorter - so if i use the headway screws allen head - with a flat washer and lock washer - two connectors - they fit fine and i have a good solid connection - i am going to not use locktite this time around if i use the lockwashers - i have some locktite - but it actually leaked - wasnt closed good the last time - not sure i have enough - i may - and i may put a touch - but i feel with the lock washer its good enough - if i feel it isnt - i will add the locktite

its an ADD ON - so its easy to check and fix if thats an issue - its not inside the chair where its a problem to get at - if i were doing the full pack in a chair - i would use locktite - the way i have up till now - this would be first with lockwashers instead of locktite -

i do have new connectors arriving in a few days - i was curious - if they are thicker and fit better - i may just use them or else - two of the ones i got with the Cells - i feel Ok with them that way - shorter screws - washers etc, i feel good about it - i like how this pack is looking so far - and it will fit nicely in my shoe box - padded around - just the top i have to see how it will end up - other than that - its going to be nice i think - i try to improve each time from previous.

using this wrap - is a bit of a pain but if its useful and fireproof - its worth it - its thin and perfect for this kind of cell.

[expresso]

yes i love that now i can measure things for sure knowing MM and inches - i never had a use for something like this - but now i do and its worth 8 dollars - makes things alot easier and i feel smarter at the same time -

[expresso]

Moving along - i wrapped them - silicone between the Cells - and connected them using 2 connectors for each one - i used the headway screws - flat and lockwasher - i left it alone for now - tomorrow i will get new connectors that i ordered and see if they are better or thicker etc, - worse case i will use the ones i have on there now

i didnt tighten it down yet - next step making the balance wires and power cables with Fuse - then finish it up - Tape it around the sides and bottom to hold them together a bit - you can see how i have so much room in the plastic box now with these Cells - where the other ADD ONs - i always had to extend this box - now i dont have to cut it at all - solves that problem - just the top cover i have to deal with - as you can see - 80ah pack is very small footprint - lets say 30mm thick each cell - about 240mm total - fits in a group 24 MK Gel size - with room to spare -

[shirley_hkg]

Still a bit too big ; if swinging back and forth on the back of a fast , responsible chair .

[expresso]

all my ADD ONs are in the same plastic shoe box in a backpack - it wont swing - it will stay put - i use these to wrap around it and stays put - using the brace bar thats on the chair - it hangs on the Push Bars - then wrapped with the bungee cord -

https://smile.amazon.com/dp/B0044FPNIG/ ... _lig_dp_it

[expresso]

https://smile.amazon.com/dp/B00YQXBDXK/ ... _lig_dp_it

few different things you can use to hold it in place - i am going to try also another thing with this one - besides hanging on the Push bars - and held with the bungee cords - i will add another strap which gets attached to the side of the backpack and then wrapped around the chair behind the seat back - it wont be seen and would hold it even more firmer to the seat back - if that works

if not - same as my others - so far no problems with them.

how do you secure your ADD Ons Shirley ?

[shirley_hkg]

viewtopic.php?f=2&t=1813&start=2070

[flagman1776]

There's nothing wrong with Shirley's bolt on mount BUT it might not be the most convenient for transferring the pack between chairs or servicing the pack.
The pack's weight is supported by non-stretchy back pack straps, that"S the important part. Bungies straps work well but you need enough strength to keep the pack from moving... possibly more than one strap.
The webbing strap you linked to would work also but I've been disappointed with various inexpensive webbing tensioners & buckles which don't stay secure. Ratchet straps would work too but the mechanism is bulky.
I'd be inclined to stay with your bungies.

[Scooterman]

The only issue with those is that they are 2c cells. So you really do need 176Ah. But its about enough.

C-Rates??? I understand what they are, charge/discharge rates. So 2C charge rate means you can charge at double the cell amp rating.

So for 100Ah 2C cell you can charge at 200A, but for example the PL8 can only charge up to 40A so there is no benefit in having a high charge c-rate?

Re discharge: 2C means the cell can supply 2x100A = 200A without heating up and being damaged.

Do we worry about c-rates with lithium because the cells heat up when being heavily discharged?

But lead acid cells don't heat up?

So lithium (apart from headways) might not be best for car batteries that have to crank a lot of amps to get a cold engine started, and lithium are better for deep cycle applications?

[expresso]

There's nothing wrong with Shirley's bolt on mount BUT it might not be the most convenient for transferring the pack between chairs or servicing the pack.
The pack's weight is supported by non-stretchy back pack straps, that"S the important part. Bungies straps work well but you need enough strength to keep the pack from moving... possibly more than one strap.
The webbing strap you linked to would work also but I've been disappointed with various inexpensive webbing tensioners & buckles which don't stay secure. Ratchet straps would work too but the mechanism is bulky.
I'd be inclined to stay with your bungies.

Actually the ones i linked too are very strong - have a wide strap and hook easy - you can adjust them to make it shorter - tighter etc, - i use Two of them one on each side - you can use 3 if you wanted but Two work fine - its been 3 years using them on all my ADD ONs - - first year i was using a thinner rounded bungee cord - didnt like them - but these are Strong - and the back pack is Strong also - its a perfect fit for the show box i use - Strong Canvas bag - - so far its been working - no signs of stress on the bag or anything - they hang solid on the push bars - the cords help to keep it from swinging - - using the brace bar which is on the chair for the cords - wrap them under and over the bag and back to the brace bar -

i will try to add even another strap if my idea works - it will wrap around the push bars lower down under my seat back and sewn to the backpack - it will snap together and hold the bottom end of the bag even more secure - leaving it still flexible to remove or change chairs in 5 mins.

[expresso]

The only issue with those is that they are 2c cells. So you really do need 176Ah. But its about enough.

C-Rates??? I understand what they are, charge/discharge rates. So 2C charge rate means you can charge at double the cell amp rating.

So for 100Ah 2C cell you can charge at 200A, but for example the PL8 can only charge up to 40A so there is no benefit in having a high charge c-rate?

Re discharge: 2C means the cell can supply 2x100A = 200A without heating up and being damaged.

Do we worry about c-rates with lithium because the cells heat up when being heavily discharged?

But lead acid cells don't heat up?

So lithium (apart from headways) might not be best for car batteries that have to crank a lot of amps to get a cold engine started, and lithium are better for deep cycle applications?

the C rate is referring to the how much the Cell can discharge at a constant rate - they should show a Constant C rate discharge and a Peak Discharge C rate - - if you have a 100A Cell at 2C rate - that would be 200A Discharge Rate in use - which is about border line since our chairs can use more than that at times - and many times less - if using 8 Cells only 100ah 2C - thats a border line C rate - they will be worked harder - shorter life - meaning it can last 5 years even at its borderline C rate - but at 3C etc, they can last 10 maybe - if taken care of them -

Smaller Cells you like to have higher C rates - usually larger Ah Cells are hard to find at higher C rates - 3C would be great with a 100ah Cell - if you used a 176Ah Cell and have a 2C that would be a bit over 300A discharge rate with 8 of those Cells and is fine.

if you had a 100Ah Cell at 2C - but used 16 of them - that would work also - giving you about 400A discharge rate that way. it depends if you are going to use 8 Cells - or 16Cells - the size of the Cell etc, -

this is about discharging Rates when in use.

[expresso]

its not the best solution but it was a fast simple easy way and its been working - so i leave it alone - makes it easy to remove to check it - or work on the chair etc, - no tools to remove - just un strap it - and lift it off the push bars - this isnt a good angle picture -

[expresso]

New connector arrived - its thicker - size wise would work - but hole is too small - not in the right location - so i figured let me use my new hole puncher - well that didnt work out well - first its too small the hole puncher - from the picture it shows a larger hole and a clean punch on both ends -

i went to try it - too small a hole and its not a clean punch - so hole puncher being returned - i ruined one new connector - i guess i just keep them since i cant return 9 instead of 10 - one is now damaged - i may try using a dremel to see if that can work - but most likely they wont be used and will leave the ones i put there now -

and hope two of them are good enough.

any good simple suggestions to make a clean hole in the new connectors ? they would be perfect other than the hole spacing and hole size -

[Burgerman]

any good simple suggestions to make a clean hole in the new connectors ? they would be perfect other than the hole spacing and hole size -

drill...

Use cables and ring terminals.

[expresso]

i tried - i will just use the connector i received - i have them on there already - two each - i want to get it done this next few days so i can start to test it on sunday - charge and a full discharge -

you dont think the connectors i have on there are good enough ? if i had to make cables now - need more time and i want to check that the pack is good - all cells good at least - and i would have to rearrange the Cells if making cables again instead - easier this way - as long as they hold up fine -

[expresso]

Balance Cable done - all thats left is the power cables with the fuse inline - and then connect the wiring and test it this way - without taping it all together - if all data graphs are good - i can assume the connectors are good enough and can leave them ?

[Burgerman]

Done is done!

[expresso]

i use what i have there now - i really want to start the testing Sunday morning - Full Charge and then full discharge to 2.9V and recharge again -

[Scooterman]

The only issue with those is that they are 2c cells. So you really do need 176Ah. But its about enough.

C-Rates??? I understand what they are, charge/discharge rates. So 2C charge rate means you can charge at double the cell amp rating.

So for 100Ah 2C cell you can charge at 200A, but for example the PL8 can only charge up to 40A so there is no benefit in having a high charge c-rate?

Re discharge: 2C means the cell can supply 2x100A = 200A without heating up and being damaged.

Do we worry about c-rates with lithium because the cells heat up when being heavily discharged?

But lead acid cells don't heat up?

So lithium (apart from headways) might not be best for car batteries that have to crank a lot of amps to get a cold engine started, and lithium are better for deep cycle applications?

the C rate is referring to the how much the Cell can discharge at a constant rate - they should show a Constant C rate discharge and a Peak Discharge C rate - - if you have a 100A Cell at 2C rate - that would be 200A Discharge Rate in use - which is about border line since our chairs can use more than that at times - and many times less - if using 8 Cells only 100ah 2C - thats a border line C rate - they will be worked harder - shorter life - meaning it can last 5 years even at its borderline C rate - but at 3C etc, they can last 10 maybe - if taken care of them -

Smaller Cells you like to have higher C rates - usually larger Ah Cells are hard to find at higher C rates - 3C would be great with a 100ah Cell - if you used a 176Ah Cell and have a 2C that would be a bit over 300A discharge rate with 8 of those Cells and is fine.

if you had a 100Ah Cell at 2C - but used 16 of them - that would work also - giving you about 400A discharge rate that way. it depends if you are going to use 8 Cells - or 16Cells - the size of the Cell etc, -

this is about discharging Rates when in use.

Thank you for explaining I understand now.

[Scooterman]

I have a set of these and have used them for punching holes in thick leather and thin aluminium sheet (which is probably harder than copper). They're not expensive.

[Scooterman]

the C rate is referring to the how much the Cell can discharge at a constant rate - they should show a Constant C rate discharge and a Peak Discharge C rate - - if you have a 100A Cell at 2C rate - that would be 200A Discharge Rate in use - which is about border line since our chairs can use more than that at times - and many times less - if using 8 Cells only 100ah 2C - thats a border line C rate - they will be worked harder - shorter life - meaning it can last 5 years even at its borderline C rate - but at 3C etc, they can last 10 maybe - if taken care of them -

Sorry but I just thought of something extra and if I don't ask then it nags away in my brain

When I was programming my r-net controllers the max current rating for the 90A and 120A controllers was:

80A max
90A boost

100A max
120A boost

Ah! but I've just realised that is probably 'per channel' so doubling boost currents gives 180A and 240A. So as you say 100Ah 2C is borderline. Oh well typing this out I've answered my own question, silly me!

[Burgerman]

Correct. That r-net is actually 2 power modules in one case. Most of the time its a lot less than 240A though. There very few times it will do full power on both channels. And because motor stall volts is lower than battery volts you dont see it when say stalled against a wall. You DO see this high amps if accelerating up a slope for eg. For a second or three.

But you see 100A per motor when zero turning on grass for eg, quite easily.

[expresso]

I have a set of these and have used them for punching holes in thick leather and thin aluminium sheet (which is probably harder than copper). They're not expensive.

what are those called - and how do you use them - with a hammer ? i returned the small hole puncher i had - was useless - i will use what i received and doubled up on them - in the future i will either have them custom made if i needed - or just use cables - the blanks i purchased are the correct size and thickness is nice but making a hole in them - not going to happen - i ruined one already - i just put them aside and maybe one day i have some use for it -

[expresso]

Ok - i made all the cables - i want to test it before i tidy up the cables and pack it before i consider it done - so far so good i think -

[expresso]

Cables done -

[expresso]

pack done - i used the headway screws lockwashers and flat washer on all of them - except the end power cables - turned out the headways are too short - so i removed the washers and lockwashers temp. to test the pack - when all done - i will use locktitle on those end screws with no washers - flat or lock - that would work

the rest i will leave it alone - much faster cleaner and easier - and i feel fine with the lockwashers in place - Worse case - its an ADD ON - very easy to check and fix if anything goes wrong - i dont think it will.

[expresso]

i used two sets of cabling on one connection for the power cables - 12awg cable is for the charging cable i will make later on -

10awg cable with the fuse in line 60A fuse - is for the ADD ON Cable going to the Chair - when i make that cable i will make it 8 AWG - the XT90 Connector works good with 10AWG - anything more is harder to solder - so i will make a XT90 to SB50 with 10AWG - then make SB50 to SB50 8 AWG that will connect to the chair pack

the Chair uses what i believe to be 6 AWG very thick cabling - with a SB120 Connector - that will be interesting to make - will try to fit 6AWG and 8 AWG in one 2AWG connector Pin - first for me - hopefully it works since i didnt buy any extra parts. it has to work the first try -

so far i am really liking this pack - i will start testing it on Sunday Morn. - i am discharging it now for a few hours - then Sunday morn.. do a full Charge and full Discharge to 2.9V - will take at least 3 or 4 days with the PL 8 - - once done - i can see what the real pack Ah is - and the Volt limit i need to watch out when in use -

then full recharge again. and thats it - move on to the next step - Pack Should be done. set aside.

[Scooterman]

I have a set of these and have used them for punching holes in thick leather and thin aluminium sheet (which is probably harder than copper). They're not expensive.

what are those called - and how do you use them - with a hammer ?

Yes just a hammer with the metal on a piece of wood. I just call them hole punches, BM or a-nother will know if there's a different name. I think they're supposed to be used with leather, but work fine for soft metals. I think I paid about £5 for them (about $8)