PINNED - Lithium battery conversion/info

[expresso]

You are getting all complicated and overthinking again. You are going to have wires everywhere!

your right - too many wires - too long etc, - i will end up most likely making a 45ah pack and just use it as needed on certain rides - the way i do now - or disconnect to charge each time -

if my friend wants my 36ah pack - i can then make another 45ah for myself - or if he wants a new 45ah pack - i keep the 36ah i have and leave it alone -

in the meantime - going to order another pl 8 and will try that 12V psu as a spare - will end up using this set up for the backup chair with lead and the ADD ON to charge since i only use 25A for that chair - this should be fine and its smaller -

will get the case to hold it in and if i needed to carry it - can carry PL 8 a few cables and smaller 12 PSU

[Burgerman]

So now you really are the lithium new york pro.

[expresso]

So now you really are the lithium new york pro.

i am trying my best - cant say its without your help for sure and everyone here - i am trying hard to get my friend to get started with the ADD ON at the very least for next summer - he is going to get a new chair and is pushing for the same one i have 646se -- his next appt. is Jan. 30 - if he does manage to get it - thats good - he can then keep up with me - speed wise - then its the range we have to work on -

the way i see it - if he gets the ADD On - hes good for at least 25 miles - if we take the bus up to the NJ bridge - that saves him 10 miles - so we can cross the bridge and ride the Henry hudson river drive - its a scenic route - along the water and mountains etc, - its peaceful and a nice ride - bikes do it - very little traffic - thats about 8 miles - he can then do that - he may have to take the bus back once back over the bridge in NY again - or if he can get a quick 30 min. charge at least may be able to ride it back -

when i did it - i found an outlet which we can plug in if needed and the boat habor if someone is there - was told it was no problem if i needed to charge there - in that case - he can get a good hour charge - 25A - and should be fine riding the whole way back -

just gives options - and he never been this far before - i havnt - but now that i can - i will be going back for sure - in that case i can carry the extra PL 8 - 12V PSU and cables - in case he needed a charge -

[expresso]

i purchased the PL 8 and some extras while i was at it - saved about 50 dollars with the discount - i am going to get this PSU -

when i get the new PL 8 - i will update it and add all the presets i use normally -

the question is - with this PSU - - do i need to make changes to the supply tab to use it ? or copy the same settings as i use on the other PL 8 - with the 24V PSU ?

i will try to see if i can use it at 25A charging - since thats what i use on the ADD ON with lead chair now -

http://www.ebay.com/itm/Power-Supply-12 ... 2258400220

[Burgerman]

Set amps to the maximum allowed, set volts to 10 and max allowed.

You will get less max power obviously.

[steves1977uk]

i purchased the PL 8 and some extras while i was at it - saved about 50 dollars with the discount - i am going to get this PSU -

when i get the new PL 8 - i will update it and add all the presets i use normally -

the question is - with this PSU - - do i need to make changes to the supply tab to use it ? or copy the same settings as i use on the other PL 8 - with the 24V PSU ?

i will try to see if i can use it at 25A charging - since thats what i use on the ADD ON with lead chair now -

http://www.ebay.com/itm/Power-Supply-12 ... 2258400220

You will see it max out at about 21A at 12.3x volts.

Steve

[Burgerman]

I see a little more doing this in my 12V van. Maybe 25A or so while lithium battery is low. But thats really 14.4V when running.

[expresso]

Set amps to the maximum allowed, set volts to 10 and max allowed.

You will get less max power obviously.

that would be the same as my current supply tab shows ?

i have it set to 50A - so i set that to 60A - thats the max the PL 8 can handle ?

the picture i posted is my supply tab now - can i just copy those settings and put the 50A to 60A ?

[Burgerman]

Yes. That should be set to the same as or less than the power supply is capable of.

[expresso]

ok it can handle 75A - so i can just leave it the same way -

if i left it the same way at 50A - would i be able to get the max out of it ? charging at 25A if i can - or at least the max ?

[steves1977uk]

Look at the below picture...

You need at least 15v and 58A to charge at 25A. So if you leave the max at 50A at 12v, then you get about 18A charging current.

Steve

[Burgerman]

At 3.65v you do. But we charge at 3.3x volts most of the charge. 3.2v some of it.
And a running engine gives 14.4V. It wont let you lower that 3.65 as its a lipo calculator.

Its also estimated and subject to error as exact efficiency isn't known at various in/out voltages. So is programmed to a worst case scenario.

[steves1977uk]

Yes that's true BM I just use that as a rough guide. So charging at 3.5x volts we can get higher Amp output.

Steve

[expresso]

well i guess i will find out and let you guys know for sure what it does

i ordered everything - what is the max i can set the PL 8 ? 60A i think right -

i can raise it to the max - if its 60A - and see how that works


for example - if i just leave it alone for now at 50A - and the preset i use is set for 25A charging -

what will happen when i start the charge ? does it stop or give errors or just charge at the max it can do - if its 18A - will it just charge at 18A - even if the preset is set for 25A charging ? or will it stop

[Burgerman]

Think about ohms law.

That calculator is a watts calc. As you charge your batts go from 2.8v ish to 3.65v. And it presumes a worst case 85% efficiency. Its better than that. But they don't want you buying a too small power supply.

Van / car power = 14.4V x 60A = 864 watts. INPUT.

PACK
2.80v (discharged 99% fully) = x 8s is 22.4V so 38A less efficiency drop of?
3.35v average for most of the charge (10 to 95% charge) = 26.8 means its dropped to 32A charge. (less efficiency)
3.65v as it reaches charge end x8 = 29.2V. So div that 864 watts by 29.2 gives 29A... Less efficiency loss.

So as it charges the amp will drop. The actual amps are between 85 and 90% of whats shown here. The calculator gives pessimistic result.
At 12V it will be about 15% less obviously.

[expresso]

Think about ohms law.

That calculator is a watts calc. As you charge your batts go from 2.8v ish to 3.65v. And it presumes a worst case 85% efficiency. Its better than that. But they don't want you buying a too small power supply.

Van / car power = 14.4V x 60A = 864 watts. INPUT.

PACK
2.80v (discharged 99% fully) = x 8s is 22.4V so 38A less efficiency drop of?
3.35v average for most of the charge (10 to 95% charge) = 26.8 means its dropped to 32A charge. (less efficiency)
3.65v as it reaches charge end x8 = 29.2V. So div that 864 watts by 29.2 gives 29A... Less efficiency loss.

So as it charges the amp will drop. The actual amps are between 85 and 90% of whats shown here. The calculator gives pessimistic result.
At 12V it will be about 15% less obviously.

whos that - he made a law ?

i heard of that law before - have you forgotten who your talking to BM - i dont know all this stuff - i read it - if i can learn something from it -

i give it a shot and leave it the same way i have it now - first i will transfer all my presets to the new PL 8 - then on the next charge for the ADD ON chair - will use the smaller PSU to see how it works -

[Burgerman]

https://en.wikipedia.org/wiki/Ohm's_law

Yes Georg made a law...

[expresso]

you want me to understand all of that ? or just driving me to drink more wine ?

i take your word for it -

[Burgerman]

Amps is Current. Thats the size of your hosepipe. Or wires in this case.

Volts is the pressure. So a hose with more pressure moves more water.

Power is the total amount of water you moved. Say a bucket. In electricity your bucket is your battery... Or whatever you are putting water or electricity in. In electrical terms this is watts.

To fill a bucket in 1 minute you can use a large hose at low pressure.
Or you can use a small hose at high pressure.
Net result is the same.

So LOTS pressure x TINY hose size = 1 bucket in 1 minute.
LOW pressure x LARGE hose size = 1 bucket in 1 minute.

And likewise
Volts x Amps = Watts. 1 bucket of electric in 1 minute.

[expresso]

thats much better for me to understand it - at least get an idea - i get it - larger hose - low pressure - is the same as smaller hose with high pressure -

its still never the less above me many times but when explained in simple dumb it down terms - i may grasp it a bit then - i am still recovering from my wine from last nights dinner

i topped it off with a Martini also - i felt good yesterday - winter is depressing - i feel it already - shopping spree is coming soon i think

[Burgerman]

So when you see the pictures of the hoover dam, take a look at the tiny wires coming out. Theres 12.



The whole power (watts) the hoover dam makes and all the power that vegas uses goes through these above.

Power = watts. There are just a few hundred Amps there. Because the cables are thin. So they bump up the voltage to half a million!

[Gnomatic]

Amps is Current. Thats the size of your hosepipe. Or wires in this case.

Volts is the pressure. So a hose with more pressure moves more water.

Taking that a step further, at the same pressure, the bigger the pipe the less friction there is on the on the water flowing through

[steves1977uk]

expresso, read here... https://learn.sparkfun.com/tutorials/vo ... d-ohms-law

Of course, if you try and push too much water (current) through the pipe (wire), what do you think will happen?

He will be an expert in electrics by the time we've finished with him BM

Steve

[Burgerman]

He has likely soaked up some red wine by now.

PL8v2 can do 1344 watts. Its on the label. That figure came from the fact that it charges 8S Lipo batteries at 40A. 4.200v x 8S = 33.6V. And 33.6 x 40 = 1344W.

Only its wrong... Lately some higher charge voltage lipos appeared. 4.27, and 4.35 charge voltage ones. It charges these at 40A too. 1392W

[Burgerman]

And if you set this, to 7S it presumes 29.4v (4.2V x 7).

And at 14.4 input, and worst case 85% efficiency, it shows 25A.

But we only want about 26V 3.25 x 8 90% of the charge) so you get 28 to 30A charge.

[expresso]

thats fine with me 28A - 30A charge is more then enough for the Lead - ADD On chair and easy to carry small PSU


i did find another PSU - 24V , 12V combo - in one unit - just double the size etc, the whole reason for the 12V PSU was the size - i didnt even know you can use a 12V to charge a 24V pack -

all news to me - once Genomatic mentioned it - i got curious - and he had a good reason for wanting it - for traveling purchase - then i figured i can use it also for the Lead ADD on - since i only charge at 25A - and can always carry also if needed

so it wont go to waste - i will always keep a good 24V PSU handy at home -

http://www.ebay.com/itm/Power-Supply-DU ... 2258400220


this one does both - not sure what benefit it would be - for us -

the 12V i got was for the size compact and will work fine with the lead and for carry if i ever really needed - never say never

[Burgerman]

You are just learning just what that single cheap plastic hobby charger can do. Can step up or down voltage. Work in a car. Charge chair from chair. Lead or lithium.

It can charge any chemistry, or voltage at up to 40A PROPERLY and accurately. 1 Cell watch battery up to a full sized electric car. From 12V up to 32V INPUT. And graph and monitor, and be PC controlled. Theres no other charger used even in industry at any price that is so accurate, programmable, or that can cell balance that gets close at any price.

[expresso]

do you own stock in the PL 8 ?

once i get this going for the indoor chair only maybe next year - will use it without PC - in my other room and maybe use PC a few times to see it - and ever now and then but just will set it and forget it -

once a week or ever other week will charge - this chair -

[Burgerman]

Not yet but I have 3. And tested all the best ones.

[expresso]

i am itching to order more cells now and make the 45 ah ADD ON -

best to wait over holidays i think - not sure - when there have a holiday there in china