PINNED - Lithium battery conversion/info

[Scooterman]

Bcause high internal self discharge? Check balance by topping up in a few days.

[shirley_hkg]

Have it balanced at lower volt first.
Set CV @3.465V
Balance starts @3.4V
CV Timeout as long as possible.

Return to normal afterwards.

[Burgerman]

I think thats too low. It appears balanced but isnt very well done...
3.45 to 3.5V is much more accurate and still safe for long periods.

Under advanced, termination, there are several options on CV charge timeout. Inc NONE.
With no balance connected, max charge time including CC stage is still limited to 8 hours total. So you must charge at a high enough rate that cc is completed in a sensible timeframe.

WITH balance connected this is 16 hours. So typically you get say 4 hours CC and then 12H at CV total. Even when set to 16 or none.

[shirley_hkg]

Don't want the full cells being cooked for long hours.

This is how I do the initial charge during assembly.

[Burgerman]

Yes but the manufacturers would have you charging at 3.650V.
Already 3.60V that we use is much kinder.
3.550V is about the lowest voltage where you will get true balance. In a sensible speed. Perfectly safe for many hours.
3.500V is the voltage where you get true balance, but it takes a very long time and will drift a bit after charge is ended. And perfectly safe for a day or longer.
3.450V is going to give a less accurate balance level no matter how long you wait. And on some cells it may never properly balance.


I wouldnt go lower. You dont get proper balance or full charge no matter how long you hold them at say 3.400V.

[Scooterman]

In general how deeply do you folks discharge your cells before charging?

[Burgerman]

Best not to go too low. So maybe on average 70% discharged. Occasionally 85% or so. Not critical as long as you stay above 3v per cell unloaded.

[ICEUK]

70% discharge is my limit,. I don't always fully charge pack maybe every two weeks I do a full charge to 3.6volts. my cells didn't come with studs but red loctite works fine you just have to make sure all threads are super clean

[Scooterman]

70% discharge is my limit,. I don't always fully charge pack maybe every two weeks I do a full charge to 3.6volts. my cells didn't come with studs but red loctite works fine you just have to make sure all threads are super clean

Best not to go too low. So maybe on average 70% discharged. Occasionally 85% or so. Not critical as long as you stay above 3v per cell unloaded.

I do the same as well, apart from the last time when they went down to almost zero But the least said about that the better!

I also do the same with my lithium gadgets. I try and follow the 80/40 rule (80%-40% SOC).

BM - But when we charge lifepo4 we have to take them above 80% SOC to get them to balance in a reasonable time. So I'm guessing lipo cells will balance at lower SOC? Cos gadget manufacturers recommend 'little and often' charging as opposed to full cycle discharging/charging.

[Burgerman]

Lipo as used in hobby stuff and lithium ion as used in phones, teslas, laptops etc all drop voltage reliably as they discharge in a linear fashion. So cell balance and state of charge are easy to monitor or do at any voltage or state of charge.

[Burgerman]

The difference between LIPO and LITHIUM ION.

LIPO, Can be charged and discharged at up to 12C and 130C, so super high currents, and very very dangerous... Can be discharged to 3.6 or 3.7V safely. 4.2V charge.

LITHIUM ION, slightly more energy dense. Cannot do more than 1C charge or prefereably less. Or between 1 and 20C discharge depending on actual cell specs. And can be discharged down to 2.5V typically. 4.2v charge. Also can be dangerous but not as bad as lipo.

Heres a comparison https://www.youtube.com/watch?v=UB8fas6zBSE

[fishinjunky]

Will 5ft ( 3ft chair side 2ft charger side) be ok length for balance lead. It's 16awg with 3 mt30 connectors no splices in the cable. And 2.4 amps balancing. I'm freaking out a bit that I made them to long. Will I get alot of voltage drop?

[Burgerman]

All that happens s that it will take longer if longer. Remember that we are talking about a couple of mV here and adding a 2 amp load to one end of a long wire means the resistance causes a difference in voltage at each end of the wire. Try it.

[fishinjunky]

All that happens s that it will take longer if longer. Remember that we are talking about a couple of mV here and adding a 2 amp load to one end of a long wire means the resistance causes a difference in voltage at each end of the wire. Try it.

im going to shorten the balance leads an charging leads to 3ft total length that way i dont have to worry about it.

the charging lead i have now is 4ft but when the charger compensates for the voltage drop it causes it to go straight into cv phase an lowering the amps. When i use a 3ft charging lead it does cc without dropping amps then goes to cv an starts dropping amps until it gets to the cutoff i set at 1%.

do you think this is something to do with the ichargers design to compensate for voltage drop an if the charge lead is over 3ft it will cause it to go straight to cv phase?

i dont think you guys have this issue with the pl8?

[Burgerman]

It could also be a less than perfect connection, or a cell thats almost charged to begin with. The diference between 3 and 4 foot is not great.

[fishinjunky]

When you have more than one cable going to the main positive and main negative do you get a better connection combining the cables into one ring terminal or is it better to use separate ring terminals and stack them?

The cables I'm taking about are the charging cable and the power cable

Also how do I tin the Ends of 6awg an 8awg cables. I thought about using a large ring terminal heating solder in it with a torch an dipping the tips in it after flux. Like a solder pot but using a large ring terminal an torch.

[LROBBINS]

Just sticking a wire into hot solder may not make a durable connection. Here's the way I do it. First, coat the inside of the terminal and the wire with flux, insert the wire into the terminal and crimp, then heating the terminal with a min torch, feed solder into the open end of the cup. You can probably also get a good connection by pushing the wire into a cup filed with molten solder IF THE WIRE HAS BEEN FLUXED and if you keep the torch on the terminal for a while after putting in the wire. I like to crimp first because it makes all the subsequent handling easier and ensures a solid mechanical as well as electrical connection. (Look around the board and you'll find links to the kind of hydraulic crimper Burgerman, I and many others here use for this.

[Burgerman]

You always heat the thing you are soldering. When its hot enough, that "thing" if it clean, fluxed, then will melt the solder as you apply it and it fuses to the metal. It will be hot enough for the solder to follow the flux and be drawn into the joint like magic. Capilliary attraction. Never heat the solder. Also once the solder has run into the joint STOP HEATING the joint immediatly!!! And so you need to add adequate solder pretty quickly.

Whole process should take 3 to 4 secs after the solder begins to run. No longer or you will burn the flux, oxydise everything and melt insulation.

This below, is an incorrectly sized anderson terminal. It isnt the best way to crimp. But it makes the process of handling it, adding flux/solder simple and allows a one handed idiot proof solder joint. Assemble, and heat...

https://www.wheelchairdriver.com/crimp-solder.htm

Crimping alone will oxidise, and give different resistance as it ages as andersons and most crimps dont have enough metal in them. So its possible to pull them out too... Soldering fills all voids, prevents future himidity or oxygen from getting into the joint and so the resistance is both low, and STAYS that way. t also icreases physical strength. Its never coming out. Its always easier if you use TINNED wires too. If copper be very sure its clean and oxide free.

[fishinjunky]

Ok thanks that's what I'll do

I took the group 24 mk gel batteries out of my chair 30 days ago I charged the chair first before removingt them Im going to put them back in but can't until Wednesday next week. I measured both with a multimeter they both measured 12.9v. Are they still good? Will they be chargeable once back in the chair?

I'm unfamiliar with the lead acid voltages

[Burgerman]

Depending on actual chemistry, then 12.9V is fully charged. They charge at a higher voltage. That doesent tell you if they are any good.

[fishinjunky]

You always heat the thing you are soldering. When its hot enough, that "thing" if it clean, fluxed, then will melt the solder as you apply it and it fuses to the metal. It will be hot enough for the solder to follow the flux and be drawn into the joint like magic. Capilliary attraction. Never heat the solder. Also once the solder has run into the joint STOP HEATING the joint immediatly!!! And so you need to add adequate solder pretty quickly.

Whole process should take 3 to 4 secs after the solder begins to run. No longer or you will burn the flux, oxydise everything and melt insulation.

This below, is an incorrectly sized anderson terminal. It isnt the best way to crimp. But it makes the process of handling it, adding flux/solder simple and allows a one handed idiot proof solder joint. Assemble, and heat...

https://www.wheelchairdriver.com/crimp-solder.htm

Crimping alone will oxidise, and give different resistance as it ages as andersons and most crimps dont have enough metal in them. So its possible to pull them out too... Soldering fills all voids, prevents future himidity or oxygen from getting into the joint and so the resistance is both low, and STAYS that way. t also icreases physical strength. Its never coming out. Its always easier if you use TINNED wires too. If copper be very sure its clean and oxide free.

I'm going to get some new flux. The liquid kind I have is crap Another lesson learned the hard way. I'm making new charge and power cables.

I'm looking for some good flux with the consistency of the kind you use. I'm finding mostly paste that is stiff.

What about this stuff
MG Chemicals 8342 RA Rosin Flux Paste, Amber https://www.amazon.com/dp/B01MS04SO4/re ... DRDHYSC6E3

[Burgerman]

I have many kinds of flux. Some highly acid that cleans oxides and lets you solder even dirty stuff. Some very non active for circuit boards and new components, some for retinning irons, and everything in between.

[LROBBINS]

The RA (= resin activated) paste flux is a good general-purpose choice. Probably should avoid using it on circuit boards with fine traces as it is a bit aggressive. Pretty good for cleaning iron tip and for soldering wires and connectors. If you want something milder (but it will struggle on copper that's even a bit oxidized) would be a RM (resin mild).

[Burgerman]

And if you want something that will tin or solder anything, get an acid pumbers solder! You can tin a hacksaw blade!

Also buy quality branded non chinese solder. Or things get difficult...

And you will see the solder reel has all the same flux acronyms like RA on it...

https://blog.gotopac.com/2020/03/24/ros ... ification/

You need a general active flux for connectors and wires. Like you linked to. But theres many. You will find that you need a few rolls of solder of thick, and thin types too depending of what you are doing. Thin ones cant get enough solder fast enough in a typical connector. Thicker ones are overkill and too big on electronics.

DONT use lead free solder. 70/30, 60/40 and all the rest like 63/37 etc are all OK. As long as quality branded and not reclaimed cheap ebay chinese crap!

[fishinjunky]

Thanks guys I'll get a few siźes and types.

What are some of your guys favorite brands of 60/40 solder?

[fishinjunky]

I may get this solder for doing the power and charging leads

https://drcproshop.com/drc-pro-solder/

[Burgerman]

Buy a large roll. That will be gone or lost in no time.

[fishinjunky]

Buy a large roll. That will be gone or lost in no time.

Glad you said that I will lose it or tangle it up for sure. I got a spool.

Mom's really liking soldering she even got herself a jewelry kit and solder for making jewelry for fun. I'm going to get us a hakko just like yours. I was going to see if I could find a deal on a used one on ebay but they resell for almost same price as a new one. Which means they must be good quality an really popular. It's what everyone is recommending. An 100$ new is pretty good for quality.

I'm going to remake new bus cables from 6awg instead of 8awg.. I'm trying to cut back on as much resistance as possible. I'm noticing with the icharger that more resistance causes more voltage drop an when the iCharger compensates if the voltage goes to high it goes into cv phase right away or very early taking FOREVER to charge.

I made the charge lead 8 awg 3ft
The balance leads are 16 awg 3ft

I may be wrong I'm still learning always.

[Burgerman]

Seems a bit overkill. I use 12swg silicone for charging at 40 Amps which works great.

[steves1977uk]

I'm noticing with the icharger that more resistance causes more voltage drop an when the iCharger compensates if the voltage goes to high it goes into cv phase right away or very early taking FOREVER to charge.

Could also be buggy/unoptimised firmware causing this as well.

Steve