PL 8 - Q and A section - How to Set up - Use etc,

[Burgerman]

I use revolectrix sized SILICONE cables. They get a little warm but silicone is heatproof.

[expresso]

At 38A , only the two 10awg wires have some mild temperature and the Dsub connectors are dead cold

I used 12AWG for my main charge wires in my charging cable. That's what Revolectrx sells. I assume that's ok, as they put 40A fuses in them. My charge cables are 4ft on the charger end. Will 6ft charger to battery cabling be ok charging near 40A is 12 AWG charge wires are used?

Is it possible to use 10 AWG wiring in those stackable safety banana plugs like the PL8 uses? The ones I picked up say 4mm outside cable diameter max. The outside of 10 AWG wire is just a bit more than that from the charts I looked at.

those are nice and prices are good - do you happen to know how much they can handle - 40A - then you can make your own cable length without connecting two cables - i am just concerned if they cant handle the heat - someone had a issue before where they melted - he used cheap versions - i found some on amazon also - were rated up to 32A - i trust the ones from relvolectrix - but if we can find them that can handle 40A - they should be good -

[Burgerman]

There are originals and cheap copies. How to tell apart? Dunno! I have two huge bags of these. Ebay. Seem fine at 40A.

Remember that most of the heli, or quadcopter lipos batteries that we hobby people use, may be the size of a cigarette packet, but are 5 and 8C charge rate! So a very small 5Ah battery in my quadcopter, can be charged happily at 8x 5A (40Amps). This means a fast "refuel" in around 7.5 to 8 mins. Ready for another flight. Its why hobby chargers are so powerful. And many use these connectors.

[expresso]

yeah thats what i am afraid of - dont want cheap ones - that will melt - the ones Genomatic linked too are nice - good price - but no Amp rating -
just remembered why i get the originals - they have the fuses built in the cable already made - makes things easier for me - only have to extend it a foot - can use butt connector for that - done it before works fine - -

[Burgerman]

Did you think about making an extension. 4 of the connectors, and one 36 inch ready made balance lead/extension.

[Gnomatic]

yeah thats what i am afraid of - dont want cheap ones - that will melt - the ones Genomatic linked too are nice - good price - but no Amp rating -

I asked the seller, they told me those connectors are 32A rated.

Which butt connectors did you use to extend those Revolectrix cables w/ built in fuses?

[Gnomatic]

Did you think about making an extension. 4 of the connectors, and one 36 inch ready made balance lead/extension.

Good idea.

[expresso]

Did you think about making an extension. 4 of the connectors, and one 36 inch ready made balance lead/extension.

you mean two connectors ? they come 2 feet - the balance leads are 3 feet - i will add another foot to the bananas to make it even and make the charge cable 3 feet - thats fine for me - i have done it with the first cable and used butt connectors - works fine - i have done other cables with the butt connectors - crimped - 3M adhesive glue etc , - works fine -

i stick with the originals i know work for sure and safe at 40A - too bad they dont offer that cable longer to make the balance leads - 36 inchs at least -

[Burgerman]

But 6 feet cable, 4 connectors... No fuse.

you mean two connectors ? they come 2 feet

[expresso]

yeah thats what i am afraid of - dont want cheap ones - that will melt - the ones Genomatic linked too are nice - good price - but no Amp rating -

I asked the seller, they told me those connectors are 32A rated.

Which butt connectors did you use to extend those Revolectrix cables w/ built in fuses?

https://smile.amazon.com/10-12-Gauge-Sh ... eat+shrink

get them on Ebay - cheaper - sames ones - they work fine - easy - simple crimp and heat it down - done - its on the outside of the chair PL 8 end - so not worried really - worse case - i have made a few this way - one cable with SB50 on other end - in case i needed it

the first charge cable i made is 3 feet - same way - used butt connectors to extend it - the charge cable on the chair end - is fine - dont need to use butt connectors - - just the ones from the charge end - the one i made for the ADD ON that stays on the chair - i kept it at 2 feet - thats fine -

http://www.ebay.com/itm/50-Yellow-Heat- ... Sw5cNYVwvX

[Burgerman]

You are making it over complicated. Buy the ebay 4mm ends!!! And a ton of silicone cable.

[expresso]

You are making it over complicated. Buy the ebay 4mm ends!!! And a ton of silicone cable.

[shirley_hkg]

BM , would you please include the followings in your suggestion list to REVOLETRIX

1,more balance starting points
2,Soft start for all charge current ; for sake of power supply and initial charging for deeply discharged cells . ( now I enter low charging rate in preset and change to higher amp after start . It then increases at around 0.5A steps . )

PL8 seems quite incompentent at start up .

[shirley_hkg]

Increase to 32A at two tiers .

[shirley_hkg]

What is that ? Power supply end is solid @28.5V .

[Burgerman]

I have never seen that. Mine shows just a few tenths of a volt, loaded/unloaded. Because:

Your supply voltage varies by several volts on and off load. Its not very well stabilized at high switching frequency. The charger is monitoring it at high switching frequency, your volt meter will never show this. Mine does but it wasn't cheap! Which leads to this:

Its instability is caused by your power supply voltage partly, and made worse by the close to battery voltage chosen for the supply.

The problem is that it uses two different types of inverter internally. A buck, and a boost converter. If the battery voltage crosses the power supply voltage as charge begins, it has to swap over. If the power supply voltage is above the battery voltage as yours is at start, it uses the buck converter. To lower the voltage. The moment it does this, the battery voltage rises up due to internal resistance, or cables resistance, (and your loaded supply drops) and it then has to try and switch from the buck part, to the boost converter. (that increases voltage from input to charge output).

As it does this, it takes a finite time. And the battery resistance lets the volts drop again... So now it needs the buck again... To stop it oscillating between these two inverters, it bumps the current (and so the voltage) higher very rapidly to move voltage up, or charges slowly for a while to introduce some hysteresis and to try and keep itself away from the transition or swap over voltage. The loaded/unloaded supply makes this worse for the charger to control.

The easy solution is to use a slightly different power supply voltage set to say 24V or lower, or 29V or greater. Even a small change may do the trick. Or even thicker / shorter battery charge cables. Then it will start and rise smoothly. https://en.wikipedia.org/wiki/Buck%E2%8 ... _converter Change this supply voltage or improve the stability of the supply and your problem is gone.

The hard spot is when the battery voltage is just below the swap/switch over point because of power supply voltage level/battery voltage level increasing as charge begins. So the thing to avoid is where supply and battery volts are close. Especially, exactly where yours is set!

[LROBBINS]

Another possibility might be to add a large capacitor across the power supply - say 500 uFd, 100 WVDC, but you would then have a charged capacitor to contend with when you disconnect the power supply from the charger.

[shirley_hkg]

Changing from 29V to 28.4V this afternoon , was a wrong move then .

Will go back to 29.5V to stay away from that switching point .

Thanks .

[Burgerman]

Should help. But remember that on load, your supply falls a few full volts! (that loaded figure). So setting a higher frequency conversion may help here but is less efficient.

Not sure what yours is set to. I usually set 62.5.

But there are 3 options.
The figure it allows you to choose depends on the charge current. Why? Because higher frequencies allow smaller components, at big amps. But lower efficiency and more heat. But its easier on the power supply. And low frequency allows better efficiency at lower currents. so 31khz is more efficient below 20A, but needs bigger components at high amps and will show bigger gap on your supply. So it will limit you to 20A max or will show error..

Options are 125, 62.5, and 31khz. Choosing a higher frequency may help your power supply not drop as low under load. If the settings for charge allow it. Try setting 125khz. But the charger will then waste more energy and not like it at high amps, and may lower the charge current if it detects its getting too hot...

Better to have a more stable supply, or set a lower voltage like, 24. Still at least you know what is going on! I hope I have not caused your brain to smoke!

[shirley_hkg]

Last time I was in a hurry , so I charged it @32A (130 Ah in 4.5 hrs )

At use, I found the voltage drops faster than usual , though slight . .

Termination @150 mA already , THAT is 1500th /C for a 216Ah pack .

I 'd prefer lower charging rate then , if time permitted .

[Burgerman]

That happens more with higher resistance lower C rated cells or old cells usually.

You can charge a lipo hobby battery that is 30C to 130C rated, in 10 mins flat! To 4.200v per cell, and terminate at almost any figure and they are 99% full. Low resistance means no waiting.

[expresso]

i charged last summer at 35A - each day since i use it alot - love how fast i can refill the whole pack now that i added an exta 30ah to it - i can lower it a bit and still finish it full in same time - charging etc on there own - 12A to 15A for the add on and 20A to 25A for the full pack -

i still love how fast it charges from empty


216ah - thats a large pack -

[Burgerman]

Its actually equivalent in range to around 10x GRP24 MKs... And same weight as 2.

[Gnomatic]

Termination @150 mA already , THAT is 1500th /C for a 216Ah pack .

Shirley how do you fit 624 of those 26650's in your chair, do you have a custom battery compartment or something? If you have any pics of your monster 216Ah pack I'd be very interested in having a look. I'm very curious. Range for days and days and days ......

[steves1977uk]

I charge my pack up to 3.548v max@15Ah. I have the frequency at 31.25kHz for my profiles that charges under 20A, the rest I leave at 62.5kHz for higher than 20A.

Steve

[Burgerman]

i charged last summer at 35A - each day since i use it alot - love how fast i can refill the whole pack now that i added an exta 30ah to it - i can lower it a bit and still finish it full in same time - charging etc on there own - 12A to 15A for the add on and 20A to 25A for the full pack -
i still love how fast it charges from empty

Headway can be charged at up to 5C max. Thats 5X your 105Ah pack, so 525A CC/CV if you want fast! If you have your own electricity pylon. It will get them hot, and that shortens the lifespan, but it depends what you are using them for. In a car wanting a fast refuel thats OK.
Most say charge at up to 1C which is still cruel, and you would need a 105A charger...
Lithium likes slow charge (if you have time) and repays you with better range for longer.

So charging at 30A isnt excessive, and will charge in 3 hours. But if you are sleeping, choose 15 to 20A instead.

If in a hurry choose 40A even for the add-on. That will charge a 30Ah add-on in around 1 hour. Of 40 mins to 95%.

[expresso]

I was under the impression that the benefits of these headways were that we can Charge Fast - i understand now - yes we can charge fast but if its not needed - its better to charge slower - now that i have the two packs combined - i can easily charge slower on the full pack and finish about the same time - i can easily use 20A on the full pack and still finish in 4 hours - unless i ride for 50 miles and more - then 5 hours - having two packs changes everything -

both in range and charging rates etc, - last summer was the first time - so i was excited and amazed how fast i can charge fully - compared to lead prior - i will try 15A and see how long that takes - if too long - 20A should be fine - i try to get it all done before i go to bed - and the spot where i park my chair to charge is also the same spot i like to watch TV at night - while its charging - i eat - drink - lay back for some music - - need a little rest after a long ride

[Burgerman]

Don worry, 3 hours is not fast. I do hobby packs in literal 10 mins from empty. Charging a battery as big as a pack of cigarettes at 40A.

[Lord Chatterley]

Thinking of upgrading from the 1420 Hyperion. Can anyone recommend a PL 8 supplier in the UK or has it been superseded by something better?

Thanks,
LC

[Burgerman]

No idea in UK as I buy stuff from the Singapore online place.