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

[Gnomatic]

So charging to say 3.500V per cell (very slow, takes many hours to end) means you would set to balance at CV. or 3.5V as theres no difference. This probably needs a 1/800 to 100th/C termination to end up at 100% full/and completely balanced.
Charging to 3.550V as I do overnight, is still kind to the cells, and increases charge speed some, but still takes quite a while if you are to end up truly 100% full and balanced. Use maybe 500th/C termination value.
Charging to 3.600V is faster, as it needs only about 300th/C termination, still a little kind to the cells because the manufacturer specifies 3.65 +/- 0.05V.
Charging at 3.650V as specified by most manufacturers is a long way above normal working voltage. It doesn't harm them as such but wont give as many cycles long term. A 200thC is usually adequate to end up fully balanced and charged.

How much longer is the charge time needed to complete, in % terms, charging at 3.55v compared to 3.6v?

[Burgerman]

Depends on how out of balance it is, as the higher the voltage the better they self balance. And how discharged it was. And how complete a charge you want. And the charge rate you choose. A higher rate charges faster but has a longer CV stage.

With a good pack, used daily, discharged significantly doesn't take much longer. Its only the last part that takes the time esp if out of balance. If you are happy to have a 95% charged pack, and near enough balance, set a large termination current. Or short CV time limit. Best to set to terminate "only if balanced" though. It will then charge at full rate to within literal seconds of ending charge. It wont hurt the cells. But I am OCD! And sleeping anyway...

You always end up with easier/better balance at higher voltages. Because full is full. Charging more than 100% doesn't actually add any significant capacity. So it self levels at the cost of a little service life. How much? Who knows. But if you have the time why do it.

[ex-Gooserider]

If one charges at a lower termination voltage, and only get to 95% charge, and 'good enough' balance most of the time, does this hurt or help the pack life?

My understanding is that Lithium packs are really happier if not charged to 100%, unlike the lead bricks that want to be 100% charged as much as possible... So does not trying to hit 100% charge help a pack live longer or is it a bad thing?

ex-Gooserider

[Burgerman]

If one charges at a lower termination voltage, and only get to 95% charge, and 'good enough' balance most of the time, does this hurt or help the pack life?

Its more about balance. Its hard to balance at less than 100% as it may not be correct based on voltage alone. Charging at 3.500, 3.550, 3.600, 3.650, or 3.700v ALL result in a full 100% charge. The lower the voltage the less the termination current has to be to get 100% full/balanced. Its a matter of time taken to get there. A fully charged cells natural full voltage a day later is around 3.4xx volts. Anything over this results in a full battery. Bit like charging a gel at 14.1v takes longer. But theres also balance to think about.

The only difference is this... The lower the voltage you charge at above the natural 3.45x ish volts, the slower they fill. because theres little difference between charge and battery voltage. So it takes longer. But it may take a while to balance anyway. So in this case its beneficial to use the lower voltages. Because you dont want the full cells sat at 3.650v for half a day as it balances. Once balanced, and regularly uses 3.600v is also OK as it doesn't sit there for long if a well balanced pack, and the charge can end at a higher termination current. And still be fully charged.

If you are using the Hyperion you cant choose a termination current. It will continue after the charge end. So use 3.55v for overnight, and 3.60 or 3.65 for attended charge if the pack is well balanced. It only balances at CV and is limited to 300mA balance so may take a while. You will notice that balance is slightly different for different voltages too.

[expresso]

How do i charge a 12 Volt pack with the PL 8 - i want to make a 12 V 15ah pack - 4 cells - but the balance wires - the cable has 8 of them - do they sell a cable that has only 4 wires - to use on the PL 8 end ?

[shirley_hkg]

Connect the 5 balance leads of your D-sub , 0V ， 3.3V ， 6.6V ，9.9V ， 13V

[shirley_hkg]

[shirley_hkg]

Or buy one .

[shirley_hkg]

[expresso]

i think i got this - http://www.usastore.revolectrix.com/Pro ... Adapters_2


i know i had extra stuff i didnt need at the time - have to check - i am a little slow with this stuff so - takes me time to get it - i dont get it just yet

i just want to use the PL 8 - balance cable but just for a 4 cells 12V 15ah cells pack - i am not using a Subd for this - i figure i just put ring ends on the batter side and leave it there - then connect balance when i want to charge etc, - will use XT90 connectors for the charge leads -
same way i did the full pack -

this is going to be a back up battery pack to my PTA - its a toilet lift - it dawned on me - this would be a great pack to have as a back up since lithium can sit for LONG time and not go dead -can charge it in a hour or so - and maybe use it for a month before needing recharging -

now its using this - http://www.interstatebatteries.com/p/to ... 2147384903

and connects to the unit - charger is always connected and charging all the time - but when it dies and it just did recently - this would be my back up till i replace it - i figure lithium would last much longer usage between charges if i needed it -

on the pack end - i figure i make 4 Cells 12V - XT90 for the leads and balance cable - then connect the balance cable to the PL 8 and leads etc charge and thats it

if this works off a 12V battery now - it should work with the lithium pack just the same - i though they sold a balance cable made already with just the wires needed - so you can plug it in the PL 8 but it has 4 or 5 wires what ever it would need -

now about where to put the balance wires - thats another story with me - have to sleep on it for now - but i do want to make this little pack for my backup - -

[Burgerman]

Yes do it. And its easy.

You could even use https://hobbyking.com/en_us/zippy-fligh ... -pack.html

[expresso]

Yes do it. And its easy.

You could even use https://hobbyking.com/en_us/zippy-fligh ... -pack.html

if i use this one battery - i wont have to do anything ? just make a cable with one end bananas which i can purchase i would think and the other end i have to add a power pole 15amp connector which is used on my PTA -

the balance wire is already on the battery - and i would need that board to connect it to for charging with the PL 8 ? this battery is 8.5 ah - - how long do you think i can power it with between charges if i had to - ?

[Burgerman]

If you dont use it? 6 months to a year.

[expresso]

Can the balance cable from the PL8 with 9 wires on it - can i make a balance wire for the 12Volt pack just using the correct wires that are needed leaving the rest of the wires not in use alone - would the PL 8 when plugged in with this balance cable this way - would work ?

[Burgerman]

Yes. I charge 1, 2, 3, 4, 5, 6, and 8S batteries like that for my hobby stuff.

If you have one of these:
http://www.store.revolectrix.com/Products/SPA/SPA-XH
And
http://www.store.revolectrix.com/Produc ... /MPA-XH-PL

Or just one of these will do the same. http://www.buddyrc.com/2s-10s-xh-and-th ... and-8.html

Then you can connect any hobby pack, that uses the common JST XH connectors. Thats most of them. No soldering needed.
You still need to connect the bigger power connectors too. So you can buy a couple of the matching red battery connectors, (or chop them off and fit your xt90 ones, and use some 14 gauge silicone cable (ebay) to add a couple of banana plugs. Preferably those eBay safe ones.

[expresso]

thanks - i think the board one is best - just connect to the pl8 and then connect my pack to it - i would use the same banana wire from the Pl8 and add XT90 to one end - to plug in the pack i will end up making with some of the cells i remove from the full pack if i have to replace them - i will reuse any good ones to make this little 12V pack and keep as a backup for my PTA -

i will look to do this after i am done resolving my issues with the Full pack and make a Cell monitor - i will ask you for a preset for charging when i am done if you dont mind -

i guess i would use 4 cells 15ah - 12V - if i have 8 cells left over i can use - i just make either two packs - dont have alot of room to sit them in - so 4 cells would be good enough to fit - i wonder how much i can have it in use before charging -

[Burgerman]

I can do a preset no prob.

But you can too! Thats what this thread was for. So you get to know what to set up and why. Look at the top

[expresso]

yes your right - but dont forget who you talking too - when i get there - i ask for you help to guide me thru one -

[Burgerman]

You need to know what batteries want and need. And you need to know what terms like CC and CV mean. Homework!

[expresso]

You need to know what batteries want and need. And you need to know what terms like CC and CV mean. Homework!

yes CC is constant current and CV is constant Voltage ?

each battery type has different needs - that much i know - what little i do know i learned from this site --

[Burgerman]

Yes. CC means the charger sets a fixed amps, and the voltage is free to rise or fall to any value, as the battery becomes charged. battery voltage generally rises as you charge at CC to a point where its at its FULL or at its highest safe (non damaging) level. But at this time its being held or "pushed" up there by the Amps you set in the charge Amp setting. So it must be held at this full point or CV until it soaks up the power, without the volts going any higher.

So once the charger reaches the voltage you have set, it it then reduces power fed to the battery progressively, by dropping charge amps to stop the voltage continuing to increase. In that way the rate of charge slows down and voltage remains constant. Thats called CV. This amp (current) level continues to drop until in theory the battery becomes 100% full, and sits at the chosen voltage forever and requires zero amps to do so. Reality is a little different. And no battery is perfect. So it never actually reaches this zero Amp point so we need to set a termination current. It needs to be above the point the battery never falls below. But as low as possible.

For lithium this needs to be as early as possible, as they dont like sitting at a fully charged state at an artificially high voltage. But we need to allow time for all cells to be fully soaked after balance has completed. To ensure true balance. So a setting for LiFePO4 should be around the 300 to the 600thC (Many LiFePO4 manufacturers say 300 to 500thC) If we choose 400thC is ideal. (that means at 0.04 % of rated Ah capacity). So by way of example, a 100Ah battery (100,000 mAh) and needs to terminate at 250mA or 0.025A. (Thats just 100.000mA batt div by 400 = 250mA).

If its an easy to balance pack, this can be set to a higher figure so it ends charge sooner. Say at 500mA. With an advantage in theoretical lifespan. And lithium does not need to be 100% full, at all. It prefers not to be. If a pack is new, out of balance, or hard to balance, it can be set to a low, slower figure however. But this may need to be watched to be sure it terminates properly.

For lead, things are a bit more complicated as we must have a totally full battery. 99 percent isn't adequate here, so we set a termination point we think they will reach, at CV thats very low. Usually between 500th to 1000thC for cyclic use. After monitoring, with an 8 hour CV stage time limit.

[expresso]

I recall remember some of this from when you explained before a while back - i understand how to adjust the term. rate from the graph - we want it down low enough to get full but not too long where it would start to raise again -

that changes with battery age also - the 500th C and 1000th C - etc, - not good with the math now - so that throws me off when i hear that or see it - sounds very impressive if i speak it - like if i know what i am talking about i do get it but not translating it to my brain correctly to know off the top of my head where to put the settings

C - Capacity - 1000th C is a lower setting then 500th C ? and that would all depend how the size of pack - battery your charging etc, - like a single Cell - 15ah - you want to keep it at 5amp hour to charge it - if 4 or 8 cells were together -

then i can raise that to 10 amp easily -

[Burgerman]

C - Capacity - 1000th C is a lower setting then 500th C ?

YES.
If you have a 5Ah cell. Then a termination of 500thC would be ONE 500th of its 5Ah.
If you divide 5Ah by 500 in mA you get: 5000mAh capacity div by 500 = 10mA termination.
If you divide 5Ah by 1000 in mA you get: 5000mAh cap divid by 1000 = 5mA termination.

and that would all depend how the size of pack - battery your charging etc, - like a single Cell - 15ah - you want to keep it at 5amp hour to charge it - if 4 or 8 cells were together -

then i can raise that to 10 amp easily -

Thats charge rate. Yes you can charge at almost any rate really. Charge a 100Ah pack at 1A and it will take 100 hours. Charge at 33A and it takes 3.

[expresso]

Ok but its best not to charge too fast on a small battery ?

i get there one day - on the discharge setting on the PL 8 - i can change that setting and the charger will slow down the rate as it reaches that set point i put there - since i am doing that right now - i have it set to 3.1V -

i remember you said the charge dosnt stop on its own - it has to be stopped during discharging - What happens then when it reaches 3.1v that i have set there now ?

which i have to stop and change to 2.9v in order to keep going -

[Burgerman]

When the first cell group drops to 2.9v it stops.

[expresso]

ok thats great - so i dont have to sit there and watch it much - i will go watch it after 4pm - but good to know that it wont over discharge past that set point -

[expresso]

http://www.store.revolectrix.com/Produc ... el-Adapter

turns out i have one of these already - it came with my first Charger i purchased - this is needed when i want to charge the 12V pack one of these days i want to make -

or use the Zippy battery you linked too - its made already - even easier - just need a cable leads from pl 8 to bananas for the battery end -

they are out of stock now - i may just try this one - instead of the 15ah cells i was thinking of using -

[shirley_hkg]

After using the PL8 a few times , everything works fine , as you can see the log I posted in another thread .

The charging leads are 4 ft. long , plus another 2 ft . at the battery end , so the entire path is 6 ft in length .

At 38A , only the two 10awg wires have some mild temperature and the Dsub connectors are dead cold (dual pins have bunch of contact ) .

I'm quite confident that the charge leads may still work on another extra 2 ft. increase in length .

[Burgerman]

I have a 2 meter one, works ok, with a slight reduction in balance current, and some mild voltage overshoot that doesn't really matter in end of cc stage.

It does some clever unseen stuff. It stops charging many times a second, for an extremely short time, to get true voltages of cells and totals and in order to read resistance which is very hard. You need a sillyscope to see it. It also means that while charging the chargers voltages will read differently to your multi-meter...

That balance adapter above is different, wont fit...

[Gnomatic]

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.