PL8 Storage Setting Question

[muscleflex]

Hi,
Just need to ask this as I have no idea...
My batteries are
Turnigy 6s 5000mah 40c and they're all in pairs - I have 3 pairs for my 700 trex and I always do them in pairs. Not singles.

What CHARGE and DISCHARGE settings do I need to choose?
for charge, I tend to put 3.5mah (don't ask me why - I don't know) but I have NO idea what discharge to put..

Is it safe to put 1c on both charge and discharge?

[Rob Barnes]

Using the STORAGE charge preset channel , I simply plug all six 5000 6s packs in and press go on what ever is preset use ! Not the best answer but it works for me !

[Planehazza]

Using the STORAGE charge preset channel , I simply plug all six 5000 6s packs in and press go on what ever is preset use ! Not the best answer but it works for me !

As always though, do not do this with 2 packs that are fully charged, and 4 packs that are discharged for example. Ohms law will balance them all out, but only to a certain degree. When parallel charging/discharging, the packs should be very close. Because parallel charging cannot monitor each individual pack, it cannot charge the low packs and discharge the high packs independently at the same time - it will instead only react to the average of all the packs, as this is all it can see.

Rob, not saying that this is what you do/don't do, just felt that this needs to be made very clear with parallel charging.

So musleflex, because they're in pairs and are being flown as such, they should be very close so you should be fine charging/discharging them together. They shouldn't really ever get out of sync, unless of course they are split up and ran in a 6S config in another model or for whatever other reason. It is good practice to cycle them individually now and again to make sure exact cells are balanced perfectly - remember, parallel charging sees averages and will only see 6 cell voltages, regardless of the number of packs connected to the charger

[muscleflex]

so what mah should i use for discharging? i can't remember what the preset for mine is... i changed it and it's currently at 450mah or something small! i can't definitely use that that would take a whole week!

[Planehazza]

so what mah should i use for discharging? i can't remember what the preset for mine is... i changed it and it's currently at 450mah or something small! i can't definitely use that that would take a whole week!

The highest it will go. I think the PL8 has a 10A discharge feature?

Yup it does: Internal discharge 10mA to 10A, 100W max.

Because it's burning off the energy as heat it is lower than the charge by quite a bit. A fully charged 6S pack is ~25V so you're limited to discarging at 4A, which is ~0.8C, give or take a bit for efficiency. At this rate you'd, be down to storage charge level for one pack in about 35-40mins. Don't forget discharge rates are much higher than charge rates of a LiPo, so you could whack it up as high it can go, which in this case is 4A (4A * 25V = 100W), which translates to 2A per pack. This is now 0.4C so you're looking at a couple of hours ish to get two 5000mAh 6S to storage.

Please correct my maths anyone if I'm wrong.

[Mike656]

PL8 can do a regenerative discharge when hooked up to a car battery at up to 40 amps, if you want a fast discharge. Using the lipo all brands storage preset will either charge/ discharge your batteries to 3.86 volts/ cell. If you want a 1C charge rate with a pair of 5000mah batteries, set your charge rate at 5 amps and tell the PL8 you have two packs in parallel. It will work out that it needs to put in 10 amps.

[Rob Barnes]

As always though, do not do this with 2 packs that are fully charged, and 4 packs that are discharged for example. Ohms law will balance them all out, but only to a certain degree. When parallel charging/discharging, the packs should be very close. Because parallel charging cannot monitor each individual pack, it cannot charge the low packs and discharge the high packs independently at the same time - it will instead only react to the average of all the packs, as this is all it can see.

Rob, not saying that this is what you do/don't do, just felt that this needs to be made very clear with parallel charging.

So musleflex, because they're in pairs and are being flown as such, they should be very close so you should be fine charging/discharging them together. They shouldn't really ever get out of sync, unless of course they are split up and ran in a 6S config in another model or for whatever other reason. It is good practice to cycle them individually now and again to make sure exact cells are balanced perfectly - remember, parallel charging sees averages and will only see 6 cell voltages, regardless of the number of packs connected to the charger

Thank you for the advice which is always greatly appreciated.

[muscleflex]

Excellent! Thank you!
Will the packs be able to handle being discharged at 1 or even 2c?

The highest it will go. I think the PL8 has a 10A discharge feature?

Yup it does: Internal discharge 10mA to 10A, 100W max.

Because it's burning off the energy as heat it is lower than the charge by quite a bit. A fully charged 6S pack is ~25V so you're limited to discarging at 4A, which is ~0.8C, give or take a bit for efficiency. At this rate you'd, be down to storage charge level for one pack in about 35-40mins. Don't forget discharge rates are much higher than charge rates of a LiPo, so you could whack it up as high it can go, which in this case is 4A (4A * 25V = 100W), which translates to 2A per pack. This is now 0.4C so you're looking at a couple of hours ish to get two 5000mAh 6S to storage.

Please correct my maths anyone if I'm wrong.

[rich-6]

Excellent! Thank you!
Will the packs be able to handle being discharged at 1 or even 2c?

Yes they will.

I generally rig mine up to some light bulbs which I mounted in an old power supply case with a small fan and an alarm rigged up. It's easier and I don't need to turn the lights on in the house, it normally gets them down to discharge in about 20 minutes a pack and saves putting a load through the charger. Bulbs are cheap to replace once they pop.

you can discharge them at 40c if you wish although I wouldn't like to try it lol.

[Planehazza]

1C or 2C discharge is nothing. Think of it this way: a 6min flight is ON AVERAGE 10C (60 min would be 1C, so 6 min is 10x quicker, thus 10C). I say on average, because general hovering is not going to take 10C, but pitch pumping will take more.