ISDT and SMART chargers - what charge rate can I safely use on my 4S batteries

[Frank Skilbeck]

If you're not going to use the batteries for a while then the storage setting on the charger will automatically charge/discharge your lipos to a condition suitable for storage.

 

As regards the charge rate, agree with what's been said, note that charging at high C rates doesn't necessarily give a linear reduction in charge time as once the voltage reaches the max the charger reduces the current, also if you are balance charging the pack, balancing the cells works by diverting a small current around the higher voltage cells, this is typically 100 to 200 mah, if you are charging at a high rate there sometimes not enough time to balance the cells so the balancing takes place at the end of charging and this can tame some time.

[toto]

Thanks Leccy,

 

for now ....... I have set up on an industrial scale .......😆

 

 

who's the daddy.

 

Some of my battery packs are ok and don't require to be touched as thankfully I did not charge them all on arrival. i did want to make sure they would take a charge when I got them.

 

Others do require attention as they are sitting at 85% charged and similar. I have set the chargers on 1.0 A and reduced them to 3.8v per cell...... or very close to that.

 

I've only got about another 20 or so to look at ..... ha ... ha.

 

Then hopefully I can forget about them for a while and concentrate on what I am currently using for the Super Cub .... 8 no $s 3300 mah batteries which I try to cycle in use.

 

cheers

 

toto   

 

 

[leccyflyer]

You certainly have gone industrial scale.😮

 

I've been electric flying for coming up to thirty years. but personally I wouldn't be comfortable charging or discharging that number of large batteries simultaneously, ion the bench, in the workshop and with no containment of any sort.

 

Well worth looking at Bat Safes, cinder block bunkers or ammo boxes for charging, discharging and storage.

[toto]

I have a bit of everything from battery pouches to ammo boxes but they are very restrictive in terms of the length of leads on the batteries for reaching the charger terminals.

 

so for now ..... I have a good pair of trainers that will see me out of the shed quick enough if it all goes belly up . 😄

 

hope it never happens though. I will look into a better set up. My mind is on a new purpose built shed which I would build a more purpose ready space for battery charging etc , but that's further down the line for now.

 

toto 

[toto]

These batteries don't half take some time to discharge. 

 

nevermind ..... I am getting there. 

 

I have a further 24 to get through which I will start on tomorrow night. I'm waiting for 5 to finally complete as I have a good old chat with my mate John Smith.

 

I'll be glad to get this out of the way and get myself in a position where I can start managing these a bit better. ..... Note I never said correctly ...... as there will no doubt be many opinions as to that ...... 🤣

 

I am starting to feel happier from a safety and battery life point of view ........ I had to start somewhere.

 

toto

[Richard Wills 2]

Might be worth considering investing in a dedicated discharger that will discharge much faster like the ISDT FD-200.  Wouldn't be without mine, don't like leaving my batteries charged for more than a day if I can help it.

[Philip Lewis 3]

Discharge capability of a charger is often woefully poor as the rate depends on the ability to waste away the excess charge as heat so never seen anything  more that about 1 amp discharge rate on any charger I've owned.

 

Whilst on the subject of charging and discharging, (and I've not seen this mentioned before) but never leave batteries connected to chargers, some will trickle discharge your packs if left connected and not turned on, long term that means dead batteries!   

[Engine Doctor]

14 hours ago, toto said:

Thanks Leccy,

 

for now ....... I have set up on an industrial scale .......😆

 

 

who's the daddy.

 

Some of my battery packs are ok and don't require to be touched as thankfully I did not charge them all on arrival. i did want to make sure they would take a charge when I got them.

 

Others do require attention as they are sitting at 85% charged and similar. I have set the chargers on 1.0 A and reduced them to 3.8v per cell...... or very close to that.

 

I've only got about another 20 or so to look at ..... ha ... ha.

 

Then hopefully I can forget about them for a while and concentrate on what I am currently using for the Super Cub .... 8 no $s 3300 mah batteries which I try to cycle in use.

 

cheers

 

toto   

 

 

Have you also  upgraded to industrial scale fire extinguishers ?  Your taking a serious risk. Once they are in runaway mode there is no stopping the the fire until the power is exhausted. Plus the gas that is emmited is highly flamable/explosive and will quickly spread fire to anything combustible nearby . Charge or discharge out doors away from anything combustible.

If you are unlucky enough to have a fire the fire brigade wont be calling you a "daddy" .

Edited May 7 by Engine Doctor

[Martin Harris - Moderator]

I do have a charger with a 5A discharge capability but this is limited by the wattage - i.e. a higher cell count/voltage battery will reduce the current limit. 
 

DickW posted a cunning plan on another thread to utilise a resistance (e.g. a headlight lamp) in series with the battery to increase the discharge rate of chargers - he cautions that not all chargers may work this way but my unqualified opinion is that the theory is sound.  See this thread:

 

[John Lee]

An interesting feature on my ToolkitRC Dual charger is that if you charge on one channel & discharge on the other it will recycle the full battery to the empty one. ie if I come back with some batteries that need topping up to storage & others that need discharging then the charger will transfer the energy between the batteries at a discharge rate of up to 350W/15A compared with the stand alone discharge rate of 15W/3A.

[toto]

Back to the shed for another discharging session.

 

Following the concerns of my charging set up, I decided to change my charging set up ..... slightly ..... and since it is a reasonable night ..... I moved it outdoors.

 

 

should anything untoward happen ..... I have a master plan ........

 

 

I boot the table clear of the shed and let them burn out in the open. I really must remember to pick up a fire extinguisuer as part of a slightly more robust plan ..... meanwhile ..... fingers crossed.

 

 

toto  

Edited May 7 by toto

[GrumpyGnome]

There's been a long thread somewhere about LiPo fires and fire extinguishers.....  bottom line, it's very hard to put out a LiPo fire, but an extinguisher for the shed is a 'must have' in my opinion.

 

Moving chargers outside is a good move.

[Philip Lewis 3]

Large bucket full of water to chuck an on fire lipo in is likely to be more use than an extinguisher which can't extinguish it anyway, it won't stop it burning but will prevent damage to anything else, or let them burn themselves out.

[Martin Harris - Moderator]

Kick the burning LiPo away from the shed into clear space and use the extinguisher on any small conventional fire in the shed - from outside…unless there’s anything in it that might go bang.  Beware of spreading the fire with the blast from a pressurised extinguisher! If there’s any chance of it spreading to where people are, warn them and make sure they get clear immediately. 

 

Ignore the burning LiPo if it’s clear of anything flammable - you won’t extinguish it…and avoid the smoke!

[Ace]

In addition to 2 fire extinguisher(foam - CO2) I have recently bought a fire  blanket to contain any fire should the unfortunate happen. At least long enough for you to get out if it went up inside and prevent anything above/around catching fire accelerating the spread. 

[leccyflyer]

You might get lucky in the event of catching the lipo whilst it is venting and before ignition, to be able to kick it away or chuck it out. Once it's lit up though, there is no way on earth that you would be able to pick it up and lob it outside. The venting with flames is very violent, even with a small lipo and they look to be virtually impossible to extinguish, so just need to be left to burn themselves out. The fire extinguisher's role is to put out any secondary fires of combustible material in the vicinity - the fire blanket is a great idea, just like a big pukka Lipo Sack. I'll be adding one to my charging station.

 

Many years ago, on the rare occasion that I actually charged a large NiMh pack indoors, I caught it venting electrolyte steam and was able to grab the pack with some long handled tongs and lob it out of the landing window. You would need to be very lucky to do that with a lipo in the seconds before it lit up.

[Duncan Disorderly]

On 06/05/2024 at 15:51, GrumpyGnome said:

There's quite a long thread on this forum about field charging at >1c

 

Thank you for noticing GG!

 

Here are my two posts on this subject Toto, though it's a shame you didn't see them before buying all those lovely LiPos...

 

(the 2nd post repeats some of the first, as it veered off and became about high C charging rather than about the battery box, so I started a new post and included some of the same information)

 

Hope it helps.

 

 

 

...and if you needed any more benefits - it means you never ever charge the LiPos indoors (or even at your property), just the Li-Ions. That's what I do now when I get home from flying - I put ONE battery on to charge (Li-Ions are happy being stored at 4.1v, unlike LiPos), along with my Tx, and that's it - and I might have had fifteen/twenty flights that day.

 

Some days I used to bring home anything up to 30 LiPos that needed charging or discharging. Then I built one of these and got my life back. The more you fly, the more of a no-brainer it becomes.

 

[toto]

I'll have a look through your posted threads as it looks like it will take a bit of digesting.

 

Thanks for posting it up.

 

Toto

[EvilC57]

On 07/05/2024 at 20:15, GrumpyGnome said:

There's been a long thread somewhere about LiPo fires and fire extinguishers.....  bottom line, it's very hard to put out a LiPo fire, but an extinguisher for the shed is a 'must have' in my opinion.

 

Moving chargers outside is a good move.

You can put them and the surrounding area out with a powder extinguisher, once they’ve more or less burned themselves out. Don’t ask me how I know!

Edited May 10 by EvilC57