LiPo Safety

[davecee]

The way this reads infers that you have charged mixed voltage batteries ( example - a 3S and a 4S) in parallel. Is this what you meant??

No. Even packs of the same nominal voltage, eg 6S, can have very different actual voltages. A fully charged 6s pack is 25.2 volts, a discharged 6S pack is 22.2 volts. The 3 volt difference is quite enough to cause a significant current flow from the higher voltage pack to the lower voltage pack. The current may be higher than the lower volt pack can safely accept. This is why it is important for all packs being parallel charged to be the same, eg 6S, and near the same state of charge.

I just did some quick and dirty figuring and connecting a good fully charged 6S pack in parallel with a good, discharged 6S pack could result in a possible current flow of as much as 60 amps (peak) delivered as charge current to the discharged pack for a short time as the packs equilibrate. The OP had six 6S packs in parallel. If one pack was significantly lower in voltage than the others, all the others would be pouring current into the lower voltage pack.

[xviper]

Read post #7. IMHO the OP could not have been charging at 5C, due to the apparent total mah of the six 6S packs he was charging and the maximum output wattage of the charger he was using.

One can only make the assumption that he knows what he's talking about. If, in fact, he does NOT understand what he's talking about or was doing, then what else does he not understand about charging batteries that may have led to this "incident"?

[OV10]

Also, the lower voltage batteries will "accept" more than their share of the input current from the charger then the higher voltage batteries, compounding the problem.

The way this reads infers that you have charged mixed voltage batteries ( example - a 3S and a 4S) in parallel. Is this what you meant??

[davecee]

I think "2C" is a far cry from the "5C" the OP was charging at.

Read post #7. IMHO the OP could not have been charging at 5C, due to the apparent total mah of the six 6S packs he was charging and the maximum output wattage of the charger he was using.

[OV10]

I think almost all chargers will "charge" without the balance lead attached. They just won't "balance charge".

Well I just learned something from you two.
Before I responded I actually had to get the equipment out (2 diff brand chargers) and verify your claims.
I didn't know they would do that as I have ALWAYS attached the balance leads, probably my ol' school techy disciplines for safety by ensuring ALL connections have been made.;)

[xviper]

I think "2C" is a far cry from the "5C" the OP was charging at.

[Mike_Then]

Each to their own and you can do what you would like. It just isn't worth it to me. Even the cautious eventually have an issue as I almost did as well.

I wasn't saying you were right or wrong; just mentioning that I've had very good experiences with charging at 2C. All good. ;)

[xviper]

I think almost all chargers will "charge" without the balance lead attached. They just won't "balance charge".

[gooniac33]

Gooniac.......:Confused:What kind of charger do you have that allows you start the charge/discharge cycle without the balance leads attached ????

Pretty much all of them will let you do that. This was an EV Peak charger. When you have it set to storage mode you don't need to connect the balance lead. it will discharge or charge depending on the state of the battery. Yes I usually do anyway but didn't that time. As of now I always connect balance leads and that prevents any confusion....

[PappaBear]

I agree safety is paramount when charging batteries. I never charge above 1C, if I do it's no more than 1.5C. I never had a fire, although I have a friend in the UK who left one unattended for less than 5 minutes in his garage. It caught fire and he had a real mess, burnt a lot of planes and was lucky the garage is separate from his house.

Martin.

[OV10]

I had set up my batteries for storage charge and forgot to connect the balance lead on one. it was a gens ace 3s 25c 2200mah pack. It had accidentally set to 4s and began to charge the pack up to the minimum voltage. Thankfully I caught this before the battery had gotten too high!! It was at 13.8v by the time I caught it and had not gotten hot or puffed yet.... but could have at any moment!!! It can happen to anyone so just be sure that you are using a high quality charger and paying attention to what you are doing!

Gooniac.......:Confused:What kind of charger do you have that allows you start the charge/discharge cycle without the balance leads attached ????

[gooniac33]

I have been charging at 2C for years and have batteries that are on their 6th season of being charged at 2C, and never had any ill effects from it. All of the charging problems I've ever had, and thankfully they were few, were due to user error (me). Never from charging at 2C. And you can ask any of my club members - I'm cautious and paranoid when it comes to charging.

Each to their own and you can do what you would like. It just isn't worth it to me. Even the cautious eventually have an issue as I almost did as well.

[Mike_Then]

Charging at anything above 1C is not a good idea. You do get a slight decrease in charging time but the end result is not really worth it to me. The batteries degrade faster and they don't totally "absorb" the charge since the last 20% of the charging phase is what takes the longest. Another thing I have noticed is that the paraboards are almost always going to fail at some point and not in ways that you would expect. The balance ports have gone bad causing one cell to exceed 6volts which is what usually leads to these flare ups. Not to mention the traces shorting for the battery connections. Everyone I know that has used them has had problems with them and eventually stopped using them all together. That alone has prevented me from doing this.

Also be careful with where you charge! Outside or away from your house is always best and on concrete or something that is not flammable. So far I have had one near mishap. I had set up my batteries for storage charge and forgot to connect the balance lead on one. it was a gens ace 3s 25c 2200mah pack. It had accidentally set to 4s and began to charge the pack up to the minimum voltage. Thankfully I caught this before the battery had gotten too high!! It was at 13.8v by the time I caught it and had not gotten hot or puffed yet.... but could have at any moment!!! It can happen to anyone so just be sure that you are using a high quality charger and paying attention to what you are doing!

I have been charging at 2C for years and have batteries that are on their 6th season of being charged at 2C, and never had any ill effects from it. All of the charging problems I've ever had, and thankfully they were few, were due to user error (me). Never from charging at 2C. And you can ask any of my club members - I'm cautious and paranoid when it comes to charging.

[xviper]

Charging at anything above 1C is not a good idea. You do get a slight decrease in charging time but the end result is not really worth it to me. The batteries degrade faster and they don't totally "absorb" the charge since the last 20% of the charging phase is what takes the longest.

Not worth it to me, either. I spent big money on my battery and my house. I'd rather not shorten the life of either. I just don't understand why some folks feel they must charge at such high C just to save a little time. Just because the battery says you can, doesn't mean it's the best. It's almost like the battery companies have planned obsolescence similar to cars, except in this case, they take your house with it.

[gooniac33]

Charging at anything above 1C is not a good idea. You do get a slight decrease in charging time but the end result is not really worth it to me. The batteries degrade faster and they don't totally "absorb" the charge since the last 20% of the charging phase is what takes the longest. Another thing I have noticed is that the paraboards are almost always going to fail at some point and not in ways that you would expect. The balance ports have gone bad causing one cell to exceed 6volts which is what usually leads to these flare ups. Not to mention the traces shorting for the battery connections. Everyone I know that has used them has had problems with them and eventually stopped using them all together. That alone has prevented me from doing this.

Also be careful with where you charge! Outside or away from your house is always best and on concrete or something that is not flammable. So far I have had one near mishap. I had set up my batteries for storage charge and forgot to connect the balance lead on one. it was a gens ace 3s 25c 2200mah pack. It had accidentally set to 4s and began to charge the pack up to the minimum voltage. Thankfully I caught this before the battery had gotten too high!! It was at 13.8v by the time I caught it and had not gotten hot or puffed yet.... but could have at any moment!!! It can happen to anyone so just be sure that you are using a high quality charger and paying attention to what you are doing!

[davecee]

I can read the mah capacity on two of the batteries as 4000 mah. If all six of those batteries are 4000 mah (they all look pretty much the same size) that would give a total capacity of 24,000 mah. To charge that large capacity at 5C would require a 120 amp charge rate, or about a 3000 watt charger output.The Powerlab 8 is capable of 40 amps or 1344 watts maximum, and it requires an input of over 26 volts to do that 1344 watts. As far as I can tell, you were NOT charging at 5C. Again, if all the packs were about the same size, you were perhaps charging at a maximum of about 1.6C. That means that something other than charge setting was the problem. The big risk with parallel charging, and the reason that I've quit it, is the extremely high amps that can flow from a higher voltage (more charged) battery to a lower voltage (less charged) battery when they are placed in parallel. This is true even with packs of the same nominal voltage, eg, all are 6S. All packs in parallel should be very near the same state of charge before placing them in parallel. A fully charged 6S pack is 25.2 volts and a depleted 6S pack is 22.2 volts, a 3 volt differential. That won't hurt the more highly charged pack, but the lower charged pack may see input amps much higher than it can accept safely. Also, the lower voltage batteries will "accept" more than their share of the input current from the charger then the higher voltage batteries, compounding the problem.

[CT]

Guys, Safety is paramount to both our equipment as well as to ourselves, believe me I know. The first incident with a Lipo is when I was charging it in the garage and came back 10 minutes later to find 18" flames from the bench. Conservative rate, no physical damages to the pack, still not know why. After that I made a small space away from all flamables outside on a concrete bench protected by the weather, also installed a smoke detector in the garage and installed fire extinguishers . Oh and forgot to mention the pack was inside a Horizon charging bag, completely charred.
DO NOT TAKE LIPOS FOR GRANTED, or I hope your fire insurance is current

[Kloverzero]

I have three chargers that I use, a Venom quad, which will charge a 7A, a Hitec quad which will charge at 6A, and a SkyRC B6 which will charge at 5A. I have always set the charge at the maximum charge rate, and the charger adjusts that rate automatically to suit the batteries needs. I have never had one even get warm, and I charge A LOT of batteries (9 at a time, between the three chargers). It is all done very similarly to TI's setup, on a metal fire proof plate, and I spread the batteries out using balance board extensions and 12 inch charge leads. NEVER charge them overnight, or leave them unattended!!!!!! Nothing ever happens while you are watching, this is a universal truth!!!

[RCjetdude]

The most I have charged mine at has been 1.5C at the field even though they are rated to take more and I check them often. Just doing that takes the time to charge my big packs from over an hour down to around 40 minutes which is good for me. At home I charge them at 1C on a charge stand in the middle of a concrete floor in my basement and I store and transport them in a military surplus Fat 50 SAW box.

[TiredIronGRB]

Lipo batteries have improved drastically and can be safety charged at 2-3C, I charge at 2C on a fire proof table.