Yes, I'm doing my best to educate myself on lipos. 25 years ago everything was NiMH and it was pretty straight forward. It didn't take long reserching these to see they are an entirely different beast and need more consideration in all regards. Thank you for the help. This forum has proven to be very valuable in my RC re-education!
In regards to LiPos Ill post a wall of text. These are some previous write ups I've done either on LiPOs or connectors. I hope this helps.
Common Connectors:
There are tons of various connectors and everyone has their own opinions on which one is the best. My personal preference is Deans, EC, XT in that order. (Those are the 3 main types for LiPo but there are others.) Each has its strengths and weaknesses.
Deans:
Strengths - Small and compact, Most common
Weaknesses - bit of a learning curve for soldering them without damaging them, can be hard to separate due to size. Some people will tell you that they come apart too easy but in my experience that is only because they didnt solder them correctly and excess heat lead to a weakening of the casing creating slop where the blades connect. Also any connector can come apart if jarred hard enough.
EC:
Strengths - Easiest to solder, bullet sizes are slightly larger than its XT counter parts, they are compatible with Spektrums IC5 connectors.
Weaknesses - Seating the bullet connectors in their housings can be a real pain. There are specialized punches you can buy for that purpose.
XT:
Strengths - Bullets already in their housings.
Weaknesses - bit of a learning curve for soldering them without damaging them, Bullet sizes are slightly smaller than EC counterparts.
**Learning curve to learning to solder a connector greatly depends on ones skill at soldering.**
The bigger the number after XT or EC the bigger the connector. Most people will use EC5/
XT90 or EC8/XT120 on 1/5 scale and larger kits because the bigger the connector the more amperage it can handle. One of the main and probably the only reason I favor Ec over XT is because the bullets are bigger in the EC connectors. For example the bullets inside of an EC5 are 5mm, The bullets inside an
XT90 (
XT90 is the closest counterpart to EC5) are 4.5mm. The bigger the bullet the more amp draw it can handle. There are also EC2 & EC3 as well as EC5 & EC8. Likewise theres XT30, XT60, XT90 & XT120. EC2, EC3, and XT30 are typically used for mini and micro scale rigs. Think anything under 1/10 scale. XT60 is sometimes used on 1/10 scale rigs. EC5 & XT90 are typically used on 1/10 and 1/8 scale and sometimes youll see them being used on 1/7, 1/6 and 1/5 scale rigs. EC8 and XT120 are generally used on 1/5 scale or larger.
No matter which connector you land on if you buy Deans make sure you're buying genuine Deans Ultra Plugs. They are probably the most heavily cloned connector out there and ALL of the clones are vastly inferior to the real deal. If you buy EC or XT connector buy AMASS brand.
Common Connector Chart:
LiPo Safety Info For Beginners:
LiPos arent as volatile as a lot of people make them out to be, but they are super dangerous if they ever catch fire so people tend to talk about them like they might go up in flames from just looking at them. If you care for your LiPos they will be generally safe but certain precautions should be taken while charging. A LiPo fire resistant bag is a step in the right direction but Id also invest in an ammo can or something similar to charge the lipos inside of. The LiPo bag will contain a lot of the fire but not all of it. In order to have more protection Id recommend an ammo can also. That way if one was to go up in flames then the bag will keep most of the fire contained and what isnt contained will only scorch the inside of the ammo box.
All of that being said the vast majority of the time LiPos only catch fire when they are overcharged or if they suffer physical damage that causes two or more cells to come in contact with one another like a puncture. Generally speaking, the only time they'll get overcharged is if your charger was to malfunction or you dont have it set to the LiPo setting which on modern chargers is a bit hard to do unintentionally. The vast majority of the time if a LiPo goes bad or is damaged they will swell up or "puff" as most people call it. If you have a LiPo that puffs you should safely discharge it and dispose of it or drop it off somewhere that recycles lithium batteries.
Couple of other notes to be aware of. Generally, if a LiPo is going to catch fire, they dont just suddenly erupt into a ball of flame. They will generally puff first and then if they get damaged enough to go in to what is called "thermal runaway" the cells wont stop at just being puffed, they will keep swelling more and more. Eventually if they swell big enough they will rupture which will release toxic gases. Once this happens its a pretty safe bet flames are going to follow. I point this out because the time it takes for a lipo to go from "holy crap that thing is really puffed up" to "flames" is usually at least 30 – 120 seconds. If you're paying attention and you pack begins to swell you generally have time to get it outside where it wont hurt anything if it does reach thermal runaway. This is why you should always be in the same room with the LiPos when they are being charged or discharged unless you are doing it outside in the first place. Some people will drag their charging equipment outside and charge lipos on a BBQ grill or the like.
I said all of that to say this. Dont let people scare you with LiPo horror stories. Can they go up in flames? Yes. Can they burn your house down if one was to go up in flames and not inside of something fireproof? Yes. Is it common for them to go up in flames? No but just be aware that it is possible and if they do go up then you'd better be following good charging practices. A lot of people go to extravagant measures to store their LiPos but as long as your LiPos aren't newly puffed and the IR (internal resistance) of the cells are good when done storage charging them then I see no reason not to store them out in the open as long as its a temperature controlled environment. I make sure I charge inside of ammo cans and all of that but once my LiPos are done being used and they've been storage charged and cell IRs look good I see no reason not to store them out in the open on a bookcase or whatever. I've been using LiPos for 12-14 years now and I've never had one go up that wasn't in use. That being said I've only ever had one actually catch fire on me and it was because my charger malfunctioned and didnt stop charging the LiPo. That being said I also have a really good home owners insurance policy in case my practices ever bite me in the butt one day. So far so good though.
When you make the leap to buying more LiPos make sure you buy a quality charger. Specifically, one that reads IRs. A good charger will at least read IRs while charging and some really nice ones will have a stand alone IR reading function that will just read the IRs without the need to charge them first. Most cheap chargers and even a fair amount of the more expensive ones dont read IRs though so be aware of that. The charger I usually recommend (as well as a couple others on the forums here) to start with is the
HOTA D6 Pro (make sure its the pro version). Hitec makes good chargers also most of which read IRs, but I dont feel like Hitec's entry level chargers are as good as the
HOTA D6 Pro. iCharger is another good quality company for chargers and I believe most of their chargers read IRs as well. I own a couple iChargers as well as older discontinued Hitec.
The IR of the individual cells inside the lipo is a general indicator of the overall health of a LiPo cell. The lower the number the better. A good LiPo will have IRs of 2 milli-ohms or lower after about 3 cycles. (that reminds me, you should always break in your new lipos by cycling them at 1-2C about 3 times before using them). Once a LiPo reaches around 10 mOhms of resistance per cell this is when I will usually only use that pack for light duty use. Something like a 2WD 1/10 scale kit. Once the IR start getting over 15mOhms per cell its time to retire the pack and safely dispose of it. The other thing to watch out for is what I call "cell drift" where one or more cells start to develop higher IRs than other cells. For example if you have a 3S (3 cell) LiPo and cell #1 & #2 are at somewhere around 4mOhm and cell #3 is at 7-8mOhm this is starting to become a big problem because the cell with the much higher IR will have to work harder (for the sake of an easy description) than the other two cells in order to deliver the batteries power. Under enough of a load during use, that can push the weaker cell in to thermal runaway and now you rig burns along with the LiPo in it. If you monitor the IRs of your packs it will go a long way to keeping your LiPos and your property safe. Some people will even keep journals where they notate the IRs of each of their LiPos after every charge so they can reference them and keep tabs on how the LiPo is doing health wise. I dont generally journal but I always pay attention the a LiPos current IRs.
I know it seems like a lot to take in and I'm sure you probably have more questions now after reading this but this is a good place to start. If you have more questions feel free to ask. You'll get a lot of varying opinions on how safe/dangerous LiPos are and the best methods to store and protect them while charging etc but this is my take on it and while I'm not a LiPo engineer or anything I'm very well versed in LiPos.
Hope this helps
