Charging protocol. Advice needed
 

Pretty new to the sport. Need some advice on charging batteries. My equipment is in my sig. Using an iCharger 4010 w/ Junsi S1200. Batteries are Promatch 100c 5000mah. All the rest of my gear is in my signature.

Running 5-8min mains, indoor clay.

Questions:
1.Should I charge my batteries any differently when I practice vs. when I race?

2.When I set up the program to cycle, should I have a minute delay between discharge and charge? From ProMatch: 'For racers who want to maximize performance you can lower internal resistance by discharging the pack from a storage level (3.8 volts per cell) at 25-30 amps down to 3.2 volts per cell. Then immediately recharge at max recommended charge rate for the pack until fully charged. This lowers the internal resistance of the pack and gives it more punch.' (Recommended for mine is 3C, 15A)

3.For the above cycle, should I do that every time I charge the battery, or just when I first come to the track? Or just for a race?

4.A few people have recommended that I don't discharge past 3.6v. Opinions?

THANKS!!!

I've always used 3.2 as a cutoff and never had a battery issue till just last week when I noticed one pack has puffing.(but its also 4.5 yrs old!) I like the ProMatch idea.

My understanding is that the cycling of the batteries makes a difference in "blinky" classes where motors are tightly controlled and where power and peak RPM are limit by class rules.

But from what I've heard, it is not relevant in offroad, especially getting into 1/8 scale. Maybe some benefit in 1/10 buggy if there is a stock class, like 13.5 blinky? But the best discussion I've heard about this says that it is 1S classes that get the most benefit. I highly doubt you will notice a difference in a 1/8 scale.

1/8 offroad is already over-powered, and you can pick whatever KV you want. If you want more RPMs, just get a higher KV motor. In 1/8, there's no limit on KV, and most guys run a fairly mild 1900kv, but you can have like 2200kv if you want it. And with offroad you are rarely flat out at max RPM. You might be spinning your tires to max motor RPMs, but you're not cruising at a constant speed that is limited by your motor's max RPM, as in the case of on road racing.

So I would say don't do it. It won't give you any benefit, it's a hassle, and extra cycles on a LiPo will shorten it's life--life span is rated in cycles typically. Fast charging/ discharging add cycles that could otherwise be used on the track!


I've been using a cut-off of 3.6v on my buggy and truggy. I still get 15-20min run time, and it reduces the chance that a single cell can over-discharge. Our ESCs don't monitor individual cells, so there is no protection from a single cell dropping below a safe limit while the rest of the cells are OK. The LVC is effectively an average of all cells, and it works when all the cells are discharging at the same rate.

Typically, people charge/discharge at high amperages only when stock racing which in your equipment I see you are. I think that people do it more in onroad racing than in offroad. In my experience, I found that you do get a slight advantage through the beginning of the race with extra punch. I feel that your batteries do not last as long as if you charged at 1c, but still last long enough. (depending on how much you race and if you store your batteries properly, you should switch them out every 1-2 years to keep performance up. Also, a new model of battery will probably come out :P). More importantly, you should watch your IR rating and should keep it low.

1. Personally, I think you should charge your batteries the same way during race and practice to keep it consistent.

2. If you are going to discharge and charge at high amperage, I would not have a delay and would charge at the highest amperage you feel comfortable with. I use team powers batteries and charge/discharge at 40 amps. I am not familiar with Pro Match batteries so I cannot give an exact recommendation.

3. If you do decide you want to do the high amp cycle, then definitely before a race if you have time and while practicing for races. While just messing around with friends, it's not really necessary.

4. It is ok to charge past 3.6v to 3.2v as long as you don't store it like that and charge it back up soon.

Doing this is a lot less important than having good tires prepped properly, having a good setup, and not crashing. If you crash once, the punch advantage won't make a difference. If I had to give a recommendation to you, I would focus more on practicing then worrying about battery science When in doubt, ask the fast guys at your track! And remember, support your local hobby store/track!

I run promatch shortys in stock 2wd buggy.

I only cycle (discharge-charge; 0 delay; 30A ) 1 time only..... before the 1st qualifier starts to heat up the battery.... aftwr that I just charge normally at 30A till the end of the main

keep in mind that if you want to do the high discharging, you'll have to get an external discharger. this is the best IMO: High Power 500 Watt Dischargers ? LIGHTner Hobbies

You mentioned being new to the sport, but didn't really say where you are placing in races or what your overall skill level is. I do see you are running spec/blinky classes with your cars. Unless you are making one mistake per 5 minute race and battling for the win, don't worry about crazy charge rates. There are much cheaper ways to go faster.

If you are new and your skills are still putting you mid pack or lower, don't worry about high charge rates and discharging your batteries before each charge. You might get a tiny bit more punch, but you are going to wear out your lipos more quickly. Stick to charging them at 2C or less, put them in storage mode between trips to the track, and charge your packs the morning you plan to use them. If you won't get to run the pack in practice before racing starts, then maybe cycle them to warm them up so they are consistent from the first qualifier to the second.

"For racers who want to maximize performance you can lower internal resistance by discharging the pack from a storage level (3.8 volts per cell) at 25-30 amps down to 3.2 volts per cell. Then immediately recharge at max recommended charge rate for the pack until fully charged. This lowers the internal resistance of the pack and gives it more punch.' (Recommended for mine is 3C, 15A)"

I am pretty sure that this is only meant to do every once and awhile to refresh the battery.

The key to good performance is to use a freshly charged battery right before each race. When the LiPo is warm you get the best performance. I don't see the need to discharge the battery in between races, just charge it. Then when the racing is over for the day, discharge each battery to the storage voltage.

Best regards,
Brian

a lipo doesn't get warm charging at 2C.

Sure it does. It's hard to measure since it's in the hard case but the temp will be higher than the room temperature.

I have an expensive IR meter and you will see IR of the battery the lowest right after the pack is charged and it's warm. The IR will go up as the pack cools down.

Best regards,
Brian

i guess it's all relative. a couple degrees above ambient isn't "getting the battery warm" in my world.

the point of the thread is high charge and discharge rates to warm the pack to the point it provides a performance improvement. a couple degrees above ambient is negligible. i know from doing it that the punch i get from a proper cycle (35a discharge/40a charge) produces IR's in the 1.0 ohm range per cell. when i'm not racing and just practicing and don't cycle, the IR's are usually about twice that (charging at usually 20a) and the difference is noticeable.

The best of both worlds would be to charge your packs at 1 or 2C rate to avoid degrading the cells in the long term while using an external heater to warm up the packs instead of relying on the internal resistance and high charge rates. Heating the pack up was deemed illegal by ROAR, thus charging at high amps became the substitute to get some heat in the pack while keeping the outside near ambient.

8.3.2.5.4 Maximum temperature for a charged li-poly battery pack shall be ambient
temperature +/- 5 deg..

If they don't follow ROAR rules, get some tire warmers, set them to 120 degrees F, and enjoy the added punch while getting more cycles our of your packs.

The problem I see with that is you’re warming from the outside in. There’s no way to tell what the internal temp is. Warming the case to 120 yields what in the cells?

Usually the pack is fully enclosed and you let it heat up like that for close to an hour to make sure the entire pack is the same temp. Tire warmers was a poor example. We used to have a hot box that had a few 60 watt led bulbs in an insulated crate with a temp gauge sticking out the side. We'd keep the box at 110-125 and just open a small door and put the packs in and let them warm up while they charged at 1C.

Same could be said for fast charging them. You see 120 on the outside, but could have pockets of 140+ on the inside that are eating away at the lifespan of the pack.

I’m also new to the LiPos. Do you always balance charge or only once a week, month, etc?