Racers And Bashers Differences

[Lemming]

I need to make it clear at the outset that this is a discussion thread, not a guide. If you manage to read the whole thing, I'm most impressed...

I also need to make it clear that I am not trying to upset/offend anyone with thoughts here...

The following is my understanding of advice from previous posts from racers, battery care guides (including those from Sanyo, Maxell and Panasonic), NIMH specs and my own battery experience.

Racers:

Recommend storing batteries at 50-70% charge - cycling when taken out of storage

Speak often of exploding cells/packs

Don't use the entire capacity of a pack in a race

Use fans/cooling methods

Cycle batteries every time

Discharge packs to 0.9v per cell

Often use discharging trays (causing the packs to be balanced)

Discharge at higher rates (20amp+ has previously been mentioned)

Charge at high rates (up to 2C)

Bashers:

Don't know about others, but I keep mine in various states, but normally fully charged...

Have heard of exploding cells/packs but most have never witnessed it/had it happen

Generally bash until the batteries are flat

Don't regularly use fans/cooling methods

Cycle batteries less often (in my case once per month)

Discharge cells to 1v per cell (in my case, and as per several bashers to whom I have spoken)

Often don't use/have equalising discharger trays

Discharge at lower rate (in my case 1-2amps - 1 amp for sub 2000mah, 2 amps for all higher capacity batteries)

Charge at rates of up to 1C

Other sites information: Taken from various sites - some points I think may be questionable... Thoughts appreciated

NIMH do not suffer from memory effect issues - I personally think they are better than NICD, but still have some issues with it

NIMH batteries are generally designed for charge rates up to 1.2C.

Some high quality Sub-C cells are designed for higher charge rates up to 2C

Cells in a pack should not be discharged below 0.9v

Excessive heat causes the battery/individual cells to vent - reduces battery capacity each time this happens

Overcharge causes excessive heat

High discharge rates can cause excessive heat (my E-Maxx batteries can attest to that after a hard run)

Over-discharging cells can cause cell polarity reversal rendering affected cells useless

Unbalanced packs are extremely prone to the overcharge/over-discharge issue

Charging at rates above 1.2C provides a burst for 20-30 seconds of running, then the pack will respond around the same level as one charged at 1C

NIMH batteries (ignoring new "clever" cells) tend to lose charge over a 30-60 day period when left

If naturally discharged, (due to storage beyond discharge point) will "come back to life" after 1 (or often several) cycles

Most NIMH packs (excluding high end ones) have a maximum discharge rate of 30-35amps

Suffer more voltage drop under load than an equivalent NICD pack

My thoughts/questions: Meant as discussion points - not trying to upset racers, just that most questions are from a bashers perspective...

Racers often recommend that packs are cycled every time and not simply charged. Is this due to the fact that the exploding cells witnessed are due to packs not being fully discharged (as per a normal bash) during a race - therefore topping a pack up?

Bashers take multiple packs along, and rarely recharge during a bash (in my experience). This generally means that batteries are cooler and more ready to take a charge (for example, the next day). Are racers prone to recharging packs whilst still warm?

Bashers will normally charge packs the day before a meet, or on the morning before traveling to the meet - allowing time for cooling. I know some racers like to fit the pack to the car whilst it is still "hot". From experience, my only blown cell was one which was still hot from charge. Does this cause excessive heat?

Even with fans/cooling solutions, high charge and discharge rates will cause heat in the pack, possibly causing venting and therefore reduced capacity. So... For a basher, is it better to stay below the 1C threshold for charging and to discharge at a low rate?

Would discharging at high rates generally reduce the battery life? Would a lower rate discharge be much more suitable for bashers?

Would discharging at higher rates actually properly discharge the battery? Due to the voltage drop of NIMH under load, surely a lower discharge rate would properly drain the pack (and balance better)

Unless the battery is rated for a high charge by the manufacturer, should bashers stick to 1C (or lower)? This would reduce the risk of overcharging and therefore overheating

Notes:

C = Capacity. Therefore 1C on a 1000mah battery would be 1amp. 2/C on a 1000mah battery would be 0.5amps.

Cycle = discharge battery prior to recharging

My Conclusion for a long and happy basher battery: In no way scientific, just my opinion

Unless the manufacturer states otherwise, charging should be done at 1C or lower

A fan/cooling system would benefit a basher as much as it does a racer (reduced heat = less risk of venting = less risk of reduced capacity)

Run the battery down fully in the car where possible (always used to be the rule for battery care with NICD - still applies)

If the battery is removed without being discharged (race/boredom), then cycle the battery to ensure it is flat before recharging

Unless you have a battery equaliser tray, only discharge to 6v (to avoid over-discharging a pack)

Discharging should be done at around 1C (so, for a 2000mah pack, discharge should be 2amps) to avoid unnecessary heat - most basic dischargers are 1 to 5amp

Always ensure your battery is stored with partial charge (50% or better)

Cycle stored batteries once per month to avoid issues

Final thoughts: I feel like Jerry Springer!

My batteries have been used/cycled/kept applying the logic for a basher as outlined above. Ignoring some current stupidity with my 3300mah packs, none of my batteries have lost more than 50mah capacity over the last few years. They are used regularly, but sometimes get left for several months at a time with the upkeep as detailed (cycling once per month).

CONGRATS IF YOU MADE IT THIS FAR!!!

PLEASE DISCUSS...

EDIT!!!! - PLEASE READ POST 22 FOR AN UPDATE ON MY TESTING TO DATE...

[dazaa]

ermm didnt managed to read everysingle word there but about the part were batterys can explode, i have a sanyo 2000 nicad pack, i charged it about 5 times and the car stil wouldnt move, i then realised the connector was at fault and i had overcharged the battery x5!!!! however it never exploded????. also i am not a racer, dont know what cycling packs are and never bother to discharge my batterys.

regards

dazaa

edit just seen what cycling is.

[Lemming]

ermm didnt managed to read everysingle word there but about the part were batterys can explode, i have a sanyo 2000 nicad pack, i charged it about 5 times and the car stil wouldnt move, i then realised the connector was at fault and i had overcharged the battery x5!!!! however it never exploded????. also i am not a racer, dont know what cycling packs are and never bother to discharge my batterys.

regards

dazaa

edit just seen what cycling is.

NICD packs are much less prone to exploding due to the the fact that they don't get hot in the same way that NIMH ones do, so that is probably why (different chemical reaction). They will also take much higher charge rates, and have a much lower voltage drop under load. Some NICD batteries can take a 5C charge (5amp charge for a 1000mah battery!!!), but I wouldn't recommend trying it!

You really need to look at cycling them regularly. NICD has a memory effect whereby if they don't get fully discharged, they start to believe that the point where they stopped being used is actually the point at which they are empty. Thus they gradually provide reduced run-times unless they are properly cycled regularly (should be after every run).

[94eg!]

Very interesting writeup Lemming! Should make for some good discussion. Here are some of my comments and opinions:

It's not so much the charge/discharge amperage that kills Nimh cells, it's the heat. High amp charges create lots of heat as they reach peak. Some more intelligent chargers can be programed to alter the amperage in stages as a pack reaches different levels of capacity. This reduces the number of false peaks, as well as the final charge temp. For discharging there is really no way to avoid heat other than using fans. But even at the 20amp discharge rate that I use, a pack coming out of storage will discharge so fast it barely has time to get warm (even without a fan). The nice thing about using a high 20A discharger is that it only takes a minute or two completely flatten a partial charge. I can get all my packs discharged before the first one is done being charged.

Another interesting facts is the higher the charge rate, the quicker the power bleeds off after the cells peak. For bashing I charge GP3300 at 4.5A. This gives plenty of power even after sitting for a couple of hours. For "stock" racing I charge GP3300 at 5-5.5A. This gives amazing power, but the pack needs to be run while cells are still slightly warm. For storage, I charge GP3300 at 3A (to 1500-2000mah). I now use a fan every time except for storage charging. This is because the cells never even get warm...

Now as far as I know, batteries should never be run HOT! A pack should be allowed to cool for some period of time before being raced if it does come off the charger hot. Unfortunately leaving a Nimh battery to cool too long will cause it to loose punch, so it is best to drive shortly after charging (while still warm). A still warm pack will perform best. I imagine this does increase the heat a tiny bit while driving, but that will be determined by how many amps you pull. In the stock-sedan I race, our cells are just barely warm after the 4 minute mains. If you are pulling to many amps and overheating your batteries, you should either gear-down, or think about switching to lipo...

I would also like to mention that using the term "cycle" implies your discharging a FULLY charged pack (multiple times even). It's not so much "cycling" that Nimh cells need as it is simply discharging before EVERY charge. You take it out of storage and discharge it before you charge it. Then after a run, you discharge it before charing it for the next run. Then before storing, you discharge it and put in your storage charge. Not quite cycling, but I see where any confusion comes from.

You have nothing to loose by following racing guidelines for bashing. In fact you only have performance to gain. Unfortunately it's such a process that most people don't have the patience or time for it.

BTW: Racers should have one pack for each heat they will be running. It's always a good idea to give a raced pack a long rest before re-charging. I've heard that most recommend a full day, so there is no HOT recharging...

[Lemming]

Hi 94eg!,

Appreciate you taking the time to read my long-winded prose, and responding with extremely useful information. It clarifies a lot of things for me, especially the fact that you charge at less than 1C for storage, around 1-1.2C for bashing and above 1.2C for racing. I've found myself charging 4400mah packs at 3.5amp for storage as they stay cooler throughout the charge (even if I'm only putting in 3000-3500mah rather than a full charge) and 1C for bashing.

Definitely have come to the conclusion that unless the user has a top-end charger, then stick to around 1-1.2C max for bashing unless they have a fan/cooling system to use.

Thanks for clearing up the Cycle point as well. That's exactly what I've been doing to recover my poor abused 3300 ones. Luckily, all 3 are now around 3000mah, so 1 more cycle before the bash on Sunday should do it.

Interestingly, even the pack that was as low as 30% of original capacity has come back up well. Average 14% increase in capacity per cycle, so pleased that I took the time rather than bin the cells.

Surprised that you reckon packs should still be discharged after every use. My E-Maxx packs are always down to around 6v (7.2v batteries) or 7v( 8.4v batteries) each after a hard run, hence I only cycle once per month as discharging further would be pointless. EDIT: Guess it depends if you run until it stops, but you are right, it is good advice generally as most people don't check the voltage prior to charging/storing.

Only done the hot pack run once and the lesson has been a harsh one - posted a pic on the Ogmore bash thread. 8.4v 4400mah packs don't come cheap (unless the supplier is really kind and does a replacement for 10 ), so I won't be doing that again. Unfortunately the E-Maxx draws a ridiculous amount of current.

Definitely agree as well on the "It's always a good idea to give a raced pack a long rest before re-charging. I've heard that most recommend a full day, so there is no HOT recharging" statement. Extremely good advice for everyone.

Hoping more people will feel happy to contribute to the discussion as all views are welcome.

All the best

Steve

[94eg!]

Surprised that you reckon packs should still be discharged after every use. My E-Maxx packs are always down to around 6v each after a hard run, hence I only cycle once per month as discharging further would be pointless. EDIT: Guess it depends if you run until it stops, but you are right, it is good advice generally as most people don't check the voltage prior to charging/storing.

Ahhh, you make an excellent point. Your right there is no reason to discharge a pack that has been run flat. I forget this because it's been many months since I've actually run a pack flat. Here in the Nevada desert, motors overheat long before packs run dry. Therefore each of us usually brings several different cars, each with it's own pack, to drive when it's bashing day. Once the motors reach a 3-second thumb-on-can hold time, the next car is brought out. And when you bring 2 to 4 cars each, that makes for a good hour & half of running (and standing in the HOT vegas sun).

[Lemming]

Ahhh, you make an excellent point. Your right there is no reason to discharge a pack that has been run flat. I forget this because it's been many months since I've actually run a pack flat. Here in the Nevada desert, motors overheat long before packs run dry. Therefore each of us usually brings several different cars, each with it's own pack, to drive when it's bashing day. Once the motors reach a 3-second thumb-on-can hold time, the next car is brought out. And when you bring 2 to 4 cars each, that makes for a good hour & half of running (and standing in the HOT vegas sun).

What's sun...? We seem to have a major lack of that in the UK!

I still think your point is valid though, as most bashers don't have chargers with LCD displays, hence don't know what the battery state is. A discharge is always safest as any reasonable discharger will cut-off anyway.

Running them flat is a hang-up I have from my Frog and nicd days with a 30min timed fast charger.

All the best

Steve

EDIT: DOH! Now I know I'm getting old. It was a Grasshopper not a Frog. That's what spending all day with a 23 month old does to your brain and memory...

[hedge]

Interesting post...

I think I can help with one of your points re-racing.

Discharging:

The 5 or 6 cells that make up a racing pack are like glasses of water as they are run each glass empties but at different speeds. The speed it empties is related to a number of things not least of which is internal resistance and the connector quality linking one cell to the other. The aim of discharging is to bring each cell down to the same point (level of water in the glass) so that on charging you dont over charge a cell or put too much water in so it vents / spills over. Equally a race spec pack that you find at the worlds or Country level championship will be so well matched that each cell will discharge at the same rate - or near as **** it - and provide punch all the way through the race.

Cycling:

A NiMh battery pack works best on its second charge it provides much more punch having been charged twice. So again - and its the only way this gets relevant - think of the highest level of competition. A driver does not want to set one tyre on the track unless they can win and if they go out with a pack thats only been charged once then they will loose. So you cycle the pack on a discharger. This is also why people/racers recommend 1 pack per race because the 3rd time you charge the battery looses performance.

Peaking:

The sooner you can start racing after charging a NiMh battery the faster it will be - the faster it will discharge its current into your motor.

Now interestingly most of this info for 19t / pro stock/ 10.5 racing where we run 6 cell or 7.2/7.4v is being put in the history books as LiPo does not adhere to the same rules. It's still very relevant to modified 5 cell but we will see what happens next year regarding that class.

I hope this helps you in someway.

[Lemming]

Extremely informative! Thanks very much Hedge - this thread is turning out exactly as I hoped it would.

Wonder how well discharging balances a pack without using a tray to equalise the cells. That's one to find out at a later date

I certainly didn't realise that a pack performs better on the second charge than it does on the first, nor that the third would be a drop off point.

I haven't even looked into Lipo yet as I'm a bit nervous of the risks involved. I admit to being a big scaredy-cat!

Thanks again

Steve

[Backlash]

Its sort of hard to comment on this topic because it is so darn long...

Some Personal thoughts, in no particular order.. for discussion, and not to be taken as advice

Racers want maximum performance from their gear (inc batteries), whereas bashers generally dont care about performance, but care more about how long the model will run for.. Charging at Higher currents will generally result in higher output voltage, where lower charge currents will generally result in slightly longer run times (and longer battery life)..

I feel that if we (as individuals or a club) are going to give advice on or about the care of batteries, then that advice should follow the manufacturers instructions, not what is considered to be "acceptable" or "common practice".. From there, the persons receiving the advice can then make up their own mind as to what "rules" they break, and/or how far they want to bend them to suit their needs.. I feel that it better to be safe than sorry...

My comments on NiMh batteries are generally based on the batteries I use, being the top end "race cells"... I have no idea if the less expensive cells suffer from the same self discharge problems as the quality IB, East power, SHO cells do..

I do feel that NiMh batteries do suffer from memory effect, albeit not as bad as NiCd..

I am not sure if HEAT is the direct cause of NiMh battery failure, or if it us (the users) charging and discharging at higher currents than rated or recommended by the manufacturers, and the heat being a byproduct of the high currents involved.. (think about it?)

From my limited experience with LiPo is that it is great, and I will not be going back to NiCd/NiMh anytime soon..

Cheers

[WillyChang]

not memory effect per-se imho, but NiMH do get lethargic if unused for a while... needs a few cycles to wake them up

Also lot more cases of IB cells going dead individually.

meh... should all start the exodus towards LiPO

[dazaa]

NICD packs are much less prone to exploding due to the the fact that they don't get hot in the same way that NIMH ones do, so that is probably why (different chemical reaction). They will also take much higher charge rates, and have a much lower voltage drop under load. Some NICD batteries can take a 5C charge (5amp charge for a 1000mah battery!!!), but I wouldn't recommend trying it!

You really need to look at cycling them regularly. NICD has a memory effect whereby if they don't get fully discharged, they start to believe that the point where they stopped being used is actually the point at which they are empty. Thus they gradually provide reduced run-times unless they are properly cycled regularly (should be after every run).

OK i will be on the look out for a discharger now :rollseyes: nicads dont get as hot as nimh? well my nicads get so hot i have to wait about 10 mins before i can remove it from the car so i wont be buying and nimh batterys soon : . anyway very good discussion going on here, even thought i dont understand most of it (you cant blame me im only 13:)

regards

dazaa

[retroman]

Good idea for a topic!

I've done the racing thing, mostly 27 turn stock, and also enjoy a nice spot of bashing

My Charger/ discharger is the good old Pro-Trak. Fantastic piece of kit, when using the remote leads on non stick packs, you can monitor what each individual cell is doing during a charge/ discharge/ cycle. The good side of this is that if you have a few packs that are going soft, you can dismantle them, and build a good pack.

I think a good rule of thumb to work to is the higher the charge rate, the greater the punch from the cells, but shorter cell life due to heat. Both for Ni-Cads and NiMH.

When I was last racing, I was running GP3300 NiMH matched packs, and always found them best straight off the charger, charged at 5 sometimes 6 amps. Straight after the race they were discharged fully, and periodically equalised.

For bashing with old tamiya cars, you tend to be stuck with stick packs. I love the old Tamiya RC1400SP stick packs for this. Good punchy Ni-Cads which seem to suite silver can bashing well, especially with fully ball raced cars. Ni-Cads seem to respond well to pulse charging, where as NiMH seem to be better with a linear charge. again, I always make sure that they are fully discharged after each run. The only way I have come up with for equalising stick packs is to trickle charge them overnight, so that each cell has been fully charged, with no false peaking to worry about. trickle charging, which at best only gets the cells luke warm definately gives better run time, and longer pack life, but at the cost of performance.

I think my closing thoughts would be try not to leave any NiMH or Ni-Cad pack charged during storage, don't run the car until it stops, run until the performance noticeably slows, and if you want your cells to last a long time, avoid charging over 3.5 amps.

This is just my opinion chaps.

[Scooter79rs]

Some very good info here.

Besides the whole discharging thing, I pretty much doing everything here.

I use a LRP 3000mah Nimh and a Carson 1900mah NiCd with a charger that only charges at 3 amps

I went to my first race meet today, I raced in 27T (and won it). For the day only raced with my 3000 I did however notice at one point my batt was hot but this may have been because of the temperature and not the actual battery heat. I do plan to get a second 3000 so I don't work the one battery as hard.

I do have the advantage with my TT-01 I can't drive it until it stop as when the battery gets low enough throttle control gets very bad and the car jerks foward when tring to move.

I will try and do some of the stuff mentioned in this thread.

[retroman]

I'm still using my GP3300 matched packs, and some of them are years old. I converted a couple of packs from saddle packs (used to be run in my old X-Ray FK04) to straight forward in line packs. Cycled them once after they had cooled from soldering, then allowed them to cool, and charged them last night, ready for a basher event I've been to today

First run wih them in my Associated B4, they were good, and the buggy went reasonably well. but on the second charge of the day, they were a lot better, had loads more punch :-)

I think that the truth of the matter is a racer will happily spend 60 GBP on a really good matched pack, and will look after their investment, from both the cost, and maintaining performance points of view. A basher will probably pay around 10 to 30GBP max for a cell pack/ stick pack, because it's not about maximum performance, it's about having great fun.

Racers and bashers both have RC as a hobby, and both enjoy their own aspect of the hobby greatly. but i guess while a racer is busy cycling packs, rebuilding motors, checking shocks, set up, tweek, gearing, etc, his basher counterpart will be busy hooning around in a local car park, or country park, having a laugh.

I guess my point is that bashers shouldn't worry too much about buying expensive gear to carry out cell maintainance, just look after them the best you can with what you've got, and try not to run them until the car stops!

[94eg!]

...but i guess while a racer is busy cycling packs, rebuilding motors, checking shocks, set up, tweek, gearing, etc....

What you mean to say is "goofing around with his friends all night"...

[richard.tufty]

What you mean to say is "goofing around with his friends all night"...

Precisely! We race for what, 13 minutes each night and we are there from 17:00 until approx midnight most weeks! It's definitely a social thing more than a competing thing for me. Caveat: I only say that cos I can't drive competetively yet...

[highflyer]

Precisely! We race for what, 13 minutes each night and we are there from 17:00 until approx midnight most weeks! It's definitely a social thing more than a competing thing for me. Caveat: I only say that cos I can't drive competetively yet...

I agree with the above in my case as well, our racing scene is all about fun.. I have basher batteries and some weak batteries for racing. The bashers I can care less about, however for the racing packs (2) I run them in my spare car to discharge before charging. Sounds dumb but I race with stick packs ..

BTW- Richard it is not your driving buddy, your car is TOOO FAST!!

[94eg!]

...your car is TOOO FAST!!

OH SNAP!!! ;)

[richard.tufty]

OH SNAP!!!

But, but, I've got the smallest pinion in it!

[MikeG8]

Lemming

Interesting and informative original post which has propmpted some interesting replies too. Not being an electrics/electronics expert, the subject of charging and discharging of both NiCds and NiMHs has confused me from the start. Every charger I've ever had has confused me with its instructions for doing either (having lead acid gel cells in a boat adds yet another angle and multiplies the confusion too!). After reading your post and the other replies, I can now make some sense of what I 'probably' ought to be doing...at least as far as the NiCds and the NiMHs!

Thanks again

Mike

[haza208]

could this thread be stickyed?

[Lemming]

Thanks to everyone who has added input to this thread.

Further thoughts from my recent battery experiments (the last few months)

______________________________________________

NICD

Definitely leave them discharged - reliable charge rates on my tests of around capacity each time.

Flat from a run has proved to be fine as long as you run it until it is almost stopped.

Keeps more charge in very cold weather than NIMH does.

Smaller size cells compared to NIMH (better for older Tamiya models - For example, my NIMH will not fit into the Avante).

______________________________________________

NIMH

Very interesting results here.

Discharge very quickly in cold weather.

Initial test of storing them charged has caused me no end of problems in total capacity when re-charged (4400mah returning 2500mah or less).

Even cycling the batteries several times has not resulted in full capacity being restored to the cells (4400mah returning 3500mah or less).

Further testing involving storing them flat (after normal runs) has resulted in much improved capacity (4400mah returning 3900mah or more each time).

Further testing of storing 3/4 charged and cycling made the capacity drop return (4400mah returning 3500mah or less) - This is using my equipment (BMI 4 in 1 Digipeak).

Testing of stroing them flat from runs again restored capacity on charge (4400mah returning 3900mah or more)

2nd charge after a hard run (and cooling time) definitely results in improved capacity (4400mah returning 4100mah or more).

Charging a hot pack (fresh from a hard run) can/will result in cell damage

Running a hot (freshly charged) pack on a high power drain vehicle can/will result in cell damage

This leads me to assume the following:

Discharge rates for NIMH needs to be high (as previously mentioned by other contributors - 20amps sounds good)

The above can be emulated by running the battery flat in the car you use it for.

My charger cycles, but the discharge cycle is only at 2amps - Not sufficient to cycle the battery properly

Without a decent discharger, it seems best to store the batteries relatively flat (but before car completely stops)

______________________________________________

As per usual, these are my current thoughts as to how I will be using my batteries and are just meant as discussion points / further information for others in finding the best route forward.

Steve

[skip665]

NIMH

Discharge very quickly in cold weather.

Very interesting thread Steve - I am only basher so only interested in that side of things really. This morning was f-ing freezing (1:1 cars thermometer thing was -1.5C) and my NiMh cells lasted about 50% of their usual runtime - I was worried something was up but then realised it must be the cold - so cheers for that!

[Lemming]

Very interesting thread Steve - I am only basher so only interested in that side of things really. This morning was f-ing freezing (1:1 cars thermometer thing was -1.5C) and my NiMh cells lasted about 50% of their usual runtime - I was worried something was up but then realised it must be the cold - so cheers for that!

Yep, most of the people at the last Cider Bashers meet noticed the drop in run-times. Quite dramatic in some cases.

Also, don't forget how much more fragile plastic is in extreme cold. At the last bash we suffered a lot of damage, Tamiya models being the most at risk. See Richytanimal's pics here (linky) to see the results, including Rabied Mushroom's Bullhead after meeting my E-Maxx face to face. Emaxx was surprisingly undamaged...

All the best all

Steve