Cells ??

[andys]

I was browsing the rcracechat forum and found quite a long thread about IB cells going BANG.

Now i've seen a pack that went BANG in our region at Durham, it would have being nasty if anyone would have being sat near them ?

The reason I ask is I was going to order some IB cells, from Voodoo, but this thread gave me pause for thought.

Has anyone from our region had any problems with these cells, aparently they need treating differently to GP's, in what way ?

Laslty, can we run Lipo in the NE Regionals if we make the car up to weight ? I bought a lipo to run my touring car and it's totally brilliant, so personally i'd prefer to just run that if I could ?

Cheers.

Andy.

[Richard Lowe]

After this season if the cells stay as they are, I'll be using GP's next year.
I bought some IB's and GP's at the same time, both have had similar (ab)use. The IB's have lost quite a bit of performance, the capacity is still there but they have lost a lot of punch. A couple of packs have leaked too which is never good. The GP's still feel almost like new cells, havn't vented/leaked and still have almost all their capacity.
Fair enough the IB's had a bit more punch to begin with, but not enough to put up with the cells fragility IMO.

I like the idea of Lipo cells, can't wait to run them :)
It's ok to hacksaw a pack in half to fit in my BJ4 isn't it?! :p

[Rob]

I'm looking for some cheap packs of cells for 2WD off road use next year. I will be using brushless, don't need to be great packs. Anyone know the best place to get some cheap matched packs of GP3700's or IB3800's?

[burgie]

TJ Cells.....I have decided to replace my GP3300's after two years worth of (ab)use :wtf:

[bert digler]

if u want sound advice speak to neal oliver he does batteries for all sorts of shit hes the man who nows so there:yawn:

[Rob]

How much are the TJ Cells packs?

Been looking at a well known store abroad they do IB3600 cells for $3.90 each, IB3800 for $4.50. IB4200 for $5.50 each and GP4300 for $6.50 each. Don't think really need 4200 or 4300, is there much difference between the IB3600 and 3800?

[bert digler]

How much are the TJ Cells packs?

Been looking at a well known store abroad they do IB3600 cells for $3.90 each, IB3800 for $4.50. IB4200 for $5.50 each and GP4300 for $6.50 each. Don't think really need 4200 or 4300, is there much difference between the IB3600 and 3800?

ur being fleeced try hong a kong a rooney pipe

[tc2k]

The 38s are probably newer and so probably have more punch.

I recently bought some new cells for regionals, they are gp33's, I believe that these new cells, although they have the punch, they drop off quickly and need a lot more TLC than the GP's. Its just whether you want cells that last or fast cells that need alot more maintenance

[Rob]

Especially with brushless I don't think you need lots of power from the cells in off road? May get the IB3800's think they have a more level discharge compared to gp3300's.

[bert digler]

The 38s are probably newer and so probably have more punch.

I recently bought some new cells for regionals, they are gp33's, I believe that these new cells, although they have the punch, they drop off quickly and need a lot more TLC than the GP's. Its just whether you want cells that last or fast cells that need alot more maintenance

are you having a laugh? i use the 42s no problem, look after them, i bought 48 cells for 177quid the shv variety matched them myself. the are great just dont kill them
the are awesome




:)

[andys]

After this season if the cells stay as they are, I'll be using GP's next year.

Hi Richard.

You've sort of said what I feared in you post. I reakon some new GP's will be the way forward for me then. If you can't look after them, then i've no chance.

Does anyone know if you can you run Lipo in the regionals ?

Trust me Rich, i've got one, the Trakpower and it's brilliant in every way !

You could always covvert your Bj Worlds to a BJ, the thought had crossed my mind, as the Pred's not keen on stick packs either :)

Andy.

[tc2k]

Can I ask a question?
I just put my new Epic Monster Metal 3300 cells on their first charge on my pulsar. Settings were 4amps at 25mv cutoff. They got to 4300mAh without peaking, so I took them off, is this normal.

[super__dan]

tc2k,

You're too high on the delta setting there, the LRP charger is different to everything else, I use 5mv (not a typo) on mine normally, 10mv if it's very cold where I'm running. Chris Doughty uses 10mv everywhere I believe. I assume the cells were pretty hot?

Andy, Lipo is not BRCA legal so to my mind cannot be used at BRCA regionals, I don't see this as optional as they are 7.4v so it simply would not be fair!

Dan

[tc2k]

Hmm, I heard new cells take in alot more than normal. Ill try lowering the delta, I heard the pulsars was high but usually 20mv works for all my other cells. Ill try 15

[andys]

tc2k,

Andy, Lipo is not BRCA legal so to my mind cannot be used at BRCA regionals, I don't see this as optional as they are 7.4v so it simply would not be fair!

Dan

Great ! I imagined as much. That's the thing I love about this hobby, something great comes along, that means it will be better and cheaper for us all in the long-run, and we have to buy more of the old stuff ! looks like GP's for me then in 2007.

PS Dan, If I start beating you at the 2007 Outdoor Regionals, you know why :)

[Dunc]

I may well be wrong, but I was under the impression that the mV setting on the LRP Pulsars is a TOTAL value for the pack? Whereas on my Orion charger it is set PER CELL. So I would use values in the range 3-5mV, which would be equivalent to 18-30mV on a Pulsar (for six cells).

Btw, there is a thread on Chris Doughty's site where he suggests using a 20mV, not 10mV cut-off.

Unfortunately, the Pulsar manual doesn't appear to answer my question above. Although, the majority of its suggested settings use a cut-off in the 20mV range or above.

Apologies if I'm sewing yet more confusion! :D :eh?:

[tc2k]

Aye, the pulsar cutoff is for the whole pack, but I believe Dan is saying that it actually has a higher cutoff than it says so they use lower settings to get a more normal cutoff.
Well I charged two sets last night, on first cahrge, both false peaked at around 150mAh which isnt a surprise as they were probably dorment for a while before I bought them. One reason I think they overcharged is theyve never been used and so the chemicals may need a bit of work to get em going like normal. Also, like you said the settings may have been high, finally, it was boiling inside and the charger had been running for nigh on 3 hours so was rather hot so I think the mAh it gave out was alot more than it was putting in due to heat loss as when I discharged the pack, it only gave out 2600mAh

[super__dan]

Hhhhmmm, that's interesting, Chris must have changed as I know he defo used to use 10mv. Doesn't the manual say 20mv for nimh on sheet supplied, maybe he was quoting the party line ;)

Judge it on temperature though I say, all cells when they are charged start to get warm. With nimh as soon as they are warm they are charged, not like the old nicads which you had to charge past the peak voltage and get them warm.

As an aside, I consider some sort of equaliser more important now than ever before. Some of the nimh cells I've had have wandered all over the place whilst left both partially charged and discharged. On assembling my latest cells I equalised them before their first charge and they were all over the place, I guess due to when that cell was actually matched. Similairly I have discharged a pack to 5.4v, left them for over 2 months and had 2 cells read 0.05V purely through self discharge. I equalised the pack and seems to have been fine, but I wouldn't want to make a habbit of it. So now I deliberatly leave my cells with charge in them and equalise them before charging on race day!

Dan

[tc2k]

Im going to have to get an equaliser I realise. However, Im skint after christmas because I spent all the money on spares and the batteries. I have about 16quid left, hopefully I can buy a decent second hand tray for that.

[LiamD]

Interesting reading on the Pulsar delta peak.

I was always told 0.5mv p/cell... hence 30mv with a 6 cell pack. Obviously I use a 20mv delta peak with my 4 cell packs. Looking at other people's chargers (especially with 4 cell packs), that's what they use. My cells don't get too hot, and i'll often charge my cells at 6 amps.

I use old Gp3700s in my buggy, they still have plenty of punch and duration.

[neiloliver]

I would suggest doing as mentioned above, equalise the cells on a board and then charge to maybe 1000mAh capacity before storing. If cells are being measured at 0.05V then they have an internal short of some sort which is depeleting the capacity faster than the other cells which are OK. This is not really a good thing as these cells will always lag behind the other in the pack, will not reach top of charge and will be over discharge in the next cycle which can mean those cells are driven negative and can vent... it becomes a downward spiral...

Never store your NiMH cells at voltages of less than 1V as this leads to permanent capacity loss due to internal cobalt migration (its a bad thing).

The crunch with these high capacity cells is life, you dont get such high capacity and voltage without trading something.. in this case (i) cycle life, (ii) reliability and (ii) self dischrage rate. Everyone wants the big number on the cell, and that is fine, but you wont get as good all round performance as you would with a Sanyo 2600mAh cell.. which would be good for 1000 cyles. (2600mAh you cry, how crap is that... maybe, put Sanyo have just launched a new version of it and I would want that in my cordless drill any day!)

I sell GP4300 cells and they are very popular, but you cant expect them to last forever.. its a case of the candle that burns twice as bright burns half as long (or something like that!).

As for the -dV question, I would personally use 5mV per cell. (30mV/pack) but this is a question of personal prefference - they longer the amount of overcharge the higher the higher the temperature and the shorter the life.

One last point. If you ever buy cells from a shop, before you do ANYTHING (in fact, do this in the shop!)... measure the voltage of each cell, if any are <1.0V give them back. If 5pcs are 1.20 V and one is 1.1V give them back. I am not saying that this has any indication on capacity because it does not, but the one cell that has the lowest voltage will die first. I would put money on it!

N

rant over.. :)

[super__dan]

Are you guys using the Pulsar 2, I can only talk about the version 1 I have and used to use a lot. I do believe these mv settings can not always be comparred from charger to charger, same as total charge values cannot be comparred. Apparently just from changing to a Protrak I used to get nearly 600mah in my cells, I have no doubt this was not the case, just however the chargers measured it.

[LiamD]

I'm using the old-skool Pulsar 1. I've used it with these settings pretty much since I got it when they first came out.

[Richard Lowe]

I use the 10mv setting at 5 amps on my Pulsar 2 and they dont get overly toasty. I think the Pulsar 1 and 2 are identical apart from the 2's 3 profile memory and higher current capability on the 'motor run in' feature. AFAIK the actual charging circuitry is the same so the delta cutoff should be comparable between them.

Neil - I think the self discharging to almost nothing is normal with the IB's, in every one of the 4 packs I got at the start of the season if I store them for more than a week (even with charge in) one random cell dumps to nothing. The thing thats strange is it's a different cell each time and they've done this from new. Nick at Demon told me to store them with whatever was left in them after the run then equalise and charge straight after. He also confirmed quite a few of the IB's do what mine are doing.

[Dunc]

Hhhhmmm, that's interesting, Chris must have changed as I know he defo used to use 10mv. Doesn't the manual say 20mv for nimh on sheet supplied, maybe he was quoting the party line ;)

Judge it on temperature though I say, all cells when they are charged start to get warm. With nimh as soon as they are warm they are charged, not like the old nicads which you had to charge past the peak voltage and get them warm.

As an aside, I consider some sort of equaliser more important now than ever before. Some of the nimh cells I've had have wandered all over the place whilst left both partially charged and discharged. On assembling my latest cells I equalised them before their first charge and they were all over the place, I guess due to when that cell was actually matched. Similairly I have discharged a pack to 5.4v, left them for over 2 months and had 2 cells read 0.05V purely through self discharge. I equalised the pack and seems to have been fine, but I wouldn't want to make a habbit of it. So now I deliberatly leave my cells with charge in them and equalise them before charging on race day!

Dan

Dan, you could well be right about Chris quoting the party line. He obviously needs to be responsible about the advice he dishes out to the general public.

Quite right about temperature too - it is thine enemy! :)

I've had some GP3700's since May, which are still going reasonably strong although I've only been using a Spintec discharger. I suspect an equaliser would help to restore a bit of 'zing', which is next on my (never ending :o ) shopping list.

Btw, I should make it clear I've never owned or used a Pulsar 1 or 2 and so my advice is not the best on the matter!

[tc2k]

Yes, I use the Pulsar 1. I think Im goingto go for a middleground of 20mv, I find that any higher should be used for my very old cells which are prone to false peaking.

[tyreman]

When I asked David Spashett what mv I should be charging at with my LRP Pulsar 1/2, he told me that at 25mv I was killing my cells, and he recommends no more that 10mv, for GP3700 or GP4300.

[neiloliver]

let me throw in a curved ball for reference only... -dV is not a great termination technique for NiMH as the cells are in overcharge when the termination occurs. Most professional charge systems use dt/DT as the primary charge termination technique for fast charging. -dV, Max T, Max mAh, Max t and Max V are redundant back-ups. The lower the -dV threhold the less damage you will do, so unless you have your cells bought for you by someone other than father Xmas, keep that -dV level low and protect your investment. The biggest issue really is that the cells diverege so much over time that they dont all reach top of charge at the same time, so some get overcharged more while others never reach top of charge. this leads to greater imbalance in the pack for the reasons I have described in my previous rant. One thing I did not mention is charge rate, I try to keep to 4A maximum. charging at rates higher than this may make you wheelie off the line and hit the guy in front of you, but it does nothing for the cell life... and at an hour a round you dont need to be silly with charge currents.

N

[MattW]

I don't claim to be a cell expert, but i've learnt a bit over the years!!!

I use a Pulsar and CE T35 GFX. On my pulsar i set the delta at 10-15mV, depending on cells and ambiant conditions. Generally newer cells are ok at lower delta's, where as older ones might need it a touch higher. On my GFX, i would usually use 30mV.

I like the Pulsar, i think it's a good charger, but to be totally honest, i don't really rate the peak detection software. I have had mine set at 15mV, but sat there watching the digital display showing pack voltage drop 30mV before it actually cuts off. For this reason, i think the delta settings on the Pulsar should be lower than for many other chargers.

There is no doubt that IB cells being below 1.0V is a serious problem. I would never knowingly take them below 0.9. I think you are ok discharging to 0.9 as they do not rest there - picking back to oer 1.0 after the load is removed. When i first had IB4200's i was equalising them on conventional resistor/diode trays to 0.7V. I had 2 packs die very quickly. I stopped this practice and the ones that survived have generally been ok.

I did lose one pack last week - but basically this was my fault as well. I had come close to dumping and then left them connected to the car for about 10 days. The entire pack voltage had therefor gone far too low. 5 cells survived (to a point) but one didn't and has gone internal short. There doesn't seem to be a way of reviving them when this happens. IB cells must be left with charge in them - i would say at least 500mAh, possibly more if they are to be left for a long period.

As a general rule of thumb, GP cells seem much more resiliant than IB. However, it is at a cost, as performance from IB's seems far superior.

[super__dan]

Good call Matt!

[tc2k]

Ah well, despite the worry over the cells, with a 19t in the buggy, they had three times the punch my old cells did, felt much nicer. Capacity isnt a problem in 2wd anyway.