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SMH's lossing runtime

SMH's lossing runtime

Old 09-03-2001, 05:51 AM
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Unhappy SMH's lossing runtime

Well I've been flakey about my "monthly cycling" of batteries to check out their number, been 2 months since I've cycled my bats on my T-35, cycled my bats yesterday and I found that my SMH's have lost between 45 - 100 seconds of runtime (everyone of my packs has lost runtime), peak voltage and pack voltage numbers are still real good & strong - and still plenty of runtime for my racing (stock class). My 2400's and powers are still very much in line with my June numbers so I know it's not something wierd in the charger ...anyone else experiencing this?
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Old 09-03-2001, 07:16 AM
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Default Re: SMH's lossing runtime

Originally posted by HarshGuy
Well I've been flakey about my "monthly cycling" of batteries to check out their number, been 2 months since I've cycled my bats on my T-35, cycled my bats yesterday and I found that my SMH's have lost between 45 - 100 seconds of runtime (everyone of my packs has lost runtime), peak voltage and pack voltage numbers are still real good & strong - and still plenty of runtime for my racing (stock class). My 2400's and powers are still very much in line with my June numbers so I know it's not something wierd in the charger ...anyone else experiencing this?
Ummm... give us some info about your charging habits. I suppose you don't use the well known 'battery killer' method of care for your batteries from big (T). Has been proved that method kills the cells in few time.

Here's my recipe:

- Charge at 4.0A.
- Repeak at 4.5A.
- Use it.
- Discharge up to 6.0v @ 20A.
- Slow discharge up to 5.4v on a equalizing tray (Team Orion discharge board).

With 6 months of use of my new SMH nowadays run very strong, like the Sanyo RC3000 and Powers that I own (Sanyos & Powers are going to have 10 months of racing) and looks very well.

Which brand of batteries you use?
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Old 09-03-2001, 08:22 AM
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Corse-R: Do you store your SMH with or without part charge?
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Old 09-03-2001, 11:10 AM
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They're Trinity SMH's, charge on my T35 at 5 amps, repeak at 5 amps. Run them in the car then discharge them @ 20 amps with a light bulb assembly and deans black box cutoff which cuts of at 5.4v, store them till next time. I run them once or twice a week (depending on weather I race or practice and race that week). This is the exact same treatment I give my powers cells, my 2400's same thing except afterwards I throw them on a trinity discharge tray.
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Old 09-03-2001, 11:53 AM
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You really need to store them with a part charge on them. That is what all the battery matchers are recommending.
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Old 09-03-2001, 12:09 PM
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Orion seems to think you should take them all the way down on a tray and store them that way If you have a T35, why not bring them down on that, then you can bring them down to different voltages to see what worlks best.
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Old 09-03-2001, 12:53 PM
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Originally posted by dtm
Corse-R: Do you store your SMH with or without part charge?
Without charge. I use them every week or two. If I need to let 'alone' for more than a montn I'll cycle them one or two times.
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Old 09-03-2001, 12:58 PM
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Originally posted by HarshGuy
Run them in the car then discharge them @ 20 amps with a light bulb assembly and deans black box cutoff which cuts of at 5.4v
This can be the base of your problem. Take a look. I'll discharge them up to 6.0 volts, this assures me that in the case of a 'weak' cell i didn't push thru their limits (1 volt on every cell, as average), then I'll put in a discharge tray that discharges every cell separatedly up to 0.9v and equalizes them.

This 'little trick' was said to me by Danny, from SMC I did it to all my packs and remains very strong. Some people may say to you that 'equalizing' cells as you did in the Ni-Cd packs is harmful for the pack. I use the Team Orion discharge tray who discharges slowly and cool to room temperature, ready for a new use in the day.

BTW, the second charge in the day is better.
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Old 09-03-2001, 01:08 PM
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Originally posted by mike_Webb
You really need to store them with a part charge on them. That is what all the battery matchers are recommending.
Don't do it, this ruins your packs. I'll reccomend to take some reading at http://www.smc-racing.com/maintenance.htm
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Old 09-03-2001, 02:08 PM
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This is what all the other Machers are saying and people like Jim Dieter and Rick Howart and so forth...all experts with these Batteries... I got this from the Pro-Match site.

How do I discharge and maintain the new Panasonic SMH batteries?
New Information!
It is very hard to retrain your mind to accept the opposite way of thinking involved with these NIMH cells. These cells need the same kind of maintenance as Ni-cads do but the maintenance has to be done right before you race as opposed to Ni-cads which should be maintained right after you race. The nature of NIMH cells does not allow them to be stored for long periods with no charge in them, without causing damage to the cell structure. With that in mind please read the information posted below.
Excellent results can be obtained by following these guidelines. After using the packs you need to determine if they are completely discharged or not. If they are you should put at least 10 minutes of charge (at 4 amps) back into them. See footnote below** Leave the packs alone until the day before you are going to use them again.The day before you use them discharge them down to .9 volts per cell (5.4 volts for 6 cells and 3.6 volts for 4 cells) and let them sit overnight. An hour or so before you plan on charging them place them into the Smart Tray II to equalize the cells. After the last led in the tray goes out put the pack on your charger and begin charging them. You can either place them directly onto your charger from the tray or wait a few hours if necessary. Some of our team drivers are reporting excellent results by leaving their packs in the Smart Tray II overnight before charging them.
DO NOT DEAD SHORT NIMH CELLS! This will adversely affect them in the long term.
**Footnote: The longer you plan to not use the packs the more charge you should leave in them. For long term storage (more than 30 days), I would completely charge the packs before storing them.
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Old 09-03-2001, 03:52 PM
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I bought some panasonic 3000s (the first ones) when they first came out, and two more about 3 months later. I did everything that Trinity said, and for both sets, two runs after i bought them the run time was down to 2500 mahrs and voltage was crap. That is why i bought 2400's, they stay good! I think my experience with the panasonics was mostly just bad cells, I can't believe Trinity could sell something like that! And a bit of it might be the method. I'm probably going to get some of these sanyo cells, cause I need a new battery or two. I don't know what exactly i should do to care for them though! There are at least 3 methods, and everyones swears by their own!
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Old 09-03-2001, 10:48 PM
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mike-webb: Woo by shear fluke.... that is exactly how I have been treating my SMH. Has been three months now and they are still very good.

Corse-R: you're right.... second charge is definately the best! I sometimes want to simply "cycle" the first charge out in order to get to the second charge!
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Old 09-03-2001, 10:56 PM
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Originally posted by HarshGuy
Run them in the car then discharge them @ 20 amps with a light bulb assembly and deans black box cutoff which cuts of at 5.4v,
I would agree with Corse-R on this one. Taking down to 5.4v can send one cell negative. You can normally see this after a few cycles on the pack.

I use a Protrak charger which monitors indivdual cell voltages during charge and discharge. It has an auto cutoff if any cell gets down to 0.5v.

It has occurred to me a few times that with a pack at greater than 5.4v that one cell has already gone to the 0.5v. If the discharger continues to bring the pack voltage down then this cell will go negative! This process is quite repeatable... and is always the same cell for that pack, thats why I normally set the cutoff to 5.7v but 6.0 would be fine also.
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Old 09-04-2001, 08:00 PM
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I used two different methods on two different packs, just to see the differences over time. It turns out these cells just seem to fall off in runtime. The voltage on both packs has increased quite a bit though. The lowest packs cycles to about 7.14 usually, while the other which has been dead shorted regularly, cycles at over 7.18v. I haven't seem any ill-effects from dead shorting other than a quicker initial loss of runtime vs my other pack which was just taken down to 5.4v. Both packs seem to have stabilzed at around 463+sec, which is fine for me using them in touring stock. One thing I do believe is that putting back a partial charge into the cells for storage as suggested by Pro-Match and others, may keep the runtime higher than just traying them. But voltage going from 6.95+ to 7.18+ has been fun to watch. It's also nice to know that no one is going to out "voltage" me....LOL. These cells are still over the 7v (7.01 - 7.05) mark at 300 seconds!
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Old 09-04-2001, 08:19 PM
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mm I think I have been doing bad things to my metal hydrides then... After I come home I just discharge 'em on a Tamiya stick pack discharger, rest for an hour or so (or overnight if it's late) then charge @ 5A/3mv per cell. Crap....

Anyhow, have you guys tried using Eagle Model's SP Saddle Pack Discharger? It states it is capable of bringing each cell down to 0.9v

http://www.eaglemodel.com/en/cont01/menu01.html

I believe Integy sells them too.

Regards,
Alvin
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