SMC goes to 35 amps for matching

[sjslhill]

Spoke with Danny today. SMC is putting the finishing touches on the 35 amp batteries.

Are we interested in 35 amp matching? I am not certain this is a good idea myself. 35 continuious is pushing things really hard. We also have the new machines and can do this.

Comments please.

thanks

Steve

 

[brooks93]

to me I would say yes its a great thing..

I run offshore so the most I pull is 38 to 43 amps.. the closer the batts are matched to that the better I think

a good cell at 20 amps might be crap at 35

 

[sjslhill]

to me I would say yes its a great thing..
I run offshore so the most I pull is 38 to 43 amps.. the closer the batts are matched to that the better I think

a good cell at 20 amps might be crap at 35

You may be correct....however....I doubt that your boat is always drawing that amount down the straights. The cells get a breath at some point.

Preception is also a problem, since some sell cells at 20 amps and the numbers look much better to some without knowledge.

thanks

Steve

 

[brooks93]

true.. on the without knowledge thing..

and yes there should be less load on the motor in the straights

 

[crowebar]

Very True Steve,

35 might get them a little too toasty by the time they hit the cutoff voltage.

Dick

 

[Patrick M]

Not sure that it's a good idea either........

Unless cells can be matched at rates close to actual running conditions, the discharge rate used for matching isn't much of a factor for us boat guys. Working the cells hard, even at 30 amps, during the matching process seems to reduce the runtime.

Danny has always been an innovator and was the first to recommend dead shorting NiMh's... who can argue with his success in the car sector of the hobby?

 

[brooks93]

during the matching process seems to reduce the runtime.

ya its going to

 

[Patrick M]

during the matching process seems to reduce the runtime.

ya its going to

Just to clarify the point....... higher discharge rates accelerate the observable reduction in capacity that occurs with repeated cycling in 3300's...

 

[brooks93]

I understand that.. what I am trying to say tell me one boat class that doesn't pull more then 30 amps over the course of the race.. besides the N1 class's even thought they can be alot also

 

[Patrick M]

Even Crackerboxes pull more than 30 amps (close to 40) continuously. The only class that I'm aware of which may benefit from a 35 amp matching rate would be LSH and then only if you're using a smaller prop to keep the draw down to 35 amps. Doubtless, there are other classes and combinations that can be tailored to draw as little as 35 amps......

But why abuse the cells before they ever see the water?

Just my opinion......

 

[brooks93]

I see what you mean but, what I am trying to say is wouldn't it be better to have cells that are matched close to the amp draw your going to put on them?

 

[Patrick M]

I see what you mean but, what I am trying to say is wouldn't it be better to have cells that are matched close to the amp draw your going to put on them?

I agree completely.

Unfortunately, the piece of equipment normally used to match cells (the CE Turbomatcher) has a maximum discharge rate of 35 amps. I would really like to know how my cells compare at 50 or 60 amps, but until someone produces a matcher, or maybe an add-on shunt for the Turbomatcher, it's not feasible. I dont believe that increasing the matching rate from 30 to 35 amps will provide a more accurate indication of the cells performance at double that rate, but the extra heat generated by 5 more amps of constant current could accelerate cell degeneration.

The ideal matcher would be capable of sampling voltages and IR's at varying and programmable amp rates rather than at a constant current...... kinda like simulated laps on the water.

 

[drobie]

How should one treat new 3300's.

Should they be C/10'd or just cycled on a 5-6 amp charger?

 

[sjslhill]

How should one treat new 3300's.
Should they be C/10'd or just cycled on a 5-6 amp charger?

I think they should be charged C/10 if not used for a few weeks. This will balance them out if they have drifted.

 

[androdz]

Hello,

what does C/10'd means or dead shorting nimh's. Any information will be greatly appreciated thanks!!

Att. Andrew