XRAY - Model racing cars

Hi Woogie, I converted from 4200 Nimhs to Lipo last December and in my view it is a no brainer, yes it is worth it.


1. Performance – we have seen no overall difference. A well maintained Nimh will tend to pull away earlier in the race but you will haul them in. I suspect that top racers still use Nimh packs but they probably get them replenished frequently very cheaply or for free.
We made the A final in a recent round of the SLCC championship running 27T (8 of the finalists had 13.5 brushless) and we had Lipos

2. Balance – people complain about the number of weights you have to add to Lipo to make the 1500gm limit. For us that was a bonus because we could not get below 1550 with 4200s, plus it means we can run at 1500 and have the car perfectly weight balanced

3. Ease of use – what is there to say. No comparison. Race; take the car off the track; whip out the Lipo and stick on the charger; run of to marshal. Repeat this process during the entire day. Get home; charge them up, leave in garage until next Sunday

Yes they should be balanced but this does not have to be done too frequently according to the experts. I use fast charge on race day and balance charge when I get home

Cost - they are no more expensive than Nimhs.

Yes a single Nimh pack probably is (although Lipo costs are tumbling) but you have to look at the entire picture.
You do not need as many. You could almost get away with one Lipo pack but certainly 2. For the last few race meetings since my son went over to Lipos we have been running the two cars on 3 Lipo packs. We would need 6 Nimh packs

You would need 3 Nimh packs. I am sure 2 Lipos are cheaper than 3 Nimhs. Of course you have to add the cost of 150+gm of lead weights

Then there is the point that Lipos will probably last longer eg twice as long (not based on experience, just based on quoted figures for Lipos ie number of charges, vs how often our Nimh packs have gone duff). So now the cost disadvantage goes out of the window.

I have not done a thorough market survey but get the feeling that the price of a half decent Lipo charger is not any different to a half decent Nimh charger.


So just rough figures

3 nimh at ?40 (easily ?60 depending on what you want)=120. Twice per year over 2 years ?480

2 Lipos lasting 2 years ?100

Charger, well the cheaper version of the BC-6 is ?50 I doubt you can get a comparable Nimh for much less. I am sure cheaper chargers with fewer facilities exist for both technologies

There just does not seem to be any contest here.

Do they fit the 008 – yes they do.
The key measurement is height. Most of the larger capacity Lipos, eg 4900, come in at 23mm height. That JUST fits the 008 without any change. The only consideration is retention. Most Lipos have flat bottoms, as does mine. Orion do batteries, at least around the 3200/3600 capacity, which have scalloped bottoms so fit very nicely into the cell slots. I secure mine with the optional battery bar (I already had one) plus one piece of tape at the rear of the battery, 90 degrees to the chassis centreline, hooked around the top deck.


Which one is best – I am not going to really comment on that. What I will say is that in everything I have read, the view seems to be that there is no difference (in performance). They are just not like Nimhs. If you do convert over you need to change your mind set away from Nimhs, they are totally different.

In terms of the entire package I went for Trakpower; packs, charger/balancer, wiring harness. It all just plugs in straight out of the box. 3 programmes to select; Lipo charge; Lipo balance charge; Lipo fast charge. The electronics then do it all, checking the number of cells in the pack (2) and capacity; it then sets the charge rate automatically

HTH

Hi Woogie, I converted from 4200 Nimhs to Lipo last December and in my view it is a no brainer, yes it is worth it.


1. Performance – we have seen no overall difference. A well maintained Nimh will tend to pull away earlier in the race but you will haul them in. I suspect that top racers still use Nimh packs but they probably get them replenished frequently very cheaply or for free.
We made the A final in a recent round of the SLCC championship running 27T (8 of the finalists had 13.5 brushless) and we had Lipos

2. Balance – people complain about the number of weights you have to add to Lipo to make the 1500gm limit. For us that was a bonus because we could not get below 1550 with 4200s, plus it means we can run at 1500 and have the car perfectly weight balanced

3. Ease of use – what is there to say. No comparison. Race; take the car off the track; whip out the Lipo and stick on the charger; run of to marshal. Repeat this process during the entire day. Get home; charge them up, leave in garage until next Sunday

Yes they should be balanced but this does not have to be done too frequently according to the experts. I use fast charge on race day and balance charge when I get home

Cost - they are no more expensive than Nimhs.

Yes a single Nimh pack probably is (although Lipo costs are tumbling) but you have to look at the entire picture.
You do not need as many. You could almost get away with one Lipo pack but certainly 2. For the last few race meetings since my son went over to Lipos we have been running the two cars on 3 Lipo packs. We would need 6 Nimh packs

You would need 3 Nimh packs. I am sure 2 Lipos are cheaper than 3 Nimhs. Of course you have to add the cost of 150+gm of lead weights

Then there is the point that Lipos will probably last longer eg twice as long (not based on experience, just based on quoted figures for Lipos ie number of charges, vs how often our Nimh packs have gone duff). So now the cost disadvantage goes out of the window.

I have not done a thorough market survey but get the feeling that the price of a half decent Lipo charger is not any different to a half decent Nimh charger.

.......

Oops sorry guys. I got a debug error on send and did not realise the post had actually been posted.

Hi ... perhaps someone can comment on this - power overdrawn from lipo.

I used a mixture of Nimh and Lipo with the Norsam ISTC ESC. I noticed that after over 10 runs, my orion 3200 lipos lost their punch. I did not change any gearing or setup, the lipos are just not giving the "kick" compared to the first few runs.

Conversely my Nimh charged at 5A consistently give the "kick" the moment I punched out from corner into the long straight. Of course the Nimh does have a shorter battery life.

Was told that my ESC overdrawn from the lipo ... was advised to get the bigger capacity lipo like 5000 over as these bigger capacity ones have better drawn resistence.

Advise ... Comments ???

The application of pseudo-science can lead to some strange conclusions.

There isn't some magical 'max continuous current' where a lipo will suddenly drop voltage. It happens progressively and somewhat linearly with increase in current draw. Two things get you higher voltage under load: more capacity, and more C rating - and the latter is subject to the marketing department's suggestions. But make no mistake: more voltage is helpful at max load (full throttle coming out of a slow corner) and lower load (topped out down the straight).

Output performance does not equal C rating.

Output performance = C rating * capacity
That's effectively the definition of C rating, actually.

This goes a bit offtopic but hope its okay. Do you know countries where modified class allows LiPos and with what motors? We have LiPos allowed only for stock and with 15.5T. I'd love to start driving modified for winter season but having to buy top-end new pricey NiMH for many hundred euros is stupid I'd like to suggest some ways to allow LiPos for modified class for local/club races. Any suggestions would be great.

Yesterday I ran stock one quali with NiMH and then loaned TeamOrion 3600 LiPo from a friend... it can't be easier with LiPo! Just charge it for about 30-45min after each run and you are ready to go again!