Converting from gas to electric

[Bande1]

2 weeks to slow the spread. remember to double mask. Trust the science!!!

you put a 45" hull on 6s up against a 4hp gas boat?

[lohring]

The difference is that our dyno measured power at the engine output. We measure electric motor power at the battery output. If you allow around 80% ESC/motor efficiency, you get 932 watts per hp. That means to get 4 hp at the motor output you need 5 hp or 3700 watts at the motor input. That's a little over 150 amps.

Lohring Miller

[Bande1]

Interesting. So it is kinda close to 1000w per HP.

[Xrayted]

No, not really. Electrical and mechanical HP conversions to watts are 745 and 746 for 1 HP, so essentially the same. Those values dont change and are what they are. What's being talked about here now is the difference in how or where those values are being measured, not the values themselves.

Sort of like having 500HP measured that the crank in car like all automakers publish, vs doing a dyno which measures at the wheels after the losses are factored in, so its lower. The definition of measured HP doesnt change, and if you want 500HP at the wheels then the crank power will need to be higher. A gas motor also has driveline losses no differently than our electrical systems do

The fact that a rigger can easily lap your higher powered cat design hull doesnt mean much either. Of course it will because it's not just about the raw power numbers. Weight and hull design matter even more, and riggers are some of the lightests with least water contact designs, so of course they will whip you every time, even with way less power.

It reminds me of the guys that constantly try and challenge me with their big 600+HP V8 Camaros and Dodge Chargers. Loud heavy "boats" and they all look stunned when I destroy them with my 500HP 6 cylinder car because they never consider that I weigh 900 lbs less than they do in a much more agile car, so I have the advantage despite having 100HP less

[vvviivvv]

Also consider a outrunner... perfect for bridging the gap between Gas and electric.

[Bande1]

No, not really. Electrical and mechanical HP conversions to watts are 745 and 746 for 1 HP, so essentially the same. Those values dont change and are what they are. What's being talked about here now is the difference in how or where those values are being measured, not the values themselves.

Sort of like having 500HP measured that the crank in car like all automakers publish, vs doing a dyno which measures at the wheels after the losses are factored in, so its lower. The definition of measured HP doesnt change, and if you want 500HP at the wheels then the crank power will need to be higher. A gas motor also has driveline losses no differently than our electrical systems do

The fact that a rigger can easily lap your higher powered cat design hull doesnt mean much either. Of course it will because it's not just about the raw power numbers. Weight and hull design matter even more, and riggers are some of the lightests with least water contact designs, so of course they will whip you every time, even with way less power.

It reminds me of the guys that constantly try and challenge me with their big 600+HP V8 Camaros and Dodge Chargers. Loud heavy "boats" and they all look stunned when I destroy them with my 500HP 6 cylinder car because they never consider that I weigh 900 lbs less than they do in a much more agile car, so I have the advantage despite having 100HP less

all you girls are adorable when I pull up on my R1. Here's another bit of science - gasoline has 33.7kwh per gallon. You average 6s lipo has about .133kwh

[Xrayted]

Yes, it’s not news to anyone that gasoline has a higher energy density than any current battery technology. That’s why we still use fossil fuels for almost everything.

It has nothing to do with available power, but you can run the same speed or slower for longer

[Bande1]

Yes, it’s not news to anyone that gasoline has a higher energy density than any current battery technology. That’s why we still use fossil fuels for almost everything.

It has nothing to do with available power, but you can run the same speed or slower for longer

You can keep up with some basic gas boats for 40 seconds! wow

now wait another 1hr for a re-charge to do 5 laps...

[Peter A]

Well this thread has derailed!

[lohring]

Electric model boats can easily run flat out for a full race including penalty laps. If you have a high power charger, modern batteries can easily be charged at 2C. That means 20 to 30 minutes between heats. These days the fastest RC model boat is electric powered. http://www.ne-stuff.net/2016/10/2853...ld-record.html IC engines are rpm limited so existing props don't have enough pitch for the highest speeds. They can be pitched up, but the maximum is still limited.

Lohring Miller

[Bande1]

you're charging lipos without a cool down period? thats dangerous.

[LibertyMKiii]

I am relatively new to RC boats.
What are the fastest SAW runs with petrol/nitro setups?

It seems like electric motors dominate that area.
RPMs are not really a good excuse as you can use a gear drive to up the prop RPMs.

[Bande1]

I am relatively new to RC boats.
What are the fastest SAW runs with petrol/nitro setups?

It seems like electric motors dominate that area.
RPMs are not really a good excuse as you can use a gear drive to up the prop RPMs.

I think theyre around 10-15mph slower than electric. around 130mph range. electric can go very fast for short periods. 10 seconds, 60 seconds, maybe even 90 seconds with extremely expensive premium batteries.

put it this way, racing orgs have to lower the electric lap counts so the boats can make a whole race.

[LibertyMKiii]

I think theyre around 10-15mph slower than electric. around 130mph range. electric can go very fast for short periods. 10 seconds, 60 seconds, maybe even 90 seconds with extremely expensive premium batteries.

I think each has its place. If I wanted long run times and cool running temps then absolutely gas/nitro setups make the most sense.
If you only need to run for 1-2 mins tops then electric has its place.

I have output 10kW on 6-cell electric and know people have gone north of 18kW on 8-cell setup. I don't think you can get that sort of power out of the small engines... short of putting a dirtbike motor in your boat.

[lohring]

The charging range is 0 to 45 C or 32 to 113 F. That's pretty warm. It doesn't take long to cool enough. Often warming the battery before charging is needed. We used 6 hair dryers in our electric hydro to warm the batteries before running.

Lohring Miller

P1010126.jpg

https://batteryuniversity.com/article/bu-410-charging-at-high-and-low-temperatures