how many cells can a b50-13xl handle? - RC Groups
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Jan 31, 2002, 10:31 AM
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how many cells can a b50-13xl handle?

will be in a hw730 fan. EJF recommends 18-20. Bruff uses 18 I think. Some of the electric boat sites show this motor on 32 cells at 50 amps !!! Im not sure if this is with water cooling, however.

Anyone with thoughts? How hot does this motor get on 18-20 cells?
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Jan 31, 2002, 01:08 PM
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The 13XL should be fine on 18-20 cells, the resistance is very low - about 1/5 what the spec is on my Ultra 3300-6 which I use @ 50 amps on 32 cells in an HW-750. Keep the current draw to 50 amps max and you should be just fine.

I think Bob uses 18 cells because that is as high as his Kontronik 70-6-18 ESC goes and he probably chose the 13XL to get 40+ amps on 18 cells. If that is true then 20 should be around 50, for the sake of battery lifetime I wouldn't go higher than that...
Jan 31, 2002, 01:54 PM
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thanks chris...Ill try 20 or so.
Jan 31, 2002, 05:37 PM
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we use 29 CP 1700 on our 4 1/4" self-made Impeller.The motor takes 57 amps. But at almost 1500watts you must do some for cooling.

regards Jürgen
Jan 31, 2002, 06:11 PM
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Gordon's Avatar
From the Hacker website the B50-13xl has a Kv of 1214 rpm/volt.

The HW730 was tested by H-W Eickehoff with a number of different Kontronik motors, one of which was the KBM 52-12 with a Kv of 1200 rpm/volt.

On 20 cells, this motor drew 49.8A, so as Chris says, 20 cells should be a reasonable bet (assuming the Kvs are really that close ). On 18 cells, the current was 46.6A.