2 Dewalt DCB210 20V Max 10Ah batteries powering my eBike.

[PapaTinkers]

Hi All, My first post. I'm not a battery expert but thought I would post what I have discovered so far. I just finished building a 2010 Norco Fluid 2.0 with Baserunner and Bafang G310 from Grin Technologies. I'm using 2 DBC210 batteries in series to give me nominal (is that the right word??) 40V. These batteries came in my DeWalt lawn mower, so making dual use. Baserunner reports 40.1 ish volts. Initial performance of the batteries seems good. Did a minor disassembly of one battery to find that the cells used are Samsung INR21700 50S 5000mah. These cells don't seem to have good life time with respect to retaining capacity after many cycles. It's ok for me thought because my bike is not a daily commuter. The cells are fused at 80A and the high power connections are all spot welded instead of soldered. I will update this post after I have put some miles on the bike (like after the snow leaves here is Langley BC) lol.
Cheers,
Stan

 

[byke]

It seems like they're matched okay for your motor. Found a chart here and it looks like the batteries are good for 25A continuous, which should be 1000 watts between the two packs and the motor is about 800 watts max? That's an hour at full throttle, little hard on the batteries and it's only 400 watt hours, be nice to be over 1000 watt hours.

 

[PapaTinkers]

Thanks byke! I'm an "active peddler" and just looking for a boost on the hills, so I think the batteries will work out fine. here is where I read about the capacity issue - 60% remaining after 250 cycles (well ... possible issue) They are talking about fairly deep discharge cycles. Anyway, the idea with my build was to keep a light as possible and so if I run out of juice i will just peddle lol. Also, I can configure a conservative cutoff voltage in the baserunner to protect the batteries. Not sure what voltage that would be yet. Maybe 30V -- 15V / pack -- 3V / cell?? (If I understand the way these things are built) lol

 

[E-HP]

Hi All, My first post. I'm not a battery expert but thought I would post what I have discovered so far. I just finished building a 2010 Norco Fluid 2.0 with Baserunner and Bafang G310 from Grin Technologies. I'm using 2 DBC210 batteries in series to give me nominal (is that the right word??) 40V.

Tool batteries tend to use made up marketing numbers to describe their batteries. 5 cells in series would be 18v nominal. Two of those packs in series would be 36v nominal. Some tool batteries will mark those packs correctly as 18v, while others fudge the naming convention to fool buyers into thinking they are getting more power. So a dewalt 20v pack is actually the same nominal voltage as a ryobi 18v pack. Marketing gimmick.
The cells are good, and with a 10s2P configuration, you should get 50A continuous, on paper at least. But with only 4Ah, it would be good for some short fast rides, or a medium ride at moderate speeds.

 

[docw009]

"Samsung INR21700 50S 5000mah. These cells don't seem to have good life time with respect to retaining capacity after many cycles."

You must have the 10AH battery, which would be 20 cells, 10x2 or 10S-2P. Two in series makes a 36V-10Ah battery, Multiply volts times ah to get watt-hours, That's 360 watt-hour.

Have you run Grin's motor simulator? Plug in the 36V 10Ah bottle battery, Something to while away the time while you wait for warmer riding weather,

Anyway, I think you'll find the Dewalts last a long time. Your bike won't be pulling the 25A continuous where they rate the cells for 250 cycles (and 40% loss of capacity). More likely 4-6A continuous, if even that high, unless you're flying around.


.

 

[E-HP]

"Samsung INR21700 50S 5000mah. These cells don't seem to have good life time with respect to retaining capacity after many cycles."

You must have the 10AH battery

.

I suffered a brain fart when I wrote 4Ah

 

[PapaTinkers]

"Samsung INR21700 50S 5000mah. These cells don't seem to have good life time with respect to retaining capacity after many cycles."

You must have the 10AH battery, which would be 20 cells, 10x2 or 10S-2P. Two in series males a 36V-10Ah battery, Multiply volts times ah to get watt-hours, That's 360 watt-hour.

Have you run Grin's motor simulator? Plug in the 36V 10Ah bottle battery, Something to while away the time while you wait for warmer riding weather,

Anyway, I think you'll find the Dewalts last a long time. Your bike won't be pulling the 25A continuous where they rate the cells for 250 cycles (and 40% loss of capacity). More likely 4-6A continuous, if even that high, unless you're flying around.

Thanks, yea 10Ah batteries. I figured they should last long enough since I can mow 1/4 acre with one charge. Yes. I will indeed have to run the Grin simulator. Thanks!