Experience with 39V NIMH 10 AH from BatterySpace??
- Thread starter sabrewalt
- Start date
xyster
10 MW
Might be OK with a 20 amp controller. Probably significant heat and voltage sag with anything more. It's made from their better-spec'd D batteries -- these:
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=325
instead of these:
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=709
But I haven't read of anybody here trying these D cells yet. One member, I forgot who, tried their lesser-spec'd D cells and reported something like an incredibly-bad 20 volt sag under full load.
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=325
instead of these:
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=709
But I haven't read of anybody here trying these D cells yet. One member, I forgot who, tried their lesser-spec'd D cells and reported something like an incredibly-bad 20 volt sag under full load.
Not sure what my amp draw is. The motor claims to be a 350watt motor. I cannot go up a steep hill without peddeling or I will melt the traces on the controller.. (done it) I get 19 mph on a flat and can climb a light hill at about 14 mph without blowing things up. I cannot(Willnot) start motor from a dead stop. It groans and twice it has left the fork so I just don't do it. I probably ought to buy an ammeter/voltmeter combo~~~
Bob McRee built a pair of packs from the Batteryspace D-cells.
Info at the PA.
Devin runs his X5 on a couple of 36V packs similar to these.
http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1039
Another possible:
http://www.poweridestore.com/NiMH-Battery-Packs/36V-13Ah-NiMH-Battery-Pack
Which is built from these cells:
http://www.sanforcebat.com/en/Products_View.asp?Class=2&ClassView=41
Info at the PA.
Devin runs his X5 on a couple of 36V packs similar to these.
http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1039
Another possible:
http://www.poweridestore.com/NiMH-Battery-Packs/36V-13Ah-NiMH-Battery-Pack
Which is built from these cells:
http://www.sanforcebat.com/en/Products_View.asp?Class=2&ClassView=41
the price of nickel has gone through the roof and justin has no more nimh packs planned, and even bs.com has drastically increased their prices.
the bs.com 50A discharge rated 10 Ah D cells are not bad, but the tab material they use to assemble their packs is too thin and almost doubles the resistive losses in the pack. their cells are pretty close to the 5 milliohm spec, and if you use two strings in parallel you can significantly reduce the voltage sag.
on my trek i have 80 of their D cells configured as two strings of 40 that can be switched between series/parallel. resistive losses increase as the square of current, so when you use half as much current the sag is cut by 75%.
when i use a single string of 40 of their D cells at 30A the sag is 6V and with two strings in parallel this is cut in half.
the 20 Ah DD Nexcell packs i am using have almost as much resistance as the bs.com 10 Ah D cells, so 2 strings of their cells in parallel would have half the sag i see in my packs. so far the bs.com cells i bought a year ago are holding up quite well. again, their assembled packs are poor performers above 20A.
the bs.com 50A discharge rated 10 Ah D cells are not bad, but the tab material they use to assemble their packs is too thin and almost doubles the resistive losses in the pack. their cells are pretty close to the 5 milliohm spec, and if you use two strings in parallel you can significantly reduce the voltage sag.
on my trek i have 80 of their D cells configured as two strings of 40 that can be switched between series/parallel. resistive losses increase as the square of current, so when you use half as much current the sag is cut by 75%.
when i use a single string of 40 of their D cells at 30A the sag is 6V and with two strings in parallel this is cut in half.
the 20 Ah DD Nexcell packs i am using have almost as much resistance as the bs.com 10 Ah D cells, so 2 strings of their cells in parallel would have half the sag i see in my packs. so far the bs.com cells i bought a year ago are holding up quite well. again, their assembled packs are poor performers above 20A.
xyster
10 MW
bobmcree said:
Isn't this a mathematical contradiction?
If you haven't tripped across this yet, one user's review running an X503 on Batteryspace D cells from Feb of this year.
http://visforvoltage.net/forum-topic/batteries-and-chargers/518-nimh-batteries-batteryspace-com
I'm using the 10ahr (really ~8ahr) D cells . I put them in 2 boxes in parrallel thus I have 60 cells in one box and another 60 in another box for a total of 120 cells (20ahr). These were bought by requesting a bulk quote which cost me just over $3.50 a cell.
Why 2x72v you ask? Well using a single box (72-84v 10ahr) I got voltage drops of 30v at 35A, and determined these batteries cannot deliver more than 1400W (more realistically ~ 1200W). Thus in parallel, the voltage sag is much less and I get 2600W combined at 65vmin and 40A
I also run pretty fast - routinely run over 40 on the flats by the bay (today was 43 coming home) and these batts have now around 300 cycles of abuse and still work fine. I've replaced a few here and there, but even thisD-cell pack works well. Average Ahr to work is 6-7 for 24 miles, and I really fly.
http://visforvoltage.net/forum-topic/batteries-and-chargers/518-nimh-batteries-batteryspace-com
I'm using the 10ahr (really ~8ahr) D cells . I put them in 2 boxes in parrallel thus I have 60 cells in one box and another 60 in another box for a total of 120 cells (20ahr). These were bought by requesting a bulk quote which cost me just over $3.50 a cell.
Why 2x72v you ask? Well using a single box (72-84v 10ahr) I got voltage drops of 30v at 35A, and determined these batteries cannot deliver more than 1400W (more realistically ~ 1200W). Thus in parallel, the voltage sag is much less and I get 2600W combined at 65vmin and 40A
I also run pretty fast - routinely run over 40 on the flats by the bay (today was 43 coming home) and these batts have now around 300 cycles of abuse and still work fine. I've replaced a few here and there, but even thisD-cell pack works well. Average Ahr to work is 6-7 for 24 miles, and I really fly.
i said "resistive losses increase as the square of current, so when you use half as much current the sag is cut by 75%."
when i use a single string of 40 of their D cells at 30A the sag is 6V and with two strings in parallel this is cut in half."
xyster responded "Isn't this a mathematical contradiction?"
first, if i use half as much current the sag is cut by 75% - if i draw 10A from a pack with a resistance of 200 milliohms my sag will be 2V. if i cut the current in half to 5A my sag will be 1V... 1V x 10A is 10W 2V x 20A is 40W, or 4x as much sag when i use twice as much current.
if i have a 200 milliohm pack and i draw 10A it is 2V which is 20W. if i put two packs in parallel it is 100 milliohms so it is half the sag or 10W
i didn't mean to say it was only 25% as much sag when running 2 packs, just that the power loss goes up as the square of current increased.
if i use 4 packs for twice the voltage the same resistance i will use only half the current so ii cut my loss in the packs by 75%
when i use a single string of 40 of their D cells at 30A the sag is 6V and with two strings in parallel this is cut in half."
xyster responded "Isn't this a mathematical contradiction?"
first, if i use half as much current the sag is cut by 75% - if i draw 10A from a pack with a resistance of 200 milliohms my sag will be 2V. if i cut the current in half to 5A my sag will be 1V... 1V x 10A is 10W 2V x 20A is 40W, or 4x as much sag when i use twice as much current.
if i have a 200 milliohm pack and i draw 10A it is 2V which is 20W. if i put two packs in parallel it is 100 milliohms so it is half the sag or 10W
i didn't mean to say it was only 25% as much sag when running 2 packs, just that the power loss goes up as the square of current increased.
if i use 4 packs for twice the voltage the same resistance i will use only half the current so ii cut my loss in the packs by 75%
Ypedal
100 TW
Hey Bob .. how's the cruzbike doing ? i remember something about a video needing to be done or something like that 8)
That was an interesting build..
That was an interesting build..
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