| Author |
Message |
Teamtanglefoot (Teamtanglefoot)
Member
Username: Teamtanglefoot
Post Number: 21
Registered: 5-2007
|
| Posted on Thursday, January 15, 2009 - 2:07 pm: |
  |
Hi Paul, Hope you are ok. Still building tanglefoot. Running into weight problems so looking at using batteries other than SLA. Am interested in using 5 4500 Mah NiMh racing packs. (I am running on 36V) Current would be 41Amps at full power so looking at the spek it should be ok. In your experience would you think 5 of these in paralell last out for a heavy? Cheers Chris |
Teamtanglefoot (Teamtanglefoot)
Member
Username: Teamtanglefoot
Post Number: 22
Registered: 5-2007
|
| Posted on Sunday, January 18, 2009 - 7:59 pm: |
|
Hi Paul, Forgot to say about using 5 X 7.4 volt packs. Would you recommend 1 X (5 X 7.4) or doubling up and using 10 X 7.4 Packs. Also can you recommend a charger that would charge 36 Volts Nimh? Setup is the Wotty speed controller with the 36V 750W motors Thanks again Chris |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 957
Registered: 10-2004
|
| Posted on Monday, January 19, 2009 - 7:09 pm: |
|
Hi Chris,
I'm very well, thank you for asking.
Not heard of anyone using NiMH racing packs in a heavy without problems. If I remember correctly, one tean used 'F' sized cells with some success. Of course, with enough packs it would be possible but the weight advantage is unlikely to be there. Also technology is always improving and maybe todays generation of packs is better suited.
Does the Wotty have current limiting that cuts in at exactly 41A and not a mA more?
NiMH technology in my experience tops out at 40A max and even that is pushing it. A 24V Bosch set up could easily draw 100A+ which is why most builders ran with three NiCD packs in parallel and those packs could cope with far higher current surges than NiMH packs.
Your first post mentioned 5 packs in parallel so that is 25 packs in total but your second post confused me rather!
Regards
Paul |
Teamtanglefoot (Teamtanglefoot)
Member
Username: Teamtanglefoot
Post Number: 23
Registered: 5-2007
|
| Posted on Monday, January 19, 2009 - 7:33 pm: |
|
Hi Paul, Thanks for your reply. Sorry if I did not make it clear. Thought of using 5 7.4 V 4500Mah packs in series (Make 1 X 36V PACK) or using 2 X 36V Packs . I would have gone for Nicad bot packs but I cannot find Nicad packs anywhere. I don't believe the wotty has that current limiting. I do have a friend who can get me some hawker cyclon batterys. I already have a few but not enough to make 36Volts, I have heard they are pretty good but need to find out more about those. Thanks again paul for all your help Cheers Chris |
Admin (Admin)
Board Administrator
Username: Admin
Post Number: 958
Registered: 10-2004
|
| Posted on Monday, January 19, 2009 - 8:38 pm: |
|
Chris,
Without current limiting (and ignoring any wheel spin), you could easily draw 120A+ nominal and far more under heavy load conditions. I would expect the batteries to go up in smoke. Naturally this is an guestimate of what could happen and all depends on gearing, grip etc.. Personally I would not even try it without at least 5 sets of NiMH in parallel. Cyclons should of course be fine. Good luck |
Teamtanglefoot (Teamtanglefoot)
Member
Username: Teamtanglefoot
Post Number: 24
Registered: 5-2007
|
| Posted on Monday, January 19, 2009 - 8:56 pm: |
|
Thanks Paul, that really answers my question. I would have to use so many to stop them from blowing up that would not really be any weight advantage. I'll see if my friend can come up with the cyclon batteries. Thanks again for your help. Cheers Chris |
