1KW said:quick couple questions.
1. Does it matter in which cell you place the balance and discharge wires? I see you put them on a few cells down in each parallel section. Could it be put on the first cell?
2. When you install the balance wires, lets just say you did a 6s pack, where do you know where to put the + and - on the balance tab, same with discharge wires?
3.Can many noobs do this pretty easy as long as they learn to solder? ETA on developing a pack like this?
1KW said:quick couple questions.
1. Does it matter in which cell you place the balance and discharge wires? I see you put them on a few cells down in each parallel section. Could it be put on the first cell?
-this is your free decision
2. When you install the balance wires, lets just say you did a 6s pack, where do you know where to put the + and - on the balance tab, same with discharge wires?
-have a look to your charger manual, in the manual are explantions for your charger
3.Can many noobs do this pretty easy as long as they learn to solder? ETA on developing a pack like this?
-this it not so easy to say, you need good tooling, and some hours of exercise, to solder the cells direct like me, is a issue you can overtemp and damageable the cells
-please look around to your buddies is there a electronic technician and learn by show it in real, sorry for the improper answers
ecross said:pics 546 to 549
kfong said:ecross said:pics 546 to 549
Nice work, I would of went with copper braided wire. Less solder and heat time needed.
tomtom123 said:whats the nominal discharge current on these cells?
tomtom123 said:are these ok? i doubt they're real ultra fire cells. but anyone used these before and know their discharge rate?
http://www.ebay.com/itm/8pcs-Ultra-Fire-Efficient-18650-3-7V-5000mAH-Lithium-Rechargeable-Battery-Yellow-/360712561632?pt=US_Rechargeable_Batteries&hash=item53fc24e3e0
ecross said:-thanks for the friendly words, I have some buddies at Sanyo, Sony and some bigger Industry-Dealer and Bosch because I`m a modeller since about 25 years. When there is some interesting I can organize maybe a group buy from some good cells for ebikes
ecross said:-thanks for the friendly words, I have some buddies at Sanyo, Sony and some bigger Industry-Dealer and Bosch because I`m a modeller since about 25 years. When there is some interesting I can organize maybe a group buy from some good cells for ebikes
mj2412 said:Dear E-cross,
i'm also very interested in this sony cells or the Samsung INR18650-20R as an alternative. I'm living south of you in Austria.
Regards, Martin
That would be most audacious and I'd definitely be interested. The following is a repost of some ideas of how to make that happen in a manner that is fair and doesn't leave anyone burned (which has happened).ecross said:Im very interested in Sony Konion US18650VTC4. These Cells have >2000mAh, 15C continuos and do not need balancing.ecross said:-thanks for the friendly words, I have some buddies at Sanyo, Sony and some bigger Industry-Dealer and Bosch because I`m a modeller since about 25 years. When there is some interesting I can organize maybe a group buy from some good cells for ebikes
To that, I'd add the possibility of more than one agent and drop point. There could be one purchase contract so as to garner the best price, and then an agent/drop point in the USA, Europe and Australia, for instance.myself said:I've tried garnering interest in the following before, without much, and will again, because its a really good idea. Its a variation of the cooperative purchasing attempts (or "group buy") here at ES with improvements.
It would of course require the ES community to get over prior failures with cooperative purchasing and acknowledge that we all share the same needs and problems fulfilling those needs.
- it takes volume to make a great price, so marshal the ES community to support a large joint purchase
- the WHAT, chemistry, format, manufacturer, etc. gets debated, summarized, voted and posted
- a purchasing, receipt and shipping agent is contracted - yea, actual contract - with a fee granted by the participants
- the agent has the paypal email and account to which the participants pay in
- the actual name, address, driver's license, phone number and photo are disclosed as part of the contract
- contract stipulates confidentiality and non-disclosure by the participants
- agent must be lithium-ion shipping certified, so as to legitimately place orders on common carriers (UPS ground); or not, there was some debate on this issue and at least in the USA, its possible to use the USPS without penalty, shipping li-ion batteries
- payment is in two pieces: 1> the bulk purchase by wholesaler cost, on a per cell basis, and 2> the final per cell cost adjusted for capacity plus shipping cost plus agent fee
- the first payment acts like a non-refundable deposit - its a buy-in cost
- upon receipt, all cells are numbered, charge/discharge/charge tested and placed into matched lots
- results are posted to the participants; higher capacity lots are at a premium; lower capacity lots are discounted; the average is the mid-point; the premium and discount rates are agreed upon by the participant group
- shipping containers for lithium-ion, external labelling, etc. are procured
- shipping costs are figured - all shipments by the same carrier (UPS ground); labels are generated
- final fee is negotiated, accounting for the actual time commitment by the agent
- final payments are made, again via paypal
- everything ships
- evaluations made, summarized and results of the cooperative purchase posted, with recommendations for improvement for the next go
- the process is repeated by the next group needing new batteries
See this search for history on group buy.