Search found 221 matches

by eMark
Aug 09 2020 11:11am
Forum: Battery Technology
Topic: What's the longest period of time you can store a Li-Ion pack?
Replies: 28
Views: 389

Re: What's the longest period of time you can store a Li-Ion pack?

I think it's more likely the pack is out of balance from BMS parasitic drain. Think about it, a BMS with a 100 uA parasitic drain, stored for 3 years (3 x 365 day x 24h/days) that's still 2.628Ah drained off of one row of cells (enough to through the battery off balance). And if the pack performed ...
by eMark
Aug 09 2020 10:47am
Forum: Battery Technology
Topic: What's the longest period of time you can store a Li-Ion pack?
Replies: 28
Views: 389

Re: What's the longest period of time you can store a Li-Ion pack?

... while VTC6A and particularly 30Q shows poor results. There's about 75 cents difference between the HG2 ($4.50) and the newer 30Q 141 ($3.75) in quantities of at least 100 ... depending on supplier. With the old saying that you get what you pay the HG2, still looks to be the better buy in the lo...
by eMark
Aug 09 2020 9:25am
Forum: Battery Technology
Topic: What's the longest period of time you can store a Li-Ion pack?
Replies: 28
Views: 389

Re: What's the longest period of time you can store a Li-Ion pack?

I bought this pack from an eBay vendor in Australia (I'm in Perth western Australia myself). They're definitely the 18650 types. That much I know. To answer your original question a pack with cells in relatively good condition (whatever that means) with let's say no more than 50mv variance from the...
by eMark
Aug 01 2020 7:36pm
Forum: Battery Technology
Topic: Laudation batteries
Replies: 18
Views: 960

Re: Laudation batteries

Remember even with genuine new top notch cells the Ah capacity IRL conditions may only be 70-80% of what the factory rating says. Therefore at a theoretical 1C rate, the pack cannot last for an hour, after 40min or so you should be stopping if you want any kind of longevity. Hoping you would clarif...
by eMark
Aug 01 2020 12:12pm
Forum: Battery Technology
Topic: Laudation batteries
Replies: 18
Views: 960

Re: Laudation batteries

Back to Laudation, Panasonic NCR18650BD is a 10 amp battery - 3p should be able to do 30 amps, and not have an issue with 10amps. Don't you mean 30Ah ? That ebay Laudation site says in prominent underlined red lettering that your pack has either of these two cells (are you positive they are PanBD c...
by eMark
Jul 31 2020 7:45am
Forum: Battery Technology
Topic: Laudation batteries
Replies: 18
Views: 960

Re: Laudation batteries

From Laudation's site: Rated discharge current (a): 15а Instantaneous maximum discharge current (a): 30A Maximum Continuous Discharge Current (A): 15a I'll agree with those parameters, but shouldn't be getting hot at 10amps. If the price seems to good to be true then it's probably true that those c...
by eMark
Jul 30 2020 12:37pm
Forum: Battery Technology
Topic: Laudation batteries
Replies: 18
Views: 960

Re: Laudation batteries

Any pack that cannot sustain a 1C continuous discharge without heat build up, it is not suitable to be used for Traction applications . My conservative riding is to hopefully get at least 700 charge/discharge cycles over 5 years with my Samsung 30Q 10S3P DIY buiild. Balance charging at 0.5C (1.5A) ...
by eMark
Jul 28 2020 6:11pm
Forum: Battery Technology
Topic: Laudation batteries
Replies: 18
Views: 960

Re: Laudation batteries

by docware » May 15 2020 8:42am ... Re: Li-ion cells cycle ageing Cells warming in the closed battery pack will be probably too high even for 5 A discharge continuous with significant temperature inhomogeneity of the cells. Without suitable thermal management of the pack we can expect faster degrad...
by eMark
Jul 28 2020 1:03pm
Forum: Battery Technology
Topic: Laudation batteries
Replies: 18
Views: 960

Re: Laudation batteries

- Heat buildup under a moderate 10amp load for an hour is concerning My 10S3P with Samsung 30Q 141 cells isn't abused. Never draw more than a 5amp load at most and then no more than 1 minute at most. IMO, a 10amp load is NOT moderate with 30Q cells making up a 36V 10S3P (9 Ah) battery pack. Samsung...
by eMark
Jun 26 2020 11:47am
Forum: Battery Technology
Topic: HobbyKing unable to provide UN38.3 and MSDS
Replies: 13
Views: 279

Re: HobbyKing unable to provide UN38.3 and MSDS

i never got that few cycles from a production hobby grade lipo. Usually many more. Usually over 100, and I beat them with 200A @ 12s. amberwolf wasn't referring to a reputable production hobby grade lipo when he posted the following to which I responded and was basically agreeing with amberwolf ......
by eMark
Jun 25 2020 7:39pm
Forum: Battery Technology
Topic: HobbyKing unable to provide UN38.3 and MSDS
Replies: 13
Views: 279

Re: HobbyKing unable to provide UN38.3 and MSDS

Remember, there's a lot of these battery companies literally selling recycled garbage to their customers, so you can't really think they care about anything beyond money? Hopefully, it's not gotten that bad in our global economy. Who can undercut the competition and still satisfy the customer. What...
by eMark
Mar 08 2020 4:32pm
Forum: Battery Technology
Topic: Batteries involving 40T, 30Q and MJ1 cells. Preferences and opinions.
Replies: 17
Views: 814

Re: Batteries involving 40T, 30Q and MJ1 cells. Preferences and opinions.

It is my preference to ignore $ cost for this discussion, since that could complicate things in a non-physics way that could make this discussion messy and vague. Being your preference is to ignore $ cost what is the reason you are set on 1p (21700) or 2p (18650) instead of 3p 18650? Is your applic...
by eMark
Mar 08 2020 12:38pm
Forum: Battery Technology
Topic: Batteries involving 40T, 30Q and MJ1 cells. Preferences and opinions.
Replies: 17
Views: 814

Re: Batteries involving 40T, 30Q and MJ1 cells. Preferences and opinions.

There are too many unknown variables ... not enough specifics (application) to offer another/different opinion at this time. That said, assuming you can adequately justify your reasoning for these 4 choices should we disagree? It's your money, your DIY build, your specific application, your preferen...
by eMark
Mar 07 2020 5:40am
Forum: Battery Technology
Topic: Need help with the battery
Replies: 2
Views: 530

Re: Need help with the battery

I know that the discharge rate of this battery is too big and i want to use a 20s 100A BMS, is it possible to use this BMS without ant problem? or im gonna set something of fire? 50A peak is a stretch when it's spec sheet says 20A max continuous discharge (20Ax7=140A). Also this ES thread suggests ...
by eMark
Mar 06 2020 4:09pm
Forum: Battery Technology
Topic: Paralleling uneven voltage cells?
Replies: 49
Views: 2692

Re: Paralleling uneven voltage cells?

If I have two identical cells, one at 3.75V and the other at 4.10V and I spot weld a nickel strip to the positive and negative of both to parallel them , how fast will it take the two cells to level each other ? Will it be a super fast almost making the nickel red kind of current share or a steady ...
by eMark
Feb 27 2020 9:58am
Forum: Battery Technology
Topic: Lithium battery question
Replies: 85
Views: 6291

Re: Lithium battery question

AGREE! :thumb: Even though twilloug's EVE battery may be overrated at 30.6 amps max continuous discharge it's still good for short bursts of 30A (15-30 sec). The previous suggestion of connecting a 7S balance lead ... https://www.amazon.com/uxcell-Balance-Connector-Extension-Charger/dp/B07GN7S7BM/re...
by eMark
Feb 26 2020 10:15am
Forum: Battery Technology
Topic: Lithium battery question
Replies: 85
Views: 6291

Re: Lithium battery question

I did some research and the 18650 cells in my battery have a max continuous discharge current of 7650mA each. So with 4 in parallel, that would be a max of 30.6. So my 28amp motor and 30amp controller should be fine right. Note the cells are eve ICR18650 26V cells. Based on my last post, if my batt...
by eMark
Feb 26 2020 2:04am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 472
Views: 49790

Re: Li-ion cells cycle ageing

Realistically, doesn't that "If" become more of a challenge the more P-groups (e.g. 10S4P vs 14S8P) even with top brand name grade A cells as the battery ages. I again ask administrators to ban this trolling member acces to this thread. eMark is responsible for weed infestation also in other thread...
by eMark
Feb 25 2020 1:18pm
Forum: Battery Technology
Topic: What is wrong with this product?
Replies: 15
Views: 1457

Re: What is wrong with this product?

28ah for a 3p 18650 pack? not a chance. that's over 9ah per cell. i find it more likely that they are using garbage cells with only a few hundred mah per cell, so the *total* combined capacity of all the cells in *1s*, 3.7v, might be 28ah (just like the many "starter" and "accessory" packs on ebay ...
by eMark
Feb 25 2020 12:02pm
Forum: Battery Technology
Topic: Lithium battery question
Replies: 85
Views: 6291

Re: Lithium battery question

As it is now his 7S4P 30.6A EVE ebay battery will be too stressed with the 30A controller especially at full throttle. Besides the actual max discharge current of his Chinese ebay battery may be closer to 26A. There is no "huge boost in power" as you contend with his 30A controller and 500W motor. T...
by eMark
Feb 24 2020 12:10pm
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 472
Views: 49790

Re: Li-ion cells cycle ageing

It is simple. If my paralel groups are within 3 mV, resolution 0,1 mV is must for reliable and repeatable measurement. Realistically, doesn't that "If" become more of a challenge the more P-groups (e.g. 10S4P vs 14S8P) even with top brand name grade A cells as the battery ages. Requirement of ten t...
by eMark
Feb 24 2020 10:00am
Forum: Battery Technology
Topic: Lithium battery question
Replies: 85
Views: 6291

Re: Lithium battery question

Just to clarify ... if my battery is rated for 30.6 amps continuous draw, am i ok with 7s4p battery or do i need to go with different battery If so what size? Everything else is new why not another battery. :D Do you have space to double up the existing battery? The second one can be higher quality...
by eMark
Feb 23 2020 3:19pm
Forum: Battery Technology
Topic: Lithium battery question
Replies: 85
Views: 6291

Re: Lithium battery question

My biggest folly was not realizing that I was stepping into a preexisting pissing match while looking for a bit of thoughtful discussion. It's an ES thread that made it's way past the first page... I should have known better. I hope that the OP is able to find the information he is seeking. It's no...
by eMark
Feb 23 2020 1:44pm
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 472
Views: 49790

Re: Li-ion cells cycle ageing

Until you check the real voltages (first without BG-8S, then with BG-8S connected) with external voltmeter having sufficient resolution 0,1 mV and sufficient input resistance, you have no idea what´s truly going on. You do realize that 0,1mV is actually 0,0001V. It isn't necessary to have a DMM tha...
by eMark
Feb 23 2020 11:50am
Forum: Battery Technology
Topic: Li-ion cells cycle ageing
Replies: 472
Views: 49790

Re: Li-ion cells cycle ageing

Until you check the real voltages (first without BG-8S, then with BG-8S connected) with external voltmeter having sufficient resolution 0,1 mV and sufficient input resistance, you have no idea what´s truly going on. Padja where are you when i could use your moral support :) docware thinks he's talk...