Search found 1054 matches

by rg12
Oct 16 2019 12:14pm
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

I think the best rule of thumb for general applicability is to ignore the fictional advertised C-rate completely. Rely on objective standardised testing only, if high C-rate is important to your use case. Most people with high powered ebikes can use the 50% of advertised C rate rule and it will wor...
by rg12
Oct 16 2019 4:33am
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

I never really looked at other cells for high discharge as I'm a business and cells that are claimed to be better (by a bit) cost at least 50% more than the 25R so it's the most affordable for sure. Just know that you shouldn't go over 50% of their C rate if you want it to have a decent life span a...
by rg12
Oct 15 2019 3:56pm
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

I'm still surprised by the super low IR it has out of the box (7 milliohm) but I still wander if I use it at half it's discharge rate for bursts just like I limit customers with the 25R which is my main cell that it will last just as long. Hi rg, What do you think about the 25R against other cells,...
by rg12
Oct 15 2019 10:54am
Forum: Battery Technology
Topic: Copper instead of Nickel, necessary?
Replies: 1
Views: 129

Copper instead of Nickel, necessary?

a.jpg I mean, of course it's better than nickel but is it really THAT necessary? I use 0.15 thick pure nickel that is "closed" no gaps, like here in the photo of the copper strips and it ends up being equal to 16mm wide piece of nickel from each parallel cell to the next one in series (you can also...
by rg12
Oct 15 2019 8:40am
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

this is my thread with my specific question about the 40T … the 40T seem awesome as they have great energy density while being rated for high discharge although that I'm not really sure about since I heard they have a short life span so this is the reason of this thread, to find out if there is any...
by rg12
Oct 15 2019 5:59am
Forum: Battery Technology
Topic: ANT BMS High Pitch Sound
Replies: 0
Views: 62

ANT BMS High Pitch Sound

Is this normal for the BMS to produce an annoying electronics interference kind of high pitch sound (like if you put your ear next to a transformer...)? It's all the time, even when the BMS is disconnected from bluetooth and is in standby mode. The app says runtime of 4 days 13 hours which is weird ...
by rg12
Oct 15 2019 4:27am
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

LiPo packs are routinely rated 30C and higher. Some are fine at 8C or even 10C. Really good way to go for maximum power density. My point was, it seems likely your problem is caused by your overestimating the ability of your pack to support your C-rate needs. Better quality cells and/or bigger Ah c...
by rg12
Oct 14 2019 6:24pm
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

I should do that actually but it's packed so nice (my 7P) to tare apart right now but I may do it if I find myself mega motivated with not much work around me...
by rg12
Oct 14 2019 8:55am
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

I am a total noob, so no advice to offer. But the past threads repeat advice from the real experts over and over, it seems every month. Most cells rated as 30C by the maker should not even be used at 5C for more than a few seconds. Every month you say I'm given an advice and I don't take it? I'm ha...
by rg12
Oct 14 2019 8:11am
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

If by "20C rated" you mean mfg specs, yes that is guaranteed to not work, those are 100% pure fiction. Anywhere above 4-5C even on much better (actual tested by users) rated cells, will mean a very short lifespan if a high duty cycle. Abuse is not a black and white issue, nor disparaging, just some...
by rg12
Oct 14 2019 6:40am
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

I am trying to imagine in rg12’s “real world” pack of many 18650s, how some of those “internal” cells with no exposure to external cooling, but infact surrounded by other “Hot” cells ..what their temperature build profile is like when the pack is subjected to bursts of 120+ amps (8C) ? Do those int...
by rg12
Oct 14 2019 6:27am
Forum: Battery Technology
Topic: BMS Programming Questions
Replies: 11
Views: 228

Re: BMS Programming Questions

What urgent, you start out, leave some settings like precharge and total cycle capacity at default, as you get more info, nothing stopping you tweaking later. Some, like the short circuit, I'd start lower / shorter and then raise them if I got too many false positives. Called scientific method, aka...
by rg12
Oct 13 2019 6:58pm
Forum: Battery Technology
Topic: BMS Programming Questions
Replies: 11
Views: 228

Re: BMS Programming Questions

Bump?
Kinda urgent for me sorry...
by rg12
Oct 13 2019 6:57pm
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

Its because you do not know what actual current you draw ar peak , and for how long...you are “guessing” And averages mean nothing when you are trying to find out what causes damage. Think.. you could swing a hammer at your head and “on average “ miss ...but one of those blows may hit and kill you ...
by rg12
Oct 13 2019 5:22pm
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

why do you stop recording after stopping the discharge? in my experience the temperaure continues to rise in high amp testing as the heat takes time to travel to the outside of the cell. Yes, you are right, there is always some thermal momentum adequate to amperage. I don´t stop temp recording with...
by rg12
Oct 13 2019 4:37pm
Forum: Battery Technology
Topic: How Hot Do BMS Fets Get?
Replies: 9
Views: 210

Re: How Hot Do BMS Fets Get?

flippy wrote:
Oct 13 2019 2:45am
open the bms and look at the fet numbers.

and ask the guy what currents he will be using.
He will use an ASI BAC4000 with max 180A but It's never constant so I need to guess the average amp draw somehow...
by rg12
Oct 12 2019 6:16pm
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

Hillhater wrote:
Oct 12 2019 6:04pm
rg12 wrote:
Oct 12 2019 8:30am
I want to log it with a line chart, not excel data, how did you do that? .....
Excel charts, ?
Hmm right :)
by rg12
Oct 12 2019 6:13pm
Forum: Battery Technology
Topic: How Hot Do BMS Fets Get?
Replies: 9
Views: 210

Re: How Hot Do BMS Fets Get?

if you have the 300A 32S bms from the bms thread then it wont get hot under 100A. if you are going to do a 100+ amps continous you will see "uncomfortable" temperatures. but those can be set in the firmware so it simply cuts out so you dont blow the fets. if you go beyond 100A continous i might rec...
by rg12
Oct 12 2019 8:30am
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

Can you please check out the link I attached in the previous message and tell me if it's a device that enables to create charts? btw, what is the difference between the temp probe that comes in the link I posted to the super thin one you use? Thermometer MASTECH MS6514 has logging possibility and U...
by rg12
Oct 12 2019 8:24am
Forum: Battery Technology
Topic: BMS Programming Questions
Replies: 11
Views: 228

Re: BMS Programming Questions

- It's default high cell protect is 4.19V while the high cell protect release voltage is 4.1V, is that common to set it to 4.19V? usually it's 4.25V but I don't wanna ever go that high. The point of a BMS is to protect the bank from your other gear failing. In this case, the HVC needs to be higher ...
by rg12
Oct 12 2019 8:16am
Forum: Battery Technology
Topic: How Hot Do BMS Fets Get?
Replies: 9
Views: 210

Re: How Hot Do BMS Fets Get?

If you know the Rds specification on the FETs, how many are in parallel, and your current drain, you can calculate how much heat is going to be dissipated. But temperature will also depend on how much cooling the BMS gets. I never really noticed the fets getting even warm and was told that they don...
by rg12
Oct 11 2019 4:13am
Forum: Battery Technology
Topic: Samsung 40T and other cells like it?
Replies: 75
Views: 1681

Re: Samsung 40T and other cells like it?

ZKETECH EBC-X0510 is 8 – channel equipment for long term cycling obtainable at Aliexpress. Allows full control of testing parameters : charge and discharge currents, charge cut-off, charge and discharge voltage, waiting time between cycles. Accuracy better than 0,3 %. Wow that is amazing! Can you p...
by rg12
Oct 11 2019 3:41am
Forum: Battery Technology
Topic: BMS Programming Questions
Replies: 11
Views: 228

Re: BMS Programming Questions

With the cell high voltage protection, you just need to make sure that either your BMS or charger cuts off charge current before it reaches 4.19. For example, my 10s 36v hoverboard pack and charger go to 42.2v, so 42.5v protection makes sense. Every basic bms and charger I've had do the same thing,...
by rg12
Oct 11 2019 3:32am
Forum: Battery Technology
Topic: How Hot Do BMS Fets Get?
Replies: 9
Views: 210

Re: How Hot Do BMS Fets Get?

There have been threads here with posts showing that under the wrong conditions, FETs get hot enough to desolder themselves from the BMS PCB. So...you'd have to test under your conditions how hot they get, with no airflow, and presumably the cells themselves up against that side (which will heat th...
by rg12
Oct 10 2019 8:18pm
Forum: Battery Technology
Topic: BMS Programming Questions
Replies: 11
Views: 228

BMS Programming Questions

I'm starting to use this awesome ANT BMS with the bluetooth app and so far so good, but since it's my first time programming a BMS, I have a few questions: - It's default high cell protect is 4.19V while the high cell protect release voltage is 4.1V, is that common to set it to 4.19V? usually it's 4...