Complex Battery project HELP!

forgotmyname

Just found a review on Amazon, claimed 8800mAh actually 1560mAh.

So yes run them in parallel and get 35200mAh but your going to need at least 22 batteries to get 3.7v and your laptop will run at 11.1v or 14.8v?

So you will need at least 66 batteries for the 11.1volts
Or 88 batteries for the 14.8volts.

With each extra battery you add the greater the cost of the charge controller and the charger itself.

Unless you dont mind waiting many hours/days for it to charge?

Why not just replace the batteries in your laptop battery? You say its 9 batteries? 3 in series and 3 in parallel. 11.1v and 4500mAh ??
9 decent cells £54 - £90.

Providing the charging circuit is all good of course.

EdwardB

Hi

Thanks for the advice.

I was actually thinking 4 batteries which is what is currently used, I would actually settle for 2200mAh each

How do I check the actual mAh delivered?

I do get that I have to find a supplier that actually sells decent stuff.

I used to think the problem with the Chinese was just very very poor quality control, but it seems that they deliberately scam people. Batteries, USB, memory etc.

A chinese guy I used to work with told me that they have these circles in relationship starting with family and extending outwards, the further out the more acceptable it is to have disdain for the person.

We see reports of their so called cancer villages and one chap got charged I seem to remember for poisoning a village with waste.

I have managed to buy decent cells for my laptop on eBay so there are clearly some out there, question is how do you spot them.

I still think it is worth trying this because the way I see it is I could buy an alternative battery and run the very same risk.

Also there has to be some value in finding a reputable Chinese supplier, if such a thing exists!!??

I need a way to test the MaH at the outset and the quality of the battery, I am wondering if the weight is a factor in determing the quality?

What I am doing is not really that different from what people do every day; using several batteries. Difference is they are taped up. Or they are connected serially in a radio or kids toys, done that for years and charged cells in chargers.

They warn not to mix old and new which I already got the advice on.





Features:
Brand new and high quality
3.7V 8800mAh TR26650 Li-ion battery
Discharge rate, no ""memory effect""
Low reoccuring operation cist
Short circuit and over-current protection
For appliances like Flashlight etc.
Environmental friendly

Cautions:
1.Do not dispose in fire or heat
2.Do not puncture, damage and disassemble
3.Do not mix fresh batteries with used batteries

Product Properties:
Type:Li-Ion
Model Number:TR16340
Quantity:1Battery
Voltage:3.7V
Rechargeable:Yes
Color:Red
Size:Approx. 68*27mm(L*D)
Net weight:87g
Nominal Capacity:8800mAh

Specifications:
Type: Li-ion battery
Model: TR26650
Quantity: 1
Battery Capacity: 8800mAh
Battery Voltage: 3.7V
Rechargeable: Yes
Color: Red
Size: Approx. 68*27mm(L*D)

GunJack

Fasttech and Gearbest are reputable for batteries, just stick with the name brands (e.g. Samsung and LG for 18650s)..

Strider590

I did mention earlier, an 18650 should weight 45g or more, anything less is a definite fake, but they're clever little sh*ts, they take a smaller battery (14505 for example), tack wires to the ends and suspend it inside an 18650 sized tubed filled with sand/concrete and they can also lie on the eBay ad about the weight.

3600mAh is currently the highest capacity possible in the 18650 cell size.

Testing them requires a battery tester, which discharges them at a set rate, until they reach a set voltage, then calculates the mAh from the discharge rate versus time. You could do this with an 18650 manually, but you'd have to make sure you catch it before it's voltage dropped below 3v, or it's ruined.

EdwardB

GunJack wrote: »

Fasttech and Gearbest are reputable for batteries, just stick with the name brands (e.g. Samsung and LG for 18650s)..

Thanks, they do not seem to sell 8800mAh ones but I will check for smaller ones.

Appreciate your time and referral.

forgotmyname

Nobody sells genuine 8800mAh batteries because they dont exist. You can get 3000mAh 18650 batteries but they are a lot dearer than the 2000mAh ones.

You claim to have bought decent batteries off ebay. OH DEAR!!!
You have not tested them yet. And you need to ask how to test them so
you wont have the equipment.

Yes nothing wrong with having batteries in parallel or in series or a mixture of both, almost every laptop will have the same configuration.
You said the existing pack is 9 batteries so thats 11.1 volts yes?
How are you going to get 11.1 volts and a decent Ah rating with 4 batteries?

You can use 3 and have a spare one, but the capacity will be much reduced.

And yes batteries have been used like this for many years even car batteries are 6 x 2v cells in one case.

The issue with lithium though is that you cannot leave them on charge. They must be charged at the correct Ah rating and at the correct voltage. Once fully charged the charger MUST switch off. Unlike old batteries it wont hurt if a small trickle charge is left on, but try that with a lithium pack and it wont end well.
You may end up on the news after the battery burns your house down.

Your trying to save money but your going to end up with dodgy rip off cells with questionable quality or kill a decent set of cells because you dont have a proper charge controller. Or a controller to prevent the batteries running down too low. Run them flat and they wont ever recharge.

wealdroam

At the moment OP, you are living dangerously.

Have a read of the Battery University website.

There are also a number of people with great experience of building, maintaining and repairing lithium ion batteries on the pedelecs forum.