Here is a good used source for 18650 batteries

[sam_sam_sam]

Re: Here is a good used source for 18650 batteries

Here is something new at BH

https://batteryhookup.com/products/p...ah-18650-cells

Quantity 10 = $16.65 shipping to my address

[eccerr0r]

Re: Here is a good used source for 18650 batteries

hmm...shipping kills the deal...

[sam_sam_sam]

Re: Here is a good used source for 18650 batteries

hmm...shipping kills the deal...

Just how much are you willing to pay for shipping just curious

[eccerr0r]

Re: Here is a good used source for 18650 batteries

well if I wanted to buy $16 worth of batteries (or even more) and had to pay $16 shipping, well, it doubled the cost of the batteries...
I'll have to see how much batteries I really want... and since these are perishable I really don't want to overbuy.

[sam_sam_sam]

Re: Here is a good used source for 18650 batteries

I'll have to see how much batteries I really want... and since these are perishable I really don't want to overbuy.

What I can tell you is if they are brand name batteries they last at lease 3 to 5 years that much I can tell you
You just got to check them every so often to make sure that they have not gone below a certain voltage which I have not been very responsive to so I have had some go bad because of my own laziness

But I would agree you about over buying them but I am going to build low voltage power high amp hour battery for my tablets I just have to finish testing a lot of batteries but the first project that I need to finish is the battery pack for the battery operated air compressor that I need to finish testing the batteries and I hope that I have enough of the same milliamperes hours rating that are close enough to each other and then make a 12 volt jumper battery pack out of some of them that use a PWM controller to being with then switch to a boost converter control the amperage to the vehicle battery until the vehicle battery can start the vehicle or least is the plan ( which I have to test this concept to see if it is doable )

I have seen some people on YouTube that have used this type of battery to start a car with the only issue is over charging the batteries that is the only reason I have not tried this yet but I have even thought of using 4 battery cells instead of 3 batteries but then you have an issue of the batteries not getting fully charged so I am not sure what the solution to this problem is

[eccerr0r]

Re: Here is a good used source for 18650 batteries

yes craptacular life. Should just get LiFePO4 cells and do away with the LiCo/LiMn cells...

Yep need to stop it from charging when done, though technically speaking they have protection boards that work for drones that pull large fractions of a horsepower. Starter motors are only like 4 horsepower max... and could work with more of the same circuit in parallel.

[sam_sam_sam]

Re: Here is a good used source for 18650 batteries

I have started testing the batteries in this battery pack and I am not real impressed with the results so far

The rating for these battery are supposedly over 8 amp hours however it falling just short of 8 hours more like 7.2 amp hour not real bad but would be better if it were over 8 amp hours

But now let’s see if the majority of them test close to each other if they do this would be great

https://batteryhookup.com/products/2...41044571062434

The description of this battery pack its says that it is 7s3p and 21 batteries but 7s 2p and there 28 batteries instead of 21 batteries so I suspect that the watt hours are not correct either

[eccerr0r]

Re: Here is a good used source for 18650 batteries

Hmm... picked up a 4S 40Wh laptop battery for $1... Unknown condition, theoretically fresh off boat... Wonder how bad this pack is...

[sam_sam_sam]

Re: Here is a good used source for 18650 batteries

Hmm... picked up a 4S 40Wh laptop battery for $1... Unknown condition, theoretically fresh off boat... Wonder how bad this pack is...

From EBay or some where else or from that surplus place that you mentioned earlier

[sam_sam_sam]

Re: Here is a good used source for 18650 batteries

I have started testing the batteries in this battery pack and I am not real impressed with the results so far

The rating for these battery are supposedly over 8 amp hours however it falling just short of 8 hours more like 7.2 amp hour not real bad but would be better if it were over 8 amp hours

But now let's see if the majority of them test close to each other if they do this would be great

https://batteryhookup.com/products/2...41044571062434

The description of this battery pack its says that it is 7s3p and 21 batteries but 7s 2p and there 28 batteries instead of 21 batteries so I suspect that the watt hours are not correct either

The description turns out to be correct very strange the way this battery pack was put together

[sam_sam_sam]

Re: Here is a good used source for 18650 batteries

Here is a super nice battery pack it tested way better than it is saying in the description

https://batteryhookup.com/products/2...-6-4a-299-99wh

I tested half of the battery pack because I split it in half which is very easily done just take the buss bar off and remove a few screws and now you two 28.6 volt battery packs when fully charged and 21 volt when discharged

Now I going to test the other half of this complete battery pack before I split in half

1.5X4=6 amps hours what the battery specifications are I got 8182 milliamperes hours

I just got to find a low watt pure sign wave inverter and the solar controller that someone talked about in a post I recently read

[eccerr0r]

Re: Here is a good used source for 18650 batteries

It was the local store, alas there was only one.
I need to dispose of the cells I destroyed by overdischarging by accident. Probably holding around 500mAh now

How do you split a 13S pack in half?

[sam_sam_sam]

Re: Here is a good used source for 18650 batteries

It is really a 13s I was confused about this at first but if you take a volt meter you figure out that it one pack has 6 cells and the other one has 7 cells

I slightly over charged the the 6 cell side to 4.66 volts this is reason I such high milliamperes hours rating and the funny thing is that it did not over heat which was a good thing ( but it is a good thing that I was only charging it at one amp so each cell was only getting about 250 milliamperes it did get a little warm but nothing terrible to be concerned about )

The other side I did not fully charge I will have to redo it to get a more accurate milliamperes hours rating of this battery pack

Actually I need to retest the first battery pack again for a real milliamperes hour reading

[eccerr0r]

Re: Here is a good used source for 18650 batteries

at least it didn't immolate...

Charging that high probably cuts some cycle life...

What will you do with the 6S vs the 7S halves?

[sam_sam_sam]

Re: Here is a good used source for 18650 batteries

I going to buy a couple of more of them and pair them up so that I the same exact number of cells for each side

Although the 7 cells one is a little odd 29.5 volt battery pack right now I do have anything that I use it on with out putting some kind-a of regular on it

I have a use for a 8 cell battery packs but not 7 cells
I have uses for a 6 cell battery packs but not 7 cells

Oh by the way I will not be charging it that way anymore I thought they were the same on both sides but they are not

It might have but I think it would be worse if you continuously over charging it which do not plan on doing

[sam_sam_sam]

Re: Here is a good used source for 18650 batteries

I destroyed by overdischarging by accident.

Maybe not try this before you throw them out

Put them on a very slow charge over night and see if they will come back ( like 100 milliamperes or less and just keep an eye on them )

I have also done this in the past and sometimes they will come back but one cell at a time not a bunch of them together

[eccerr0r]

Re: Here is a good used source for 18650 batteries

Oh they charge fine, got them back up to 4.2V and they don't warm up...just doesn't hold as much energy as they used to.

BTW I overdischarged them to like 1V or so. Not down to 0 but well below the 2.5V typical low voltage. They were running 2S with a fairly substantial load, and were still producing electricity when I stopped it, but they have not behaved the same since.

[sam_sam_sam]

Re: Here is a good used source for 18650 batteries

Oh they charge fine, got them back up to 4.2V and they don't warm up...just doesn't hold as much energy as they used to.

BTW I overdischarged them to like 1V or so. Not down to 0 but well below the 2.5V typical low voltage. They were running 2S with a fairly substantial load, and were still producing electricity when I stopped it, but they have not behaved the same since.

This is weird what brand are these batteries

You are not using a BMS protection board

I will test batteries with out a BMS protection but not use them with out one

[eccerr0r]

Re: Here is a good used source for 18650 batteries

I was trying to balance them outside of the BMS balancing... with the other two that are weaker but ended up killing them instead....uuggh.

They are panasonic IIRC.

[sam_sam_sam]

Re: Here is a good used source for 18650 batteries

I was trying to balance them outside of the BMS balancing... with the other two that are weaker but ended up killing them instead....uuggh.

They are panasonic IIRC.

Unfortunately I have seen this also but this seems to happen to certain series of them but not all them