Here is a good used source for 18650 batteries

[eccerr0r]

How much current can one safely get through those typical lithium ion pack slide-in-blade contacts?

I suppose slide in contacts like most laptop batteries and apparently tool batteries too.

Not sure what kind of load these packs were designed for other than the ampere-hour rating so at 1C it should be 6A, so I would hope that it at least would survive 6A... but more? Will it take 12A if the batteries can take 12A?

I don't think I'll do much more than draining the cells at 2C as that's kind of rough as it is, but curious how much these things can take, how it compares to like XT60s.

[sam_sam_sam]

Originally Posted by eccerr0r

How much current can one safely get through those typical lithium ion pack slide-in-blade contacts?

I suppose slide in contacts like most laptop batteries and apparently tool batteries too.

Not sure what kind of load these packs were designed for other than the ampere-hour rating so at 1C it should be 6A, so I would hope that it at least would survive 6A... but more? Will it take 12A if the batteries can take 12A?

I don't think I'll do much more than draining the cells at 2C as that's kind of rough as it is, but curious how much these things can take, how it compares to like XT60s.

What I can do when I get the new battery pack I can test it what ever amperage you would like and post the results

I did test them before I modify them briefly at 8 amp and they seem to alright but I only did it for 5 minutes
But if you want any certain amount of time that you would like to test them at just let me know and I can do it as long as the battery pack does not get to warm or the voltage drops to fast

I do have 4 loose batteries that I have left over from the battery pack that I can test individually and post the results just give me the parameters that you want them tested at

If I was doing it I would use the X90s they are little harder find but I have seen them before

[eccerr0r]

I think they're dual wipe tin plate, but hard to gauge how strong they grab onto the blade when inserted. Also wonder specifically these contacts, regardless of whether the battery can handle it or not.

Laptops seem to have gold plate and might handle more amps, but I suspect contact area/contact size also has an important role.

I suppose I can measure the voltage drop across it. hmm... just enough space that I may be able to get a probe on both contacts...

[sam_sam_sam]

You could use something like this

https://www.ebay.com/itm/32241575748...3ABFBMvLu1ws5f

Or

This type

https://www.ebay.com/itm/30367643235....c101113.m2108

[eccerr0r]

Well, once again, trying to use the existing hardware especially if the cells aren't up for more anyway.

I have a few XT90s to play with if needed but curious how much those blade connectors can go. Ease of assembly (eject/insert battery) is probably the main focus of these connectors versus current capacity, though it may well be "enough" ...

[sam_sam_sam]

Well I just received the two battery packs and they are charged up 51.something and each battery of cells are 3.9something to 4.something so I am ready to test these batteries over the weekend

( maybe I have to test some other batteries that I am having some issues with so I can get an adjusted refund on this battery pack that I mentioned earlier in this or another post )

This is the way these batteries come most of the time the first one that I got was only 49.something volts but they had sat for about 4 months before I did anything with them and they have tested good so I just have to get the BMS protection board wired up and put it in its enclosure

( which is made for these battery packs ) that I also bought from BH and put the battery hookup wires and ready to be put in service 15.something amp hours to 16.something amp hours
The way I have them configured so with both half’s they will total to about 30.something to over 32.something amp hours

The only time that I get concerned about battery that I get from BH is when the battery voltage is below 2.5 volts or below this but have some that are so low because the BMS protection board are bad and have run them down this low and have to take them apart and cycle them a few times and they should be ok

[sam_sam_sam]

Originally Posted by eccerr0r

Tried to connect the two packs in series for 48V and fed it to a 1500W @ 120VAC RMS heat gun. It drew around 4A for about 175W and yes it spit out quite hot air. That is about the limit at 48VDC into a 120VAC device. As for capacity, not sure how long it can maintain this power... and now need to find something that can draw even more power...

I have to try this myself with the two battery packs that I just bought and see how well this would work for a testing load the next time I defrost my freezer who knows it might work better than I think

[eccerr0r]

Dont think it will push enough hot air for freezer defrosting, but who knows.

I wonder if I can pop popcorn with a hot air popper at 48V though need to put less corn in the chamber as there won't be as much hot air...

[sam_sam_sam]

Did you get your order from BH yet

[eccerr0r]

I didn't order from there, shipping cost was too high.

[sam_sam_sam]

Originally Posted by eccerr0r

I didn't order from there, shipping cost was too high.

Can I ask you where you got your batteries from

[eccerr0r]

oh it was that local shop that closes out stuff, so they only had one (or actually, two, but they were bundled) ... so not a good place to get cells. TBH not sure about the effort, have to scan them in person for new inventory to see if they just so happen to have li-ion packs or not. So yes I had to pay sales tax on them. And my car was the shipping fee...

[eccerr0r]

Ooh... now the local shop has two 40V 6Ah li-ion packs for Ryobi tools... alas they're not at a price I'd pay for just storage capacity as I don't own Ryobi tools. To buy the packs out it's about $200/kWh which is way out of my range...

I did snatch up a 10S charger brick from there today however. Who knows if I someday get a 10S pack or modding to a different voltage is never out of the question...

[sam_sam_sam]

Originally Posted by eccerr0r

Ooh... now the local shop has two 40V 6Ah li-ion packs for Ryobi tools... alas they're not at a price I'd pay for just storage capacity as I don't own Ryobi tools. To buy the packs out it's about $200/kWh which is way out of my range...

I have done a Forensics investigation into these battery and they are not a good choice for harvesting battery cells from because either the batteries fail or the BMS protection board takes a shit and destroy the batteries I am not sure exactly which one happen first

A better choice it there 18 volts 6 to 9 amp hour batteries these BMS board are made a little bit better and NOT always destroy the batteries when they fail they just do not put out power most of the time at least the ones that I have repaired because of mosfet failure

[eccerr0r]

Supposedly these packs are new, hence the "premium" price - I paid far less for the other packs though they hold far less too, though they should likewise be new.

Looking at the Despot these packs are like $400/kWh OUCH... though granted one of the two packs at the liquidator was an off brand.

[eccerr0r]

I hooked up the two 24V packs in parallel and fed it to a 24V hot plate I had... it drew about 7.5 amps - about 175 watts from the packs. The set of packs drooped ~0.6V. Not great but it did pump out the watts, now not sure how long it can sustain it.

[sam_sam_sam]

Put a pot of water on the hot plate and let it rip until the battery voltage drops to around 18 volts and time how long it takes to get to that voltage and you can then estimate how many amp hours they have

The battery packs that I made modifications to I get around 14.5 amp hours which is not bad for the price I paid for them

Now that I know how to modify them the easiest way I am going to make two 20 volt battery packs for the air compressor that I have talked about before

[eccerr0r]

At 175W it'd take a while to boil, though it's not really meant to heat food, it was meant for 3d printers...

Anyway I need to make a receptacle for the packs so they can be more used together. 3D printing time...

[sam_sam_sam]

Originally Posted by eccerr0r

At 175W it'd take a while to boil, though it's not really meant to heat food, it was meant for 3d printers...

Anyway I need to make a receptacle for the packs so they can be more used together. 3D printing time...

Can you please post some pictures of this when you finish this because I would like to see what you came up with

[eccerr0r]

Not really much of a design but swiped an existing design on thingiverse and something like this will hold the two packs together...