Battery Hookup new listing “Case 100x 3.3v 2200mah - 200x 18650 Lifepo4” for $100.00 + shipping

[sam_sam_sam]

Glad to hear that you do not have to weld anything
As far as the BMS board if it is damaged then you really do not have a choice

[eccerr0r]

Hopefully it's repairable and moddable at the same time, no loss if it's a failure, it was left for dead to begin with.

Really need to look into tab welding again.

[sam_sam_sam]

Microwave oven transform and a controller will work just fine if you are on a tight budget

[eccerr0r]

or if those car batteries could be resurrected ...

[sam_sam_sam]

or if those car batteries could be resurrected ...

Yeah you could go that route as well but you still need a controller with that setup as well but do your research on that because some of the controller have issues

[eccerr0r]

going to run out of mosfets... or have to farm more mosfets. Probably homemade microcontroller based controller, that's a lot easier to make than a low power BMS since I think I have the proper parts because I won't need to worry about power consumption.

Then again the lowest Rdson spare mosfet I have is more like 10mΩ which means I'll probably need to parallel a lot of them.

I still need to get tab wire however. need to try to avoid having to buy that...tariffs and all...

[sam_sam_sam]

I still need to get tab wire however. need to try to avoid having to buy that...tariffs and all...

Pure nickel tabbing is better than steel coated nickel but the pure nickel is more expensive than steel coated nickel

You can see steel coated nickel but keep in mind to not scratch the nickel surface because if you do it does not solder very well when this happens

Here is an example of an eBay seller who sells pure nickel tabbing material

https://www.ebay.com/itm/38273586207...3ABFBM8O3Ow9ll

Can you make the source code available if you go down this route I would greatly appreciate it and a diagram for how you hooked up the mosfets to control the voltage and current cut in and cut out

I know it can be done with a DAC ic chip and I have idea how to write the parameters I would like to see but to wire the source code is a another story

[eccerr0r]

btw, those 24V packs uses nickel coated steel... cheep cheep cheep eh?

[eccerr0r]

DAMN this conformal coating that didn't help...

[eccerr0r]

Ugh. Looks like these 24V packs are on the threshold of being able to run my GTI before it kicks off due to UVP. So barring getting a 12V pack going, I used a 12V7Ah lead acid battery in series with the 24V pack.

Holy crap. GTI draws >350W through the series/parallel combination. Of course it's not very healthy for the lead acid, so I didn't leave it connected for long, though there is probably around 10A flowing. If I had another LiFePO4 there it'd probably fry the GTI however, at least until the batteries' protection circuit kicks in.

Really need to figure out this BMS, though can't figure out how this thing is connected and whether or not the backside of the board was compromised which would explain the confusing connectivity I'm seeing...

[sam_sam_sam]

When you figure out what voltage an current is required to effectively power your GTI I think half of your battle will be won then you will know what BMS voltage current requirements are needed for GTI to run efficiently

Jus be careful about what BMS protection boards you buy if you are doing 12 volt one and you are trying to get to 36 to 48 volts because not all BMS mosfets can handle that high of voltage from what I have read and understand

[eccerr0r]

Ugh. Modding the existing BMS will suck. They deliberately made it hard to mod
Will take a bunch of jumper wires. *sigh*
And a capacitor fell off the bottom side as I removed it... means the tracks are really bad shape from the water damage.

[eccerr0r]

After studying this some more... maybe it is possible, but requires a lot of surgery:
Need to:
1: add two wires (eiew. SMT surgery)
2: remove two resistors *maybe* (eiew. SMT surgery)
3: move one resistor around (eiew. SMT surgery)
4: reconfigure interstitial nodes of the pack. (big regular soldering, easy)

Hmm! I wonder if this will actually work... and this 8S BMS will become a 4S BMS...

Of course this depends on whether this bms is still working after the water damage.

[eccerr0r]

Oh this water damage bites the big one...
found one dead resistor, one severely broken track, capacitor fell off (I *had* it and then I dropped it... yay for dropping 0603 smd caps).
At least the conformal coating gets eaten by methylene chloride so it's a bit easier to work with.
Still not sure if I'll come out of this with a PoC of a modded BMS and a 12V battery pack made from the cells that weren't sitting in the water. On the positive note, those cells that weren't sitting in the water is still measuring 12.55V after sitting for a few days.

[sam_sam_sam]

Well I split one. Of the 24 volt Lipo 4 in half and using the plastic prying bar made it very easy to to do and it did it cleanly I was very surprised by this so I have two 12 volt battery enclosures that I could not make my about what battery cells to put in them and decided to put half in one enclosure and the other half in the other enclosure and put the BMS balancing leads and board in one of them and just pass the other battery connections to the one that has the BMS board in it although I might change my mind about doing it this unless I can find a BMS board that I can put it in series I would prefer to do it this way

Use the 24 volt BMS balancing board on some other battery cells that are also made in China but are high current capacity and make a high current long running capacity battery pack

One note the first two battery packs I took apart have green heat shrink tubing and this one has blue heat shrink tubing and do not think that are made in the same factory but they might be

[eccerr0r]

Grr still cant make this bms turn on with only 12V...

Should I crack another 24V pack and experiment on that instead of this water damaged one...

[sam_sam_sam]

Grr still cant make this bms turn on with only 12V...

Should I crack another 24V pack and experiment on that instead of this water damaged one...

Probably but I am wondering if you start from the side that hooks up to the power supply rail because if I remember right some of them do it this way and some of them you just tie the positive side leads that are not used together and it supposedly works fine that way I really have to look at it very carefully and closely to see how this one is done

Dose have two BMS voltage sensing ic chips or just one if just has one for all of the battery cells you might not be able to do it on this one


Oh by the way what did BH tell you about your bad battery pack

When I told about testing BMS balancing protection ( for BMS balancing protection functionality ) on these battery testing machines they said that they have tested thousands of battery cells packs with BMS balancing protection boards and never had any issues but I noticed that they changed the description and now it says that you have to put the parameters of the battery cells that you are using which kind a warning of sorts and this implies you should not let the BMS balance protection board turn ON or OFF interesting that they change the description of it

[eccerr0r]

it *looks* like the negative side is hooked up to the mosfets but having a hard time tracing. I think they're using a strange method to attach the temperature sensor which is why this is so difficult - plus whether or not any of the devices were damaged from the water.

Supposedly they shipped me a replacement so hope that comes.

Well that isn't a good sign that you can't depend on the BMS board...

[sam_sam_sam]

Well that isn't a good sign that you can't depend on the BMS board...

What do you expect from something that got damaged by sitting in water or what ever it was that caused this damage

Here are some pictures of the 24 volt battery split into two battery packs now I hooked one of them and testing it out on the battery testing machine

I had to hot glue the battery cells back together when I split it into two half's because they were all loose then
I also put a little bit of hot glue underneath the BMS balancing protection board as well to hold it down on the plastic plate and reused the tape to hold the plastic plate on the battery cells

I am not impressed by this BMS balancing protection board it cutoff voltage is around 15.5 volts but it turns right back on again several times but the battery cells have become a little bit warm because it not functioning properly and I not going to use it for this project I will have to try another BMS balancing protection board that functions properly for this project

[eccerr0r]

The BMS on the 24V packs are significantly different from the reference design.
Tracing vias that go underneath components sucks.