Replacement BMS/ Charging protection

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James13963

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I definitely have a bad BMS / protection circuit fault. Is this board a possibility to replace the defective P-2S3015C? This goes in a Hypertough 5000 Lunen rechargeable work light from Walmart. I’ll attach pictures of everything. Any advice greatly appreciated.
 

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Isn’t this the exact one I have a picture of in my original post? If so, does that mean it is ok to use ? Thanks for your reply.
 
James13963 said:
Isn’t this the exact one I have a picture of in my original post? If so, does that mean it is ok to use ? Thanks for your reply.
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It looks like it to me - and it's listed as "2s". The main thing to confirm is that you're battery is indeed 2s4p and it should be good to go - just wire the new one in to replace the old one.

As a secondary issue - you said the old one failed but I'm not clear if you're cells were damaged / any cells need replacing. You could start by measuring the voltage of each cell with a volt meter. You can measure them without taking them out - just put the probes on + and - of each individual cell. If they're above 3.0v and 'pretty close' in voltage then likely the cells are OK and BMS replacement will do it. If not - then maybe they're still OK but that's a longer post.
 
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I checked all the cells when it quit working and I took it apart. They were all within .01 of each other at a hair over 3 volts. They’re at 2.7 now. The entire pack is charged with a 9v 2A charger so it seems that configuration would work right? (4 groups of 2 batteries positive to negative) which are connected positive to positive. (One straight strip of nickel across 4 batteries) I hope that’s right. 4.2v X 2 is 8.4v and adding the capacity of 2000mah X 4 should be 8,000mah. All that sound ok? I really appreciate your help. I have no idea but I want to learn.
 
James13963 said:
I checked all the cells when it quit working and I took it apart. They were all within .01 of each other at a hair over 3 volts. They’re at 2.7 now. The entire pack is charged with a 9v 2A charger so it seems that configuration would work right? (4 groups of 2 batteries positive to negative) which are connected positive to positive. (One straight strip of nickel across 4 batteries) I hope that’s right. 4.2v X 2 is 8.4v and adding the capacity of 2000mah X 4 should be 8,000mah. All that sound ok? I really appreciate your help. I have no idea but I want to learn.
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Yes - that's 2 x groups of 4 cells in parallel. The 2 groups of 4 cells are in series which increases the voltage of the overall battery.

As you say, these cells range from 2.8v (absolute empty) to 4.2v (absolute full). When you have 2s (2 in series) then you have a voltage range of 5.6v (absolute empty) to 8.4v (absolute full).

The BMS's job #1 is protect against too low a voltage (damage) and too hi a voltage during charge (risk of fire). A BMS will typically cut-off the flow of power in/out of the battery as it's means of protection. The BMS may also keep the 2 groups of cells in series balanced (e.g. at the same voltage).

With the cells a hair over 3.0v and very close in voltage the cells should be OK.

What exactly is the issue? Is it that you don't have any power flow? Maybe the battery drained so far the BMS cut-off and all you need is to add some charge to raise the cells up to 3.3v or higher to reactivate the BMS.

A hobby charger like this - https://www.amazon.com/Hobby-Fans-Professional-Balance-Discharger/dp/B09XC91BWJ/ref=sr_1_2 - where you select 2s mode would work to manually bypass the BMS and add some charge to the battery.
 
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OffGridInTheCity said:
Yes - that's 2 x groups of 4 cells in parallel. The 2 groups of 4 cells are in series which increases the voltage of the overall battery.

As you say, these cells range from 2.8v (absolute empty) to 4.2v (absolute full). When you have 2s (2 in series) then you have a voltage range of 5.6v (absolute empty) to 8.4v (absolute full).

The BMS's job #1 is protect against too low a voltage (damage) and too hi a voltage during charge (risk of fire). A BMS will typically cut-off the flow of power in/out of the battery as it's means of protection. The BMS may also keep the 2 groups of cells in series balanced (e.g. at the same voltage).

With the cells a hair over 3.0v and very close in voltage the cells should be OK.

What exactly is the issue? Is it that you don't have any power flow? Maybe the battery drained so far the BMS cut-off and all you need is to add some charge to raise the cells up to 3.3v or higher to reactivate the BMS.

A hobby charger like this - https://www.amazon.com/Hobby-Fans-Professional-Balance-Discharger/dp/B09XC91BWJ/ref=sr_1_2 - where you select 2s mode would work to manually bypass the BMS and add some charge to the battery.
Click to expand...

Again, thank you for your reply and help. So the BMS can reset at 3.3V? I didn’t know how to check the BMS with a meter. I was wondering how to test it. Hopefully I won’t confuse but here’s the whole story. Issue originally was went dead and when I plugged it in to charge had no idiot light showing it’s charging when plugged in. The light wouldn’t come on either.

I have a 2500 Lumen and this 5000 Lumen work light (both Hypertough from Walmart) When trying to figure out what’s wrong with the 5K light I took the 2.5K apart because they’re almost identical. I was going to swap parts around to find the culprit. They looked very similar and the BMS to an untrained eye looked identical. They both had the same number printed on their boards (P-2S3015C) I assumed they were the same. After a detailed inspection I noticed the 5K light had more little black squares on the PCB than the 2.5K. ( I did take the BMS from the 2.5K and put it in the 5K-maybe I got lucky but the light on the 5K did come on so I shut it off immediately) That’s how I decided this BMS is bad. It worked in the 5K one and the 2.5K one.

I’ve looked everywhere for the P-2S3015C BMS and even emailed lots of vendors on eBay and Allie Express. Nobody even gave me a direction to go. They replied simply saying they don’t have it and that’s all. I even considered buying another at Walmart just to see what’s inside but thankfully didn’t waste more money. Sorry it’s so complicated. Hope it makes sense. I do have some TP 4056 here that I can charge the batteries individually to 3.3V and it sounds like I need to do that immediately so the new BMS will work right. Last thing is I didn’t see how to wire this new one. The markings are different than the P-2S3015C board. I’ll Google it now. I’ll be happy to take the 2.5K light apart if that’ll help. The difference is it has 4 batteries instead of 8. I cannot thank you enough for your help.
 
James13963 said:
I do have some TP 4056 here that I can charge the batteries individually to 3.3V and it sounds like I need to do that immediately so the new BMS will work right.
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I don't know how this specific BMS works, was just suggesting that it 'might' have stopped letting the battery work to protect it because the battery got to a very low voltage and/or out of balance. When BMS protections activate, the BMS won't allow current to flow out or in - e.g. you can no longer give the battery a charge. The BMS just shuts off flow in both directions.

I don't know what the low voltage setting is in this particular BMS - could be 3.0v or 3.2v or ?? but was suggesting that (perhaps) an easy thing for you to try is to bypass the BMS and put some charge into the battery to raise it's voltage a bit. The 3.3v / cell was just a suggestion - perhaps 3.2v or 3.4v would work. Sometimes, this will allow the BMS to start working again once it senses the battery is 'out of danger'.

If you bought a hobby charger, hookup the sense leads, then you could bypass the BMS and 'take direct control' of the battery and charge it up / make sure it's balanced. Then, if the BMS still doesn't work t's clearly the BMS and you could buy a replacement from aliexpress.

If you do buy the replacement BMS from aliexpress - you have the "Balance" version per you pic (the BMS keeps the cells in balance) and the description shows the wiring diagram.
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I will buy the hobby charger you recommended. I have looked everywhere for a BMS
like the one in it a cannot find one anywhere. That's why I am asking about this BMS.
Thanks again for your help. I don't take it for granted.
 
OffGridInTheCity said:
I don't know how this specific BMS works, was just suggesting that it 'might' have stopped letting the battery work to protect it because the battery got to a very low voltage and/or out of balance. When BMS protections activate, the BMS won't allow current to flow out or in - e.g. you can no longer give the battery a charge. The BMS just shuts off flow in both directions.

I don't know what the low voltage setting is in this particular BMS - could be 3.0v or 3.2v or ?? but was suggesting that (perhaps) an easy thing for you to try is to bypass the BMS and put some charge into the battery to raise it's voltage a bit. The 3.3v / cell was just a suggestion - perhaps 3.2v or 3.4v would work. Sometimes, this will allow the BMS to start working again once it senses the battery is 'out of danger'.

If you bought a hobby charger, hookup the sense leads, then you could bypass the BMS and 'take direct control' of the battery and charge it up / make sure it's balanced. Then, if the BMS still doesn't work t's clearly the BMS and you could buy a replacement from aliexpress.

If you do buy the replacement BMS from aliexpress - you have the "Balance" version per you pic (the BMS keeps the cells in balance) and the description shows the wiring diagram.
View attachment 33577View attachment 33578
Click to expand...

OffGridInTheCity said:
I don't know how this specific BMS works, was just suggesting that it 'might' have stopped letting the battery work to protect it because the battery got to a very low voltage and/or out of balance. When BMS protections activate, the BMS won't allow current to flow out or in - e.g. you can no longer give the battery a charge. The BMS just shuts off flow in both directions.

I don't know what the low voltage setting is in this particular BMS - could be 3.0v or 3.2v or ?? but was suggesting that (perhaps) an easy thing for you to try is to bypass the BMS and put some charge into the battery to raise it's voltage a bit. The 3.3v / cell was just a suggestion - perhaps 3.2v or 3.4v would work. Sometimes, this will allow the BMS to start working again once it senses the battery is 'out of danger'.

If you bought a hobby charger, hookup the sense leads, then you could bypass the BMS and 'take direct control' of the battery and charge it up / make sure it's balanced. Then, if the BMS still doesn't work t's clearly the BMS and you could buy a replacement from aliexpress.

If you do buy the replacement BMS from aliexpress - you have the "Balance" version per you pic (the BMS keeps the cells in balance) and the description shows the wiring diagram.
View attachment 33577View attachment 33578
Click to expand...
This is probably gonna sound stupid and show my ignorance. On the wiring of the BMS above it only shows 2 batteries but i have 8. It shows a wire going from an area *between* positive and negative and looping around to where the P+ and P- are as well as a 4.2V pad. Since I have 8 batteries so I connect a wire between any 2 positive and negatives and where does it connect at the other end ? Connect it to P+ or P- or 4.2V? I’m sorry for such a dumb question but I haven’t learned the “loop” part yet and I don’t want to start a fire. Any help appreciated. Almost done with this. Sorry I’m so slow.
 
Study this a bit and see if you can apply it :) I grabbed a typical hobby charger pic - https://www.amazon.com/Hobby-Fans-Professional-Balance-Discharger/dp/B09XC91BWJ/ref=sr_1_1 - bit of course you may buy something different. You have a 2s battery so you need a charger that has an option to accept 3 wires for the balance wires. This charger has the option to charge 2s (3 wire connector) and 3s (4 wire connector) and 5s, 6s, and 7s - that's why there's 5 different connectors. You only care about 2s - 3 wire connector.

1757001939340.png


Essentially, the blue charger in the pic is replacing the BMS. You'll notice the wiring to the BMS in the BMS pic above (wires #1, #2, and #3) do the same as the 3 wires to the blue charger in this pic - they let both devices see the voltage of each group of parallel cells so they can monitor what's happening. The balance wires are like voltmeter probes.
 
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OffGridInTheCity said:
Study this a bit and see if you can apply it :) I grabbed a typical hobby charger pic - https://www.amazon.com/Hobby-Fans-Professional-Balance-Discharger/dp/B09XC91BWJ/ref=sr_1_1 - bit of course you may buy something different. You have a 2s battery so you need a charger that has an option to accept 3 wires for the balance wires. This charger has the option to charge 2s (3 wire connector) and 3s (4 wire connector) and 5s, 6s, and 7s - that's why there's 5 different connectors. You only care about 2s - 3 wire connector.

View attachment 33593

Essentially, the blue charger in the pic is replacing the BMS. You'll notice the wiring to the BMS in the BMS pic above (wires #1, #2, and #3) do the same as the 3 wires to the blue charger in this pic - they let both devices see the voltage of each group of parallel cells so they can monitor what's happening. The balance wires are like voltmeter probes.
Click to expand...
The thing that confuses me is the lead showing it goes BETWEEN 2 batteries. Is there any instance where attaching a wire between two batteries is done or does every connection start and stop connected to a positive or negative? Hope that makes sense. On this supposedly bad BMS I’m replacing one wire went to a positive and one to a negative and one went from the bottom of the pack up to the BM- pad. Nothing was connected to the BM+ pad of the BMS. I want to thank you again for your efforts and offer my phone number in case that’s an option. (478-258-0023) If I know it’s you calling I will answer. (Or text first) I don’t answer unknown calls because of telemarketing. If I know your area code I’ll answer all those calls if you call. Sorry I’m confused. I do understand the chart you sent with the charger showing the connections with their harnesses. I will indeed buy the exact charger you recommend if that’s the one you prefer. In fact if you reply to buy that one I’ll order it tonight from Amazon. I think it said Tuesday delivery to Georgia. Thanks again and if you disappear I don’t blame you. I’ll figure it out sooner or later
 
OffGridInTheCity said:
Study this a bit and see if you can apply it :) I grabbed a typical hobby charger pic - https://www.amazon.com/Hobby-Fans-Professional-Balance-Discharger/dp/B09XC91BWJ/ref=sr_1_1 - bit of course you may buy something different. You have a 2s battery so you need a charger that has an option to accept 3 wires for the balance wires. This charger has the option to charge 2s (3 wire connector) and 3s (4 wire connector) and 5s, 6s, and 7s - that's why there's 5 different connectors. You only care about 2s - 3 wire connector.

View attachment 33593

Essentially, the blue charger in the pic is replacing the BMS. You'll notice the wiring to the BMS in the BMS pic above (wires #1, #2, and #3) do the same as the 3 wires to the blue charger in this pic - they let both devices see the voltage of each group of parallel cells so they can monitor what's happening. The balance wires are t
Click to expand...
 
I tried to send videos to make it easier but said file too large. My email is ...... in case you want to send yours and I can email whatever is needed. Sorry to bother
 
Just upload the video to either YT (make it Unlisted) or to Google Drive and create a shared link for the video.

Also, use DM to share emails, please do not post emails publicly. Our site is just like any other site on the internet and does get scraped by scammers/spammers and bots.
 
The balance wire between the 2 sets of cells in parallel is just a wire so the equipment can read the voltages of each group of parallel cells independently. Exactly the same as using a voltmeter to measure the 1st 4 cells in parallel and then the 2nd set.

If you take a volt meter and measure then wire #1 and wire #2 you'll get the voltage of the 1st group of 4 cells - somewhere between 3.0v and 4.2v. Notice that #1 will be negative and #2 will be positive.

If you use the volt meter to measure #2 and #3 you again get somewhere between 3.0v and 4.2v that shows the 2nd group of 4 cells. Notice that #2 will be the negative and #3 will be positive.

#2 wire can be both the positive for 1 measurement and the negative for the 2nd measurement at the same time - e.g. if you have 2 voltmeters, you can measure both groups of 4 cells in parallel at the same time to demonstrate this.

If you measure from #1 to #3 you get's the 6.0v to 8.4v - as this is the same as the main load/charge wiring.

Get a voltmeter and try it out! It's perfectly safe.

1757033973972.png



The BMS and the Charger balance port use wires #1, #2, and #3 the same as the volt meter experiment above - to see the voltage on each group of 4 cells in parallel - independent of each other so they can maintain balance between the parallel groups of cells. Balance means that if group 1 is 3.71v then group 2 should also be very close to 3.7v at the same time for a healthy / safe battery.
 
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Korishan said:
Just upload the video to either YT (make it Unlisted) or to Google Drive and create a shared link for the video. Also, use DM to share emails, please do not post emails publicly. Our site is just like any other site on the internet and does get scraped by scammers/spammers and bots.
Click to expand...
Korishan said:
Just upload the video to either YT (make it Unlisted) or to Google Drive and create a shared link for the video. Also, use DM to share emails, please do not post emails publicly. Our site is just like any other site on the internet and does get scraped by scammers/spammers and bots.
Click to expand...
Sorry about that
 
Hi guys, just on the subject of small BMS boards, I only became aware yesterday that all the small boards actually have (passive) balancing, correct?
I have bought boards in the past that had what appeared to be balance resistors but an inquiry to the retailer said no balance, I usually wire in a plug for my active balancer on most projects but it would be nice to confirm all these small boards actually have passive balancing, what say you gentlemen?
1757550676299.jpeg
 
Tex said:
Hi guys, just on the subject of small BMS boards, I only became aware yesterday that all the small boards actually have (passive) balancing, correct?
I have bought boards in the past that had what appeared to be balance resistors but an inquiry to the retailer said no balance, I usually wire in a plug for my active balancer on most projects but it would be nice to confirm all these small boards actually have passive balancing, what say you gentlemen?
View attachment 33602
Click to expand...
I’m not qualified to even comment. I don’t have a clue how this all works but others have been kind enough to dumb it down until I get it. I think I get it. I’m still trying to understand connecting a wire between two batteries. I saw a video where a guy was building a pack and said he solders between the two batteries so as not to apply more heat than necessary to a battery. Soldering between them reduces possibility of overheating either of the two batteries. Is that the reason for soldering between them or some other?
 
OffGridInTheCity said:
The balance wire between the 2 sets of cells in parallel is just a wire so the equipment can read the voltages of each group of parallel cells independently. Exactly the same as using a voltmeter to measure the 1st 4 cells in parallel and then the 2nd set.

If you take a volt meter and measure then wire #1 and wire #2 you'll get the voltage of the 1st group of 4 cells - somewhere between 3.0v and 4.2v. Notice that #1 will be negative and #2 will be positive.

If you use the volt meter to measure #2 and #3 you again get somewhere between 3.0v and 4.2v that shows the 2nd group of 4 cells. Notice that #2 will be the negative and #3 will be positive.

#2 wire can be both the positive for 1 measurement and the negative for the 2nd measurement at the same time - e.g. if you have 2 voltmeters, you can measure both groups of 4 cells in parallel at the same time to demonstrate this.

If you measure from #1 to #3 you get's the 6.0v to 8.4v - as this is the same as the main load/charge wiring.

Get a voltmeter and try it out! It's perfectly safe.

View attachment 33597


The BMS and the Charger balance port use wires #1, #2, and #3 the same as the volt meter experiment above - to see the voltage on each group of 4 cells in parallel - independent of each other so they can maintain balance between the parallel groups of cells. Balance means that if group 1 is 3.71v then group 2 should also be very close to 3.7v at the same time for a healthy / safe battery.
Click to expand...
The last BMS had 3 connections. Positive to a battery positive, negative to a battery negative and BMS negative to a negative battery. I assume it’s to a contact point between the two groups of four? Sorry I’m so slow
 
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