PowerSonic PSL-12450 BMS Replace?

[ShalomOrchard]

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I have four of these LiFePo4 Valence U1-12RT Batteries, I got from a friend who is an electronic scrap dealer. They Work Great. I can get a dozen similar Power Sonic Batteries, but their BMS may be bad. The battery pack reads ~14V, but the terminals don’t show any voltage. The voltage stops at a gang of eight ?MosFets? On the BMS. I replaced the fuse, and tried to charge the batteries in parallel from a two amp car battery charger for a day to try to wake them up. That didn’t seem to help. What would be a good (cheap) replacement BMS for these batteries? Can I use them without a BMS? I’m going to try to charge one battery pack bypassing the BMS with the 2 amp car battery charger. I figure the current is low enough not to hurt it, and the voltage is going to top out at around 12V well short of the battery’s max voltage, so that won’t hurt it I hope that will wake up the battery and BMS once I get it charged up. What do you think? Any advice?

 

[A.Justice]

It sounds like a bad BMS, without being there to mess with it, it's hard to say for sure though.

Do NOT use the cells without a BMS, unless you are right there watching the voltage during testing. Valence most likely uses grade A cells that have matching specs (or they should for the price they are ?) so they should stay somewhat balanced, but for me, it's not worth the risk.

A "cheap" replacement BMS and a "good" BMS are two different things. I use JBD's which is the same manufacturer as Overkill, and a few white label products. I haven't had any issues, and they are on the cheaper side. They are available here:

https://www.lithiumbatterypcb.com/

You would need a "4s" module, select the amperage based on your requirements +25%.

I prefer "smart" BMS's, you can set custom settings via a phone app. Some of the preprogrammed ones have parameters that aren't where I would like them to be. They are a few extra bucks, but well worth it (to me).

 

[ShalomOrchard]

The Valence Batteries seem to be workin well, but I only have four of them. I am hoping to add about a dozen PowerSonic PSL-12450 Batteries which look similar That I got from E-Scrap. The BMS on the PSL seem to be dead, but there is supposedly a way to revive a dead BMS? I have charged the batteries, bypassing the BMS, with a smart charger. I have a couple of 4S 30A Daly BMS to play with, a smart one and a dumb one, but there seems to be an incantation involved in marrying the new BMS to the battery, so I could use any advice.

How can I test the batteries? What happens if there are some dead 18650 cells. Is a capacity test all I need to do?
As I understand it each battery needs a BMS to balance the 4 sets of 18650 cells in series, and limit charging and discharging. Do I then need a overall BMS to manage the whole bank? I’ve played with disassembling the batteries, and reconfiguring each battery as a set of parallel cells, then wiring three batteries together in parallel in a series of four. This allows me to not have to have a separate BMS for each battery, just one overall BMS. But it sounds like a lot of work, if it’s even possible. I don’t know if it’s even necessary, but I guess it would allow me to test each 18650 cell separately.

Thanks , I’ll check out the JBD BMS that you mentioned.

 

[ShalomOrchard]

It sounds like a bad BMS, without being there to mess with it, it's hard to say for sure though.

Do NOT use the cells without a BMS, unless you are right there watching the voltage during testing. Valence most likely uses grade A cells that have matching specs (or they should for the price they are ?) so they should stay somewhat balanced, but for me, it's not worth the risk.

A "cheap" replacement BMS and a "good" BMS are two different things. I use JBD's which is the same manufacturer as Overkill, and a few white label products. I haven't had any issues, and they are on the cheaper side. They are available here:

https://www.lithiumbatterypcb.com/

You would need a "4s" module, select the amperage based on your requirements +25%.

I prefer "smart" BMS's, you can set custom settings via a phone app. Some of the preprogrammed ones have parameters that aren't where I would like them to be. They are a few extra bucks, but well worth it (to me).

There a a LOT of BMS on the site. I’m looking for a 12V 4S BMS. How many Amps would be appropriate for a Shuttle Bus RV? I’m not one to waste power profligately, but want plenty of headroom. Since X Amps at 12V = X/10 at 120V, that could be a LOT of amps! Somewhat scary…. 100 Amps is only 10 Amps at 120V. Even 300 Amps is only 30 Amps at 120V.

 

[Substrate]

Sounds like you are trying to marry a bunch of crappy E-waste trash together as a way to run a shuttle-bus for others. (Despite the major brand-names)

Based on your questions, you may be presenting a danger to yourself and others if you follow through with this plan. In addition to setting yourself up for litigation if something goes wrong heaven forbid.

 

[ShalomOrchard]

Substrate: you’re wrong on all counts. I’m doing this for my self. I like recycling old things. I like figuring out how things work. why shouldn’t I try to recycle some hospital grade LiFePo batteries?

 

[A.Justice]

There a a LOT of BMS on the site. I’m looking for a 12V 4S BMS. How many Amps would be appropriate for a Shuttle Bus RV? I’m not one to waste power profligately, but want plenty of headroom. Since X Amps at 12V = X/10 at 120V, that could be a LOT of amps! Somewhat scary…. 100 Amps is only 10 Amps at 120V. Even 300 Amps is only 30 Amps at 120V.

It all depends on your loads. What do you intend to run?

Most 4s BMS units are 100-150 amp, so 3 batteries, each with a BMS, could put out 3x the amount. For a 12 volt system, I recommend keeping it limited to 2500 watts or so, MAX total load. That's still more than 200 amps, and would require either a very large BMS, or 2 smaller ones in parallel, not to mention the very large wires you need for that current.

If you are mostly using automotive parts, a 12v system is much easier to maintain in a mobile setting. If your endgame is high power AC, then a higher voltage system is a must.

 

[Substrate]

Substrate: you’re wrong on all counts. I’m doing this for my self. I like recycling old things. I like figuring out how things work. why shouldn’t I try to recycle some hospital grade LiFePo batteries?

Cool for just yourself. The problem is that starting your LFP project with used batteries only teaches you how to bolt things together, and not really engineer based upon good working new units.

Kind of like buying used tires that don't match your car, or trying to re-purpose hospital-grade masks as coffee filters. You just never know what caused things to fail by the former owners.

 

[ShalomOrchard]

It all depends on your loads. What do you intend to run?

Most 4s BMS units are 100-150 amp, so 3 batteries, each with a BMS, could put out 3x the amount. For a 12 volt system, I recommend keeping it limited to 2500 watts or so, MAX total load. That's still more than 200 amps, and would require either a very large BMS, or 2 smaller ones in parallel, not to mention the very large wires you need for that current.

If you are mostly using automotive parts, a 12v system is much easier to maintain in a mobile setting. If your endgame is high power AC, then a higher voltage system is a must.

These batteries are on the small side, 50Ah, so I will have to hook a few of them up in parallel. The problem is that each battery has a BMS (which I may have to replace if I can’t the BMS working. Do I then need a master BMS to manage the whole bank.

I tend to be frugal with power. An AC, or possibly a small mini/split heat pump will be the biggest energy hog I would use. Probably more then the rest of the load combined.

I did replace one of the BMS with a dumb Daley 4S 12V 30A BMS. It charges and discharges. I suppose I should to a stress test on it…

 

[ShalomOrchard]

So I replaced four of the BMS circuit boards in the liFePo4 Powersonic Batteries with Daley 4S 12V 30 Amp BMS modules, two dumb hardware BMS, and two Smart BMS modules. The Daley Smart BMS modules are twice as expensive, but they allow you to set various parameters, includes a temperature sensor, and you can hook up a small display that shows the approximate state of charge & has a reset button. You can also hook up a Bluetooth dongle to read/set various parameters on your phone app, or a custom touch screen.

So, after installing four BMS boards, I started looking at the original BMS board on the next battery. The flaw seemed to be in the bank of MOSFETs right before the output. I started measuring the voltage on each of these MOSFETs, and lo and behold the BMS started working! I did this with eight more batteries, so it doesn’t seem to be a fluke. The disadvantage of the OEM BMS, is that you can’t read/set various parameters.

I bought these for 25$ each for a 50Ah battery, (I actually could have got them cheaper) so this seems like a pretty good deal compared to $700 for a 100Ah Battleborn battery!

The next question is what’s the best way to wire them up. The problem with a 12V system is that you need a scary amount of Amps to get a decent amount of 120V Amps. #2 AWG wire is good for about 120 Amps. That will only give you about 12 Amps 120V after going through an inverter.

I originally used #8 wire going from each of four batteries to my inverter. #8 wire is good for about 40 Amps and the max of my Valence batteries is 30 Amps, so that’s good. I also got a bunch of #4 wire from my friend, and I bought some #2 THHN to run to the relay in my electrical cupboard above the drivers seat to my Renogy 60 Amp DC-DC charger. The relay is connected to another #2 cable that runs to the bus’s two high capacity alternators. #4 wire is good for about 100 Amps, so that’s nice. #2 in the chart I used is not too much better. https://www.bluesea.com/resources/1437

So a dozen batteries means about 48 connector terminals. I’m lucky, I have a big old 2 ft long Nicopress crimper that will crimp the hell out of any terminals. Should I solder them in addition? Seems unnecessary…. I have to arrange my batteries in a grid under a bench seat right behind the drivers seat In a 4x3 grid or a 2x6 grid. The batteries are 7.7” x 5.2”. I could wire them all in parallel with #4 wire, but that’s a little skimpy. Or I could wire each row with #4, and wire the rows together to the inverter with #2. Still not heavy enough to get me more then 10-12 Amps 120VAC. Or am I figuring this wrong? How long should I make the cables? A standard 12 Inch or 6 Inch? Or custom just long enough? I know that the total path to each battery needs to be the same with the same wire.

The other option is to use sizable rigid bus bars. That’s cheaper, but it’s … well …not very flexible, you have to arrange the battery terminals just so in a line. You have to drill holes for each connection. My batteries have recessed terminals, so I would need to find some stand-off bushings. But then you don’t need to worry so much about wire size or length.

 

[ShalomOrchard]

So, after waffling back and forth a couple of times, I choose to mostly use 4AWG cable that I can get for .50$/ft. The main reason for this instead of bus bars is because then everything can be easily insulated. It’s harder to insulation busbars. I will have a 4x4 battery bank of 50Ah batteries. So I will wire each row on 4 batteries in parallel with #4 wire, with the pos & neg at the opposite ends of the row. Then each row is wired with 2 AWG wire to a circuit breaker and the inverter & Dc-Dc charger. That lets me use 4AWG for the majority of the wiring, and 2AWG I where needed to beef up the gauge to carry a heavier load.to carry quite a large load.

I wanted to make sure I used the best cables. The wire I have is copper THHN cable from Home Depot which is quite stiff. The other wire is much more flexible, but did not appear to be copper! It is marked as SAE J1127 SGT. When I googled that, says that it is a marine grade (tinned?) copper cable. I used copper lug connectors crimped with my 2 ft Nicopress crimper, and soldered. the battery terminals are M6 metric, with lock washers.