Smart BMS Identification

[thequeenbeep]

I am now the proud owner of a defective Renogy 200ah lifepo4 battery. The battery is brand new and never gave a correct voltage reading from the terminals. The bluetooth readout was showing -8 to -9amps of discharge rate (while the battery sat disconnected and not actually losing power) and the cells would sometimes show up in the app but never with the correct voltage. I'm getting a replacement sent, but decided to take this one apart to investigate. Using a multimeter, the cells are showing the correct voltages, so I can only assume that the BMS is the problem. So far I can say that it looks very much like a Daly unit, but I can't find a 4s 12v 200ah unit from daly with the exact same connection layout.

1. Is there a direct replacement unit available or is this a custom unit for Renogy?
2. Is it possible to repair the BMS?
3. If I replace the BMS and am able to get the battery functioning again, is it safe to use in parallel with the replacement battery that is being sent?

Thanks in advance for your help!

 

[sunshine_eggo]

I am now the proud owner of a defective Renogy 200ah lifepo4 battery. The battery is brand new and never gave a correct voltage reading from the terminals. The bluetooth readout was showing -8 to -9amps of discharge rate (while the battery sat disconnected and not actually losing power) and the cells would sometimes show up in the app but never with the correct voltage. I'm getting a replacement sent, but decided to take this one apart to investigate. Using a multimeter, the cells are showing the correct voltages, so I can only assume that the BMS is the problem. So far I can say that it looks very much like a Daly unit, but I can't find a 4s 12v 200ah unit from daly with the exact same connection layout.

1. Is there a direct replacement unit available or is this a custom unit for Renogy?

No idea on either.

1. Is it possible to repair the BMS?

Unlikely.

1. If I replace the BMS and am able to get the battery functioning again, is it safe to use in parallel with the replacement battery that is being sent?

If you mean use two BMSs on one battery, no. Generally never advisable and most if not all manufacturers recommend against it. If you're asking if you can parallel two 12V batteries, each with their own BMS, almost certainly.

 

[thequeenbeep]

No idea on either.



Unlikely.



If you mean use two BMSs on one battery, no. Generally never advisable and most if not all manufacturers recommend against it. If you're asking if you can parallel two 12V batteries, each with their own BMS, almost certainly.

Thanks. Yes I do mean paralleling two 12v batteries, each with their own (different) BMS. I assume it’s best to get to the same resting voltage before wiring them together, but wasn’t sure if there would be any conflicts between the different BMS.

 

[sunshine_eggo]

Thanks. Yes I do mean paralleling two 12v batteries, each with their own (different) BMS. I assume it’s best to get to the same resting voltage before wiring them together, but wasn’t sure if there would be any conflicts between the different BMS.

As long as the batteries are paralleled at their main terminals and nowhere else, should be fine. I like to achieve a 0.1V difference; however, if you don't initially tighten one end of one of the parallel conductors, there will be substantial resistance at that connection acting to limit the current.

I recently connected two NMC cells with about 0.25A difference, and it peaked at 88A using a 2' cable intended to equalize the cell voltages.

Here's a test Andy did with parallel cells:

 

[Wacdam]

I am now the proud owner of a defective Renogy 200ah lifepo4 battery. The battery is brand new and never gave a correct voltage reading from the terminals. The bluetooth readout was showing -8 to -9amps of discharge rate (while the battery sat disconnected and not actually losing power) and the cells would sometimes show up in the app but never with the correct voltage. I'm getting a replacement sent, but decided to take this one apart to investigate. Using a multimeter, the cells are showing the correct voltages, so I can only assume that the BMS is the problem. So far I can say that it looks very much like a Daly unit, but I can't find a 4s 12v 200ah unit from daly with the exact same connection layout.

1. Is there a direct replacement unit available or is this a custom unit for Renogy?
2. Is it possible to repair the BMS?
3. If I replace the BMS and am able to get the battery functioning again, is it safe to use in parallel with the replacement battery that is being sent?

Thanks in advance for your help!

I'm Just wondering how you went
I had a Renogy 200ah DOA it was from Ebay and I was travelling so too hard to organise a courier Renogy Australia just let me keep the old one and they sent me a brand new replacement.
I was not sure what was the problem so I took a chance and ordered a Daly 200ah with Active balance
After I managed to get the top off it today it looked like a daly but I wasn't game to try to remove the old one from down the side of the battery.
How did you get it out? It's. Got gell poured in the bottom and double sided tape. Did you distroy the case?

I just plugged the old balance cables into the new Bms and I also used the old temp sensor.

I'm using the Daly Bluetooth dongle and the Daly app.

I didn't try plugging in the old renogy BT as their app is crap.


I'm planning to leave the old Bms inside the case too hard to remove and mount the new one on top.

I was going to get a square of rubber ro sit between the new Bms and the cells.
I used the old Blue lead for the Negative as it was longer and will reach the battery contact.

I'm currently trying to work out the best settings for the new BMS
Il probably add the active balancer as I have it too

It seems to be charging fine.

I have set the cuttoff values to the ones in the battery manual

 

[Wacdam]

If it's not too hard to get the old bms out maybe I'll give it a try but would be good to know how hard it was. did you just slide a knife down between the battery and the cells, and pry it out? don't want to damage the cells or the case

 

[thequeenbeep]

You are probably better off leaving the old BMS where it is. I had to use an oscillating tool to cut down the side of the case in order to get the old one out. It was nice to get the defective BMS out and to be able to mount the new one in its place, but not worth the effort and mess it made. I ended up using a non conductive glue to reattach the side of the case, and tucked the eyesore behind the replacement battery where no one will notice!

 

[Wacdam]

You are probably better off leaving the old BMS where it is. I had to use an oscillating tool to cut down the side of the case in order to get the old one out. It was nice to get the defective BMS out and to be able to mount the new one in its place, but not worth the effort and mess it made. I ended up using a non conductive glue to reattach the side of the case, and tucked the eyesore behind the replacement battery where no one will notice!

Just a follow up I managed to pull the old bms out quite easily I had to snip the tape so I hope it doesn't allow the cells to swell ,some of the foam that was poured in the bottom came out with it and I just pulled it off and poked it back. The new daily bms was almost identical to the old one except for the generic Bluetooth dongle and I managed to slide the new one back in the same place it has been working perfectly along side the new renogy for 3 months now.

 

[LydMekk]

Looks very much like a Daly BMS.