diy solar

diy solar

Finally found a LiFePO4 BMS with Low-temp Charging Protection

Bob B said:
@FilterGuy .... That is exactly what I am planning to do ... and I have already ordered 8 of the 190AH cells. I am still undecided about buying this BMS .... or handling the low temp protection in a different way.

When are you planning on doing your project?
Click to expand...
If you use this BMS, you will be limited on your current to ~.5c, but depending on what you are doing that may be fine.
 
FilterGuy said:
If you use this BMS, you will be limited on your current to ~.5c, but depending on what you are doing that may be fine.
Click to expand...
That will work fine for me ..... I am planning to have 150A draw max with the 2 batteries in parallel ... with a sustained current current of probably 120A.

I may eventually reconfigure the cells to 24V and convert the RV for that, but if I can get the performance I need at 12V, I won't do that.
 
searey said:
would I need 2 16s bms for 2p16s or 16p2s for 32 cell 48 volt battery
Click to expand...
For 2P16S you would use one BMS for 16S2P you would use 2 BMSs. However you need to pay attention to the current capability of the BMSs. The single BMS for 2P16S would have to handle 2 times as much current as the BMSs for 16S2P.

Also, 16S2P gives you a little redundency, if one string goes out, the other string can still be used (at a reduced current).
 
For anyone interested in Arduino, there are a few library and project available for JBD BMS. You don't need to add any other external sensor or shunt and can get the BMS internal values :)

hackaday.io

JBD BMS Arduino library

In this project, I collect any information about BMS that is compatible with the JBDTool program.
hackaday.io hackaday.io
github.com

GitHub - rakhmaevao/JbdBms: Library for working with JBD BMS

Library for working with JBD BMS. Contribute to rakhmaevao/JbdBms development by creating an account on GitHub.
github.com github.com
github.com

GitHub - flashtel/Smart-BMS-arduino-Reader

Contribute to flashtel/Smart-BMS-arduino-Reader development by creating an account on GitHub.
github.com github.com
 
I may have missed this earlier, confusing, but does this BMS allow batteries to be series connected. ?
 
Last edited:
When I talked to the guys at Battery Hookup, they said they do not recommend series. I did not ask why (but I wish I would have). As I think back on the conversation, it almost sounded like that was a general recommendation, and not specific to this BMS..... but I could be wrong about that.
 
FilterGuy said:
When I talked to the guys at Battery Hookup, they said they do not recommend series. I did not ask why (but I wish I would have). As I think back on the conversation, it almost sounded like that was a general recommendation, and not specific to this BMS..... but I could be wrong about that.
Click to expand...
That is what the manufacturer told me that I bought my battery from with the smart BMS installed. (I had previously remembered it wrong .... Went back and looked and they said parallel OK but not series.)
 
In the comments on wills recent video on the Renogy Tear-down, one guy said that the reason Renogy can't be wired in series is that the charge and discharge circuits are separate.

"Does anyone know why they say not to use them in series? "

"At minute 1:36 you will see 4 black wires. 2 for charging and 2 for discharging, that is the reason this bms is not able to connect in series. If you have an external bms that control the charge/discharge of all cell then you can connect all cells in series. "

"The bms charge or discharge at different times. Never at the same time. If it is in series and one of the battery pack is fully charged it will change to discharge state and cut the power to others pack that may need more charge. The same situation occurs when discharging. If one pack is too low it will change to charging state while the others packs still with charge level higher than the others. "

I can't claim to fully understand but it kinda makes sense.

The big question is whether the BMS we are discussing in this thread has the same issue. (Battle Born proves it is not a universal issue with all BMSs).

At first I thought this probably does not have the issue because it does not have separate wires for charge and discharge. However, I looked closer at the pics and can't tell if the two wires are connected together or not. I'll look when mine arrive but if anybody knows, please speak up). Edit: I found a pic on the manufacturers site and the two input wires are tied together on the board)
However, the BMS could split the charge/discharge even if the wires are combined coming onto the board.
 
Last edited:
I just sent a message to the manufacturer asking about series connection of two 12 volt banks using this BMS. I will post any response I get here.
 
I would expect that you can always put battery banks in parallel (after matching their voltage) because they will then experience the same voltage and will be "synchronized", the same way you can put cells in parallel without any need to monitor their individual voltage (because it's the same for all of them). Then putting batteries in series seems to me equivalent to putting two large "hyper-cells" in series.

If we consider that the BMS of each battery keeps their respective cells balanced, one whole battery basically behaves like a big cell. Then when you put two in series, you have the same problem as when you put two cells in series in a regular battery: they can go out of balance, meaning that one will reach its low/high voltage before the other and open the circuit. You would need then an "hyper BMS" that will take this into account and balance both batteries between themselves so that they are synchronized in voltage, exactly the same way a BMS does with cells in series. But I guess you can also manage such a system by having both BMS of the batteries talking to themselves and making one battery bleed off some power when it's fully charged for instance, so that the battery does not go in overvoltage while the other battery gets fully charged, like a passive balancer in a BMS is doing. It needs to be engineered in the BMS from the start though.

I guess that all must get a bit more complicated when you have separate charge/discharge ports, but I didn't think about it.
 
astronom said:
I would expect that you can always put battery banks in parallel (after matching their voltage) because they will then experience the same voltage and will be "synchronized", the same way you can put cells in parallel without any need to monitor their individual voltage (because it's the same for all of them). Then putting batteries in series seems to me equivalent to putting two large "hyper-cells" in series.

If we consider that the BMS of each battery keeps their respective cells balanced, one whole battery basically behaves like a big cell. Then when you put two in series, you have the same problem as when you put two cells in series in a regular battery: they can go out of balance, meaning that one will reach its low/high voltage before the other and open the circuit. You would need then an "hyper BMS" that will take this into account and balance both batteries between themselves so that they are synchronized in voltage, exactly the same way a BMS does with cells in series. But I guess you can also manage such a system by having both BMS of the batteries talking to themselves and making one battery bleed off some power when it's fully charged for instance, so that the battery does not go in overvoltage while the other battery gets fully charged, like a passive balancer in a BMS is doing. It needs to be engineered in the BMS from the start though.

I guess that all must get a bit more complicated when you have separate charge/discharge ports, but I didn't think about it.
Click to expand...
All true. Clearly, if you put two battleborn in series, they can be out of balance. The result is that one will hit over/undercharge and shut down before the other. The only(?) problem with this is that you are not able to get to the extra capacity of the one that is not shutting down. Just like with individual cells, the weakest 'hyper-cell' will define the capability of the total system. This is probably not a big deal unless you are trying to get every last electron/ion of storage you can.

In the Renogy tear-down, Will hinted (let slip?) that Battle Born would be comming out with batteries with communication on them. I wonder if it will coordinate between batteries like you suggest?
 
astronom said:
If we consider that the BMS of each battery keeps their respective cells balanced, one whole battery basically behaves like a big cell. Then when you put two in series, you have the same problem as when you put two cells in series in a regular battery: they can go out of balance, meaning that one will reach its low/high voltage before the other and open the circuit.
Click to expand...
A point to note, every BMS is different, some don't balance at all (quite a few actually), some only balance when in storage mode, other's when battery is being charged, others when being discharged and some do it in a combination... A BMS with Balancing Functions, even low amp balancing is obviously more desirable, one which these can be configured to suit specific use cases and configurations is optimal.

The ideal BMS allows for series and/or parallel connections of packs, is configurable, has balancing capability, preferably something with an easy to use interface be it BlueTooth App, a Remote control device or a computer app which can communicate with the BMS for config & monitoring.
 
In any country, whether it's the fault of deception, translation, or merely oversight, there's a lot left to desire when it comes to advertising. And that's probably due to the fundamental purpose of advertising being to attract people's attention rather than educate them. At any rate, with regards to the BMS in question, it can only be assumed that it has a low-temp cutoff since the software that monitors and controls the BMS provides a user with that adjustment. However, there's no need to argue about it since thanks to Will, no one has to risk buying a BMS that might not actually have a low-temp cutoff. Will has purchased a bluetooth BMS that has an adjustable low-temp cutoff; he has tested it; and he has provided a link to that BMS. Here's the video, with a link to the BMS in the description:
 
I have been keeping a list of what I consider the features of an ideal BMS. (See this thread)
The BMS from battery hookup that Will Reviewed is checking most of the boxes. I have 2 on order and am excited about getting them.
1578782504495.png

If you see corrections or can fill in the TBDs, Let us know.
 
Last edited:
On the "permanent display" front my plan is to mount a old smartphone as a display. Permanent power USB, access to screen on/off button and have the app running 24/7. Should be low power consumption and touchscreen from what otherwise is a junk Galaxy S2 with a few hours battery only (has/may also been used as an MP3 player for the camper.
 
Stupid Monkey said:
On the "permanent display" front my plan is to mount a old smartphone as a display. Permanent power USB, access to screen on/off button and have the app running 24/7. Should be low power consumption and touchscreen from what otherwise is a junk Galaxy S2 with a few hours battery only (has/may also been used as an MP3 player for the camper.
Click to expand...
That is not a bad idea. It is certainly cheaper than the 200 battery monitor. My plan is to try one of the cheap AILI $30 monitors.

The board has a communications port. If someone had the protocol details they could probably code a small hobby display to do the job.... but I am not going to try doing that.
 
Does anyone know what exactly is Battery Hookups Nickel Fuse Shipping,
It was their cheapest shipping option.
I find nothing anywhere pertaining to what
Nickel Fuse US shipping is. ✌️
 
You must log in or register to reply here.

Similar threads

J
Adding low temperature protection to a BMS
Replies
4
Views
311
Jim T
J
michypara
bms jk B2A8S20P-HC temperature setting error does not start
Replies
3
Views
269
michypara
michypara
A
Daly 8s LifePo over voltage, temp error, act balancer
Replies
0
Views
231
arjuna34
A
M
Daly BMS
Replies
1
Views
345
upnorthandpersonal
upnorthandpersonal
Y
BMS Failing? Help! ** FIXED ** :-)
Replies
2
Views
295
yachtdr22
Y
Back
Top