Even Newer 4 to 24-cell Battery Management System (BMS)

[dermot]

Gary, do you have the schematic/assembly instructions ready yet?

I'd like to have a look at how the charge controller works, especially since sometimes getting exact parts in the UK can be a bit of a challenge (had to make a couple of substations on my v2 BMS). Great job on pretty much finishing this latest project - I look forward to diving in!

dermot

 

[ejonesss]

i asked the same thing and he is working on it.

i too hope he gets something too as i already ordered the board.

Gary, do you have the schematic/assembly instructions ready yet?

I'd like to have a look at how the charge controller works, especially since sometimes getting exact parts in the UK can be a bit of a challenge (had to make a couple of substations on my v2 BMS). Great job on pretty much finishing this latest project - I look forward to diving in!

dermot

 

[nieles]

for the charge controller, what is the range for the amp limiter? i would like to charge at 1A, 5A 10A and 15A. is this possible?

 

[GGoodrum]

Gary, do you have the schematic/assembly instructions ready yet?

I'd like to have a look at how the charge controller works, especially since sometimes getting exact parts in the UK can be a bit of a challenge (had to make a couple of substations on my v2 BMS). Great job on pretty much finishing this latest project - I look forward to diving in!

dermot

I will have the Charge Controller and LVC-HVC instructions done a little later today. I'm also adding to the BOM files, to add alternates for the parts that are not in stock. the Battery Medic instructions will follow.

In order to lessen the confusion, please post questions/comments related to the LVC/HVC boards, the Charge Controller and the Battery Medic Booster to the A different approach to battery management... thread.

-- Gary

 

[GGoodrum]

for the charge controller, what is the range for the amp limiter? i would like to charge at 1A, 5A 10A and 15A. is this possible?

http://endless-sphere.com/forums/viewtopic.php?f=14&t=17168&p=259419#p259417

 

[ejonesss]

let me see if i get this correct
for the charge controller the gnd connection is self explanatory but

i am not sure where the other wire of the hvc would go?

my guess is point a witch is the junction of r108, d101 and d102

connection b is any shunts active and c is all shunts active.

the other problem how would the existing bms get the 12 volt power needed to power the bus

Gary, do you have the schematic/assembly instructions ready yet?

I'd like to have a look at how the charge controller works, especially since sometimes getting exact parts in the UK can be a bit of a challenge (had to make a couple of substations on my v2 BMS). Great job on pretty much finishing this latest project - I look forward to diving in!

dermot

I will have the Charge Controller and LVC-HVC instructions done a little later today. I'm also adding to the BOM files, to add alternates for the parts that are not in stock. the Battery Medic instructions will follow.

In order to lessen the confusion, please post questions/comments related to the LVC/HVC boards, the Charge Controller and the Battery Medic Booster to the A different approach to battery management... thread.

-- Gary

 

[GGoodrum]

let me see if i get this correct
for the charge controller the gnd connection is self explanatory but

i am not sure where the other wire of the hvc would go?

my guess is point a witch is the junction of r108, d101 and d102

connection b is any shunts active and c is all shunts active.

the other problem how would the existing bms get the 12 volt power needed to power the bus

It would be "B", to the ANY SHUNT ACTIVE bus. That is equivalent to what we now call the HVC signal. Here's where it would be on the PCB:

View attachment 24-Cell LiFePO4 BMS-v2 6c Charge Controller Mod.png

The Charge Controller normally has the matching male JST-BEC pigtail, but this could also be hard-wired. In fact, you could just mount the card above the left-hand side of the v2.x board, and not use the box. Here's a couple pics of the Charge Controller, with and without the box:


View attachment Charge Controller-05a.jpg
View attachment Charge Controller-02a.jpg

The v2.x boards are 3.3" wide, I think, and these Charge Controller cards are 3.0" long and 1.95" (50mm...) wide.

-- Gary

 

[michaelplogue]

Sorry if this has been asked before - 119 pages of posts is a bit long to search through.

Can the 24+ BMS setup: Can you use a single charger running to multiple packs - each with it's own BMS? Would you need to isolate the packs with schottky diodes?

 

[fechter]

Sorry if this has been asked before - 119 pages of posts is a bit long to search through.

Can the 24+ BMS setup: Can you use a single charger running to multiple packs - each with it's own BMS? Would you need to isolate the packs with schottky diodes?

I think it would be safer to isolate them with diodes otherwise a high pack could discharge into a lower pack (though that may not really cause a problem).

 

[michaelplogue]

Sorry if this has been asked before - 119 pages of posts is a bit long to search through.

Can the 24+ BMS setup: Can you use a single charger running to multiple packs - each with it's own BMS? Would you need to isolate the packs with schottky diodes?

I think it would be safer to isolate them with diodes otherwise a high pack could discharge into a lower pack (though that may not really cause a problem).

Roger that. But can a single charger be used for multiple BMSs?

 

[fechter]

Generally that would not be advised, but as long as the charger can support the load of multiple packs and the packs can withstand the charge rate individually (like what happens if only one pack makes connection) I think it could be done.

The ver.4 has an adjustable current limiter section that can be set so that the maximum charging rate into each unit does not exceed the cell's charge rating, so if this is working properly, then there should be no limit to the number of parallel packs as long as the charging source can handle it.

 

[chxs]

Hi ! When u think the V4 will be ready to sold ? My e-bike is waiting a BMS

Tanks

 

[GGoodrum]

Andy is testing what we think is the right auto-fan logic. Actually, he's already tested this, but he's doing it with an new build, to make sure. As far as I know, this is the only remaining issue. As soon as we get confirmation, I will submit a new run of boards. Hopefully these will actually be releasable. I'm getting pretty tired of doing a run of boards that I think is it, and can be released, only to have some other issue pop up. I've got a couple thousand dollar stack of those.

-- Gary

 

[amberwolf]

I'd recommend that you put those "beta" boards up for sale, too, along with a basic info about what was changed on the versions beyond them to fix their issues. Then anyone that is sufficiently technical and tenacious could still buy them, understanding that there is no support for those versions, and complete their own modifications to them to bring them up to the current revisions.

If they are sufficiently cheap perhaps enough people will eventually buy them to at least let you recoup your costs on them. I'd be one person that would buy such things, as long as I have the rest of the parts needed to build the thing (and/or can afford to order parts I don't have from wherever, like Avnet, since I have a free shipping coupon from them good thru May). At least that would get me another possible BMS option.

 

[ejonesss]

i agree to 1 step further.

set up a fund raising project to auction off the useless boards on ebay and use the profits to pay for more disk space on the forum server so we will not have a repeat of the last couple days.

I'd recommend that you put those "beta" boards up for sale, too, along with a basic info about what was changed on the versions beyond them to fix their issues. Then anyone that is sufficiently technical and tenacious could still buy them, understanding that there is no support for those versions, and complete their own modifications to them to bring them up to the current revisions.

If they are sufficiently cheap perhaps enough people will eventually buy them to at least let you recoup your costs on them. I'd be one person that would buy such things, as long as I have the rest of the parts needed to build the thing (and/or can afford to order parts I don't have from wherever, like Avnet, since I have a free shipping coupon from them good thru May). At least that would get me another possible BMS option.

 

[amberwolf]

What would more disk space do? AFAICR the server had to be reset, and that (probably) wouldn't fix a disk space issue, so it's unlikely it was caused by low disk space either. Actual cause could have been a lot of things, though, and he didn't say specifically what it was.

 

[ejonesss]

when the disk gets full the server crashes.

have you ever had your pc slow or lockup when the drive is down to a few megs or k?

it is especially critical because there is no room for the virtual memory files to be written.

What would more disk space do? AFAICR the server had to be reset, and that (probably) wouldn't fix a disk space issue, so it's unlikely it was caused by low disk space either. Actual cause could have been a lot of things, though, and he didn't say specifically what it was.

 

[amberwolf]

Low disk space *could* cause a crash under the right conditions, but as I said, it is unlikely to be fixed by a simple reset of the server.

Either way, you'd have to ask KnightMB about the actual problem to see if more disk space would have any effect on the issue, or what it was caused by. IIRC, disk space on the servers should not be an issue, based on discussions during the previous forum problems we had earlier this year.

 

[liveforphysics]

Didn't knightMB say the entire forum and archives, every file and attachment and post in the history of the forum is under 1gb?

 

[Kingfish]

Servers should rarely need rebooting. Biggest reasons have to do with updates, reconfiguration, or hardware. From the brief exposure that I have seen it appears the downtime has more to do with topology. For this reason I like to park my clients on a robust ISP; they can have their downtimes too mainly for the same reasons though it is scheduled typically in the wee hours of the morning. That said, even when the primarys are off-line alternate servers are available if for nothing else but to provide status.

 

[chxs]

I will buy one of this beta board if u can All is ready to go ! all i need its a BMS im ready to improve it with my 28S5P battery !

 

[wookey]

getting off-topic here, but this misaprehension needs correcting:

when the disk gets full the server crashes.
it is especially critical because there is no room for the virtual memory files to be written.

The server is a (Mandriva) Linux box (running apache2). It is very unlikely to crash due to the disk being full. Space is automatically reserved for system use on a Linux drive such that so long as it was filled by applications/users there will remain plenty of space for the system to use. This doesn't help if the system itself has filled up all the drive (which can happen). The 'virtual memory' space (Swap space) _is_ always separate and will not be filled by any normal disk activity. These are examples of why Linux (and Unix generally) makes for reliable servers.

An application can die/stop working when it runs out of space (the application in this case being the phpBB forum software), but that's not a 'server crash'.

 

[MikeB]

Back to the topic of the BMS design:

There's probably a whole new thread worth of discussion to be had on this, but what about making the LVC adjustable for cold-weather usage?

My understanding is that LiFePO batteries can tolerate a slightly lower LVC when they are close to freezing, and they also have more voltage sag. An electric vehicle that operates fine in warm weather might, under cold-weather conditions, hit the LVC while the batteries still have a reasonable charge level and under reasonable current load. It seems that lowering the LVC slightly might make sense.

Is this at all practical? Could the BMS circuit accommodate two LVC paths, and a switch to toggle between them? Or perhaps send out two different signals when different thresholds are reached? Or is this just a bad idea, and we should always base our LVC on warm weather thresholds?

 

[fechter]

I've been looking at that, but it is pretty tough to do without resorting to microprocessors. It is possible to use a thermistor in conjunction with the regular TC54 LVC detector, but the voltage trip point will vary with temperature over the entire temperature range (which might be OK). The thing I really don't know is what the desired compensation would be. Like at what temperature do you want what voltage. This will be a function of the cells.

 

[chxs]

Hi ! Do you think the V4 will be ready at the end of this month ? I need some information about the date of release ... or i will get a obsolete V2.6C

Tanks
Chris