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

[chxs]

If i have a CC/CV charger charge to 103.4 Volts the V4 its perfect for my setup ? When do u think i can get an BMS from u ???

My actual setup is :
28s5p of A123

Tanks Chris

 

[ejonesss]

@fechter you may want to redo the pack + wire it looks like a few strands are hanging out and could short to the transistor pads if they get flexed around enough.

Thanks Amberwolf, I'll check that out.

Here's Gary's picture of the exploded cap:View attachment 1

Dang, I just melted the end off of a nice grabber hook on an overheating resistor. This project can be measured by the number of destroyed components, which is considerable at this point.

 

[amberwolf]

Dang, I just melted the end off of a nice grabber hook on an overheating resistor. This project can be measured by the number of destroyed components, which is considerable at this point.

No project is complete until the number of destroyed parts equals or surpasses the mass of the actual project, and the length of bandages used is sufficient to package it with. :lol:

 

[ejonesss]

questions about KSA931.

would any pnp transistor work as a substitute as long as the current and voltage load handling is above 500 ma?

does the transistor do any oscillating? meaning does it do any pulse width modulating?

because since mouser is out of KSA931 i may be able to substitute with driver transistors harvested from old dot matrix printers that use individual transistors instead of an ic and cheap audio drivers and such?

 

[amberwolf]

The IXDF404 trigger threshold is around 1v. You need something with a fast rise time to square the pulse. Just about any logic chip could do this. If you used an inverter chip, this could also be used to invert the signal for the other LED.

That's an idea. Got lots of inverters of various types, 74yyxx and 4000-series, and some wierd stuff in arrays meant to drive power transistors out of a laser printer, I think it was.

Good to know on the LTV-829 pricing. I don't see any reason why it shouldn't work. I know I looked at using these before but didn't want to risk that it would screw something up, which is still a remote possibility. The ILD2 was inhereted from the very early designs and I just never got around to experimenting with alternte parts.

Well, I'll letcha know how it works out once I get that far.

One other thing to consider would be to add some .1uf caps across each cell circuit to suppress voltage spikes. These could be stuck directly to the board or possibly attached to the legs of the power resistors. I think the best location would be close to the LM431 and TC54, since those are the parts that will blow with a spike.

I'll do that then, because I won't have any extras of those parts laying around, and ordering just one or a few would be prohibitively expensive due to shipping.

Alternately, unidirectional TVS diodes could be placed across each cell. I haven't experimented with these yet, but from reading a lot of datasheets, it seems the lower voltage units (5v) have a fairly high leakage current when off. The 10v devices are way lower, like maybe 10uA, so they may be preferrable. I think all the parts in the cell circuit can withstand a 10v spike.

I think I've found those on motherboards for USB ports and such. I don't know what voltage level they are suppressing at, though, so I'll have to check and see. If they're the right ones, I can salvage them off of there, if you think they'd work. (I'll have to find post their specs first).

 

[fechter]

questions about KSA931.

would any pnp transistor work as a substitute as long as the current and voltage load handling is above 500 ma?

does the transistor do any oscillating? meaning does it do any pulse width modulating?

Most any PNP with enough current and dissipation rating should work, but I would avoid Darlingtons. It's always good to use a part that has a higher rating than needed to allow a safety factor.
The KSA931 is pretty close to the max dissipation under some conditions. A larger package can dissipate more without overheating.

Under normal conditions, the transistor is running in linear mode. It can be pretty slow.
I've looked at running it in the switching mode, which would reduce the dissipation greatly, but there are some issues with doing that. Eventually, I think that's what I'll go to.

 

[ejonesss]

@ggoodrum

If this change is not done, the current limiter function still needs to be disabled, by removing D3. This change is mandatory, or the FETs could blow during the current limit operation.

wouldnt a better option than to remove d3 is to omit the shutoff jumper?

pin 7 from u2b goes through d3 then through the jumper to r5.

another option wouldnt shorting the d and s pins of the fets do the same thing?

 

[ejonesss]

another bms question.

when i ordered the parts to fill the unused sections from the v 2.x bms they was out of the pnp transistors.

now i discovered i ordered the wrong color leds.

i know the leds are critical to the hvc function i think they act as a voltage reference or something.

i meant to order 859-LTL1CHKFKNN witch is orange with operating voltage of 2.05

i got LTL2R3KSK witch is yellow clear with the same operating voltage 2.05.

is the color going to affect the operation or is it more the operating voltage that counts?

 

[GGoodrum]

Is it possible to connect one of the 4-cell breakoff sections from V 2.6c to the much older V1.5 (16-cell) such that I can have LVC/HVC for 20 cells? I am using LiFePO4's.

Thanks,
Dick

Sorry, I missed this earlier.

The cell circuits of the v1.5 board and the v2.6c are basically identical, except for the shunt transistors. The older v1.5 boards used KSA931s and the v.6c used BD136s, but that doesn't mean they couldn't also use the KSA931s. For the 4-channel v2.6c section, just use the same shunt resistors (6.8 ohm/5W), and the same divider resistors (75k/180k...), and it should be the same.

Here's how to connect the two boards together, and then to one of the Charge Controller cards:

View attachment CC-v1.5-v2.6c.png

It's really pretty simple. Both of these older boards have separate opto lines for the HVC signal, which is called "ANY SHUNT ACTIVE" on the v2.6c board, and for the LVC signal. the picture above only shows the HVC connections, but the LVC opto lines can also be paralleled.

-- Gary

 

[chxs]

Any news about V4 ??? it is possible to use older V2.6c 4s section with new charge controller ???

 

[GGoodrum]

Any news about V4 ??? it is possible to use older V2.6c 4s section with new charge controller ???

Yes, I just showed how in the post above yours.

 

[chxs]

how can i connect only 4S breakout to make a 28S for my Lifepo4 ??? like 7 board interconnected ???

 

[ejonesss]

not to sound impatient or anything but we are wondering how close to board production we are?

 

[GGoodrum]

not to sound impatient or anything but we are wondering how close to board production we are?

This coming week.

 

[chxs]

not to sound impatient or anything but we are wondering how close to board production we are?

This coming week.

REALLY ??? The board is ready ??? I Hope

Tanks
Chris

 

[wookey]

Wahey! Well done chaps.

My batteries thank you for your perseverance.

It's taken so long that in the meantime I've got a new job much closer to home so I shan't actually be needing the moped for more than another couple of weeks Still, I'd better put a BMS in before flogging it on (or maybe the wife will start using it).

 

[Indubitably]

No updates this past week... dare I assume that this means nothing has exploded yet, and everything is actually going as planned?

 

[GGoodrum]

No updates this past week... dare I assume that this means nothing has exploded yet, and everything is actually going as planned?

Yes, I'm working on the "final" layout right now. I'll post something here soon, hopefully this weekend.

-- Gary

 

[ejonesss]

finally!!!! lets hope that a bom and assembly instructions can be posted so i can order parts and have them on their way while the boards are in production.

No updates this past week... dare I assume that this means nothing has exploded yet, and everything is actually going as planned?

Yes, I'm working on the "final" layout right now. I'll post something here soon, hopefully this weekend.

-- Gary

 

[MitchJi]

Hi Gary,

No updates this past week... dare I assume that this means nothing has exploded yet, and everything is actually going as planned?

Yes, I'm working on the "final" layout right now. I'll post something here soon, hopefully this weekend.

-- Gary

We've heard that before :

not to sound impatient or anything but we are wondering how close to board production we are?

This coming week.

 

[ejonesss]

@ggoodrum

is there any differences between the version 2.2 and 2.6c in the position of the any and all shunts active rails?

because i have the 2.2 version of the board and you are connecting to the all active rail.

is it me or are other users seeing this mistake too?

Is it possible to connect one of the 4-cell breakoff sections from V 2.6c to the much older V1.5 (16-cell) such that I can have LVC/HVC for 20 cells? I am using LiFePO4's.

Thanks,
Dick

Sorry, I missed this earlier.

The cell circuits of the v1.5 board and the v2.6c are basically identical, except for the shunt transistors. The older v1.5 boards used KSA931s and the v.6c used BD136s, but that doesn't mean they couldn't also use the KSA931s. For the 4-channel v2.6c section, just use the same shunt resistors (6.8 ohm/5W), and the same divider resistors (75k/180k...), and it should be the same.

Here's how to connect the two boards together, and then to one of the Charge Controller cards:



It's really pretty simple. Both of these older boards have separate opto lines for the HVC signal, which is called "ANY SHUNT ACTIVE" on the v2.6c board, and for the LVC signal. the picture above only shows the HVC connections, but the LVC opto lines can also be paralleled.

-- Gary

 

[Kaplag]

woo! Go version 4.0! (I'm really out of the loop)

 

[The Mighty Volt]

Hi there,

What is the retail for one of the better 24s BMS, intended to be used with A123's?

Voltage is 72 nominal, 80+ off the charger.

Capacity is 11.5Ah or so.

Thanks.

 

[MitchJi]

Hi,

What is the retail for one of the better 24s BMS, intended to be used with A123's?

Voltage is 72 nominal, 80+ off the charger.

For 24s a123 nominal is 3.3 x 24 -> 79.2v and off the charger is roughly 3.6 x 24 -> 86.4v.

 

[The Mighty Volt]

Hi,

What is the retail for one of the better 24s BMS, intended to be used with A123's?

Voltage is 72 nominal, 80+ off the charger.

For 24s a123 nominal is 3.3 x 24 -> 79.2v and off the charger is roughly 3.6 x 24 -> 86.4v.

Yes, that is correct, but how much can I expect to pay for a BMS that can handle these specs.

Thanks Mitch.

TMV