Big Battery 24v A123

[MrNatural22]

So I don't know if this is a PSA or not. I just put the makerhawk loadtester on my battery and it let out the magic smoke. The transistor went up in a plume of smoke. I guess it's my week for messing things up. Good thing I have a bigger 800w load tester I purchased on ebay inbound. Before you ask I did set the makerhawk up for the correct voltage and according to the specs I should have been fine. This is why I hate buying cheap stuff like this.

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I went thru the same magic smoke on the first one I bought when I set it at 150watts. They can’t handle the heat. ?
The replacement I got I run at only 130-140w and it performs well. I’ve run many tests at that level with no problem, just takes a little longer. I know these are rated higher @150w but can’t be run higher than 140 to be safe.
Some say theirs can but not going to watch another one go ? Don’t trust that second one to run 180w or it might ?
This is what I got out of the test on my second A123.....down to 2.8 LVD. Took almost 19 hrs @ 135w.

 

[softdown]

OK now your just answering your own posts. ?

That was for everyone's information - an important factor for many. Plus the important question for someone with more experience. I have exactly three weeks of lithium battery knowledge to work with.

 

[softdown]

I went thru the same magic smoke on the first one I bought when I set it at 150watts. They can’t handle the heat. ?
The replacement I got I run at only 130-140w and it performs well. I’ve run many tests at that level with no problem, just takes a little longer. I know these are rated higher @150w but can’t be run higher than 140 to be safe.
Some say theirs can but not going to watch another one go ? Don’t trust that second one to run 180w or it might ?
This is what I got out of the test on my second A123.....Took almost 19 hrs @ 135w.

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If they over produced using your conservative, lifespan oriented, settings - that is remarkable.

 

[MrNatural22]

Over produced? Not clear what you mean.?

 

[softdown]

Rated at 2.45 kWh, you got 2.55

 

[MrNatural22]

Confusing, labels on battery say different things and web site says another. ?
LOL.
Over all a great 24v LiFePo battery for the money. ?

 

[softdown]

With each having a 130A BMS - how many watts are real world available to a 3500 watt inverter I wonder. As I recall my "math" churned out ~ 3000 watts. But I'm new to BMS.

Their Live Chat has not answered this important question. I think my math was generally acceptable for one 24V battery with 130A BMS. Having two in serial though? Hoping the number is doubled.

Have a lot of things on my mind.

 

[No.15]

What voltage are you guys charging these at?

Also is there a consensus on the settings for the BMS?

 

[MrNatural22]

What voltage are you guys charging these at?

Also is there a consensus on the settings for the BMS?

Im using a switched bench power supply 30v 10a. Bolts set at 28.8 current at 10a I’m still playing with the settings.

 

[MrNatural22]

Not giving BMS setting advise and I’m no expert so be aware of that.

These are the settings I’m running for now.
I’m still in the early stages so others may have different BMS settings but for now these are working for me.

 

[Rmeadomavic]

Not giving BMS setting advise and I’m no expert so be aware of that.

These are the settings I’m running for now.
I’m still in the early stages so others may have different BMS settings but for now these are working for me.

View attachment 19746View attachment 19747

Have you collected more temperature data under load? I'd like to bracket my perimeters to more acceptable levels. I ran a 1500w load for 30 minutes and the highest temperature I picked up with an infrared thermometer was 97f (36c) on my main fuse.

 

[MrNatural22]

Have you collected more temperature data under load? I'd like to bracket my perimeters to more acceptable levels. I ran a 1500w load for 30 minutes and the highest temperature I picked up with an infrared thermometer was 97f (36c) on my main fuse.

I haven’t run any heavy loads yet so I couldn’t say. When I complete my planned set up its uses are powerIng
my 24v Samlex 2k inverter set up as a portable shore power for my cargo conversion higher power uses.
Trailer currently has a single 12v 100ah LiFePo w/1500w pure sine inverter system w/ solar. This 24v would run higher demands when I use the micro, making coffee etc
In stead of firing up my genny.
And as a portable can be used at home too for power outages.

 

[Argosy]

Anyone used the BMS that they sell on BigBattery with any success? Ive seen a post that it should essentially be "BYD" and have bluetooth....but....

 

[softdown]

Anyone used the BMS that they sell on BigBattery with any success? Ive seen a post that it should essentially be "BYD" and have bluetooth....but....

They sell it for $135 or you can buy it installed for $150. Apparently you also need this $20 adapter:https://bigbattery.com/product/a123-battery-module-to-8s-bms-adapter/
Either purchase includes Anderson SB175 connectors which I am a fan of. These connectors have been used for very reliable off roading winch connections for a long time. I think they use 6AWG wire which is big in the BMS world.

I know many of you are fans of bluetooth and that should be fantastic for monitoring when away. I saw the lack of bluetooth in a favorable light but I'll reserve my rational for my "bias". I'm no geek, not even nerd class.

I ordered two yesterday with their BMS installed. I do hope they are slightly adjustable (as advertised). If not, they gave themselves plentiful leeway for manufacturing variations. I have never used a BMS though. There is that.

I can't quit thinking that a charge controller does so much of the work of a BMS. I'm not fully convinced a BMS is an absolute necessity with new batteries - when properly using a quality charge controller and keeping the batteries in a suitable environment. But I am new to lithium technologies and eagerly learning. So very much to learn.

I will note that BigBattery has not responded to my question about available wattage from two serial connected 24V A123 LiFePO4 batteries. It is also of interest that are called both LiFePO4 and LFP (same thing) AND Li-ion on the batteries themselves. There seems to be some confusing data.

Oh well - it is not realistic to expect everything. I think we are getting pretty good quality at a really great price. That rarely comes with exceptional service.

What is "BYD"?

 

[Rmeadomavic]

My BMS's cell high voltage disconnect has saved my brand new battery about 4 times now, so there's that....

 

[softdown]

My BMS's cell low voltage disconnect has saved my brand new battery about 4 times now, so there's that....

Inverter settings also do that. I should have said charge controller/inverter settings.

 

[Rmeadomavic]

My cell 8 voltage spikes to 3.65v when the battery is at 28.0v and appears to grow exponentially. I could just imagine if I charged to the rated 28.8v without the BMS. 4.0v is detrimental to the cell.

 

[Argosy]

BMS also balances cells.
Would love to see your review of their BMS.

 

[softdown]

My cell 8 voltage spikes to 3.65v when the battery is at 28.0v and appears to grow exponentially. I could just imagine if I charged to the rated 28.8v without the BMS. 4.0v is detrimental to the cell.

Healthy cells should not do that. Exponential growth?! Shiver me timbers! Sounds like a bomb.

I just don't see what BMS does that a properly set up inverter/charge controller with a cell balancer in a stable indoor environment will not do. A BMS is absolutely needed sans the inverter/charge controller and cell balancing. If we duplicated everything the costs would be ridiculous.

I bought the BMS nevertheless - when in doubt, safety first.

 

[softdown]

BMS also balances cells.
Would love to see your review of their BMS.

That is much of the reason for buying the BMS. Cell balancing should not be required for several months on a good, new battery. But good, new batteries have a way of becoming old, used batteries.

While I am stoking the coals - according to Will's Active Cell Balance reviews - what is called "active cell balancing" may only be passive cell balancing. Which gets the job done but slowly. More like .2 amps instead of the touted 1.2 amps. Seems to me like small connective wires with alligator clips could also do that. Did I just build a bomb?