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Rant: EG4 48v 100ah battery has faulty BMS. Signature solar customer service is TERRIBLE

AntronX said:
EG4 manual says 1 sec delay at > 250A. You may want to update it.
Consider adding short circuit trip level vs. risetime chart to better spec how short circuit protection behaves so you can avoid future misunderstandings like this thread.
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Can you link me to where you see this file? I am under the impression that all manuals and spec sheets have the most recent info.
 
RichardfromEG4 said:
Thanks, having Signature Solar update that ASAP.
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Cool, glad to help. I think you guys should send mberding's battery back to him and pay shipping (Edit: or do a full refund) and write this off as a learning experience for both. I think EG4 learned some spec sheet ambiguity and another end user use case flaw that can help with product improvement. Consider releasing another "high power" option of BMS with more MOSFETS in parallel to withstand 500A surge current without nuisance short circuit detection trips. But i really think you as a business that cares about customer PR should do a good deed and send him that battery back at no cost.
 
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AntronX said:
Cool, glad to help. I think you guys should send mberding's battery back to him and pay shipping and write this off as a learning experience for both. I think EG4 learned some spec sheet ambiguity and another end user use case flaw that can help with product improvement. Consider releasing another "high power" option of BMS with more MOSFETS in parallel to withstand 500A surge current without nuisance short circuit detection trips. But i really think you as a business that cares about customer PR should do a good deed and send him that battery back at no cost.
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He doesn't want the battery back. After looking deeper into this, he was not charged the entire restocking fee of 30%. They gave him a refund taking into account we will relist the battery at a discounted price.
 
RichardfromEG4 said:
I don't think anyone here is saying his vacuum is drawing 12kW. The battery doesn't care for the load amount, overcurrent is measured in amps only - and if it exceeds 250a it will turn off in .1ms.
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No, we're just saying it appears vacuum plus inverter drew > 250A from 48V battery. (however briefly)
250A x 48V = 12,000W

.1ms? as in 0.1ms, 100 microseconds?
Fast cutoff like that may be just what is needed to prevent MOSFETS from being killed by a short circuit. It is about the spec for a 100A MOSFET. So I'd rather have higher current or multiple MOSFET in parallel.
This is the basic problem with semiconductors for power circuits.

It is possible to have complete protection, but it requires inductors. An inductor in series with battery or other power source will deliver a current ramp rather than instantaneous short-circuit current. A switch-mode power supply can then operate as CV/CC, and never exceed maximum allowed current.

The "400V" batteries like LG RESU-H worked this way. 48V (?) battery and boost converter deliver 400V with limited current. That way they never exceed the 30A short-circuit current some inverters specify.

BMS doesn't implement such inductor. Inverter does or could. OP's inverter probably can deliver a high surge current, and draws a high current (maybe insufficiently filtered.) If an inverter could be configured to draw a programmed maximum surge from battery, we would have greater options to mix-n-match. Brute force sufficient battery is all we've got for now.

My 120V 6kW Sunny Island has spec to deliver 180A for 60 milliseconds. That is 21.6kW, 450A from 48V. At peak of sine wave I would expect sqrt(2) higher, 636A. I have four such inverters connected to a 405Ah battery.

There is a reason I like lead-acid :)
5C discharge rate for an instant? Oh, I didn't even notice. Lithium can handle that too (portable jump starters). BMS can't.
Do you realize 636A doesn't even exceed the CCA rating of a modest size automotive starting battery?
 
Hedges said:
5C discharge rate for an instant? Oh, I didn't even notice. Lithium can handle that too (portable jump starters). BMS can't.
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Would this be why some prefer the BMSs that don't have power flowing through them and rely on triggering an external relay to kill the power if needed?
 
RichardfromEG4 said:
This is such a disingenuous post. You are quoting someone who posted on the first page of a 5 page post, in which I later VERY CLEARLY advise that we are taking care of this. You are literally going out of your way to paint us in a bad light by quoting an issue that was addressed and fixed and the misunderstanding from our team was cleared up. He received the full refund, with no issues. Here's a screenshot a page later:View attachment 95933

Seriously, if you are going to try to make me look bad don't make it so easy for me to find a post on the same thread where I fixed the issue.
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I guess i missed the part where you admitted an employee was wrong. It's hard to keep track of what the message of the day is! I stand corrected. Good on signature solar for doing the right thing and refunding peoples shipping costs! woohoo!
 
I have not gotten it all into production yet (I have far too many projects going on all at once right now...) but I purposely got the JBD 300A contactor BMS because I didn't want to rely on FETs to not fail short circuited. I preferred the specs of the JK with 2A balancing, but no contactor option, so JBD it is. Hopefully my cells aren't wonky and the lower balance current is fine.
 
rhino said:
Would this be why some prefer the BMSs that don't have power flowing through them and rely on triggering an external relay to kill the power if needed?
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Or just for 500A continuous draw, that smaller BMS can't handle.

While a relay is closed, it can handle a massive brief current pulse that MOSFET could not. But it also is subject to arcing.
Forum members have welded relays shut on a single capacitor precharge inrush. An engineered solution of precharge for closing and snubber when opening under load should be pretty robust.

Since inverter has inductors and switched MOSFETs, I'd rather BMS didn't interrupt on overload, rather wire inverter directly to cells and BMS tells inverter (and charge controller) what to do. Class T fuse protects against wire shorted, also protects battery in the event MOSFETs fail shorted.

BMS MOSFETs, and their heatsinking, are pretty wimpy compared to what's in the inverter. BMS costs $100 and inverter $3000?
 
houseofancients said:
conclusion : you'll never be happy with ss, eventhough you got upgraded batteries and the issue seems isolated to your specific setup/inverter.

give it a break dude, your whining is getting old
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One could say the same thing about your non stop whining on Sol-Aks prices. You want a Sol-Ark so bad that you chase around post on knock off versions and constantly complain that the Sol-Ark is over priced. Got news for you bud, it's not overpriced in the field it's competing against. Schnieder, Outback, SMA, Enphase they all are in that price range and tend to have a lot less features.
 
1 i don't want a sol-ark, as it is useless here
2 i hate liars, cheats and tricksters
3 i would opt for going to the ones actually creating and producing the thing, which would be sun synk or deye, and i can, because theirs no playing the market protection game here

in short
 
robby said:
One could say the same thing about your non stop whining on Sol-Aks prices. You want a Sol-Ark so bad that you chase around post on knock off versions and constantly complain that the Sol-Ark is over priced. Got news for you bud, it's not overpriced in the field it's competing against. Schnieder, Outback, SMA, Enphase they all are in that price range and tend to have a lot less features.
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I believe it's called inverter envy.
 
houseofancients said:
1 i don't want a sol-ark, as it is useless here
2 i hate liars, cheats and tricksters
3 i would opt for going to the ones actually creating and producing the thing, which would be sun synk or deye, and i can, because theirs no playing the market protection game here

in short
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in short.... I want a Sol-Ark but they are to expensive :cry:

Love how you always go to that totally debunked theory that Deye and Sunsynk created the Inverter. Even the owner of Sunsynk makes no such claims and neither does Deye.
 
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