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WTB Battery Relay Controller 100V 20S

Posted: May 06 2021 4:47am
by monette999
Hi FOLKS WTB a 100V Battery Controller Relay.
That should disconnect the charge if my Batt voltage is above 84V and disconnect the Battery below 60V.

Who knows an affordable product?
I have bought this and it blow up
At the first usages.

Thank you
BobImageImage

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Re: WTB Battery Relay Controller 100V 20S

Posted: May 06 2021 6:23am
by flippy
these devices are fairly common. its called a BMS and your battery already should have one. and your charger would never get above 84V unless you are doing something stupid with the wrong model charger.

Re: WTB Battery Relay Controller 100V 20S

Posted: May 06 2021 6:42am
by monette999
No that is not what I want.
I am charging my packs with a balanced charger. I HATE BMS.
I want a low voltage disconnect by relay.

Any better proposal?

Thanks

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Re: WTB Battery Relay Controller 100V 20S

Posted: May 06 2021 7:12am
by flippy
monette999 wrote:
May 06 2021 6:42am
No that is not what I want.
I am charging my packs with a balanced charger. I HATE BMS.
I want a low voltage disconnect by relay.

Any better proposal?
yes, i have a perfect device that does EXACTLY what you need. its called a BMS. that you "hate" a bms is separate from the fact that from the looks of it you really do need. a balance charger is NOT a replacement for a bms.

i get the impression you see a bms a bit like a seatbelt but refuse to wear one "because i never crash".

still.... you need to set up your consuming device (aka: the thing that uses power) to stop before it reaches 60V. using a box with a cheap chinese 12V rated relay is not the way to go about this. at the very least you need a massive contactor.

Re: WTB Battery Relay Controller 100V 20S

Posted: May 06 2021 7:26am
by john61ct
BMS functionality does not always include per-cell balancing. But then you should be balancing via other means, at least periodically.

But HVC and LVC should be based on the first cell/group level to reach the setpoint, and yes that is the core definition of a protective BMS.

That said, it certainly is possible to get separate devices for LVC and HVC at the pack voltage level

but that will require being more conservative, thus utilizing lower % of potential capacity.

Re: WTB Battery Relay Controller 100V 20S

Posted: May 06 2021 8:28am
by monette999
I guess I will wait for someone who know about voltage programmable relay. I run many battery packs at my cart in different voltage configuration

No BMS from me Jose.

Good bye



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Re: WTB Battery Relay Controller 100V 20S

Posted: May 06 2021 9:30am
by flippy
you do know that a bms and a "voltage programmable relay" are basically the same thing right?

you are not switching 100VDC at dozens of amps with cheap chinese relays. you need contactors and those consume more power then you care for.

a bms is litteraly designed to do exactly what you want it to do.

Re: WTB Battery Relay Controller 100V 20S

Posted: May 06 2021 10:15pm
by john61ct
Yes prejudice against an arbitrary label just shows a closed mind and limited experience.

There are BMS costing thousands that are more robust than most industrial scale contactors.

And any decent BMS even cheap ones have adjustable setpoints and the ability to disable those functions you are handling with other devices.

If such a BMS is configured to control external contactors, then **all** it is doing is acting as an automated voltage-sensing switch.

Anyone marketing such a device these days would put the "BMS" label on it anyway.

But someone wanting that switching based on pack-level voltage rather than cell/group level IMO doesn't understand what they're doing,

and stubbornly ignoring this kind of consensus implies suffering from chronic Dunning-Kruger syndrome

Re: WTB Battery Relay Controller 100V 20S

Posted: May 07 2021 1:14am
by monette999
I have a inert gas filled contacter
Judging without details is funny.

I want to limit the failure rate for defect
BMS

I want no passive balancing nor some fets who are my electrical switch. I am running hight current through my contacter. I don't want to get limited by the Fets nor suffer under a bad RDS on.

So I just want an automatic disconnect at low voltage and it would be nice if I have an simple device for it.

Greetings Bob

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