Battery Protector : overpriced ?

[Koincave]

Looking for battery protector - battery guard

Theres a large brand name company ( V .... ) out there selling a
battery protector / battery guard but their various versions are
$80 - $160
Terrific value if your spending $10k on a lifepo powerwall
however im experimenting in the garage with second hand car batteries

Im looking for something that goes between batteries and load that
cuts out at say 21v and returns power to load at say 27v

There are hundreds of little electronic devices for voltage control
but ive been searching for something more industrial with chunky
battery terminals for connections


ive been struggling on my various searches on AliX etc

any thoughts , LINKS , abuse for being a cheapskate welcome
im a big boy and can handle it

 

[SamDeleted]

I know victron battery protect isn't rated for use with an inverter if that's useful to you ...

 

[B-ManFX4]

I know victron battery protect isn't rated for use with an inverter if that's useful to you ...

Actually it can be used with an inverter or inverter/charger if the inverter has a remote control port like the Victron units have.

From the Victron SBP manual:

"In case you want to control an inverter or inverter/charger via a SBP, you must use the SBP to control the inverter or inverter/charger via its remote port. See example below. Note that the image shown below is an example for all BatteryProtect models including the smart
models."

 

[HRTKD]

The BatteryProtect device is a one-way circuit. It will work with an inverter, but not an inverter/charger.

From the Smart BatteryProtect data sheet.

 

[Koincave]

The victron product range is awesome but out my price range as im running 4 solar arrays and
4 battery banks so need 4 of them so looking for something a lot cheaper

 

[sunshine_eggo]

The victron product range is awesome but out my price range as im running 4 solar arrays and
4 battery banks so need 4 of them so looking for something a lot cheaper

more detail would be helpful.

 

[Koincave]

more detail would be helpful.

Im looking for something that goes between batteries and load that
cuts out at say 21v and returns power to load at say 27v

 

[sunshine_eggo]

Im looking for something that goes between batteries and load that
cuts out at say 21v and returns power to load at say 27v

Pure DC load? no inverter?

 

[Koincave]

Pure DC load? no inverter?

Ah , its to go between the battery and the inverter , its to turn the invertor off and on
based on battery bank power level

 

[sunshine_eggo]

Ah , its to go between the battery and the inverter , its to turn the invertor off and on
based on battery bank power level

No products that I know of. the surge associated with charging inverter capacitors when connecting can destroy them.

Most 24V inverters have a ~19.5-21V cut off anyway, and some can be programmed for higher.

 

[B-ManFX4]

The BatteryProtect device is a one-way circuit. It will work with an inverter, but not an inverter/charger.

From the Smart BatteryProtect data sheet.

View attachment 152056

It will in fact work with an inverter/charger, if you wire it like the diagram I posted AND if the inverter/charger has a remote control port.

 

[B-ManFX4]

Im looking for something that goes between batteries and load that
cuts out at say 21v and returns power to load at say 27v

You can't program your inverters to cut off at a defined input voltage level?

 

[Koincave]

my experience is from around 5 different invertors, and when low or high voltage appears
they SCREAM a really annoying beeping sound

Apparently trucks have these things to protect the leisure battery overnight but im struggling
to find anything cheap

 

[Koincave]

would this do the job , appreciate your thoughts

"The output voltage is detected to be greater than the input and the output is immediately turned off"

Im guessing this might cycle too much as you cant specify a restart voltage mmmmm

https://www.aliexpress.com/item/4000220602270.html?spm=a2g0o.productlist.main.29.cceb6953oxsfsz&algo_pvid=3459c34d-a1b4-48f7-951a-ca4bcd07d46c&algo_exp_id=3459c34d-a1b4-48f7-951a-ca4bcd07d46c-14&pdp_npi=3%40dis%21GBP%219.52%217.24%21%21%21%21%21%40212278bd16862198956173685d07cd%2110000000858904377%21sea%21UK%21801222344&curPageLogUid=i226Jp7D0Hvl

 

[sunshine_eggo]

my experience is from around 5 different invertors, and when low or high voltage appears
they SCREAM a really annoying beeping sound

Apparently trucks have these things to protect the leisure battery overnight but im struggling
to find anything cheap

I've opened up multiple inverters to either snap off or desolder the speaker. They still shut off, but without the warning.

would this do the job , appreciate your thoughts

"The output voltage is detected to be greater than the input and the output is immediately turned off"

Im guessing this might cycle too much as you cant specify a restart voltage mmmmm

https://www.aliexpress.com/item/4000220602270.html?spm=a2g0o.productlist.main.29.cceb6953oxsfsz&algo_pvid=3459c34d-a1b4-48f7-951a-ca4bcd07d46c&algo_exp_id=3459c34d-a1b4-48f7-951a-ca4bcd07d46c-14&pdp_npi=3%40dis%21GBP%219.52%217.24%21%21%21%21%21%40212278bd16862198956173685d07cd%2110000000858904377%21sea%21UK%21801222344&curPageLogUid=i226Jp7D0Hvl

That's a diode. How would that help?

 

[Koincave]

I've opened up multiple inverters to either snap off or desolder the speaker. They still shut off, but without the warning.



That's a diode. How would that help?

Interesting i had never thought of disabling speaker

however is it a clean start ? and clean cut off

im concerned the solar would almost immediately restart the invertor not giving chance for
batteries to recharge a bit and the load would immediatly drain it again so it would go into a cycle
of on / offs : or is there a voltage differential before invertor would restart or do these things require a manual restart
every time , any more thoughts appreciated

 

[Koincave]

"That's a diode. How would that help?"

err what am i missing ? , its a diode that works out of the the source power and load power and if the load power
exceeds the source power it cuts off the load , giving chance for solar to recharge the batteries , what im not
sure about is how it would restart

 

[Koincave]

I bit the bullet and ordered a Victron non smart one

any ideas for cheaper non branded ones im still in the market for more
any leads / ideas appreciated

 

[SamDeleted]

How about monitoring voltage with a victron 712 shunt , it can trigger relays at set voltages or SOC%. ,

Have the shunt fire a suitable relay in the inverters DC line

 

[cs1234]

If you don't mind the idle losses of whatever inverters you are using, you could use whatever cheap DC voltage monitoring relay you can find, and couple it with a UK appropriate version of an AC relay toggle strip. This United States compatible one is $45. Some outlets are always on, some toggle off with the relay.

Cutting off the AC side instead of the DC side would prevent any issues with capacitor surges from removing battery access, at the expense of inverter idle loss.