Cheap way to prevent battery drain?

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FFMG

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I posted a message a couple of days ago and, one of the issue I had was because my batteries drained below 50%.

Until I can afford lithium batteries I need to keep my batteries, (6 to 9 months).

My main problem is that my Mecer is pretty dumb and will only cut off at 21VDC, I cannot change that value/setting.

As mentioned by others, 21V is effectively a dead batterie.

So, I would like something I could add to my system to cut off power as soon as the battery gets to around 50% ... the Mecer would then cut off because of no power.

After 2 hours of load shedding my batteries are down to just under 25V, (I think ~70%?)

If we have a second round of load shedding, the batteries might not charge in time, but I would prefer the power to cut off rather than risking killing my batteries.

Can someone suggest something I would add to my system to "disconnect" the batteries when they get to ~50%

Thanks
 
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wingnut771 said:
So now you have to disassemble the battery box and purchase another charger? Things are getting complicated.
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No, I don't know why you would do that, technically the inbuilt charger should be able to do that?

Says you are using the system and it has been set to cut off at 12.4V, during loadshedding it should cut off at 12.4V, if there is nothing coming through from the charger it should remain off.

Say power comes backon, you should reduce your load until the charger has an upper hand over the current draw, if you don't do that it keeps cutting off until you get the message.


I am not saying that's how it works, I have never used it before, just thinking that's how it's supposed to work.
 
TheChamp said:
No, I don't know why you would do that, technically the inbuilt charger should be able to do that?

Says you are using the system and it has been set to cut off at 12.4V, during loadshedding it should cut off at 12.4V, if there is nothing coming through from the charger it should remain off.

Say power comes backon, you should reduce your load until the charger has an upper hand over the current draw, if you don't do that it keeps cutting off until you get the message.


I am not saying that's how it works, I have never used it before, just thinking that's how it's supposed to work.
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Haven't used one myself, but I know the inverter won't switch on if it doesn't see a battery, in which case the charger won't charge the battery.
 
wingnut771 said:
Haven't used one myself, but I know the inverter won't switch on if it doesn't see a battery, in which case the charger won't charge the battery.
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Yeah, that could be a smallernyana problem, maybe it dies it intermittently like the ones used in cars?
 
The easiest way IMHO is to install a voltage display and monitor it manually.

DSN-DVML-568-2-RD - PANEL MOUNT DC VOLTMETER RED 4.5-30VDC

Mantech Electronics is an Electronic Components, Test and Measurement instruments, Consumables, Tools and Power Products, Distributor. Products are available from our branches and distributors throughout Southern Africa. We are committed to helping our customers succeed.!
www.mantech.co.za
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200526811-001-56a5a63e5f9b58b7d0ddd35e.jpg
 
wingnut771 said:
Haven't used one myself, but I know the inverter won't switch on if it doesn't see a battery, in which case the charger won't charge the battery.
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Thanks, that's a good point ... maybe I will try it manually and "disconnect" the battery to simulate the protector cutting the power off and turning the power off.

Or maybe I will use my dead batteries, (I still have them), and disconnect just before the Mecer kill it and see if it restarts properly when the power comes back on.

But, even if it does not come back on then I will know that I need to manually restart the system.

Bottom line my batteries will be protected and if they die faster than 2 hours then I will know that I have died.
 
wingnut771 said:
The easiest way IMHO is to install a voltage display and monitor it manually.

DSN-DVML-568-2-RD - PANEL MOUNT DC VOLTMETER RED 4.5-30VDC

Mantech Electronics is an Electronic Components, Test and Measurement instruments, Consumables, Tools and Power Products, Distributor. Products are available from our branches and distributors throughout Southern Africa. We are committed to helping our customers succeed.!
www.mantech.co.za
View attachment 1564900
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Yeah, I saw that, but my other worry is that I am out when LS happens a second time.

But yeah, it would be the simpler solution short term.
 
FFMG said:
Yeah, I saw that, but my other worry is that I am out when LS happens a second time.

But yeah, it would be the simpler solution short term.
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Maybe with the victron thing you can go in the phone app and just turn it back on?

We have been down this road before with this device but no one has every actually taken one for the team and tried it.
 
FFMG said:
Yeah, I saw that, but my other worry is that I am out when LS happens a second time.

But yeah, it would be the simpler solution short term.
Click to expand...
For that you can get a Sonoff to switch the output off remotely. I think you can get the power off messages iirc.
 
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