diy solar

diy solar

Lithium Batteries for Alarm Panel

gabe1475

New Member
Joined
Nov 23, 2020
Messages
75
Its time to replace the battery in our alarm panel and was thinking of going lithium.

The panel I have is a Vista 21p as I measured the voltage looks like the charge voltage is right at 13.7. If I hook up a lithium battery to that, I don't see how it could ever get overcharged, but wanted to see if perhaps I am missing some other considerations.

Is there any issue with the voltage being lower other than the system taking a longer time to charge the battery in the event of power loss and utilizing the battery for an extended time?
 
I've done the same thing with a UPS, it floated it's lead acid at 13.8v, I added a diode to float my LiFePO4 at 13.5v, and it works just fine. Don't expect fast recharging though.

It should still work fine without a diode, I just prefer floating at a lower voltage.
 
I've done the same thing with a UPS, it floated it's lead acid at 13.8v, I added a diode to float my LiFePO4 at 13.5v, and it works just fine. Don't expect fast recharging though.

It should still work fine without a diode, I just prefer floating at a lower voltage.
Got it, thanks for the feedback.
 
I wouldn’t do it. That panel uses a cheap plug in transformer that typically gets pretty hot with sla battery. If that lithium battery is low that chargers going to work even harder. That panel is not listed (UL) to use lithium as a replacement battery.
 
I agree with @Spliss. The most important reason is that those security panels use a constant Float charge which long term is not good for any Lithium chemistry since Lithium batteries do not self discharge like Pb batteries. You would have to change out the battery charging circuit with one that would cutoff charging at a set voltage.
 
So I was about to post this very question when this thread popped up.
Aside from the lack of falling within the UL listing, I'm not sure why it wouldnt work. I'm looking at replacing a 14ah 12v agm that costs $90 with a 20ah LiFePo 12v that costs $80. The BMS will keep it from undervolting and overvolting, and the alarm panel itself states that it limits to either 400ma or 700ma charging current, based on a preference you set. If the panel is already limiting current then it's not going to "work harder". And keeping the battery at close to it's nominal voltage should make it last even longer, right?
 
So I was about to post this very question when this thread popped up.
Aside from the lack of falling within the UL listing, I'm not sure why it wouldnt work. I'm looking at replacing a 14ah 12v agm that costs $90 with a 20ah LiFePo 12v that costs $80. The BMS will keep it from undervolting and overvolting, and the alarm panel itself states that it limits to either 400ma or 700ma charging current, based on a preference you set. If the panel is already limiting current then it's not going to "work harder". And keeping the battery at close to it's nominal voltage should make it last even longer, right?
@Spliss and @Ampster are also correct, it's not good to float a lithium battery for a long time. I've since modified my setup.

I HAD two diodes, both facing opposite directions to drop float voltage. Now I use a single diode to block charging / floating from the UPS itself. I just leave the LiFePO4 cells charged up and sitting, rather than constantly float charging. After an outage, I will use a bench power supply to top it off. I'd like to add an ammeter later to check SOC.
 
Back
Top