Had a sort of fun service call today. AC has been out on a fire panel since the 31st. Customer was notified that day. Today was the first day they could coordinate to look at it. The panel has been sending abnormal tests the whole time and started sending low battery signals this morning.
Every breaker in the panel for the building was on except the breaker for the fire panel. It was not tripped it was turned off. I turned the breaker on, checked voltage on the batteries (22 volts) and waited about five minutes. Al troubles cleared. I gotta love those Yuasa batteries. I think those will pass the 24+5 rule. LOL.
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B
Bob La Londe
Yes I did notify the customer that they were supposed to have a clip on that breaker to prevent accidental turnoff. I don't do much fire so I don't carry them in my truck.
J
Jim
Except for the few years that they were bought out by someone, I've used nothing but Yuasa all these years.
N
NickMark
Yuasa makes great batterys use them all the time
J
Jim Rojas
A few months back I started experimenting with Li-Mn batteries on my own security system.
At the moment I have 2 banks of four 18650 2200ma Li-Mn batteries. It is roughly a 4AH setup at the moment. So far, no problems whatsoever. I did have to discharge the batteries down to 3 volts each so the security system would be able to charge them up to about 13.5 volts. So far, no problems at all. I still need to fully test backup time though. Since I am not over stressing the batteries at 3.7-4.2v, they should last a lot longer, and provide roughly 10 percent less of their overall rated capacity. This is something you just can't do with SLA batteries.
I plan to add 2 more banks to give me a total of 8AH more or less. The nice thing about this setup is that it allows me to replace a single bad cell without tossing out the rest of the batteries. This is something I always disliked about SLA batteries. Sure I can buy Li-ion or Li-Mn battery for about $100 each, but then I have the same problem with them being sealed.
I wouldn't recommend doing this out in the field, but it would be nice to see these type batteries used for security systems in the future at a much lower cost. I can see this battery bank lasting 6-8 years without any real issues.
If all works as planned, I will encase the completed battery bank in a metal or plastic enclosure to minimize the possibility of a short circuit.
Hi Jim, haven't see you around these here parts for a long time. Hope all is well in the "sunshine (among other things) state".
So now you had to put new input into my brain that forced me to Google some stuff. LiMn Lithium Manganese. From what I have read they have high amp short life or something like that.
I assume that you are using something like these.
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Assuming that you are putting 3 batteries in a bank?? Then you have a voltage per bank of 3 = 11.1 to 12.6vdc
So what happens when you pull the AC from the panel?? How long do they stay up before a low battery happens??
Interesting stuff.
Thanks,
Les
J
Jim Rojas
Hi Les. No, I am using four 18650 batteries in series which comes to around 15v. If you use 3 batteries, then you are over stressing the batteries and it would last no longer than SLA batteries. So what I do is drain each bank down to no less than 11 volts under a light load. Then you can connect it to the alarm system. It works like a charm so far.
Ok, so you are tricking the panel and the batteries to some extent. Battery bank charges to 13.7vdc and the are happy, panel sees a charged battery so it is happy. I get that and it is cool thinking.
But, what happens at AC failure?? How long will it stay up before going into Low Battery?? That would be the true test.
I know it will depend on that actual load of the panel and devices but is it better or worse than a SLA??
What kind of holder are you using to fit batteries or are you just soldering wires on the ends as a temp??
Thanks,
Les
J
Jim Rojas
With this first test, I was using 6 year old 18650 cells. They lasted 20 minutes before it went into low battery. I know this is terrible, but these same cells would no longer hold a charge in a laptop.
I am using a plastic 4 battery holder specifically made for 18650 cells. I then connect each 4 cell bank to a terminal bus strip in parallel. From there it goes to the charging circuit. I can add as many banks as I like to get the desired backup time needed.
When connecting battery banks in parallel, the key is to cross connect the charging leads. At the first bank I connect only the positive lead, and at the last bank I connect the negative lead. If you fail to follow this important step, all the batteries in between will all die prematurely. This is especially true with just about any battery. A cross connection forces the charge to travel throughout all the battery banks evenly. The batteries then balance themselves out without the need of any additional balancing circuits that are commonly used on 18650 batteries.
I ordered some better made plastic battery holders from China, and I have plenty of brand new 18650 cells. They should arrive in about a week or so. It will take a few days to charge down & up the new banks with the panel, so you will have to wait until then.
Sorry Jim, I am really not getting that. Maybe it is my old brain but are you not connecting the positive leads from each battery bank together as well as the negative leads?? And then you end up with 1 positive and 1 negative that will connect to the panel battery leads??
I can't see where one bank would be first or last or in between.
The banks in parallel the voltage will remain the same but the amps would double with two banks, triple with three banks etc. etc.
Am I missing something??
Les
J
Jim Rojas
Yes, but if I bought one "made in the USA", it would be cost 10 times more and on the bottom it would be stamped made in china.
You don't want to connect battery banks together with a wire nut and hope for the best. You need to use a bus bar or terminal strip. You must force the charging voltage to flow evenly. It will only take the path of least resistance by connecting them together with wire nuts.
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---- is a bus bar or terminal strip
If you connect the negative to B1, you will cause B2-B4 to die prematurely. The current flow is only going through B1.
Honeywell panels that use the dual battery harness is a perfect example on how not to connect batteries. Eventually, one battery will die before the other.
If you look on Google, there are pictures that show how to properly connect battery banks.
You can just make parallel cable wires with crimp on terminals, but if you want to add another battery, you then have to modify the cable assembly to accommodate the new battery. The bus bar or terminal strip works quicker and multiple bus bars can be added without too much trouble.