Re: Easy Service Call - Impressive Batteries

[ABLE1 <someone@xxxxxxxxxxx>]

On 8/8/2015 3:06 PM, Jim Rojas wrote:
> On 8/8/2015 2:48 PM, ABLE1 wrote:
>> On 8/7/2015 9:13 PM, Jim Rojas wrote:
>>
>>>
>>> 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.
>>>
>>> Jim Rojas
>>>
>>
>> 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.
>> http://www.smoktek.com/Efest-18650-Hybrid-IMR-Li-Mn-Battery--2200mAh-37V-button-top_p_862.html
>>
>>
>>
>> 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
>>
>>
>>
>>
>>
>
> 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.
>
> Jim Rojas
>

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