[time-nuts] Li Ion Battery for HP 5065A

[ew]

 A123 7Ah "brick" LiFePO4   who is the vendor?Bert Kehrren


In a message dated 3/8/2019 4:03:53 PM Eastern Standard Time, jimlux at earthlink.net writes:

On 3/8/19 5:38 AM, Bob kb8tq wrote:
> Hi
> 
> If you are headed into a “cost is no object” sort of battery backup bank for the lab / shelter / cave
> there are some interesting options out there. The RV world is very slowly waking up to the fact that
> big heavy lead acid batteries may not be ideal. For a ghastly amount of money, you can now get
> 12V 100AH “drop in” (no they are not drop in) Lithiums with fully integrated BMS systems in them.
> They *appear* to be safe and come with cute things like 10 year warranties . Be aware that you
> can buy a nice 5065 on eBay for what a couple of them will set you back …..
> 

I've used the A123 7Ah "brick" LiFePO4 that replace the standard Lead 
Acid - they weigh a LOT less, and cost a LOT more ($100 vs <$10) - 
They're pretty nifty devices.  As you note internal battery management, 
built in (easily replaceable) 30A fuse, etc.

They weigh about 850g (vs 2.6 kg) and work well at low temperatures (-20C)

One peculiarity is that if you discharge them below minimum voltage, 
they cutoff and put out nothing. You have to put a charging voltage on 
them to turn them back on.  This fouls up some "smart" battery chargers 
which use the "discharged" battery voltage to tell them that there's a 
battery connected.  So we always had our smart chargers for day to day 
use, but had a couple wall wart trickle chargers around to turn the 
battery back on.

100 Ah would set you back well over a kilobuck.  But, you would be able 
to lift it without you going over the OSHA 55lb/25kg "one person lift" 
limit.




> In return for your massive cash outlay, you get a battery that does not outgas or have the need
> to be watered along with the plants. It has a much flatter discharge voltage curve than a lead acid.
> Their peak current vs voltage generally is better than a lead acid. The BMS may impact this if it
> is an issue in your setup. They also is a *lot* lighter / smaller for the same amount of useful
> capacity. The built in BMS *should* take care of all of the fiddly little issues that might burn the
> house down. Lots to like other than the absolutely giant hole in the wallet ….
> 
> Bob

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