Re: [EVDL] FW: A123 ALM12V7 Battery internal electronics drop-out; now OK, A123 needs - DIY Electric Car Forums
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Old 06-29-2012, 11:35 AM
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Default Re: [EVDL] FW: A123 ALM12V7 Battery internal electronics drop-out; now OK, A123 needs

With A123 instead of Lead, 13.5V is only 3.375V/cell average. This is
barely over nominal voltage; I think you'd want to float them to at
least 3.4-3.45V/cell (13.6-13.8V).

-Morgan LaMoore

On Fri, Jun 29, 2012 at 11:27 AM, Cor van de Water <xxx@xxx.xxx> wrot=
e:
> Mark,
>
> How frequently are you cycling your UPS?
> I do not understand why you are concerned about the time
> it take for UPS batteries to get full and the main issue
> with many UPS'es is that their float voltage is too high
> for the battery temp and they cook the batteries to an
> early death. I would never think of increasing a float
> voltage much above 13.6V and at elevated temps (like inside
> a UPS case) the 13.5V sounds about right, there is little
> to gain, even for a Lead-acid, when floated higher, but
> there is a lot to lose.
> I keep my standby battery floated on a power supply set for
> 13.5V
>
> Regards,
>
> Cor van de Water
> Chief Scientist
> Proxim Wireless Corporation http://www.proxim.com
> Email: xxx@xxx.xxx Private: http://www.cvandewater.com
> Skype: cor_van_de_water XoIP: +31877841130
> Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203
>
> -----Original Message-----
> From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On Beh=
alf Of Mark Hanson
> Sent: Friday, June 29, 2012 7:03 AM
> To: xxx@xxx.xxx.edu
> Subject: [EVDL] FW: A123 ALM12V7 Battery internal electronics drop-out; n=
ow OK, A123 needs to note this on batts
>
> Hi,
>
> After charging overnight per the A123 manual and holding at 14.4V with a =
bench supply, the batteries now appear to be OK. I ran a UPS cycle loade=
d at 1A 230V (230W) and it ran through the 5 minute discharge OK with the b=
atteries dropping from 14 to 12.5V. The QUINT-UPS by Phoenix Contact has=
a design issue though, it only charges the LiFePO4 batteries to 13.5V per =
battery (27V total), when according to the A123 ALM12V7 manual float charge=
should be 13.8V per (27.6V total) and hold for 14.4V for 4 hours or 28.8V.=
It does not do that so I'll check with Phoenix Contact and see if they =
know anything otherwise I'll have to modify the circuitry. The float vol=
tage is even a bit too low to get a full SOC on the lead acid batteries I b=
ought (they like 27.6V float, 27V gets them about =BE charged and takes a l=
onger time to get there, about 8 hours instead of 1 hour.)
>
> mark www.REEVA.info
>
> -------------- next part --------------
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