Holding Voltage for 48v 600a system.

[clockmanFRA]

After 3 years my battery system holds at about 52.7v when all batteries are gently-fully charged.  5 days later with No use and no charge the voltage has dropped to 52.5v.

2 off Hugh P's 3.7m design wind turbines, 2 off 45a Tristar's set at 56.6v charge and 54v float.

I am interested to know if any one else has data for holding charge for 48v battery system?.

[zap]

Without knowing what your batteries are, what type of charge control (if any) etc... no one can really answer your question.

We need more information on your system!!!

[clockmanFRA]

Hi Zap,

Further information.

Batteries :- (24 off) 5 strings of 4, each 12v 110amp sealed felt type (ultra deep cycle Gel Marathon 35kg each), 1 string of 4 sealed lead acid type 12v 110amp (ultra deep cycle Lucas 28kg each).   

Power supply :- 2 off 3.7m diameter wind turbines, output DC from 10amp at 48v to 56.6v. Normal max 60amp at 48v to 60v (when automatic furled). Max gust recorded 83amp at 60v.

Controllers :- 2 off Morningstar Tristar 45amp. Both set for diversion load at 56.6v and when controllers go to float mode at 54v. 2 Dump loads, air heaters (large coil type 4mm dia wire) matched resistance 1.36ohm each.   

Trust this clarifies.

[zap]

.2v isn't much and probably not something I'd be worried about.
Did your bank hold the 52.7v longer than 5 days when it was new or is this just something you've checked for the first time recently?

I assume all the batteries are 3 years old?  Have they been cycled deeply?

On another note...
Your charge voltage of 56.6 is near the high side for SLA.
Is this the voltage recommend by your battery's manufacturers?  Do you have/use a temp prob with the Tristar?

[clockmanFRA]

52.7v seems to be the holding voltage after 24hrs without wind. Every 3 months or so i go away for a few days (this time 5 days) I shut the system down, and on my return the voltage is at 52.5v. And this holding voltage has been consistant for the past 3 years.

I do not let the voltage drop below 48v when pulling power for the inverter. Inverter is 3.7kw but in general do not pull more than 2kw. And i only use the power when the wind is blowing, ie, dump loads working then turn on the inverter.

SLA says 14 to 14.2.

No temp probes, as batteries are stored in a natural regulated stable environment.

Is 52.5v a normall holding voltage for a 48v system?

[ghurd]

It sounds fine to me.
I would expect more like 51.2V or so after 5 days.
G-