[T3] Electrical questions

[Keith Park]

well the numbers I use were derived from industrial batteries, a somewhat
different animal.  I have 2 375ah forklift batteries that power my off-grid
camp, with those the charge controller (or charger) does an initial charge
at
full capacity till they reach 13.5v  then float charge them till they reach
14.6v, but periodically they reccomend an equilization charge to break up
any sulfation etc. for a few hours at 15v and equilize the cell voltages.

Keith

Topnotch Restorations
topnotch at nycap.rr.com
http://www.a383ina68.addr.com/radiorest/main.htm
71 Squareback  "Hothe"
65 Notchback  "El Baja Rojo"
93 RX7  "Redstur"
87 Golf  "Winterat"
 

-----Original Message-----
From: type3-vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]
On Behalf Of Jim Adney
Sent: Tuesday, August 25, 2015 11:45 AM
To: type3 at vwtype3.org
Subject: Re: [T3] Electrical questions

On 25 Aug 2015 at 9:52, Keith Park wrote:

> flooded lead acid cells are 80% charged when they start to boil.

Keith, you're killing me here.  ;-)

Now you've forced me to go back to my Bosch handbooks and double- 
check everything.

Okay, gassing (commonly, but incorrectly called "boiling" starts at 
~2.4 V per cell. That's 7.2 V for a 6 V system or 14.4 V for a 12 V 
system. Gassing refers to electrolysis of the water in the acid. We 
can charge higher than that, but it's hard on the cells and reduces 
their lifetime. Gassing is undesirable because it can cause breakdown 
of the sintered lead and lead oxide cell plates.

At 2.4 V per cell, Bosch claims we're at ~90% of "full" charge, but 
going higher than that, while possible, is hard on the battery, so we 
try to avoid it.

It's possible to continue charging above 2.4 V per cell, but never at 
a rate higher than 10% of the A-Hr rating (and more like 1% if the 
battery is sulfated after long discharged storage.) Charging like 
this will increase the cell voltage rapidly to 2.7 V, which is 100% 
charged.

The numbers above are for batteries sold with acid diluted for use in 
temperate climates. Batteries sold for arctic or tropic use, use 
weaker or stronger acid and follow different curves. US and European 
batteries all use the temperate climate dilution.  

-- 
*******************************
Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
*******************************

_______________________________________________
VWType3.Org mailing list - type3 at vwtype3.org
To unsubscribe or change subscription options, visit:
http://lists.vwtype3.org/listinfo.cgi/type3-vwtype3.org
If you need more help, contact: gregm at vwtype3.org