Re: (ET) charger voltage

[David C Robie <mycroftxx1 juno com>]

Depends on the age of your batteries.   New batts are about 6.5 ea.  
Average batteries chg to about 6.25 6.3 (where do you think vacuum tube
heater voltage std 6.3 came from?  2.2V/cell).  Older ones (like some I
got) chg to maybe 6.15. No matter how long or what rate you charge a lead
acid battery like we use, it will not go over this 'age and abuse
related' voltage. 
    If you find one in the string that's consistantly low, swap it outa
there.  Your tractor will thank you.

Occasionally. people 'equalize' batteries by intentionally overcharging. 
 This ain't good for them.  If I find a low one. I put it on a separate
6V charger to bring it up as far as, by experience, I know it will go.  
My packs were not bought new, they are recycles and inherently some are
better than others.  I make sure each fall that the best ones go in the
tractor that has the snowblower.  

Charge em to the point that every cell is gassing.  Then leave em
overnite to remove 'surface charge'.  Test em in the morning.   That will
tell you where your batts are at agewise.   Of course, to charge them the
voltage of the charger must be a little over this.
    So, depending on battery condition, anything from half a volt over
about 36.5 to 39
will trickle charge em, and a volt or two above will hi rate charge em.  
(the charge voltage automatically tapers down because of the capacitor -
it and it's winding is called a ferro resonant circuit which is a form of
regulator) (therefore, open circuit voltage means little except too low =
bad capacitor.

Dave
Weymouth MA



On Wed, 26 Jul 2006 18:50:03 -0400 (EDT) Michael S Briggs
<msbriggs alberti unh edu> writes:
> 
> I've been scanning through the archives, and also the Service 
> Manual, and 
> am seeing some mixed messages on this - what voltage should the 
> charger be 
> putting out to the batteries? Mine's putting out a shade under 40 V 
> (39.5V or so), and they seem to not be holding as much energy as I'd 
> like 
> (T-105s that are a few years old, bought used). According to the 
> Service 
> manual, 40-45 V is ok (well, not on exactly the same wires as I'm 
> measuring the voltage, I'm measuring across the battery pack, rather 
> than 
> at S3 and S1 directly on the charger, so there's presumably a small 
> amount 
> of voltage lost between the points the manual says and the points 
> I'm 
> measuring at, especially if some weak connections, such as at the 
> Diode 
> heat sink). According to the archives online, I've seen people 
> saying that 
> if the voltage isn't 42-45V, the charger won't fully charge the 
> batteries 
> enough (some people who replaced the capacitor when the charger was 
> only 
> putting out 39V or so, for example).
>       With mine charging, the charge meter goes slightly into the 
> white 
> section - whereas in the archives, I've seen statements that if the 
> meter 
> doesn't go all the way to the high end of the white section, the 
> batteries 
> won't get a full charge.
>       On the other hand, the Landis controller only has the 
> charger on 
> when the pack voltage falls below 38V, by default, unless you adjust 
> it 
> up. So, if charging to 38V will give you a full pack, then there's 
> no need 
> to have the charger putting out more than 39V or so (other than that 
> the 
> higher the voltage it puts out, the quicker the pack will charge).
>       So, which is it? Is 39-40V from the charger ok, or should 
> it be 
> 42-45?
>       Essentially it comes down to - what should be the voltage 
> of a 
> fully charged battery pack (I know it's higher than 36V, but how 
> much?)?
> 
> Thanks,
> Mike
> 
> -- 
> 
> --------------------------------------------------------------
> Michael S. Briggs
> UNH Physics Department
> (603) 862-2828
> ---------------------------------------------------------------
> 
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