More charger questions

[Chuck Wheeler]

Your close Pete! Batteries in good condition have a pretty constant
resistance. But as they charge the terminal voltage rises and as the
terminal voltage approaches the regulated charger voltage the current
deceases due the lower voltage across the batteries resistance. Battery
condition indicators usually just measure this terminal voltage. For
example a Trojan T105 has a terminal voltage of 6.37 at full charge and 6.05
at 50% charge. A properly regulated charger (or alternator) will initially
charge at 7.4vdc. (Actually 14.8vdc for our 12 volt systems.) The
alternator will modify this charging voltage based on battery temperature.
That is why we have remote regulators in the wanderlodge FCs., located in
the battery compartment, because the batteries are not in the engine
compartment and are not at the same temperature as the alternator.
Regulators back off the charging voltage as the temperature rises.



Well designed chargers electronic chargers base their charging current based
on terminal voltage. The original "battery boilers" have no such sensing.
They just charge on no matter what the battery condition.



- Chuck Wheeler -

82 FC 31 SB

Fort Worth, TX

_____

From: WanderlodgeForum@yahoogroups.com
[mailto:WanderlodgeForum@yahoogroups.com] On Behalf Of Pete Masterson
Sent: Monday, May 14, 2007 8:21 PM
To: WanderlodgeForum@yahoogroups.com
Subject: Re: [WanderlodgeForum] More charger questions



Having had battery chargers (automotive) dating back to the 60's that
exhibited this effect, I believe that the resistance of the battery
increases as the charge level increases. However, that is not the
same as the controlled voltage of the modern 3-stage chargers.

Pete Masterson
'95 Blue Bird Wanderlodge WBDA 42
aeonix1@mac. com
On the road at Lockhart Texas

On May 14, 2007, at 6:37 PM, Scott Forman wrote:

> Hate to split up the thread, but the other one was getting long.
>
> My 86 PT38 has what I assume are the original battery chargers. I
> have
> noticed, though, that on the 'D.C. Charge' gauge above the co-pilots
> chair, the juice being applied to the batts trails off over time,
> presumably as the batts get closer to full charge. Why is this if the
> chargers put out a constant flow of juice?
>
> Scott Forman
> 82 FC35RB sold today, but still in my possession
> 86 PT38
>





[Non-text portions of this message have been removed]