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1. 11:27 AM - Re: Re: Excessive Amperage (Robert L. Nuckolls, III)
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| Subject: | Re: Excessive Amperage |
Sorry to bug out on you last week.
Had a death in the family that needed our
attention. Been 'off line' for a few days.
>Upon starting my IO360 (only 12 hrs on engine) I noticed the "Low
Voltage" warning light did not go out (typically I get a flashing
lite when battery relay is activated and light goes out when
alternator >kicks in after engine start). I checked voltage and it
was about 12.5v and the amperage was 37 amps. Increasing RPM from 1k
RPM idle the "Low Voltage" light went out at 1.5K but the amps went up to 40.
>Turning off switches/loads made no difference in amperage.
>Inactivating the alternator brought amps down to 0.
>I have a B&C 40 A alternator with the B&C OV controller.
I suggest that when questioning such behaviors
of a B&C product, the FIRST, BEST source of
technical assistance is with B&C. They are
most willing and able to work with you by
phone or email and will be best able to
ask the right questions to sort through
your concerns.
Questions they might ask at the outset:
What's the make/model of your battery?
Was the battery in a state of full charge
when you started the engine?
What was your observed alternator current
at engine idle?
How fast was the engine turning at the
highest observed readings?
Over what period of time were these
observations made?
What is a 'new' experience with
battery recharge currents and durations
with this configuration. I.e. were
pervious behaviors more benign?
Analysis:
The fact that you saw 12.5v system
voltage at low rpm and low voltage light
still on suggests the battery was seriously
discharged and chemically primed to accept
a high rate of recharge.
The fact that your alternator current 'topped
out' at 40 indicates that the alternator is
functioning as expected (they inherently
self limit their output current).
The fact that your low volts warning went
out at higher rpm reinforces the suggestion
that the battery was significantly low
in state of charge.
With information currently in hand, I
deduce no anomalies in your electrical
system's behavior.
==== <correction for last post> =====
> It's NOT physically
> possible to OVERLOAD an alternator at idle.
======================================
Further, a properly integrated alternator
should be bullet-proof with respect to
damaging overloads. So if there's anything
to be concerned about with respect to
battery recharge currents after engine
start, damage to an alternator is not
one of them.
>There are gizmos made to take control of the charge rate such that
>it stays under the alternators design limits.
>The marine and RV folks use these controllers to safeguard their
expensive stuff.
>Check out the various YouTube videos that deal with RV travel with
the solar market.
>Many have converted to lithium batteries for their solar storage
and great power capacity.
>They have the same problem, namely stock alternators burning up
trying to supply max amperage at idle speeds.
>Resulting in too little air cooling.
>Companies like Victron, Renegy, etc., etc., make "Charge
controllers" to safeguard the alternators from overheating.
Solar charge controllers? I agree that Youtube
CAN be a valuable resource for tapping the experience
of others before launching off on your own
'adventure'. I used it heavily but find that
perhaps 1/4 of the information concerning
physics is factually correct.
In your particular case, I suggest YouTube will
be of no value since virtually ALL presentations
will focus on fixing a problem you don't have.
Virtually no one publishes videos on things that are
working okay.
I presume we're talking about a lithium battery.
There have been suggestions for limiting recharge
current with connection of two diodes back-to-back
in series with the battery.
This is NOT a current limiting technique. It
serves only to insert a VOLTAGE DROP in the
battery connection of approximately 0.8 volts.
One can achieve the same result by adjusting
the regulator set point down by the same
amount of voltage (see below). The notion that adding
diodes is an appropriate prophylactic against
alternator damage is in error.
Experience demonstrating reduction in
alternator failure by the addition of these
diodes HIGHLIGHTS a deficiency in alternator
design, fabrication or installation.
If the lithium battery featured in this
thread is promoted as a plug-n-play substitute
for an SLVA or even a flooded battery,
then under normal circumstances there are
no concerns for damaging an alternator.
We're not in possession of sufficient
information to completely resolve the ORIGINAL
query prompting this thread. At the same
time, there are individuals experiencing
alternator failures which in my opinion are
improperly diagnosed as to root cause. These
failures are popularly attributed to the
quality or style of battery installed.
Repeat: A judicious alternator design and
installation can't care less about the type
of battery installed. If changing a battery
increases likelihood of alternator failure,
it's NOT a fault of the battery. I.e.
the alternator is crippled.
Although a battery supplier's fondest wish
is to assume plug-n-play compatibility
of their lithium offering, I suggest
that competent literature suggests that
recharging stress can be lightened by simply
turning down the regulator set point. See
https://www.powerstream.com/lithium-phosphate-charge-voltage.htm
I have repeated and confirm assertions offered
in this article.
Note that LiFePO4 cells will achieve essentially
full charge at any voltage above 3.4 volts per
cell (or 13.6 volts bus). When your system is
fitted with a remote bus voltage sense feature
(like the B&C products), TARGETING an operating
setpoint of 13.8-14.0 volts is not a bad thing
to do.
Bob . . .
////
(o o)
===========o00o=(_)=o00o========
< Go ahead, make my day . . . >
< show me where I'm wrong. >
================================
In the interest of creative evolution
of the-best-we-know-how-to-do based
on physics and good practice.
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