Alec, if you are going to quote from Battery University, then at least **broken link removed**...Are you sure you get 'longer useful life'?
article suggests battery life would be shortened.
I thought I hadAlec, if you are going to quote from Battery University, then at least **broken link removed**..
I thought I had. Here's what it says:-
"The correct setting of the charge voltage is critical and ranges from 2.30 to 2.45V per cell. Setting the voltage threshold is a compromise, and battery experts refer to this as 'dancing on the head of a needle. On one hand, the battery wants to be fully charged to get maximum capacity and avoid sulfation on the negative plate; on the other hand, an over-saturated condition causes grid corrosion on the positive plate and induces gassing."
Indeed I did. Looks like it's a fine balance between lengthening and shortening the battery lifeDid you read the two articles I linked to?
My concern there would be that any downstream voltage regulators in the vehicle's electronic systems would have to drop more volts and so cope with dissipating more power. Could that compromise the lifespan of the ECU for example?fool the alternator into putting out a higher voltage?
....
My concern there would be that any downstream voltage regulators in the vehicle's electronic systems would have to drop more volts and so cope with dissipating more power. Could that compromise the lifespan of the ECU for example?
W
No ECU in my boat, Jeep or airplanes. The avionics in the airplanes operate on any voltage from 10V to 35V (smps power supplies designed for either 14V or 28V aircraft). The Voltage Regulators in my newish GMC truck, and Toyota are already factory set to ~14.6V. We are talking about raising the battery/bus voltage from 14.6 to 15.5ish. I'm not worried about the car's electronics...
Mike,
Are you going to answer the question about how you fooled your alternator or not?
MrAl; Have you looked at desulfation?
The answer depends your specific type of Voltage Regulator. Some are potted, some are pot adjustable, some you can open by drilling out rivets, some are inside the alternator, some are inside the ECU, some are in a separate box mounted on the firewall...
Basically, the VRs I have worked on and the ones I designed have used similar methods to implement the voltage-controlled switch I described in the previous post. They all use a voltage reference (like a Zener, or an IC voltage reference, or a TL431), a comparator (made from transistors, IC, Opamp), a power switch (NPN, PNP, Darlington, FET), a catch diode (Silicon rectifier) and a resistive divider to sample the bus voltage. Adjusting the output voltage involves tweaking either the upper or lower resistor in the divider...
In the case of my boat alternator, there is some history. The cabin cruiser is powered with a (Swedish) Volvo I/O with a Chev V8. The OEM alternator was originally a French POS made by Paris-Rohne (reputation sort of like Lucas). It had an internal potted VR that failed, so quit charging. I took the alternator apart, and everything but the VR was ok. I called the Volvo boat parts dealer and they could not sell me just the VR; I had to buy a whole new alternator to the tune of $750. I said B.S. and went an bought a external solid-state regulator that fit a 1970's Ford at NAPA for $15 and wired it to the existing alternator. It has been working for over twelve years...
The Ford regulator is the same as the one used in my Cessna, so I was familiar with it and I knew it would work with the French alternator. It was sealed with rivets, so is not "servicable". However, it was easy to drill out the rivets. I found a trim-pot inside. It was an easy matter to shunt the lower part of the trim-pot with a separate resistor in-series with an external switch. I empirically found the resistance value which would boost the battery voltage from a nominal 14.25V up to ~15.5V. The switch is mounted by the engine cover, so I can "equalize" either my starting battery or the "house" battery at will while cruising down the lake...
To trick the VR without taking it apart might be tough.
The extra "diode-trio" was used on the original Motorola Alternator Patent and on some of the one-wire alternators. The purpose of the three extra diodes is to make the alternator self-exciting, without using the battery as the source of the rotor current. Most of the newer designs have done away with the diode-trio and the idiot lamp. The newer regulators have a low-voltage alarm LED but it has nothing to do with the old Volvo burned-out lamp, my alternator won't bootstrap issue... In this design, only a few ma flows in the sense wire, so adding some resistance (few tens to hundreds of Ohms) to the sense wire might raise the output voltage. It is likely that the wire coming through the Ignition switch could be both a turn-on signal as well as the sense wire...
There are some VRs that use the same wire for both supplying the Rotor current (~2A) from the battery and for sensing the battery voltage. The one used in Piper aircraft (Chrysler alternator) is of this type. This can create oscillation or instability because of the voltage drop due to the large current flowing in the sense wire. With this type, you can also jack the voltage by adding some resistance in this common wire, but here it might be a fraction of an Ohm, and adding the resistance may make the system unstable (oscillate).
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