[AT] OT Buck-Boost convertor for charging auxiliary battery

[Stephen Offiler]

A small 2:1 transformer will take care of the 24V "W" terminal to the 12V
tach.   Unfortunately you can't wander down to your local Radio Shack any
more, but a transformer like this is easily sourced from any of the big
online electronics vendors,  including Newark, Digi-Key, Mouser, Allied,
and some others.

SO


On Sat, Jan 19, 2019 at 5:35 PM Cecil Bearden <crbearden at copper.net> wrote:

> I have already replaced the Voltage convertor.  This problem will raise
> its ugly head again.  At my age and the difficulty involved in raising
> the hood on this tractor with the loader down,   that voltage convertor
> will get replaced.   It is just a stupid design.  One battery is being
> charged by two chargers and the other by one.   The voltage convertor
> cannot keep up.  I have changed the others over from the series-parallel
> switch to a 24V alternator and they work great.  The only question I
> have is if the tachometer can operate off of the waveform terminal of
> the 24V alternator.
>
> I have run 110V hydraulic solenoid valves off of 12v inverters, but when
> I had the funds to convert the valves to 12V DC, I did to eliminate the
> extra electronics.
>
> Cecil
>
> On 1/19/2019 10:21 AM, James Peck wrote:
> > I worked on a 12 volt battery vocational truck that used voltage
> converters to get 24 vdc to run a plc and  electrohydraulic valves.
> >
> > I personally would try to determine if the problem is just a poorly
> performing voltage converter. I would avoid modification if the problem can
> be rectified by replacing a poorly performing component.
> >
> > ]Cecil Bearden] To update the VC problem, after measuring the voltages
> and looking at diagrams again I am beginning to understand the system, but
> I don't understand the reasoning behind it.   In a nutshell, the alternator
> charges the main battery, at the same time the VC charges both batteries in
> series at 24V.  Definitely something lost in translation in their
> engineering.
> > All I can think is What the H*#L ?!?!?!?
> > I have found a 24V alternator of the same size and connections.
> >
> > ]Cecil Bearden] Guys: I need some help with the wiring on my MTZ 1220.
> in an earlier post I mentioned that this voltage convertor (VC) will not
> keep the auxiliary battery charged.  The factory furnished a new VC and the
> dash warning light indicates that it cannot keep up with the battery when
> using the lights, or the cab fan.  Perhaps the alternator is not providing
> enough current on the main battery, or the signal from the alternator is
> not triggering the VC to operate.
> > I have tried to convince the factory to change over to a 24V alternator
> and use one battery for the 12V accessories.   The alternator is an ISKRA
> brand  and a one wire Delco is not easily mounted the way the ISKRA is..
> The only wiring diagram of the alternator shows a battery connection and
> the sensor connection to the alternator.  The W terminal is not shown to be
> connected in the diagrams I have.   I need to know if the ISKRA alternator
> uses the battery terminal to sense the voltage for the regulator as a one
> wire Delco does, or if it need a wire to the W terminal to turn the
> alternator on.   If it uses the Bat terminal then changing to 24V won't be
> a big deal.  If the W terminal or another needs the 24V input, then I will
> have to install a relay to turn on from the ignition switch as the ignition
> switch is on 12V.   the starter and the glow plugs are 24V.  To change over
> to the 12V system as the factory has suggested, will require changing 6
> glow plugs, the starter, alternator, and new cables.  My solution only
> requires changing the alternator.
> > I know some of you guys are much better at reading electric diagrams
> than I am.   I can usually wire things up without any trouble, but
> sometimes wiring diagrams give me trouble.  If you could take a look at the
> attached, I would certainly appreciate it..
> >
> >
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