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

[Cecil Bearden]

I can only ask WHY????

The alternator is setting here at a cost of $265.  It will take an 
additional $5 in wire and terminals.  Probably another hour in labor.

A 28 volt 30 amp voltage convertor will cost over $400, and is still a 
stupid design.  It may not be considered defective, just not efficient 
and reliable for agriculture.  Usually when VC's are used the batteries 
are charged separately and only connected together for starting.  I am 
waiting on word from the factor rep who was going to talk with the truck 
division over the weekend. The truck engines are built for 24V 
operation.  At further investigation I don't think the Waveform terminal 
on the alternator is used.  the signal terminal will not be used when 
the VC is removed, so this will become a one-wire alternator....  I need 
to remove the mesh guard on the side of the engine covering the 
alternator.  I am not a fan of these and it will probably not be 
re-installed.  They are a PITA when changing the fan belt.

Cecil

On 1/20/2019 9:36 PM, James Peck wrote:
> I have a small amount of disbelief that a company would sell a product worldwide that has a defective design.
> https://en.wikipedia.org/wiki/DC-to-DC_converter
>
> Could you upsize the overtaxed voltage converter. It is a smaller hack.
>
> (Cecil Bearden] 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.
>
> ( James Peck}  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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