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

[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

On 1/16/2019 10:59 PM, Cecil Bearden wrote:
>
> 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..
>
> Cecil
>
>
>
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