Fmtv no more dual voltage

Ronmar

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i think its the heat that kills it as it gets/ stays hot from trying to convert down to 12V from 24V all the time.

note: on battery equalization in a 24V system with two 12V batteries, the batteries are like two kids in a trench coat pretending to be a adult 24v battery.
So we have an upper(one you take 24V from) and a lower battery(the one connected to ground/chassis.)
In normal operation the voltage of both batteries should be equal. but when we take 12V loads(current) from the lower battery its voltage drops below that of the upper battery. With no equalization the 24V changing system doesn't see this imbalance and does nothing to fix it.
we add in a equalizer/dual voltage alt to bring the lower battery back up to an equal charge voltage as the upper battery. we do this by sending current back to charge the battery/provide current to loads so the battery it self doesn't need to do it. also if the lower battery voltage is higher than the upper no equalizer/dual alt can do anything about that and you need to either discharge via 12v loads or swap battery locations.

so technically you can treat the lower battery like a load and "charge" it with a Converter/Equalizer. this is why the bussman has the two different hook up methods.
Yea, we know the problems/complications with pulling 12 outta the middle of 24, that is why many of us are contemplating or are actually shifting to a straight 24v bank with converter...
 

Ohiobenz

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About 95% completed.
Waiting on the marine circuit breakers, 80A per 24v bank, 140A for the 12v was as close to Bussman specs as I could find, and 1 more terminal block for the 12v leg.
Bussman is installed, Smart Isolator is installed, battery banks are split, everything except for the 12v leg is wired up.
Alternator is installed - haven't figured out what to do with the wires off the regulator since this is an internally regulated and self-exciting unit.
Installing the radiator fan is next while waiting on the breakers to arrive.
 

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Ronmar

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About 95% completed.
Waiting on the marine circuit breakers, 80A per 24v bank, 140A for the 12v was as close to Bussman specs as I could find, and 1 more terminal block for the 12v leg.
Bussman is installed, Smart Isolator is installed, battery banks are split, everything except for the 12v leg is wired up.
Alternator is installed - haven't figured out what to do with the wires off the regulator since this is an internally regulated and self-exciting unit.
Installing the radiator fan is next while waiting on the breakers to arrive.
I would just insulate and tie the excitation and sense wires back To the wiring bundle they come out of. one has 24v on it when the engine is running, so you need to make sure it doesn’t find a connection to ground...
 

Ohiobenz

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I would just insulate and tie the excitation and sense wires back To the wiring bundle they come out of. one has 24v on it when the engine is running, so you need to make sure it doesn’t find a connection to ground...
Been trying to follow the A0 schematic rather unsuccessfully for those wires. How does the dash gauge get it's signal?
 

Ronmar

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Been trying to follow the A0 schematic rather unsuccessfully for those wires. How does the dash gauge get it's signal?
The dash gauge reads voltage from the power dist panel... neither of those wires On the reg goes to the gauge. One is 24v supplied from K11 to excite the alt once oil pressure is over 15PSI... the other wire runs to the STE connecter under the Drivers dash and is only used by the STE equip to monitor how hard the alt is working when testing the systems... I would just insulate and secure them...6ECA623D-92A9-4DB3-B957-7ECF281E782D.jpeg
 

Ohiobenz

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The dash gauge reads voltage from the power dist panel... neither of those wires On the reg goes to the gauge. One is 24v supplied from K11 to excite the alt once oil pressure is over 15PSI... the other wire runs to the STE connecter under the Drivers dash and is only used by the STE equip to monitor how hard the alt is working when testing the systems... I would just insulate and secure them...View attachment 809175
Thx.
So this is on foldout 7. On which page(s) do I find the continuation of that connector plug P31x ? At least P31 is labeled and tells me where things go. I just haven't figured out their schematic system yet.
I'm almost done doing the electric fan swap. Hope to fire it up today.


NVM... My smart wife picked up on the reference to the grid numbers.... it all makes sense now lol. As she said, I was stuck in the paradigm of prior schematics...
So if I disconnect 568A at K11 it would appear there is no other power going out that harness.
I've pulled the STE and it's harness some time ago.
 
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coachgeo

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The dash gauge reads voltage from the power dist panel... neither of those wires On the reg goes to the gauge. One is 24v supplied from K11 to excite the alt once oil pressure is over 15PSI... the other wire runs to the STE connecter under the Drivers dash and is only used by the STE equip to monitor how hard the alt is working when testing the systems... I would just insulate and secure them...View attachment 809175
thanks for pointing this out. thought for myself when get round to it is to use the excite wire to trigger a solenoid placed between headlight switch's main power line..... this way when truck is shut off...... no lights.... and lights if left on do not come back on till after engine is started (to reduce stress on starter/alternator) . PM me if Im wrong and this wont work... I'll find my old thread on this and pull it up so not to hijack this one further.

Oh and Jerrit.... you should consider using this excite wire for one side of its intended purpose of not powering anything of heavy drag on engine while starter is engaged... Lights like suggested above..... maybe an aux circuit that may have radios, camera's, etc on it.... ? Alternator itself is drag on engine.... think this is why it is NOT excited during start up too. Other benefits: Helps in cold weather starts?, helps prevent power spikes? reduce alternator wear? If recall right Ron or someone else mentioned that this spike may also be a cause of history of failures of ctis controller..... so maybe put that power source on it too.
 
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Ohiobenz

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thanks for pointing this out. thought for myself when get round to it is to use the excite wire to trigger a solenoid placed between headlight switch's main power line..... this way when truck is shut off...... no lights.... and lights if left on do not come back on till after engine is started (to reduce stress on starter/alternator) . PM me if Im wrong and this wont work... I'll find my old thread on this and pull it up so not to hijack this one further.

Oh and Jerrit.... you should consider using this excite wire for one side of its intended purpose of not powering anything of heavy drag on engine while starter is engaged... Lights like suggested above..... maybe an aux circuit that may have radios, camera's, etc on it.... ? Alternator itself is drag on engine.... think this is why it is NOT excited during start up too. Other benefits: Helps in cold weather starts?, helps prevent power spikes? reduce alternator wear? If recall right Ron or someone else mentioned that this spike may also be a cause of history of failures of ctis controller..... so maybe put that power source on it too.
With the split battery system the starter will always have at least 26.7V
Fired it up today!! Success on all fronts.
 

Ronmar

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Yes, you could disconnect 598a, or you could simply remove K11. The other switched contact of K11 goes back in the harness to the troop switch(provides power when engine off) but its purpose is not specified anywhere that I have found.

Coachgeo‘s idea of using it to enable lights is interesting, there is already a radio relay and power circuit that removes radio power while using the starter...
 

Ohiobenz

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Up and running!!

I do like the idea of using that output for something.
Lighting may not be my option just in case I need to see when the engine isn't running.

Videos in the Military Vehicle Camper Mods FB page.
 

coachgeo

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...
Lighting may not be my option just in case I need to see when the engine isn't running.
...
Yeah ... thought same thing and was thinking a separate/second switch and relay to activate power to light circuit when engine not running. Maybe a timer type switch on this one so you cant leave lights on overnight etc. with this swtich
 
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