Double alternator

[serpico760]

Anybody ever try these? Thought? review?

Military Alternator Alternative - Double Alt

The Military Alternator Alternative As of April 1st, 2019 No core charge! Contact info ron@double-alt.com Compare Niehoff Brand Double Alternator Popular model (model N1506-1) (model 2J or 2P) 14/28 volt output Yes Yes Amperage total output 100 230 or 320 Internal Regulators No Yes...

www.double-alt.com

 

[Ronmar]

Well there was someone selling a “double alt” once upon a time, no support and not well built… it was basically 2 alternators connected end to end. I have seen one using a custom mount that used two common alternators side by side, which kinda shorts one of them for belt-pully contact area…

Every double alt scheme I have seen all have one major issue. They use commonly available 12 and or 24v alternators That are independently regulated. Any way you do this(two 12s in series, or a 12 within 24 working together) the two regulators regulate independently and react differently to the 12 and 24v loads they must bear. This equals over or undercharge/unbalanced batteries And premature failure. The Neihoff not only regulates, but it provides the 12 at exactly 1/2 of the 24v output (14.1/28.2V) to keep the batteries in balance.

This is really a bad idea from an engineering standpoint. Even the dual volt done properly with a single integrated regulator like the Neihoff, is really hamstrung pulling 12v out of its middle. Using the 100A Neihoff(60@12, 40@24) as an example as I am most familiar with it. With both 14 and 28v fully loaded, the alternator only delivers ~1930 watts. A straight 28v alt @100A delivers 2800W. Thats 33% MORE POWER!

what knucklehead came up with this scheme, when it is completely unnecessary. Decent 24-12 power converters have been available for a very long time… a dual alt in any form is a really bad idea…

1. Replace 12/24v alt with a straight 24v alt feeding a 24v battery bank.
2. Install a 24-12 power converter to provide for the truck 12v needs.

Both commonly available parts, like Delco alternators and Victron orion 70A 24-12 converter(70A@12 is double the trucks max 12v load). If you are only feeding and drawing 24v from the batteries, there are no balance issues beyond the naturale native chemical ones inherent in all batteries.

I am confident I could install these and make any necessary changes to the vehicle(A0 ign and start system to 24v control) for ~$500 or less…

common parts, commonly available, very robust and easily maintained by you anywhere anytime, not some custom crap or old milspec unobtanium that is now priced like it was dipped in gold…

 

[Keith Knight]

Why does everyone put the 24v to 12v converter near the dash instead of in the battery box where you would have plenty of space if you removed 2 batteries?

 

[aw113sgte]

Why does everyone put the 24v to 12v converter near the dash instead of in the battery box where you would have plenty of space if you removed 2 batteries?

No reason you couldn't, but you would want one rated for weather exposure in that case.
Also perhaps to be able to remove those large gauge 12v cables.

 

[serpico760]

Well there was someone selling a “double alt” once upon a time, no support and not well built… it was basically 2 alternators connected end to end. I have seen one using a custom mount that used two common alternators side by side, which kinda shorts one of them for belt-pully contact area…

Every double alt scheme I have seen all have one major issue. They use commonly available 12 and or 24v alternators That are independently regulated. Any way you do this(two 12s in series, or a 12 within 24 working together) the two regulators regulate independently and react differently to the 12 and 24v loads they must bear. This equals over or undercharge/unbalanced batteries And premature failure. The Neihoff not only regulates, but it provides the 12 at exactly 1/2 of the 24v output (14.1/28.2V) to keep the batteries in balance.

This is really a bad idea from an engineering standpoint. Even the dual volt done properly with a single integrated regulator like the Neihoff, is really hamstrung pulling 12v out of its middle. Using the 100A Neihoff(60@12, 40@24) as an example as I am most familiar with it. With both 14 and 28v fully loaded, the alternator only delivers ~1930 watts. A straight 28v alt @100A delivers 2800W. Thats 33% MORE POWER!

what knucklehead came up with this scheme, when it is completely unnecessary. Decent 24-12 power converters have been available for a very long time… a dual alt in any form is a really bad idea…

1. Replace 12/24v alt with a straight 24v alt feeding a 24v battery bank.
2. Install a 24-12 power converter to provide for the truck 12v needs.

Both commonly available parts, like Delco alternators and Victron orion 70A 24-12 converter(70A@12 is double the trucks max 12v load). If you are only feeding and drawing 24v from the batteries, there are no balance issues beyond the naturale native chemical ones inherent in all batteries.

I am confident I could install these and make any necessary changes to the vehicle(A0 ign and start system to 24v control) for ~$500 or less…

common parts, commonly available, very robust and easily maintained by you anywhere anytime, not some custom crap or old milspec unobtanium that is now priced like it was dipped in gold…

Thank you Ron for your input!
What 24 volt alternator would you suggest that not only fits well but has enough amperage to deal with the truck plus extra electronics and extra off-road lights as well as charging 4-8 house batteries in a 24 volt setup through the victron 24 volt 3000 watt inverter charger?

 

[Ronmar]

The balancers are waterproof typically most of the 24-12 converters are not. Pitting the 24-12 in the dash makes the wiring dead simple as that is where the 12 v goes anyway… only reason to put it in the box is if you are using a “balancer(output exactly 1/2 of input)…

 

[MatthewWBailey]

Why does everyone put the 24v to 12v converter near the dash instead of in the battery box where you would have plenty of space if you removed 2 batteries?

I would never install any electronics inside the battery box. It's the definition of unsafe. Refer to the h2 explosions posted on SS for data points.

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No one remembers that H2 is generated during heavy early recharging of LA batteries, after startup. Any failure of electronics will ignite the gas in that little space. Hence the reason the manual disco AND power relay are in a separate box. Unless you're using non LA chemistry, I would avoid this.

 

[Keith Knight]

A sealed waterproof unit like would be fine in that space.

 

[MatthewWBailey]

View attachment 934701
A sealed waterproof unit like would be fine in that space.

A definite maybe. Certainly better than a typical converters IP rating but those ratings are not for ignition, they're for waterproofing and corrosion proofing. This would not pass for use in an ambient environment with gas% above the LEL but only bc it's not tested as explosion proof. Any 'devices' added to the battery box should be supplemented with forced ventilation. It's (low probability) + (extreme high hazard) which = active engineered solution required, in the govt safety realm. Besides there are a dozen other places to put this.

 

[Ronmar]

If it is weatherproof, it can also take the place of the PPD/LBCD, which is also an easy place to wire it in.

 

[GeneralDisorder]

If you are going to do "double alternator" you have to do it the way the CUCV did it. GM knew the answer - two alternators with isolated grounds that each charge their own battery. Both were 12v and each handled one battery independently. The 24v for the starter, glow plugs, and slave receptacle were powered off a 24v buss-bar which is the only place the two batteries are tied together to achieve 24v.

 

[coachgeo]

If you are going to do "double alternator" you have to do it the way the CUCV did it. GM knew the answer - two alternators with isolated grounds that each charge their own battery. Both were 12v and each handled one battery independently. The 24v for the starter, glow plugs, and slave receptacle were powered off a 24v buss-bar which is the only place the two batteries are tied together to achieve 24v.

After the alts isolated (ground all the way to the partnering Neg. stud at battery bank) ... am I correct in thinking that generic ground can be used for everything else no matter its voltage?

 

[serpico760]

I think with all the information I have received I would rather switch to a purely 24 volt setup with the 12 volt converter at the dashboard. The question is whether to have the alternator and the solar through the victron 24 volt 3000 watt inverter charger charge the same set of batteries as both the truck and house batteries combined or have two batteries for the truck and the rest for the house.

 

[GeneralDisorder]

After the alts isolated (ground all the way to the partnering Neg. stud at battery bank) ... am I correct in thinking that generic ground can be used for everything else no matter its voltage?

Correct. Ground is still ground for all the chassis circuits. It's only the charging circuits that have isolated grounds.

 

[Ronmar]

Thank you Ron for your input!
What 24 volt alternator would you suggest that not only fits well but has enough amperage to deal with the truck plus extra electronics and extra off-road lights as well as charging 4-8 house batteries in a 24 volt setup through the victron 24 volt 3000 watt inverter charger?

Well the alt choice depends entirely on your load. If you have dropped to 2 service batteries you will have some surplus typically As the truck loads including all the lighting, are going to be under 30A @24v. So a 110A delco 28SI would have 80A available once the service batteries are peaked. Whatever house battery charge controller you use needs to be able to work with what y0u have leftover from whatever alt you choose. It may also need a little additional control to hold off the house battery charging until the service batteries stop drawing significant current. Is the Viltron charge current adjustable?

if so, i like the 28SI just because it is so available and serviceable…. With a little modification, a J180 alt can ride on the military mount. At keast for the A0.

what truck is yours again?

 

[Ronmar]

yea the issues arise trying to feed a series battery bank with multiple alternators. An alt knows one thing, make regulated voltage untill the load is so great it cannot. Without intelligent control they do not load share and will never balance. In fact the one way the two alternators will interact causes the battery imbalance situation.

12v standard reg voltage is 14.5v. 24v standard reg is I believe ~27.3V(13.65v per batt, better high hour high float charge voltage). If you feed these two into a series battery, the 0-12v batt sees 14.5 from the 12v alt. The 24v alt already being presented with 14.5v only inows to make up the difference to reach its regulators 27.3V setpoint. So the 12-24v batt only ever sees 12.8v and never reaches full charge…

now a standard alt referenced to ground and a second alt referenced only to the output of the first alt(wired in series like a battery) would probably work the best, as the two outputs would be reasonably close to each other. 14.5+14.5 =29V They would still however diverge with different loads applied. You would also need an alt with a completely chassis isolated ground which sounds like a pretty rare duck to me(probably custom or at least as rare as a reasonably priced neihoff)…

Again, absolutely pointless in todays world with 24-12 converters readily available…

one simple 24v power system, and you pull your 12v off of the 24 like any other 24v load. @24v, the 12v load = ~15A. That is about as much as the truck pulls from 24v natively with trans, blower and wipers all pulling power…

if you are worried about redundancy, if the 24-12 converter fails you can still draw 12 out of the middle of the 24 to complete the mission. It will unbalance the batteries, but it will work to get you home. In fact if you rotate the batteries regularly, you could maintain this state indefinitely till you replace the 24-12 converter…

 

[MatthewWBailey]

Is the Viltron charge current adjustable?

On my 20A Orion Smart units, the voltage levels are adjustable but not the current limit. You can choose "power supply" or " battery charger" as the function, then adjust voltage setpoints


These screenshots below are of the demo screens. Mine are set differently. I think my engine shutdown is set to 23v, so basically they turn Off during start cranking

 

[serpico760]

Well the alt choice depends entirely on your load. If you have dropped to 2 service batteries you will have some surplus typically As the truck loads including all the lighting, are going to be under 30A @24v. So a 110A delco 28SI would have 80A available once the service batteries are peaked. Whatever house battery charge controller you use needs to be able to work with what y0u have leftover from whatever alt you choose. It may also need a little additional control to hold off the house battery charging until the service batteries stop drawing significant current. Is the Viltron charge current adjustable?

if so, i like the 28SI just because it is so available and serviceable…. With a little modification, a J180 alt can ride on the military mount. At keast for the A0.

what truck is yours again?


View attachment 934730

Thanks Ron, my truck is a 2001 early A1, 3126B

 

[Ronmar]

Thanks Ron, my truck is a 2001 early A1, 3126B

So you should have the same alt mount as I pictured above. fairly easily modified to accept a J180 type alternator.

as Matthew pictured, your charge controller may have voltage controls but it may also have amperage controls as well. For what you described, a large house battery you really need a something with charge amperage control, to limit the amount of power you draw from the alternator circuit, same as you do trying to charge lithium from an alt. The low resistance of lithium will be like arc welding with an alternator and since it will bust itself trying to maintain regulated voltage output, smoke usually follows. The intermediary charge controller limits the current draw from the alt to a set or perhaps an adjustable ammount [to control alternator loading.

another way to control this is with a shunt and a voltage control circuit installed in the circuit to the service batteries. If the current flow to/from the service battery is above a certain point, it will lock out the house charger, until the voltage created by the shunt with current flowing thru it is low enough to allow the house charging scheme to come online, say less than 10A flowing to/from the service batts.

Say the truck, worst case consumes a total of 30A@ 24v(full lights, heater and wipers on) Once the batteries are charged you have ~70A(plus an extra 10A) available to feed the house with a 28SI. A shunt monitoring the service battery line would tell you when the service batteries have been satisfied and are drawing minimal current, and allow the house charge to start consuming power from the alt. But you would want to limit that house charge power draw to within that 70A of available from the alt…

 

[serpico760]

So you should have the same alt mount as I pictured above. fairly easily modified to accept a J180 type alternator.

as Matthew pictured, your charge controller may have voltage controls but it may also have amperage controls as well. For what you described, a large house battery you really need a something with charge amperage control, to limit the amount of power you draw from the alternator circuit, same as you do trying to charge lithium from an alt. The low resistance of lithium will be like arc welding with an alternator and since it will bust itself trying to maintain regulated voltage output, smoke usually follows. The intermediary charge controller limits the current draw from the alt to a set or perhaps an adjustable ammount [to control alternator loading.

another way to control this is with a shunt and a voltage control circuit installed in the circuit to the service batteries. If the current flow to/from the service battery is above a certain point, it will lock out the house charger, until the voltage created by the shunt with current flowing thru it is low enough to allow the house charging scheme to come online, say less than 10A flowing to/from the service batts.

Say the truck, worst case consumes a total of 30A@ 24v(full lights, heater and wipers on) Once the batteries are charged you have ~70A(plus an extra 10A) available to feed the house with a 28SI. A shunt monitoring the service battery line would tell you when the service batteries have been satisfied and are drawing minimal current, and allow the house charge to start consuming power from the alt. But you would want to limit that house charge power draw to within that 70A of available from the alt…

Thanks, in the victron apparently you can control the charging amperage however you want. Here is what the screen looks like for that. https://www.victronenergy.com/media/pg/VEConfigure_Manual/en/charger-settings.html