Convert 24v alternator to 12v?

[justinm001]

My coach came with a 50dn alternator and the faceplate is kinda rusted but it clearly stated 270 amps. My understanding is the 50dn comes in 300a 12v or 270a 24v but it was obviously setup for only 12v. I hooked up a wakespeed ws500 and it also shows its 12v (auto selected 12v voltage). I've had a problem where the alternator would run for 10 minutes at 13ish amps charging my lithium then get a battery overvoltage error 13 and shutdown . I assumed it was just a bit higher than it should have been so I adjusted the voltage from 12v to a custom 13v system and tried it out. Well turns out it ended up spiking to just over 20v before frying my firefly 12v control panel and a thermostat.

Now I'm wondering how alternators are converted to a lower voltage and if its possible something triggered it to switch back to 24v, or if they just replaced the insides of the alternator with a 12v model and it's just defective.

I'm a bit at a loss on what I should do as I planned on using this 12v alternator for the 12v system and adding a 48v alternator in another spot.

 

[HarryN]

If the BMS on the LiFe batteries tripped, then it creates an open circuit for the alternator output.

When this happens, there is a large voltage spike and unless your system has a voltage suppressor in it, the voltage can go quite high.

This happens far too fast for any alternator controller to deal with. The result is often that anything attached to that circuit will be fried.

For better or worse, I have a post in the smoke and something thread about this as well for 48 volt alternators set up with that WS. Don't expect them to help either as no matter what you did correctly, they will find a reason to not be helpful.

________________

As far as 12 vs 24 volts - you cannot change an alternator's base output voltage by changing the external controller. An alternator is built from the ground up to be 12, 24 or 48 volts.

If you need a different voltage from an existing alternator + starter battery:
- Leave the existing system in place
- Use a battery to battery charger that takes in the voltage you have and outputs the voltage that you need.

For instance sterling and SEC america sell these.

 

[justinm001]

If the BMS on the LiFe batteries tripped, then it creates an open circuit for the alternator output.

When this happens, there is a large voltage spike and unless your system has a voltage suppressor in it, the voltage can go quite high.

This happens far to fast for any alternator controller to deal with. The result is often that anything attached to that circuit will be fried.

For better or worse, I have a post in the smoke and something thread about this as well for 48 volt alternators set up with that WS. Don't expect them to help either as no matter what you did correctly, they will find a reason to not be helpful.

________________

As far as 12 vs 24 volts - you cannot change an alternator's base output voltage by changing the external controller. An alternator is built from the ground up to be 12, 24 or 48 volts.

If you need a different voltage from an existing alternator + starter battery:
- Leave the existing system in place
- Use a battery to battery charger that takes in the voltage you have and outputs the voltage that you need.

For instance sterling and SEC america sell these.

Thanks I was aware of that but my BMS didn't trip or at least it wasn't in an alm state. Whenever my 12V goes high or low it trips my firefly panel which then resets my entire 12V system which takes 10 seconds or so.

I believe my alternator is the device thats spiking power somehow. I'm not sure if its defective or something else. But my biggest question is if my alternator was 24V originally from the Prevost factory then the custom coach manufacturer (Nashville Coach) converted it to 12V somehow, how does that happen? They make 12V and 24V 50DN alternators (12V is 300a 24v is 270a) So I'm wondering if they took the entire thing out of the case and swapped the internals OR did they disconnect half the diodes or something to make it pump out half the voltage. I don't know how alternators work or how they configure the voltage.

Now I'm concerned my alternator will continue to spike voltages so the wakespeed is disconnected to disable the alternator. I know sterling has the alternator APD which is designed to protect the alternator but is there also anything I can put to protect my 12V house and batteries from it spiking? Fuses only protect against over-current not over-voltage.


My chassis has a 24V alternator also so I might just run a 24 to 12v 70a Victron Orion and call it a day, although I wanted over 1500w so we can run 1 AC while driving without losing power. Gotta check the size of the house alternator though. I'm trying to be done with electrical for a bit and work on the rest of the coach but keep spending cash. I want the Balmar 48V 100a alternator below but seems a bit much for my needs.

96-48-100-K8 - Balmar

48 Volt, 100 Amp Alternator (4.8kW), K8 Pulley J-180 4″ Dual Foot Mounting To be used exclusively with the MC-620-H regulator with a 12V supply to the regulator. Click Here to view the 96-Series Operation Manual. Click Here to review Silent Running – A Case Study for 48V Systems

balmar.net

 

[HarryN]

It is possible for a pro alternator company to re-wire it inside but that isn't so common. Not impossible but if someone asked me how to do that - I would swap alternators.

As far as spikes and disconnects - one way is to always have a 12 volt lead acid battery attached - no matter what.

Any product that switches over the connection from one battery to another ----- well I know that they talk about doing it but I just don't see how that can really work unless the batteries are cross connected during the transition.

 

[Vigo]

One way to do it is to hook the charge source to the lower voltage lead acid through one or more large diodes in addition to the switching device that would let you switch back and forth. Thus, even when you are switching between lithium and lead, there is a path that leads to the lead bank to eat voltage spikes, but the voltage drop of the diodes prevents the lead from charging when hooked to lithium. I have done this but i have not actually tested the ability of this arrangement to deal with spikes. In my mind it works out just fine..

 

[justinm001]

I'm surprised there isn't some surge voltage protection device for 12V that'll just disconnect the source when power rises or drops below safe values. And one that can handle 150-200amps

 

[HarryN]

I'm surprised there isn't some surge voltage protection device for 12V that'll just disconnect the source when power rises or drops below safe values. And one that can handle 150-200amps

It is more challenging than it initially looks.

When an alternator goes open circuit and it rotating at highway speeds, it can push out more power than it is even rated for - as that number is a continuous rating vs instantaneous.

It is a fairly massive amount of power backed up by a healthy rotating inductor setup.

For short periods of time it can output 100s of volts and 10 + kW of power. Not that many setups can absorb all of that for more than seconds and that is what the related surge protective devices attempt to do.

If it were me, I would start by putting a conventional battery ( AGM or flooded ) on the alternator and see if it runs and what kinds of voltages and currents you are seeing that way.

If you are in the area you can stop by and I can look at it with you.

 

[justinm001]

It is more challenging than it initially looks.

When an alternator goes open circuit and it rotating at highway speeds, it can push out more power than it is even rated for - as that number is a continuous rating vs instantaneous.

It is a fairly massive amount of power back up by a healthy rotating inductor setup.

For short periods of time it can output 100s of volts and 10 + kW of power. Not that many setups can absorb all of that for more than seconds and that is what the related surge protective devices attempt to do.

If it were me, I would start by putting a conventional battery ( AGM or flooded ) on the alternator and see if it runs and what kinds of voltages and currents you are seeing that way.

If you are in the area you can stop by and I can look at it with you.

Thanks for the offer i'm across the country (Ohio). Good idea ill hook up my genny battery to it and see what happens. Its a new optima blue top AGM

 

[Partsjockey]

Thanks I was aware of that but my BMS didn't trip or at least it wasn't in an alm state. Whenever my 12V goes high or low it trips my firefly panel which then resets my entire 12V system which takes 10 seconds or so.

I believe my alternator is the device thats spiking power somehow. I'm not sure if its defective or something else. But my biggest question is if my alternator was 24V originally from the Prevost factory then the custom coach manufacturer (Nashville Coach) converted it to 12V somehow, how does that happen? They make 12V and 24V 50DN alternators (12V is 300a 24v is 270a) So I'm wondering if they took the entire thing out of the case and swapped the internals OR did they disconnect half the diodes or something to make it pump out half the voltage. I don't know how alternators work or how they configure the voltage.

Now I'm concerned my alternator will continue to spike voltages so the wakespeed is disconnected to disable the alternator. I know sterling has the alternator APD which is designed to protect the alternator but is there also anything I can put to protect my 12V house and batteries from it spiking? Fuses only protect against over-current not over-voltage.


My chassis has a 24V alternator also so I might just run a 24 to 12v 70a Victron Orion and call it a day, although I wanted over 1500w so we can run 1 AC while driving without losing power. Gotta check the size of the house alternator though. I'm trying to be done with electrical for a bit and work on the rest of the coach but keep spending cash. I want the Balmar 48V 100a alternator below but seems a bit much for my needs.

96-48-100-K8 - Balmar

48 Volt, 100 Amp Alternator (4.8kW), K8 Pulley J-180 4″ Dual Foot Mounting To be used exclusively with the MC-620-H regulator with a 12V supply to the regulator. Click Here to view the 96-Series Operation Manual. Click Here to review Silent Running – A Case Study for 48V Systems

balmar.net

Best bet phone prevost w/vin they will tell ya what voltage it is.

 

[justinm001]

Best bet phone prevost w/vin they will tell ya what voltage it is.

I'm 99% certain it's a 24v alternator... or at least was. The model number is 10459123 which Googles to 24v and its clearly 270a which is 24v and 12v is 300a. The volts show a 2 then something after it too. But it was wired up to power 12v battery bank and the 120v charger was also 12v.

What I don't know is how they changed it to get 12v

 

[Partsjockey]

I'm 99% certain it's a 24v alternator... or at least was. The model number is 10459123 which Googles to 24v and its clearly 270a which is 24v and 12v is 300a. The volts show a 2 then something after it too. But it was wired up to power 12v battery bank and the 120v charger was also 12v.

What I don't know is how they changed it to get 12v

I would say it is 24v.

 

[justinm001]

I would say it is 24v.

It's outputting 12v fine for 10 minutes then gets a random voltage spike just for a second to shut down. I don't think a 24v alternator could output 12v. It's pumping 2000w through the whole time too.

I guess I could wire up a couple car batteries to 24v and see what happens. 24v would be nice since it has 2/0 wire 40ft so if 24v I could use 24 to 12v orions and double my power

 

[Partsjockey]

It's outputting 12v fine for 10 minutes then gets a random voltage spike just for a second to shut down. I don't think a 24v alternator could output 12v. It's pumping 2000w through the whole time too.

I guess I could wire up a couple car batteries to 24v and see what happens. 24v would be nice since it has 2/0 wire 40ft so if 24v I could use 24 to 12v orions and double my power

It should have a part that takes the 24v and splits down grades it to 12v. I will take a picture of my electrical bay later on today of my bus which is an MCI but similar to Prevost, and we can go from there. Ok!

 

[justinm001]

It should have a part that takes the 24v and splits down grades it to 12v. I will take a picture of my electrical bay later on today of my bus which is an MCI but similar to Prevost, and we can go from there. Ok!

I have 2 alternators my chassis is 24v delco 36si which is connected to a Vanner that equalizes the 12v chassis batteries which pull 12v loads for the engine.

But this is dedicated for the house. It goes straight 40ft to my battery bank in the front. I swapped out the external regulator with a wakespeed for my lithium to get the charging profiles also to limit the output since 2/0 isn't thick enough to carry 270a. I should have the old regulator still on the bus so I'll make sure that's 12v.

When I bought the bus it sat for a year and the huge 8d batteries were dead but they had a 120v to 12v charger connected to it and all loads are 12v.

At some point they upgraded the 12v system so it's possible they had the alternator disconnected and just used the charger for all loads since it seems they used the generator the entire time it was driving.

I'm going to order a 24 to 12v Orion today wire it up to that and program the wakespeed to 24v then see what happens.

 

[HarryN]

It would be good to know if the WS500 is being used to control the alternator voltage / current or for a different function.

Did they give you a wiring diagram of any kind? Of the firmware settings that are programmed into the WS500?

The settings in those are programmable and are not always correct. Let me put emphasis on the words "not always" because my experience is "nearly never" and it is very dependent on the alternator it is attached to.

 

[justinm001]

It would be good to know if the WS500 is being used to control the alternator voltage / current or for a different function.

Did they give you a wiring diagram of any kind? Of the firmware settings that are programmed into the WS500?

The settings in those are programmable and are not always correct. Let me put emphasis on the words "not always" because my experience is "nearly never" and it is very dependent on the alternator it is attached to.

didn't come programmed at all so I had to do all the programming using this software below and wired it myself. I think only the field goes to the alternator but there's a bunch of other wires that go to the shunt and other things.

I set the lithium profile up with the charging voltages as well as limited the output. For voltage it auto detects the voltage which it did at 12V but now I'm wondering if thats just because of the battery. Here's my graphs from Victron from my labor day trip, from the Wakespeed itself and my shunt. The Inverter was running a 2000w AC unit the whole time. Looks like I turned the key to on around 8am which turned on the wakespeed but didn't start the engine until 8:45am which it ran fine until 9:06am which I must have turned off the bus for a few then restarted where it worked from 9:20 to 9:56 and spiked at 16.53V. Then from 11 to 11:08 it spiked to 19.42V and blew my 12V panel.

After that first spike when we stopped I reprogramed the wakespeed voltage settings where it has 0=auto 1=12V 2=24v 3=36v 4=48v, I changed it from 0 to 1.1 (it says custom voltages put a decimal) I figured this will put it just above 13V and maybe my lithium profile voltage was a bit high. I also turned the amperage down from 250 to 200 or 175 i can't remember.

I'll get the 24 to 12 orion tomorrow and hopefully will have time to install it or maybe Friday. I'm planning on configuring the wakespeed to 24v and running that to see what voltage it reads coming in and if I can get 24V from it. If that works I could get 5 total Orion 24-12 70a and pull 175A from the alternator then get 350A of 12V to really charge my batteries. Pull the wakespeed out and replace with the original external regulator (if its actually 24V) and be good to go. Use the wakespeed on a new 48V alternator down the road and have all 3 running

WS500 Configuration Tool-Config Version Life Time- Windows

WS500 Smart Regulator Configuration Tool, Configure Version Not sure which version you need? Here's a quick overview: If you want to be able to view your system operating parameters in real time and edit your profile, adjust regulator settings and backup/restore your profile, then the "Config"...

ogm-energy.com

 

[jberger]

I'm 99% certain it's a 24v alternator... or at least was. The model number is 10459123 which Googles to 24v and its clearly 270a which is 24v and 12v is 300a. The volts show a 2 then something after it too. But it was wired up to power 12v battery bank and the 120v charger was also 12v.

What I don't know is how they changed it to get 12v

FWIW, you could get the 50DN in a number of different amp outputs, even at 12V. I had both a 270 and a 300 that were 12v. I think it was a difference in the rebuild kits.

The model number in your photo is for the 24V version:

10459123 50DN Reman Alternator | Product Details | Delco Remy

www.delcoremy.com

I think you need to disconnect it from your LFP bank, connect it in a 24V configuration with lead acid, reprogram the regulator for 24V and see what you get out of the alternator.
I seriously doubt someone re-wired that alternator for 12V and didn't label it as 12v.

What Voltage Regulator was on it before you changed to the Wakespeed?
Assuming it's the 50VR, those came in 12V and 24V versions so you can track down the voltage from the regulator too.

Harry is absolutely correct about how a sudden disconnect from the battery can smoke the alternator and/or regulator.
Balmar makes alternator protection devices to help prevent that damage but they are ordered by voltage so you need to get that figured out first.

Alternator Protection Modules - Balmar

Alternators can be subjected to voltage spikes caused by lithium battery shutdowns, intermittent connections and other over-voltage events. Balmar has introduced a robust Alternator Protection Module which helps protect the alternator’s diodes and internal regulator against spikes (clamping up...

balmar.net

How were you testing when you saw 13 amps at 12V?
Was this at low idle then it spiked when you went to high idle?

 

[justinm001]

FWIW, you could get the 50DN in a number of different amp outputs, even at 12V. I had both a 270 and a 300 that were 12v.

Thank you that's really helpful. My coach was built in 2005 and finished in 2008 so its not too old so i'm assuming online stuff would be right. All the 12V I see are 300 amp and the brochure shows the PN is 24V. But its really odd the voltage is impossible to read other than the 2 on the nameplate, almost like someone scratched it out and maybe put a 1 with a sharpie in front that wore out.

https://www.delcoremy.com/getmedia/5dd8761a-36b4-4f56-82d8-1c3036ac9a5b/Delco-Transit-Brochure-5-15.pdf.aspx?ext=.pdf&ext=.pdf

 

[HarryN]

FWIW, you could get the 50DN in a number of different amp outputs, even at 12V. I had both a 270 and a 300 that were 12v. I think it was a difference in the rebuild kits.

The model number in your photo is for the 24V version:

10459123 50DN Reman Alternator | Product Details | Delco Remy

www.delcoremy.com

I think you need to disconnect it from your LFP bank, connect it in a 24V configuration with lead acid, reprogram the regulator for 24V and see what you get out of the alternator.
I seriously doubt someone re-wired that alternator for 12V and didn't label it as 12v.

What Voltage Regulator was on it before you changed to the Wakespeed?
Assuming it's the 50VR, those came in 12V and 24V versions so you can track down the voltage from the regulator too.

Harry is absolutely correct about how a sudden disconnect from the battery can smoke the alternator and/or regulator.
Balmar makes alternator protection devices to help prevent that damage but they are ordered by voltage so you need to get that figured out first.

Alternator Protection Modules - Balmar

Alternators can be subjected to voltage spikes caused by lithium battery shutdowns, intermittent connections and other over-voltage events. Balmar has introduced a robust Alternator Protection Module which helps protect the alternator’s diodes and internal regulator against spikes (clamping up...

balmar.net

How were you testing when you saw 13 amps at 12V?
Was this at low idle then it spiked when you went to high idle?

Thanks for the link to that Balmer APM-48. It is one of the few that comes in a 48 volt configuration. Have been looking for options like that.

 

[HarryN]

Thank you that's really helpful. My coach was built in 2005 and finished in 2008 so its not too old so i'm assuming online stuff would be right. All the 12V I see are 300 amp and the brochure shows the PN is 24V. But its really odd the voltage is impossible to read other than the 2 on the nameplate, almost like someone scratched it out and maybe put a 1 with a sharpie in front that wore out.

https://www.delcoremy.com/getmedia/5dd8761a-36b4-4f56-82d8-1c3036ac9a5b/Delco-Transit-Brochure-5-15.pdf.aspx?ext=.pdf&ext=.pdf

Thank you for posting those curves.

The voltage spikes shown are more than enough to trip the BMS of at least some LiFe batteries. What WS suggests is to have a delay built into the system to prevent the BMS from tripping faster than the WS can shut down and the field coil de-energize. Easier said than done but possible sometimes.

If you look at the curves, the out is spiking when the rpm is high - maybe during an acceleration?

Try cutting your power output to 50 % while you fine tune things - it will not solve all issues but it helps to soften it a bit.