External Alt regulator

[yoggie]

Hi all. I am currently putting an OM605 into an old Volvo C304 to use as a sort of weekender camper van. I am converting the vehicle to run on 12v but I am adding a second 24v alternator mostly to run an AC system for the rear seats and also to cool it off at night for camping.

What I have so far for my house system:
24v AC mini split, claimed max usage is 55 amp
2x LiTime 24v 280ah batteries (max charge 200a, recommended 56a)
24v alternator for a Mercedes bus, but the more I look at it the more I think this needs to be set aside for an alternator with an external regulator

It seems like most people use DC to DC chargers, but I have seen that most boats use external regulators on alternators, most the Wakespeed WS500 or ACRO Zeus. It seems like the boat community is very concerned with load dumps, basically if the batteries get full and the BMS turns off charging, then a huge voltage spike can happen and it fries everything. Are load dump and the associated spike not an issue on vehicles? is using an external regulator instead of DC to DC chargers a bad idea?

Would an alternator protection module also be needed?

 

[justinm001]

Sterling makes an alternator protection device to help protect this.

No it's not a bad idea but DC DC converter usually makes more sense. Orion XS is perfect. They're $350 each so 2 would give you 100amps for $700 which is about the same price as a Zeus or wakespeed.
I use 6 DC converters but convert 24v to 12v or 48v. I have a wakespeed but don't use it.

 

[yoggie]

Sterling makes an alternator protection device to help protect this.

No it's not a bad idea but DC DC converter usually makes more sense. Orion XS is perfect. They're $350 each so 2 would give you 100amps for $700 which is about the same price as a Zeus or wakespeed.
I use 6 DC converters but convert 24v to 12v or 48v. I have a wakespeed but don't use it.

Sadly the Victron 50 amp are 12v only. Even the upcoming 1400 is good for a max of 50 amp input, making only 25 amp 24v output

 

[justinm001]

Sadly the Victron 50 amp are 12v only. Even the upcoming 1400 is good for a max of 50 amp input, making only 25 amp 24v output

The 1400 says max 50a output. Luckily Im going 24/12 and 24/48 the 24/12 they make 70a for like $130 so I have 2 of those and 4 350w of the 48s.

Checkout that etaker f1000 I saw someone posted about it on here and looks promising

 

[Backyard]

Couldn't one put a large capacitor on the alternator output to absorb that spike if the BMS was to suddenly shut off?

I like the idea of an external regulator for a regular alternator to boost it to 24V. Got to be careful on the load the batteries might put on it though.

 

[outboard1196]

Couldn't one put a large capacitor on the alternator output to absorb that spike if the BMS was to suddenly shut off?

I like the idea of an external regulator for a regular alternator to boost it to 24V. Got to be careful on the load the batteries might put on it though.

The Orion XS 1400 is 12/24v ( any combo) due to be released in May. To me the Orion XS is the only Orion worth getting.

 

[seneysolar]

It seems like the boat community is very concerned with load dumps, basically if the batteries get full and the BMS turns off charging, then a huge voltage spike can happen and it fries everything. Are load dump and the associated spike not an issue on vehicles?

You could keep an AGM (or 2 if 24v) battery in parallel with the LFP for protection sake. They can live happily in the voltage range of LFP and it really won't get cycled. It will keep spikes under control and your other components (solar/inverter/monitoring) wont fault or shut off if BMS shuts down.

 

[justinm001]

Couldn't one put a large capacitor on the alternator output to absorb that spike if the BMS was to suddenly shut off?

I like the idea of an external regulator for a regular alternator to boost it to 24V. Got to be careful on the load the batteries might put on it though.

I don't think it works that way. If the BMS shuts off there will be a huge voltage spike which backfeeds the alternator and can blow it.

I highly recommend against boosting any alternator. My coach had a 12v regulator on a 24v alternator, so when switching to LFP I put a wakespeed and set it to 12v. The thing kept shutting off as it couldn't regulate below 15v. One time like an idiot I changed a setting and it bumped to 18v and fried everything 12v. In my defense they make 50DN alternators in 12 and 24 volt with the same 270a and whoever swapped it scratched off the voltage marker on the alternator plate.

 

[justinm001]

The Orion XS 1400 is 12/24v ( any combo) due to be released in May. To me the Orion XS is the only Orion worth getting.

The Orion XS is ana amazing device but there's plenty of use cases for dumb DC DC converters. My 24/12 70a Orion is like $120, I have 2 of those and 4 24/48 350w giving me about 1500w to both my 12v and 48v LFP systems. I set them just a bit higher than each other and they slowly drop current as the LFP charges which works perfectly for a coach. I wouldn't want my converters to charge to 100% because that's what solars for, but I'd like it to charge to 70-80% and absorb all loads in the process. 3000w is about 4HP which is a decent load, even on my huge 12.7 S60 engine.

To compare pricing the XS 1400 is like $350 and 50a, so to get 150a it'll be $1050 vs $250 for a pair of 24/12 Orion 70s. Which boosts to 85a. Double that if they make a 48v version.

 

[yoggie]

The Orion XS 1400 is 12/24v ( any combo) due to be released in May. To me the Orion XS is the only Orion worth getting.

https://www.victronenergy.com/upload/documents/Datasheet-Orion-XS-DC-DC-battery-charger-EN-.pdf

Based on the data sheet for the XS, it's limited to 50 amp input. For a 12v to 24v setup, this limits output to 25 amps. It can only do the max 1400 wars at higher voltage

 

[yoggie]

The Orion XS is ana amazing device but there's plenty of use cases for dumb DC DC converters. My 24/12 70a Orion is like $120, I have 2 of those and 4 24/48 350w giving me about 1500w to both my 12v and 48v LFP systems. I set them just a bit higher than each other and they slowly drop current as the LFP charges which works perfectly for a coach. I wouldn't want my converters to charge to 100% because that's what solars for, but I'd like it to charge to 70-80% and absorb all loads in the process. 3000w is about 4HP which is a decent load, even on my huge 12.7 S60 engine.

To compare pricing the XS 1400 is like $350 and 50a, so to get 150a it'll be $1050 vs $250 for a pair of 24/12 Orion 70s. Which boosts to 85a. Double that if they make a 48v version.

I am looking at going from 12v to 24v. The largest Victron other than the XS is 15 amp output

 

[outboard1196]

https://www.victronenergy.com/upload/documents/Datasheet-Orion-XS-DC-DC-battery-charger-EN-.pdf

Based on the data sheet for the XS, it's limited to 50 amp input. For a 12v to 24v setup, this limits output to 25 amps. It can only do the max 1400 wars at higher voltage

Correct, the XS is the only Orion that can be de rated. That's why I prefer it overthe others. But I understand the price issue.

 

[yoggie]

Correct, the XS is the only Orion that can be de rated. That's why I prefer it overthe others. But I understand the price issue.

Don't get me wrong, I love that the XS is coming! It's just that for my situation, I would need 7 of them!

 

[justinm001]

I am looking at going from 12v to 24v. The largest Victron other than the XS is 15 amp output

Orion IP67 24/12 and 12/24 DC-DC Converters - Victron Energy

Completely encapsulated: waterproof, shockproof and ignition protected. Water, oil or dirt will not damage the Orion IP67 DC-DC Converter. Find a dealer nearby.

www.victronenergy.com

They make a 50a. Sterling also makes some. You said you're getting a 24v alternator.

You can always get a bunch of smaller ones and Daisy them together. I run 4 24/48 together

 

[justinm001]

Don't get me wrong, I love that the XS is coming! It's just that for my situation, I would need 7 of them!

14vx50a is 700w per XS. 7 of them is 4900watts. I'm assuming you have a 500amp alternator?
Even then your batteries recommended charge is 56a so 112a for the pair. So you really only can have 4.

 

[yoggie]

14vx50a is 700w per XS. 7 of them is 4900watts. I'm assuming you have a 500amp alternator?
Even then your batteries recommended charge is 56a so 112a for the pair. So you really only can have 4.

The XS has a limit of 50 amps in. With a 12v input, that's only 25amps out at 24v. I have two batteries that recommend 56a charging, and a 55amp AC, plus some small stuff for a total of around 170 amp 24v max draw. 7 XS units going from 12v to 24v is 175 amps. Granted, this is a nice to have max, but not the minimum.

I will do more research into the Sterling units, thank you for the tip!

For the Victron voltage converters, will that cause issues over a DC to DC charger?

I am currently debating between a 400amp 12v alternator with 12v to 24v chargers, or going with two alternators and a dedicated voltage regulator (Wakespeed or Zeus) on the 24 alternator. Both routes are expensive.

 

[justinm001]

The XS has a limit of 50 amps in. With a 12v input, that's only 25amps out at 24v. I have two batteries that recommend 56a charging, and a 55amp AC, plus some small stuff for a total of around 170 amp 24v max draw. 7 XS units going from 12v to 24v is 175 amps. Granted, this is a nice to have max, but not the minimum.

I will do more research into the Sterling units, thank you for the tip!

For the Victron voltage converters, will that cause issues over a DC to DC charger?

I am currently debating between a 400amp 12v alternator with 12v to 24v chargers, or going with two alternators and a dedicated voltage regulator (Wakespeed or Zeus) on the 24 alternator. Both routes are expensive.

But you don't have 12v input you have 14v+ which at 50a is 700w... An extra 100w.

The problem is when you're at 170a and your ac is off it'll charge the batteries that 170a, which is within the BMS but I wouldn't want to spend it.

Converters will provide a flat voltage which won't charge the batteries 100%. a charger will charge the batteries to 100% . I prefer converters because I don't want my engine charging the batteries fully. Mine charge to 70-80% then absorb all the loads which is perfect. If I leave with 100% batteries then the batteries will stay at basically 100% unless I'm using more than the converters have

 

[yoggie]

But you don't have 12v input you have 14v+ which at 50a is 700w... An extra 100w.

The problem is when you're at 170a and your ac is off it'll charge the batteries that 170a, which is within the BMS but I wouldn't want to spend it.

Converters will provide a flat voltage which won't charge the batteries 100%. a charger will charge the batteries to 100% . I prefer converters because I don't want my engine charging the batteries fully. Mine charge to 70-80% then absorb all the loads which is perfect. If I leave with 100% batteries then the batteries will stay at basically 100% unless I'm using more than the converters have

The benefit of the smart external alternator regulators over a normal alternator is they can reduce the amps being produced. They connect to a shunt at the batteries and will limit the amps coming in to what I set it at (56a x 2 = 112a in this case). For example, the AC is maxed out, the alternator puts out 175 amps; the AC clicks off, it reduces the power to just 112a. Apparently this is how most larger boats do it. I am not saying its the best for my use case, just explaining how I think they work.

I am going to do some serious looking into converters vs chargers, so thank you for the idea! Another idea, what about several cheaper convers in parallel with a charger? Use the converters to get the batteries to ~75%, then the charger to 100% so they can internally balance?

 

[justinm001]

The benefit of the smart external alternator regulators over a normal alternator is they can reduce the amps being produced. They connect to a shunt at the batteries and will limit the amps coming in to what I set it at (56a x 2 = 112a in this case). For example, the AC is maxed out, the alternator puts out 175 amps; the AC clicks off, it reduces the power to just 112a. Apparently this is how most larger boats do it. I am not saying its the best for my use case, just explaining how I think they work.

I am going to do some serious looking into converters vs chargers, so thank you for the idea! Another idea, what about several cheaper convers in parallel with a charger? Use the converters to get the batteries to ~75%, then the charger to 100% so they can internally balance?

Yes you absolutely can run multiple converters in parallel with a charger. On my system I run 4 converters to my 48v bay. I set each just a bit higher than the others and they slowly ramp down from 65% to about 80%. My solar into the MPPTs will charge the remaining 20%. I have 5kw of solar so it works perfectly as otherwise my engine would charge batteries and solar would be wasted. I also have automations for when the batteries are above 90%.

I like this as if I'm driving at night I'm not going to be running more than 1 AC so my converters can handle it but during the day I might be running a couple of them depending on if I have passengers or what. Plenty of time I'll start the coach and kick on 4 ACs (6000w) so it cools down for 15 mins or so then just leave 1 on while driving.

It makes sense for boats to do that as 1HP is 745watts and boat engines are designed to run at a constant rpm so it says power which is knots

 

[yoggie]

Yes you absolutely can run multiple converters in parallel with a charger. On my system I run 4 converters to my 48v bay. I set each just a bit higher than the others and they slowly ramp down from 65% to about 80%. My solar into the MPPTs will charge the remaining 20%. I have 5kw of solar so it works perfectly as otherwise my engine would charge batteries and solar would be wasted. I also have automations for when the batteries are above 90%.

I like this as if I'm driving at night I'm not going to be running more than 1 AC so my converters can handle it but during the day I might be running a couple of them depending on if I have passengers or what. Plenty of time I'll start the coach and kick on 4 ACs (6000w) so it cools down for 15 mins or so then just leave 1 on while driving.

It makes sense for boats to do that as 1HP is 745watts and boat engines are designed to run at a constant rpm so it says power which is knots

Thank you for your help!