Multiple charge controllers for 24 to 48V alternator charging

[FloaterBoater]

I'm looking to build a 48v system on my barge. Currently all DC loads are 24 volt. I don't expect that alternator charging will be a primary source of power (I have a 7000w generator plus planning for solar). The boat currently has separate 24v alternators for house and starter batteries. I've been quoted a price of around £1700 for a custom built 48v 100A alternator and wakespeed controller.

One alternative would be to run the alternator directly into a 24v - 240v inverter, then that into the 240v 48v main inverter, but it seems clunky.

The other thing I'm wondering about is using multiple 24v -> 48v victron DC DC charge controllers. The biggest one they make only outputs 8.5 amp at 48v, however for the price of the new alternator and a wakespeed controller, I could buy quite a few charge controllers and run the in parallel. In practice I would not try to make the equivalent, but at least it's a way to get some charge out of the engine. Is this something that's possible? Can you run multiple charge controllers in parallel on one alternator, to feed one battery?

Any thoughts welcomed.

Rob

 

[time2roll]

Yes multiple DC-DC converters can be run in parallel. Get a couple and see how it goes. Can always add more. Need to be careful the alternator is not overloaded at some point.

Must be a compelling reason to go 48 volt house battery. I would really try to stay at 24v and just add more capacity and possibly run parallel inverters for more power.

 

[FloaterBoater]

Yes multiple DC-DC converters can be run in parallel. Get a couple and see how it goes. Can always add more. Need to be careful the alternator is not overloaded at some point.

Must be a compelling reason to go 48 volt house battery. I would really try to stay at 24v and just add more capacity and possibly run parallel inverters for more power.

Thanks for this.

Compelling reasons:

The boat is my full time home. Appliances are 240 domestic variety. There's no gas on board so all cooking is electric. Peak load is about 32A. We are normally on 32A shore line, but for cruising we need enough juice to be able to cook, etc.

48v means greater flexibility in selecting inverters, (there's only one 8000 watt 24v victron inverter). Also more flexibility in terms of battery selection as 48v is common. I want to have a data connection from the batteries to the inverter. There aren't a lot of options for this at 24v.

 

[time2roll]

Got it. Although I might try to get by with a 3000w/4000w inverter and manage the load accordingly until back on utility power.
Possibly have a dedicated inverter to the main stove and a second inverter to everything else. Just depends on where you want the complications.
48v certainly has advantages.

Also consider boating safety for if something fails. Not sure what pumps, motors, lights and equipment are set for 24v.

 

[toms]

What you can do is build two 24V batteries, and have them supplied with their own charge source and BMS.

You can then place them in series, and use one or two 24V inverters from the 24V batteries, and a 48V inverter off the series pack.

The charge sources need to be configured to roughly match the loads on each battery.

I use this setup in mobile applications with two 12V batteries in series, and a 24V inverter across the series pair.

At first glance it seems weird, but if your whole environment is 24V, it will work well for you.

 

[Lifepobuildandservice]

I am new to this problem. I am looking to change over my trawler to LiFeP house batteries, probably 25-40 kw. I am aware that there exists alternator overheating issues as LiFeP batteries usually are a dead short to the DC power source on the trawlers main motor because the battery's acceptance rate is so high resulting in overheating of the DC power generator (not sure if alternator or generator makes a difference here??). Obviously from the posts suppliers have addressed this problem but have pulse width modulation (PWM) been considered as an alternative. DC PWM controllers are used to control speed on DC motors, and thus in effect these may not be as expensive as existing alternatives?? It would still require temperature monitoring of the DC charging source and adjustment of the modulation to control heat. Any comments??