Dumping 12V house batteries

[freds]

Hi Everyone

OK, my 1980 Prevost currently has a dual voltage system with 24V start batteries and 12V house batteries with separate engine driven alternators.

I am changing my main house battery system that is the storage for solar and driving the house inverter to 24V Tesla modules (if you don't like this approach it could be a couple of Battle Born LiFePO4  batteries).

To drive the 12V side I am going with a Victron Orion 24/12-70A DC-DC Converter IP20 which will handle the normal 12V draws for the house systems. (The cruise control for the bus might be 12V.)

The only heavy draw on the 12V side is starting the 12.5KW Kohler/Perkins diesel generator.

I was originally thinking of maybe buying a Battle Born LiFePO4  battery to replace the lead acids in the 12V system, but the cost of one of them is a substantial percentage of the cost of another Tesla Module (1.2KW for the Battle Born verses 5.1KW for another Tesla Module).

Anyway back to the diesel generator with feedback from a solar forum I kicking around the following ideas:

1. Split tap off of the pair of 12V main start batteries that make up the 24V start battery bank.

2. Separate small lead acid start battery for the generator that is diode isolated from the new 12V house circuit.

Another thought is to maybe to remove the old 12V alternator and replace it with a wind alternator and controller to charge the new 24V house battery bank for charging while in motion.


Feel free to weight in....

[richard5933]

Why not just get a 24v starter/solenoid for your Perkins? They should be pretty easy to find, based on the search I just did. Or check at a local starter shop and see if they can just rewind yours to 24v if you can't find one.

Then the only thing on your Perkins that would remain 12v would be the fuel solenoid and the fuel pump. Those could easily be run from the house system.

BTW, did you ever find a new fuel solenoid?

[buswarrior]

If you centre tap the chassis batteries for the generator, add a Vanner Battery Equalizer, or similar, so that pair do not become imbalanced, and murder one another.

Every scrapped transit bus has one or two of them.

Please tell us that there's a typo in that last bit... you aren't putting a fan into the wind while moving to make 24 volts...?

Happy coaching!
Buswarrior

[chessie4905]

He's  talking about a generator that is used on a windmill.

[lostagain]

I would have a dedicated battery for the generator. The generator is the most important thing on the bus, and it needs to start reliably.

JC

[freds]

Why not just get a 24v starter/solenoid for your Perkins? They should be pretty easy to find, based on the search I just did. Or check at a local starter shop and see if they can just rewind yours to 24v if you can't find one.

Then the only thing on your Perkins that would remain 12v would be the fuel solenoid and the fuel pump. Those could easily be run from the house system.

BTW, did you ever find a new fuel solenoid?

Hi Richard

Still noodling away on the fuel solenoid solution and the lift pump is mechanical.

I found an interesting WiFy stepper driver board that treats a stepper as a servo, where you command it to turn X degrees. Have one on order so I am waiting for it come in to play with. If so I will have less than $100.00 in it verses the $1200.00 that the part hoarders want for the original.

My thinking is that I will modify the firmware and attach extra sensors/relays so that the generator can be auto run when needed from my energy management system for the house.

Lots of discussion on the marine forums on converting the starter motor for our Perkins 4-108 diesels to 24V, consensus seems to be just drive the 12V starter with 24V. In your searching did you find a 24V starter part number?

 

[richard5933]

...In your searching did you find a 24V starter part number?

Sorry, no. Didn't stick around the search page long enough to see a part number.

[TomC]

I was going to use Lifeline AGM batteries-4 of the 300a/h 6v for a total weight of 460lbs of batteries that also may last 5-7 years (5 year warranty). I decided to bite the bullet and bought 3-100a/h Battle Born batteries that are the same usable a/h. Granted they were $2,700, but with 10 year warranty. Only weigh 93lbs total. Good Luck, TomC

[Jim Blackwood]

When we convert from 6v to 12v systems we generally use the same starter and it tends to run a little faster but that just starts the engine quicker and starter life seems about the same. It might make good sense to limit the length of a cranking cycle and allow more cool down time if cranking repeatedly.

Jim