INOP Generator contingency plans – What do you think?

[Barn Owl]

Since my bit of excitement I had with my generator not working for a brief moment, I was wondering if there where ways to limp home without one. I came up with two ideas and I wanted to know if they would work.

Plan A: My bus has a 40 amp AC to DC converter in it. At this time I do not know if it works or is hooked up (I doubt that I will get to it before my trip). But, if it did work and I lost my bus generator for whatever reason, could I run my genset to power the converter and run jumpers to the batteries?

Plan B: If the converter is not an option, could I run my genset to a battery charger and run the leads to the batteries? How big of a battery charger would it take to pull this off?

I think I could go a long ways on just the batteries if I didn't use any lights, but if I was traveling at night with lights, I don't know how far I would make it. Any other ideas?

[Tony LEE]

I once had a broken field wire inside the alternator and it really caused very little inconvenience on a couple of short trips til I had time to fix it. 9This is an MC8 with little essential electrics)
In daytime running, starting the engine really takes a very small amount of charge from the battery and the basic instrumentation also takes very little -- so if your batteries can be recharged from shore power at the beginning, you would get a days running before things got tight.

I have plenty of solar power anyway so by interconnecting the engine and house batteries I would be able to go indefinitely. Night running on low beam only would still allow a few hours running.

If you can run your generator and use a battery charger - say 5 amps capacity -- you could go forever.

[pvcces]

Barn Owl, if you used a lead from a 12 volt source to the regulator positive terminal, the generator should put out its normal power. You would need to be sure that it was turned off when the engine wasn't running because it would discharge your batteries while trying to overheat your generator, if it was left on.

If your wiring is still OEM, then the following should work. If the power came from your master switch or better yet, your terminal 42 in your rear electrical compartment, then it looks as though it would be shut off when you shut off the master switch. To do this, I would remove the sensing relay wire from terminal 42 before connecting the regulator wire.

After you made the connection, you could check the voltage at terminal 42 to make sure it was only on when you have the master switch on. The current draw through the regulator with the switch on should be about 8 amps.

Good luck with your problem.

Tom Caffrey

[jjrbus]

Another good reason to go with a 24V house system tied with a selector switch or solenoid to bus system.

[Jerry Liebler]

Barnowl,
     Either plan a or plan b will work fine.  I'll add a plan c that I've actually used, I have an SW2512 inverter/charger as the heart of my electrical system and a 7500 w diesel genset and provision to charge my house batterys from the bus alternator via a contactor.  When my bus alternator failed I got home by running the genset with the contactor powered via a jumper wire, the inverter charger kept both house and coach batterys fully charged.
Regards
Jerry 4107 1120

[NJT5047]

A friend has been moving his bus around for two years using two WalMart 12V battery chargers and the genset.  His alternator failed, and he has not found anyone to repair the thing...within his time constraints. 
Sold his home.  Now the bus is home...and headed for Florida.   Cannot leave the bus in a shop while living in it.
My 24V inverter, which will operate off the genset, charges the house batteries, and i can parallel the house and crank batts (2 grp 31s) when traveling (or sitting still), or for starting if the crank batts failed.  They haven't so far.  They are 3 years old and it's about time I suppose. 
All of your ideas will work.  Without AC and heat, the bus uses very little DC voltage to operate.   
I believe this is plan "C"? 
Best, JR

[Don4107]

This is just the problem I hope to avoid by putting a one wire alternator on the engine to charge the house batteries while the OEM alternator charges the start batteries.  Hate to add a belt to an otherwise beltless setup, but oh well!

I may even get creative and hook the big OEM alternator up to the house batts since they will get drained more and use the one wire alt to charge the start batts. 

A 200 amp solenoid will allow the batt banks to be connected to charge both if one alt dies.  A separate manual disconnect for each bank and a manual switch to jump both banks together for emergency jump start.

An isolated battery to start the genset as a last resort.  Maybe I can find a way to wind a rope around the genset for a pull start!   There are those that have had dead batteries and those that will.

[Hi yo silver]

L,
I see no reason at all why your contingency plans wouldn't work indefinitely.  As a precaution, I would keep frequent checks for overheating, overvoltage conditions, etc., but you shouldn't see any problems. A volt meter and a hand held infared thermometer are handy for checking conditions.  A hydrometer will tell you the state of charge on your batteries.
Dennis

[NJT5047]

A dedicated genset battery should be a priority.  Don't depend on the house or chassis crank batteries to start the genset.  Don't forget to maintain the generator battery.  The genset battery shouldn't be in the generator compartment.  Adjacent is good.
A parallel switch from a house battery would be a nice insurance policy, but the generator needs its own battery.  When charging the house batteries with the genset..or bus cranking batteries, use a charger and the 110VAC function.  The 12V genset start battery charging rate is almost useless on a pair of large batteries.  However, a typical inverter charge rate is 70 A bulk,  and that will get some fast action. 
Cheers, JR