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Author Topic: Options for charging battery bank with engine alternator  (Read 2751 times)
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« on: September 15, 2008, 01:36:49 PM »

I know that Trace has a switch that allows one to use your main engine alternator to charge your house battery bank.   

Any other recommendations.    I have a Bosch 160 amp alternator on my Series 60.    Is it wise to purchase another alternator and keep things seperate.
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luvrbus
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« Reply #1 on: September 15, 2008, 01:45:30 PM »

one alternator works fine if the voltage is the same on both systems with a isolator between the systems has for me over the years but my alternator is 300 amps    good luck
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gumpy
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« Reply #2 on: September 15, 2008, 04:17:08 PM »

Buy a 200 amp continuous duty solenoid. Grainger has one for about $70. Hook them together and put a toggle switch on the solenoid coil control line. Works just fine. Make sure you do proper battery maintenance every 4-6 months on both banks.


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Craig Shepard
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« Reply #3 on: September 15, 2008, 06:11:29 PM »

I second Gumpy's solution with exception that I also recommend running the switch off of my ignition circuit, so there's less chance to turn the engine off and forget the switch, which would result in the system not doing what it should do.  When the key's on or in "aux" the solenoid will work... when the key's off, so is the solenoid.  Helps us brainless old farts when we forget too many details!
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luvrbus
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« Reply #4 on: September 15, 2008, 06:46:53 PM »

No idea what your inverter powers but one thing to take in consideration is a alternator has to have more amps than what is drawn from the battery bank for instance if you ran a AC the 160 will not charge the batteries fast enough to keep up with the demand.I don't use the solenoids but they are more economical than the isolators and they work for most but not for me
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quantum500
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« Reply #5 on: September 15, 2008, 07:10:15 PM »

I second Gumpy's solution with exception that I also recommend running the switch off of my ignition circuit, so there's less chance to turn the engine off and forget the switch, which would result in the system not doing what it should do.  When the key's on or in "aux" the solenoid will work... when the key's off, so is the solenoid.  Helps us brainless old farts when we forget too many details!

There is a way to make the solenoid connect only when the alternator is charging also.  Thats how I have mine wired.
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gumpy
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« Reply #6 on: September 15, 2008, 08:13:59 PM »

I second Gumpy's solution with exception that I also recommend running the switch off of my ignition circuit, so there's less chance to turn the engine off and forget the switch, which would result in the system not doing what it should do.  When the key's on or in "aux" the solenoid will work... when the key's off, so is the solenoid.  Helps us brainless old farts when we forget too many details!

Good idea, unless you want your inverter to charge your coach batteries, too. I'm sure there's a way to wire it so both solutions work. Currently, I have on the manual switch on mine.

I set one up for a friend in AK this summer, and we wired the solenoid ground through a lighted toggle switch on the dash. When he turns on the switch, the light comes on. It works great.

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Craig Shepard
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« Reply #7 on: September 15, 2008, 08:31:30 PM »

I have 2 Trace SW4024's (stacked), and 12 8D's..    I don't think the 160amp Bosch is going to cut it. 
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luvrbus
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« Reply #8 on: September 15, 2008, 08:35:43 PM »

Hell of a battery bank and 8000w of inverter no way is the 160amp is going to handle that
« Last Edit: September 15, 2008, 08:37:59 PM by luvrbus » Logged
gumpy
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« Reply #9 on: September 16, 2008, 05:16:06 AM »

I have 2 Trace SW4024's (stacked), and 12 8D's..    I don't think the 160amp Bosch is going to cut it. 

So, what's the total Ah capacity of your battery bank?

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Craig Shepard
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« Reply #10 on: September 16, 2008, 05:28:21 AM »

Heck, hook up 10 of those 8D's in series and do away with the inverter and its loss.
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« Reply #11 on: September 16, 2008, 09:31:13 PM »

Gumpy 490ah per inverter
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Gary '79 5C
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« Reply #12 on: September 17, 2008, 12:33:40 AM »

Wow, that is alot of stored energy with (12) 8D's, but each to his.

If you need a 200 amp continous duty contactor, and have removed the OEM A/C from you coach, you still have a 200 amp contactor for the condenser motor within your coach. That is where I scored mine to isolate the two systems.
Gumpy is correct in this recommendation. Your application with (12) 8D's may take additional consideration due to total amps available.

Have a great day.
Gary
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« Reply #13 on: September 17, 2008, 10:26:32 AM »

Gumpy 490ah per inverter

So from this post, I assume you have the batteries set up in two separate strings of 6 each at 24V, and are using each inverter to charge it's own bank?

If this is correct, you could put two 200 amp solenoids in for your crossover, connecting one to each bank, and wiring them to the same switch.

I hope you have a very strong alternator, as you could easily see charging currents in the 200+ amp range when your batteries are 1/2 discharged, which doesn't leave a lot for charging coach batteries or running the a/c or heater blowers if you're running the 50DN alternator.

Without knowing your application and usage, this setup seems like tremendous overkill in power, money, space and weight. I'm sure more than I are wondering what went into your decisions to put two SW4024's in your coach with such a huge bank of batteries. Please give us some details on why you went this route, and how you use your bus.


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Craig Shepard
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« Reply #14 on: September 17, 2008, 11:18:13 AM »

Gumpy, as you know some of us still at the age that we still are working (married with kids).   I want to hit the road for 2 weeks at a time but I have to provide emergency service for some of the components that I build and service.  For my "job" (specialty automotive)I have the need to run smaller electric motors.  The equipment will be in one of my bays.   I also have a fully self contained (mobile)2000HP hub dyno system that also requires a inverter for constant power thus the Trace units.   I was able to acquire the factory Trace refurbs for decent prices (that's a story in itself).  The coach did not come from the factory with "Bus air"  >> with the color being dark charcoal,  my A/C loads are up there.  I am removing my basement air, and will put on 4 15K Penguin heat pumps.   

Supplying over the road DC current to multiple banks is my last hurdle.   Please forgive me for my "lack of knowledge" but are you folks manually engaging the contactors to switch the current path.   TIA for all you folk's help.
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luvrbus
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« Reply #15 on: September 18, 2008, 11:10:31 AM »

Zero, thought I would pass this information a friend of ours stopped to show his new Marathon last night and I checked his battery system for you  they use 2- 140 amp alternators for the house and 1- 140 amp for the chassis and this is for only 6 4-D house batteries and 2- 4000w stacked inverters, you may need something larger for 12 -8Ds     good luck
« Last Edit: September 18, 2008, 11:36:25 AM by luvrbus » Logged
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« Reply #16 on: September 18, 2008, 11:51:23 AM »

You need to size for the load, not the number of batteries.  Marathon is probably assuming the two inverters could be heavily loaded thus the two alternators. 
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Kenny
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« Reply #17 on: September 18, 2008, 12:58:00 PM »

What about sizing the charging system for the rate of battery drain and battery recovery you can live with. The load is going to vary depending on what your using. To size for the worst case load, you don't need all the batteries but you would need a rather large charging system. The beauty of having many batteries is you can down size all of your battery charging systems. The batteries are now there to provide power in times when additional loading is needed for short periods. The rate of discharge and recovery is now dependant on the charging system and what you can live with.

Rather than adding an additional alternator, you may want to utilize the original bus alternator to charge both the bus and house batteries using a high amp relay. This was depicted in a recent issue of the Bus Conversion Magizine wereas the alternater with the engine running always charges the bus batteries and after the engine is started and aired up, a relay connects the house batteries to the same alternator. This senerio keeps the house and bus batteries separate while the engine is not running.

The purpose of a large battery banks is to provide reserve power in times of high current usage and to downsize the charging systems. Why put a lot of money into hugh power generation (generators, chargers) if its really only used for short periods. Let additional batteries provide that reserve power for those short periods.

Kenny 


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1941 and 1945 Flxible - South Lyon, Michigan
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« Reply #18 on: September 18, 2008, 01:45:14 PM »

Thanks guys for your latest replies.   I have a question with regards to the isolators.   If the alternator is charging the house batteries, what prevents the "bus" voltage to drop on it's battery bank.   ie driving at night with headlamps on. 
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Kenny
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« Reply #19 on: September 18, 2008, 01:58:00 PM »

An isolator or relay connects the house batteries to the alternator after the engine is running. The bus batteries are aways connected to the alternator thus always charging when the engine is running.

Kenny
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luvrbus
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« Reply #20 on: September 18, 2008, 02:16:16 PM »

Zero, his coach  had  Newmar Integrators on the battery banks not isolators to me they worked like a solenoid but were automatic or manual may be something else for you to consider. Isolators work like a check valve allowing current flow in one direction and integrators worked on the same principal but have a override      good luck
« Last Edit: September 18, 2008, 03:21:07 PM by luvrbus » Logged
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« Reply #21 on: September 18, 2008, 03:25:54 PM »

So per one of the recent Bus Conversion articles, a pressure switch could be put in place to trip the relay/isolator.   I'll Google the Newmar hardware>BTW, Thanks for looking at the Marathon.
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Kenny
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« Reply #22 on: September 19, 2008, 06:19:25 AM »

Zero
I'll look for the issue of the article and let you know. It was well written, listed many options and in the end provided a simple and effective solution.

Kenny
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