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Author Topic: alternator to house batteries  (Read 3093 times)
roger dolan
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« on: September 07, 2009, 06:58:37 PM »

   I notice that you folks are connecting your house and/or start batteries to the bus charging system. I have this system also but only either/or (not combined) of which I can do but that is manual. If my house batteries are dischared down to 11.5 volts or more the bus alternator will  put over 200 amps in to 8-6volt golf cart batteries (not combined with the start batteries) can they stand that and if so for how long. I can control the charge to either the start or house batteries from the cab or no charge to either battery. This brings up another questionwill this damage my alternator if there nowhere for the charge to go. 1962 4106

                                                                    Roger 4106
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luvrbus
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« Reply #1 on: September 07, 2009, 07:41:55 PM »

I do mine with a battery isolator never had a problem with the setup   


god luck
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TomC
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« Reply #2 on: September 07, 2009, 08:13:53 PM »

Think of charging batteries like water pressure.  As long as your voltage regulator is set at around 14 volts, when the deep cycle batteries get up to 14 volts, they will not accept any more charge.  Then the charging will seek out the path of least resistance, which in this case will be the still discharged batteries-which will get the heavy charging.  Good Luck, TomC
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Sean
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« Reply #3 on: September 07, 2009, 08:28:01 PM »

If my house batteries are dischared down to 11.5 volts or more the bus alternator will  put over 200 amps in to 8-6volt golf cart batteries


OK, I am a little confused by this.  Isn't the 4106 a 24-volt coach?

Quote
can they stand that and if so for how long.


That depends on how large they are and whether they are flooded, AGM, or gel.  Also, this is a yes or no question, the "how long" part is irrelevant -- the amperage will drop as the batteries charge; when they no longer need any charge, the alternator will stop providing it.

This, of course, assumes the regulator sense lead is properly connected.  I'm concerned, though, because you have a manual switch.  You'll need to check where the sense lead is connected.  Having the sense lead connected to one set of batteries, and the output going to a different set of batteries will likely cook them beyond repair.

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I can control the charge to either the start or house batteries from the cab or no charge to either battery. This brings up another questionwill this damage my alternator if there nowhere for the charge to go.


Yes, it can destroy the alternator in a matter of just a few seconds.

I very strongly recommend against an either-or type switch.  The alternator should be connected to the chassis batteries at all times, and a simple SPST switch can be used to bridge the house batteries in as needed.

If you are going to have an either-or type selector, it should NOT have a setting for "neither," and, furthermore, it should be of the make-before-break type.  This is a very rare item, especially in 200+ amp ratings -- the vast majority of double-throw switches are break-before-make.

Again, the other issue with this type of selector is the connection of the charge sense lead.  Ideally, the sense lead should run directly from the regulator to the positive terminal of the battery, without going through any other hardware.  Also, it should be connected at the battery end, not the alternator end of the large positive cable from the alternator.

With a double-throw battery connection setup, you will need to either use a double-pole switch, and use the second pole to connect the regulator sense lead to the proper battery bank (troublesome because split ratings are hard to find in double-pole switches -- you'd probably end up using a switch with both poles rated for 200 amps, even though the sense current is hundreds of times lower than that), or you'd have to just connect the sense lead to the input side of the switch, which puts it farther from the batteries it is trying to measure.

HTH,

-Sean
http://OurOdyssey.BlogSpot.com
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JohnEd
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« Reply #4 on: September 07, 2009, 08:32:30 PM »

Roger,

What Tom said is critical.  The charge voltage from your alt must not be too high.  I think the max is 14.5 but you need to verify that with the bat mfr.  Whatever your charging sys can put out at 14 volts is what the bats will take.  Verify that your charging system is set to the correct voltage.  Too low and you don't get FULL charge.  To high and that will shorten the life of your bats.  .2 volts too high will hurt.

If you use a bat isolator you should also move you regulator bat voltage sample point to the physical bat terminal.  An isolator will drop .7 volts so if your alt is set at 14 and the pickup point is the alt output the volts at the bat will be 13.3.  Not enuf to get full charge.  Also. an isolator that will pass 200 amps will be a very expensive item.  Mine was spendy and I can only charge at a 80 amp rate.  My alt is much weaker than yours.  My pick up is at the bat select switch so I charge at the rate the bat in use will take it.  Alt with a built in reg are hard to get set up.  A shop can break out your reg connection so you can connect it properly.  My regulator is external and is adjustable.

HTH,

John
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chris4905
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« Reply #5 on: September 07, 2009, 08:53:37 PM »

Roger,

My bus is a 24V but the principal is the same, just different parts 12V vs. 24V.

I have a solenoid connecting both the start and house batteries while underway, and the large amp bus generator charges both sets.

I have attached a hand drawn diagram, I hope you get the idea.

I have had this on our bus for over 10 years and it has worked just fine for me.  I can even run one of the roof airs off the inverter and the bus large generator charges the house batts faster than the a/c uses them.
« Last Edit: September 07, 2009, 08:59:00 PM by chris4905 » Logged

Chris & Cheryl Christensen
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« Reply #6 on: September 07, 2009, 09:05:51 PM »

That works Chris but it can cause problems Dick Wright (WRICO) has good info about using that system on his web page.
Fwiw I passed through Eagle today going to the place at Garden Valley



good luck
« Last Edit: September 07, 2009, 09:14:43 PM by luvrbus » Logged

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« Reply #7 on: September 08, 2009, 07:26:43 AM »

Roger,

That is how mine is wired.  I am really interested in what Clifford said about complications.  I could not find a discussion or info site for Dick Wright/ WRICO.  I need more info....please help....anybody?

John
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« Reply #8 on: September 08, 2009, 07:33:39 AM »

JohnEd, it is under isolators on his new web page

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Sean
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« Reply #9 on: September 08, 2009, 09:15:08 AM »

I'm sorry, but I disagree with Dick on this (and several other things, too).  Remember, he has an axe to grind -- he sells those isolators, and they have a tidy mark-up.  Solenoids are widely available from more conventional sources (e.g. Grainger) and, as more of a commodity item, have a much lower profit margin.

Isolators and solenoids are two different ways to achieve the objective.  Each has its benefits and its limitations.

One limitation of isolators is that a tremendous amount of energy is lost in the process, given off as heat.  High-amp isolators have to have enormous heat sink fins to provide for this.  Another limitation is that, unless you have a fancy two-bank regulator, the battery sense lead will have to be connected to one bank or the other, and the un-monitored bank will not receive the proper charge.  This can actually destroy batteries:  if the sense lead is connected to a nearly completely discharged bank, the regulator will begin calling for maximum voltage from the alternator, whereas if the other bank is already mostly charged, this much voltage can boil the batteries.  IMO, a very serious problem when banks receive significantly different usage patterns.

OTOH, a limitation of solenoids is that you must, indeed, size the cross-tire wiring appropriately for the amount of current that a fully depleted bank can attempt to draw from a fully charged bank.  This is not rocket science -- the draw can be calculated or measured.  The solenoid itself must also be appropriately rated for this draw, both as a continuous rating and to be able to make or break with that amount of current applied.

Moreover, an isolator provides no "emergency jump start" capability, whereas a solenoid can do that by merely providing a way to energize the coil when the engine is not yet running.  For this reason, many people who choose to use an isolator rather than a solenoid for dual-bank charging purposes, also install a solenoid to bridge the banks for emergency start purposes; if you do that, then you are right back to having to deal with all of the concerns Dick raises on his site.

FWIW, when I got my bus it had two massive, 300+ amp battery isolators on it.  I would guess each cost well over $400 new.  I ripped them both out and sold them cheap at a bus rally, and went with a $50 solenoid instead; simpler, no wasted power (or excess heat to get rid of), and the regulator can properly see the "average" SoC of the combined bank for better charge control, plus I can tie the banks together instantly for emergency starting, or even to charge the chassis batteries from the house charger.  For safety's sake (and to keep me informed at all times of what is happening with my charging system), I installed a shunt in the cross-tie, wired to a bi-directional meter on my console.  I can see at a glance exactly how many amps are flowing between the banks in either direction.

-Sean
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« Reply #10 on: September 08, 2009, 11:50:53 AM »

Sean,

The part about one depleted bank drawing large currents from the charged bank was what was giving me3 the problem with the theory.  I guess they can't hurt each other, as you said.  I also pondered the Continuous Duty Solonoid and the 2 or 300 amps I envisioned.  Where do I get that $50 solonoid you mentioned?

Thanks,

John
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« Reply #11 on: September 08, 2009, 12:13:26 PM »

The part about one depleted bank drawing large currents from the charged bank was what was giving me3 the problem with the theory.  I guess they can't hurt each other, as you said.


As I said, so long as you do the math and size things accordingly.

Quote
I also pondered the Continuous Duty Solonoid and the 2 or 300 amps I envisioned.  Where do I get that $50 solonoid you mentioned?


I bought most of my solenoids and similar items on eBay, where they are often surplus and discounted.  However, a 200-amp, 24-volt unit is available new from Grainger for about a C-note, as I discussed in this post:
http://www.busconversions.com/bbs/index.php?topic=12028.msg126976#msg126976

(The archives, as always, are a wealth of information -- when I can't remember what I said last year, or whenever I did the actual research, I always delve into the archives myself.)

-Sean
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« Reply #12 on: September 08, 2009, 12:31:40 PM »

JohnEd , I buy 200amp 12v Cole Hersee brand from West Marine for around 45 bucks they seem to hold up better than the 20 dollars unit from NAPA or a RV store.
 I Help guys do that setup that want it.
I thought you guys may like to read both sides of the options available to you  wrong again lol  


good luck
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Sean
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« Reply #13 on: September 08, 2009, 12:41:59 PM »

Clifford,

Nobody said you were wrong.  It is, as I said, a different option, and there are pros and cons going either way.

-Sean
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« Reply #14 on: September 08, 2009, 12:56:10 PM »

Sean, no way was that reply intend for you but some of these guy like to send PM telling you how dumb it was and that pisses me off.
 BTW did you get your oil leak repaired   

good luck
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« Reply #15 on: September 08, 2009, 01:09:10 PM »

Thanks, Clifford.  I guess I should stop taking everything personally  Grin

Yes, we got the leak fixed.  The gorilla that helped install the turbo managed to take a bite out of the brand new drain gasket in the process.  I only hope the missing chunk of gasket is not plugging anything up further downstream.

-Sean
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