humbojb

Your alternator will charge both batteries if it set up to do so. On my coach, I have a battery isolator that allows for both batteries to be charged. I don't know how effective the charging process is or if it is managed very well. I don't have an exotic multi-stage charger, however; I would like to get a better converter. Next year I'll be replacing the house batteries with two 6 volt golf cart batteries and would like to manage the charging more appropriately.

If any one has any suggestions on an appropriate converter upgrade, I would appreciate hearing your thoughts on this subject. I don't have an inverter.

Bill G

[This message has been edited by goodwinw (edited November 13, 2005).]

I'm with Bill H. on sticking with stock alternators. Available at any auto parts house, they'll usually do the job. I told my NAPA guy I had a motor home on a P-30 chassis, & he pulled an alternator off the shelf.

About the max draw you're lkely to have all at once would be headlights, heater- a/c, both windsheld wipers & fans. I went over the Siskiyou's once in just that condition with an alternator that wasn't charging properly, only showing about 10v on the voltmeter. I fully expected to have to use the auxiliary switch to start the next morning, but didn't. When we got home, I bought the new NAPA alternator.

That was daytime in rainy, foggy weather. At night, I probably wouldn't have had enough headlights. With all that stuff turned on now, voltage stays up with the new stock alternator.

I've been there, done that with exotic DC systems on big boats. Finding a replacement is tough to start, & you might have to mortgage the farm to pay for it.

quote:

Originally posted by goodwinw:
humbojb

Your alternator will charge both batteries if it set up to do so. On my coach, I have a battery isolator that allows for both batteries to be charged. I don't know how effective the charging process is or if it is managed very well. I don't have an exotic multi-stage charger, however; I would like to get a better converter. Next year I'll be replacing the house batteries with two 6 volt golf cart batteries and would like to manage the charging more appropriately.

If any one has any suggestions on an appropriate converter upgrade, I would appreciate hearing your thoughts on this subject. I don't have an inverter.

Bill G

[This message has been edited by goodwinw (edited November 13, 2005).]

A converter just gives you 12 volts or a little more. My Barth came with one. A converter/charger does both.

I don't like isolators. They drop the charging voltage by at least .7 volts to both chassis and coach batteries. This slows the charge and assures you will never get optimum charge. But they are simple and pretty reliable. Many folks are OK with them for years.

I don't like to charge coach batts with the engine, anyway. The well-charged chassis batt rules and keeps the coach batteries from getting what they really need. And running your engine when camped is a real waste of fuel and engine life.

If you want to charge your batts in parallel with the alternator, search my posts for a switch/wiring arrangement that uses the existing paralleling relay. I have used it with success for years.

Another plan is to use a marine switch to let you select which battery the alternator will charge. This is less than ideal, as automotive alternators are temperature compensated, and will drop the voltage as the alt senses heat. This is fine for one chassis battery, as all the alternator has to do is replenish the capacity taken out by starting, and carry normal operating load, which are very happy with any voltage above 12 volts. Your coach batteries, however, like 14.2 volts for bulk charging, and don't want to see 13.2 until they are at the float stage.

Converter/chargers:-----I presently use an Iota DLS 75/IQ3. It is not a current model, but the current IQ4 series is the same except for the addition of an LED that is of limited usefulness. I recommend it highly, but I have knowledgeable friends who swear by the Progressive Dynamics. When my batts get below 50% on my Trimetric meter, I fire up the genset and the Iota puts about 40 amps into my two golf cart batteries. I continue charging until about 80% is reached. That is the "bulk" stage of charging, and is where charging makes the most efficient use of your genset fuel. It also allows you to make noise for the shortest time. Some will say that 40 amps is too much for a 225 amp battery bank, being more than some percentage figure or other. Trojan says 13% max, but that is a hard figure, and batteries can take more current in the bulk stage a long as electrolyte temperature does not get too high. I use a Raytek IR to monitor that.

I also recommend the Trimetric battery meter. It pays for itself in the long run, and avoids having your batteries fail at an inconvenient time at an inconvenient and expensive place.

OK, your batteries are now at 80% and you are good for another day or three. When you move on and plug in or get home, be sure the batteries get fully charged. Some say every few days, some say in a week, it is not a hard figure, but they do need to be charged fully when convenient, preferably by a good three stage charger. However, Sears sells a line of 10 and 12 amp automatic chargers with a setting for deep cycle batts that are good for finishing up charging.

If the finances are not right for a three stage "smart" charger, you can use a heavy duty automotive charger for bulk charging from the genset. I did it for decades. Remember that all chargers will not put out their rated output unless the batts are way down. They typically put out a little more than half when your battery is at half mast. I bought an old ugly wheel-around 100 amp charger and remounted all the components in a more compact enclosure with fan cooling and mounted and connected it permanently. Their innards are not near as big as their outards. Used it for maybe 20 years. I just shut it off if the batts reached 80% or so. Always used an automatic auto charger to finish up when back home.

The whoop-de-doo chargers (and some solar controllers) also incorporate an equalization feature. I am not sure that is necessary. A hydrometer will tell you. I am on year 6 of my Trojans and no equalization yet. Experts are of mixed opinion on both equalization and desulfation.

I also dump a little EDTA in my batteries, but that is another story, along with the mineral oil...........

Another factor that enters into my genset charging, is that whenever Susan wants to run the blender, convection oven or toaster oven, the batts get a big charge from the Iota.

We also use solar to charge, so the genset does not get as much use if the sun shines or we are not in a forest.

This is not the only way, but it is a good way. My batts always last a long time.

Great, informative, post by bill h as usual.

I'd add:

Converter/charger: I ripped out the old 2-way (with 15 A charging capacity) and replaced it with an Intellipower 60A 1-way (with the Charge Wizard). Older C/C's have a relay to switch power to the house battery (2-way); the IP connects directly to the battery, and the Charge Wizard monitors its state, and runs a desulfating cycle every 3 weeks. The replacement was easy, but be forewarned, if you're replacing a 2-way, some rewiring will be needed, as will upgrading some of the wiring as well. It's worked out great for me.

The next motorhome I get will be gifted with ample solar capacity.

Battery Chargers: I got a decent automatic (3-stage) from Wal-Mart, which rides now in the RV. I blew an alternator (1 AM in Kentucky's Desolation Alley), and although I ran the generator, the charge to the chassis battery was meager...I finally limped into Clarksville, TN, and replaced the alternator, but got the charger so I could make the last 4 miles to the auto parts store,and not have to worry about alt failure again.

Rusty, wasn't your 60 amp converter enough to charge the chasis battery while the generator was running?
Jim

I talked to GM and the only alternator they show for a big block P30 for 1985 is a 80 amp unit.Then I got an American Wire Gauge table off the internet and it says that a #8 AWG will handle 73 amps. A #6 AWG will handle 101 amps. So I guess I'll have to make sure I have at least a #6.

On wire charts, you also need to consider length, ambient temp and whether it is in a bundle or in free air.

Wire charts also are different for one-way, as in circuits with a chassis ground, and both directions, where the ground is provided by a wire.

I tell the parts guy I have a 76 Chebby pickup. It seems to be the most gen for the money, and is always in stock. Rebuild kits are always available, too.

quote:

Originally posted by humbojb:
Rusty, wasn't your 60 amp converter enough to charge the chasis battery while the generator was running?
Jim

The new one is, but the old one wasn't enough to charge the battery (or keep it from discharging) with the headlights/nav lights on. I got the Wal-Mart charger before I tore into the old converter (rated at 45A, which should have been enough) to find that the charger was a separate circuit, and the charger section was rated at only 15A.

So in the Kentucky adventure, I'd drive for 10-15 miles, then stop and let the gen recharge for an hour, then go another 10 miles....

Went to NAPA to get the alternator and they asked if it was a single or double groove pulley. Being brain challenged, I didn't think to check that before leaving the Barth in Tennessee. Don't really want to bother the daughter with the question. Any ideas? 85 Regal, 454, no smog pump (I think)
Jim

My '90 Regal w/454 has a serpentine belt. Don't know if the '85s would have that or not.

Get a double; if yours is a single the outside groove will be a "spare".


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"You are what you drive" - Clint Eastwood

My 84 has a single. I will check with my old one which is an 85 when my neighbor gets home. I think it is a single, too. CRS.

Thanks Bill, I'll look forward to hearing from you. Won't have to buy two then.
Jim

Dang, he went pig hunting up at Hunter-Ligget. But he left the MH here, so I will see if his consort will let me in it tomorrow.

OK, someone was finally home. Just checked it and it is a single pulley. Mounted on upper right side of engine.