Batteries again!

[Sammy]

I have had excellent results with this method on many non-converted motorcoaches.

Ace,
I cannot tell you if your friend's method is correct or not. I have no experience with converted coaches.
I'd be very interested to find out if there is a different charging rate for converted coaches too.

[mikelutestanski]

Hello   
     Check the website below for basic charging voltages of lead acid cells. The minimum charging voltage is as Sammy stated  13.8V or 2X that which is 27.6V for a 24V system. 
    The charging voltage is a function of the battery chemistry and what is required to keep the battery cells charged correctly.  The load that the battery sees is more linked to how long the battery will last ie charging cycles and how deep the battery is discharged before requiring charge.   This is a very simplified explanation and probably does not accurately reflect the whole story however if you search the web for charging lead acid batteries you will find lots of info to help you determine the correct charging voltage for your application.. 
     It is my opinion that you should follow the MCI manual recommendations however opinions are like #$%^&   everyone comes with one and you need to separate the wheat from the chaff.

    http://www.powerstream.com/SLA.htm

        Regards and Happy bussin....   mike   

[Blacksheep]

Sorry Sammy I forgot to mention that both his and my bus started out as seated coaches and we both self converted them. Not sure if this makes a difference but now I hope its clearer!

Ace

[VanTare]

Sammy I have a converted H-45 VIP chassis and the voltage on it is set at 27.5 volts   

David

[Sammy]

David, thanks for charging info on your coach. 

[Sojourner]

About charging rate for either seated coach or motorhome...it makes no difference what so ever except for nearly steady 24/7 or stop to rest a few days or weeks then go. A car to gigantic earth mover use exactly same voltage setting for its design battery. Only difference is if you are using other than wet cell battery design such as gelled, and AGM (Absorbed Glass Mat). They have their own charging voltage setting.

Ace...just go for the coach recommends setting for standard battery (wet cell). It usually 14.7v @ 70°F for 12v wet cell with head light and heater motor on. Double the voltage for 24v system.
However for very warm climate, setting should be at least 28.5v for 24v system
FWIW

Sojourn for Christ, Gerald

[luvrbus]

Gerald, if you double the 12v for 24v that would be 29.4 volts are you sure about that formula my Prevost manuals states 27.5 for both the seated and conversion shell .     good luck

[Blacksheep]

The power stream site was very informative and I thank you for posting it. I now understand charging just a little better and will make the necessary adjustments to get my charging voltage up to 27.6 across the 24 volt leg or 13.8 for each battery. Right now if I calculate correctly, I'm set somewhere around 12.8 per battery which makes my 24v leg exactly what is reads 25.7.

Now is all I have to do is slightly adjust my voltage regulator? I know it doesn't take much to move it a lot! AND I should turn every possible item on that would load the system? Is this correct? My concern with setting it at a higher rate when loaded was that when I ran with no lights and no fans, a/c, blowers etc., that it would overcharge! I assume I was wrong in my theory?

Ace

[Sojourner]

Thank you for asking...luvrbus.

Battery gets less sulfating if you charge at high end of adjustable setting.
The lower the setting the thicker the sulfate coating in time.

Charging the lead-acid battery
http://www.batteryuniversity.com/partone-13.htm

MCI call for 28 volts @ 80°F is for 24hrs day uses. Very little cranking cycle per "passenger" miles.

However, for us motorhome uses...higher setting is better at 29.4v @ 70°F (alternator & regulator temperature). You may use little more water in battery but it keeps it more alive and last as long or longer however, if you can desulfate the batteries....you will get even more life still.

All electronic devices, blower motor, headlight and miniature bulb are factory design to be a least 15v for 12v and 30v for 24v system.

This one of the common reason for the 8D batteries that came with from charter companies for bus conversion is very weak to say the least. Voltage setting is too low for bus nuts purposes.

Do can do what you want to set it at whatever. It your money and time for the long run.

Car & light & medium truck of today are set at the middle range.

Ace...Now that I was thinking why you said that?...you are right about bus being use passenger and motorhome, have difference voltage setting. Only because it not running nearly 24hrs every day and never stay warmed ...you need to set higher then their spec our uses.  Set it at least 28.5 for warm climate to 29.4 volts @ 80°F for cold climate with a load on such as bright headlights and front heater motor on.

Sorry for confusion but after seeing many bus nuts post about the hard starting with old 8Ds in mild cold day that it starter barely cranks the DD fast enough to raise the combustion temperature high enough (at least 700°F) to ignites. So I am learning that buses manufacturing is spec for low voltage setting, we need to increase it to be in our style of uses.

BTW...High end charger is set 15.5v for 12v and 31v for 24v battery.

Gerald, if you double the 12v for 24v that would be 29.4 volts are you sure about that formula my Prevost manuals states 27.5 for both the seated and conversion shell .     good luck

[Sojourner]

Ace...about the load require before adjusting....you only need partial load to stabilize and heat-up alternator's windings for repeatable adjusted setting, such as bright headlight and front heater blower on and run at least 15 minutes before adjusting. For your case, adjust to 28.5 v.  Caution...always adjust from low & up to 28.5v...not from the higher voltage down to 28.5v. Otherwise you will not get repeated voltage setting.

FWIW

Sojourn for Christ, Gerald

[niles500]

I beg to differ with all the recommendations - You should set the charge rate at what the battery manufacturer states - A battery doesn't know if its in a GM, MCI or Prevost - Bus manufacturer's give spec's on Batts that are FACTORY installed, not after market - In this case when you  go by "Da Book" it's the "Battery Book" - HTH

[Busted Knuckle]

Ace I ain't positive on this, but if the relay was sticking on and closing (completing) a circuit even with "everything supposed to be off" could have been back feeding thru the alternator and draining the battery!
I used to have the same problem on my derby cars where if I left the battery hooked up it would be dead in no time (3-4hrs)! Then friend rewired my alternator for me (told me I had the field permanently energized or something like that! And after he did whatever it was only on when the engine was running.) and after that I could leave the battery hooked up for weeks at a time and it'd always be fully charged! (I was the only idiot in this area who used an 8D battery in my derby car, but I always had plenty of recranking power no matter hot hot the engine got! LOL)
FWIW   BK 

[Blacksheep]

Jerry, thanks for the very informative site. I have been reading about batteries now for two days and I feel like I'm sort of charged up myself.

Niles, as far as setting the charge rate according to the battery mfgr rather than the bus mfgr, where would someone find this information? I have looked at the label on the batteries but it really doesn't say but reading the charts and info provided by others, it says charging the batteries at a higher rate will ultimately make the batteries last longer (I think). Charging them at a lower rate will cause them to go weak or dead faster (again, I think)

Now I also read someplace that you should check the battery temperature while charging. Is that the battery case? Do you check it with a digital temp gun?

Today the batteries read 25.5-6, down from 25.6-7 when I installed them. Nothing started and nothing on!

Bk, not sure what your saying but what I do know is the relay made everything work like it should. Why? Your guess is as good as mine! I was thinking of carefully cutting it open to see what shows on the inside and maybe that would tell me (us) more!

Ace

[niles500]

Ace - post the battery info and I'll try and find it for you - HTH

[Sojourner]

Ace...about battery temperature is the electrolyte however, you can use your IR gun to measure cell # 3 or # 4 case's side at about 1 ½ inch from the top or into the water level.


"TEMPERATURE COMPENSATED BATTERY
     STATE-OF-CHARGE (SoC) TABLE"                  
Deg. F column is Electrolyte Temperature
     
All reading for Wet "Mainteneance Free" (Ca/Ca) or AGM/Gel Cell VRLA (Ca/Ca) Battery
            
      Open Circuit Voltage Reading            
Deg F   100%     75%     50%     25%     0%
           SoC      SoC      SoC      SoC      SoC
120   12.813   12.613   12.413   12.013   11.813
110   12.811   12.611   12.411   12.011   11.811
100   12.808   12.608   12.408   12.008   11.808
90   12.805   12.605   12.405   12.005   11.805
80   12.800   12.600   12.400   12.000   11.800
70   12.793   12.593   12.393   11.993   11.793
60   12.784   12.584   12.384   11.984   11.784
50   12.772   12.572   12.372   11.972   11.772
40   12.756   12.556   12.356   11.956   11.756
30   12.738   12.538   12.338   11.938   11.738
20   12.716   12.516   12.316   11.916   11.716
10   12.692   12.492   12.292   11.892   11.692
  0   12.666   12.466   12.266   11.866   11.666

niles500...all electrolyte batteries are same voltage per percentage of state of charge per given degree in Fahrenheit

Charging voltage is base on type of battery, type of used and type of driving and storage temperature and length of time storage.

FWIW

Sojourn for Christ, Gerald