How much alternator for 8 batteries?

International has their optional battery power apu heater and a/c system. They have 8 batteries total. I believe the alternator they use for that is 320 amps!!! They have a recharge time of about 4 hours in ideal situations. You are certainly not in an ideal situation simply due to the cold. I would say 185 is on the light side. You would need something more to recharge that many batteries in that climate with the loads you mentioned. I do know the 320 amp alternator is about $1200!!! So be prepared to spend some money. Plus, with a heavy output alternator you need heavy gauge cable to recharge with, so you may need to upgrade your cable aswell.

 

Have seen 2 alternators used.Seperate drive belt, wiring, etc. Good insurance, just in case one goes bad..

 

i have 4 batteries webasto engine heat and bunk heater.. im good for 12 hrs before i need to restart to charge batteries.. its a good idea in canada to start it anyways twice a day if laid over unless you pull reefer and run a positive to keep batteries up. 8 batteries run low to save fuel can freeze in our cold temps

 

I run 4 normal batteries and 4 deep cycle batteries with a good battery ISOLATOR in between the sets, heat and A/C run off deep cycle as well as inveter, rest of truck is on normal batteries, only 1 altenator which i a 185 amp... battery isolator will shut circuit off between both sets of batteries if current drops below 12.7v keeping enough power to start the truck, when current is above 12.7v in main batteries circuit opens up to charge deep cycle batteries.

 

I went with a Maxwell ESM Ultracapacitor to crank the truck that is the size of one battery, puts out 1,800 cranking amps, not effected by the cold weather and only weighs 21 lbs that I grouped together with 7 AGM deep cycle batteries to handle my hotel loads. This set up does not require a battery isolator to separate 2 battery banks (1 for cranking and 1 for loads) and does not require 2 alternators. I upgraded my alternator to a 200 amp one a long time ago and I do have solar panels to help with no-idle charging of the batteries.






The Maxwell ESM is like another battery bank by itself and the starter is isolated to it separate from the other batteries. The ESM is hooked to the other battery banks to recharge after cranking and it will not discharge back into those batteries. It is only for cranking the truck.



A great set up for an all electric APU with 7 AGM deep cycle batteries only used for hotel loads in the truck and with 1,800 crank amps, my truck never started so easy no matter what the temperature is outside.


If you want a battery isolator, I am selling one on E-Bay that ends tonight (12/27/13) around 10 pm EST. It is a big one rated at 300 amps: http://my.ebay.com/ws/eBayISAPI.dll...MyeBayAllSelling&ssPageName=STRK:ME:LNLK:MESX



This is a $400+ battery isolator and the Maxwell ESM eliminates the need for one of these to separately charge 2 battery banks.

Note: Truck Country in Davenport, IA had the Maxwell ESM for $747 plus tax and shipping and Sams Club has the Group 31 AGM marine deep cycle batteries for $179.32 each plus tax.

 

really if you have 8 batteries, weaker alternator needs more time to charge them, but if they are really deep discharged.

Ok, 8x130 batteries - 1040 amh, so, if alterantor output is 185 amp you need 5 hours to charg them if no any other power consumpters are on, so IMO, about 8 hours. But usually no one let batteries be fully discharged

 

Here's the factors:

1) Amperage output at driving speed. There are alternators at 200+ amps. More amps means less charging time.

2) Amperage output at idle. Some drop as much as 50%. This is important for a layover.

3) Efficiency. This is much more important than you think it is. Over a year you could easily save hundreds and hundreds of dollars going with a more efficient alternator.

3) Heat. I would stray towards a brushed alternator like the 28SI. They cool much better than the brushless ones and are smaller. EGR engines, idling down south, layovers are all factors.

4) Remote sense wire. Delco-Remy alternators have a wire you hook up to the far battery to "sense" the voltage at that battery and adjust the voltage regulator to see fit. This allows more complete charging when you're running a huge bank.