Two Batteries Instead of Four - Issues?

[GeneralDisorder]

..... Yeah sorta. It's not actually a 100A alternator *at idle* though - it's like 60A.

And if you have any additional battery banks like a house bank, etc. I'm running four Victron Orion chargers for up to 68A @ 24v going into my house bank.

The 100A dims the lights at idle on a fully kitted overland application and has NO overhead to make use of which is just a non-starter for me. The 260/300 does not have either limitation. Pretty much that simple for me.

 

[aw113sgte]

Negative of 2 6tl flooded lead acid - not enough CCA in -F temps to crank engine fast enough. 2 AGM would likely work just fine - or add a battery heater.

 

[GeneralDisorder]

Negative of 2 6tl flooded lead acid - not enough CCA in -F temps to crank engine fast enough. 2 AGM would likely work just fine - or add a battery heater.

The 100A draw of the grid heater is a LOT for two batteries on top of the starter - especially flooded wet cell batteries which take a HARD hit in the cold. You flip that ignition switch and it's 20 degrees - that grid heater is going to do a MASSIVE burn on the batteries for 15+ seconds at 100A before you are ready to crank.......... Situation is actually better at lower temp since it engages the Ether. But once it starts that alternator is going to be hit with a massive immediate draw - some of the 100A units will drop offline when the grid heater kicks in. All the BIG diesel military trucks always had four 6T wet cells. The HMMWV and the CUCV also use two 6T's but with smaller V8 engines. With AGM's they have dropped the FMTV A2 down to just two 6T-AGM's and they are also 24v only with a 600A alternator.

Army trucks sit around a lot. The batteries are frequently low and the fuel system de-primed. Two flooded 6T's were just a fail most of the time - and if the HMMWV has mushroomed glow plugs..... forget about it. Come back next spring.

That these older trucks have a four battery setup is one of the platform advantages in my opinion. The military doesn't care so much about redundancy but the four battery tray coupled with the later advances in AGM battery technology is a very fortunate happenstance for these truck's new life as a solitary overland camper without a convoy of other trucks and a whole Motorpool with a contact truck and a wrecker........

 

[Ronmar]

Well it utterly amazes me that everyone else in the world seems to get by with just 2..., And a 75A@24 alternator typical...:0

batt heat, block heat/webasto ect is how you deal with cold, AH is the crude way of dealing with it, and as demonstrated causes other problems if not done properly...

 

[GeneralDisorder]

All degrees of preparedness. Block heat, battery heat, Webasto, etc - all require time. If my phone just alerted me that the local volcano is rumbling I'm not really inclined to sit around waiting for my block heater.

And yeah Ether is the answer and I have that too but for the A1+ trucks the computer is in control so you best have both working so it has that choice to make. If one doesn't work you are back to that block heater and doom scrolling about the impending eruption......