High output alternators (how much amps?)

4BY4ADV

4BY4ADV

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I'm starting to camp more and more from the Jeep and power is pretty important for all my accessories. I am running a dual AGM setup, however it really doesn't do well running my fridge when I'm parked for 2+ days unless I have PLENTY of sun. After a long weekend camping under pine trees I got fed up killing my house battery and ordered a LiFePo battery. It turned out to be a huge improvement camping this weekend, however when I got home and had time to wire up the 60A DC to DC charger... I found a new problem. The charger pulls so many amps that my primary and house batteries started dipping in voltage on considerably while trying to charge the LiFePo back up. So now I need to buy a new alternator.

So If I've got a 120A alternator... how much of those amps are used by the vehicle? I get that every accessory will eat up some of the alternator's capacity... I'm just trying to decide, will a Durango 160A alternator add enough to be in a good place... or should I be looking for a minimum of 60 additional amps(180A+)?
 
Why not get a premier power welder?

You'd get a high amperage alternator...a stick welder and a 120v inverter all in one slick package.

-Mac
 
How about letting the Jeep idle for an hour or so during the day to top off the batteries? I think at the end of the day the amount of fuel used would pale in comparison to cost and simplicity of other options.
 
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macleanflood said:
Why not get a premier power welder?

You'd get a high amperage alternator...a stick welder and a 120v inverter all in one slick package.

-Mac
Click to expand...

Hmmm. I forgot about this option. More than I would like to spend at the moment considering all the other things I want to change (suspension, tires, and exhaust), but I’ve been wanting to learn welding.

Vinman said:
How about letting the Jeep idle for an hour or so during the day to top off the batteries? I think at the end of the day the amount of fuel used would pale in comparison to cost and simplicity of other options.
Click to expand...

Idling won’t provide as much power, not to mention the problem is the power requirements of the DC to DC charger. Definitely not going back after trying LiFePo… it’s just such a better house battery. I’ll try disconnecting the second AGM and turning off other accessories next time I try charging it, maybe that will be enough short term.


I was hoping there was another option similar to the Durango alternator that provided 180A at a similar price point. Might just make the most sense spending the $450 for a 240A alternator.
 
Ideally the goal is not to run the Jeep during the day just to charge batteries. If the fridge isn’t running at 100%, say a cooler climate/shade, then the LiFePo battery should give me a weekend of power. Maybe I shouldn’t have gone with a 20 or 40A instead of the 60A DC to DC charger… but I like the idea of a short drive putting my back at 100%.

Found a 320A alternator that puts out 180A at idle for $525. I think I’ll just have to bite the bullet and know my power issues are solved.
 
mrblaine said:
How about finding a more efficient fridge and lower the overall demand on the system?
If a decent solar panel and two AGM batteries won't keep up with the demand, then something is very wrong.
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Well, one AGM is my starting battery. I’d rather not pillage power from it. A 55Ah AGM is really only safe to discharge to 50%. So I’ve got roughly 27.5Ah available. Before I start damaging the battery.

My 100Ahr LiFePo battery was $360, just a bit more than my AGM in price and I can use all 100Ah.
 
Is there any adjustment on the charge modes on the charger? Sounds like the "boost" mode is pulling a lot of amps. My old camper one was rated at 45 amps on "boost", and it had three modes as the voltage got higher.

As far as high-po alternators, you may want to look at a Mechman alternator. Can't say I've seen one on a 4.0, but we've used them on race cars for the high demand of multiple fans and lights. Spendy but 240 amp output.
 
pcoplin said:
Is there any adjustment on the charge modes on the charger? Sounds like the "boost" mode is pulling a lot of amps. My old camper one was rated at 45 amps on "boost", and it had three modes as the voltage got higher.

As far as high-po alternators, you may want to look at a Mechman alternator. Can't say I've seen one on a 4.0, but we've used them on race cars for the high demand of multiple fans and lights. Spendy but 240 amp output.
Click to expand...
I haven’t seen any ability to change the power consumption on the standard DC to DC chargers (Renogy or Victron). Their purpose is really one thing… get your lithium/LiFePo battery fully charged as fast as possible.

I looked at the mechman alternators last night. $419 for a 240A and they don’t state the idle amp output. Not to mention they are built to order, so I’d be looking at several weeks vs spending a $100 more for an additional 80A and knowing that I have enough power at idle.

I guess I have my answer. Spend the money and move on.
 
4BY4ADV said:
Well, one AGM is my starting battery. I’d rather not pillage power from it. A 55Ah AGM is really only safe to discharge to 50%. So I’ve got roughly 27.5Ah available. Before I start damaging the battery.

My 100Ahr LiFePo battery was $360, just a bit more than my AGM in price and I can use all 100Ah.
Click to expand...
If you can't get 4 days out of your Li battery alone then your cooler is not very efficient or way too large for what you need.

You should learn how to set up a good mechanical voltage sensitive isolator to protect the main battery and then use supplementally down to slightly above starting voltage and get a better designed system to lower the demand.

Safe is also very relative with regard to discharge levels. At the end of the day, you are just reducing the number of deep discharges it can endure.
 
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What is your solar setup, panel specs, wiring and controller? Sounds like you could use more output there.

I have a large National Luna fridge/freezer and a small AGM battery. I forget the group number but it's an Optima blue top ~35AH and not really a dedicated deep cycle (aka dual purpose). For solar I have 2 100W panels wired in series (Important!) to a Victron controller. My strategy is to recharge to full charge daily even in less-than-ideal conditions. It's a fairly new setup but it's worked well so far. Before I got the second panel, it would get back to full charge under ideal conditions with no problem. However, part shade or cloudy conditions prevented getting back to full charge.

My solar panels are portable so I can usually place them out in the sun even if my camper is in the shade. I have roughly 40' or 50' of cable to place the panels remotely. I have it set up so I can use 1 or 2 panels just by plugging them into a series adapter I made or using a single panel alone when sufficient.
 
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mrblaine said:
How about finding a more efficient fridge and lower the overall demand on the system?
If a decent solar panel and two AGM batteries won't keep up with the demand, then something is very wrong.
Click to expand...

+1. A long weekend is doable with a walmart cooler and ice. Is everything cold when you head out? Can you fit some ice in to buy some extra time?

Are you camping in a furnace?
 
Unless I was lied to, supposedly my fridge (that I don't have yet and won't be seeing for another 9+ months) will run off 2 car batteries for 4+ days (if pre-cooled) or a 100w roof mounted solar panel indefinitely. And that's with using lights at night. So I agree with the others that a lower draw fridge might be available for you.
 
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