Big current needs in bed of Gladiator. Home run, or 2nd battery and gauge concerns......

[ducktapeguy]

I have a 160A Leece Neville rated for continuous duty, the problem is the size makes it difficult to fit into an engine compartment without relocating a lot of components that aren't easy to move. On a newer vehicle with a cramped engine compartment it would be like a game of tetris to shoehorn it in there.

I think by the time you add up all the costs and difficulty of beefing up an automotive electrical system to handle the kinds of loads the OP wants, a Honda EU2000 or equivalent looks cheap by comparison.

 

[Superduty]

What about switching over to Milwaukee battery powered tools? I guess it depends on how much work you plan on doing with the saws. But it seems easier to charge the 18v Milwaukee batteries.

 

[luthj]

I have run 100-150A loads from my 200A alternator for 5-20 minutes often without issue. It's the hour plus at full output in 110f temps that can sometimes cause damage.

 

[john61ct]

There are specialist sellers of high output small frame alts.

But yes the large frame are much better for continuous output in hot conditions.

External VR like Wakespeed or Balmar MC-614 is required for staged charging, automatic current de-rating based on overtemp, custom voltage setpoints.

Yes not a cheap option, and as noted impossible for many modern trucks.

But nice when a short drive gives you all the power you need for many days of off-grid living, lets you park in the forest rather than out in the sun.

Bog standard stuff for liveaboard boats. . .

 

[shade]

Having the fine manual control offered by the MC-614 would be nice. One more layer of control to keep everything happy.

 

[shade]

I use a lot of DeWalt cordless tools for construction, and they work fine for most things. If the OP can go cordless, it can save time and trouble, especially if you standardize on one battery system. I chose DeWalt because I work with someone that already used the brand, but I'd give Milwaukee the edge overall.

Otherwise, I have a Honda EU2000 I use occasionally for larger tools, like an air compressor or a large hammer drill. At less than 50 lbs, the new EU2200 is powerful, portable, and quiet. It'll run a 15A load for hours on a tank of fuel, and can be transported without making a smelly mess. The Yamaha equivalent is another good option. I know less expensive inverter generators are available, but those two are the standard.

 

[luthj]

I have done pretty extensive testing on my 200A bosch small frame alternator. It can supply 120-150A at hot idle. Since about 30A of that is for my engine systems, I have 90-120A available at hot normal idle. The alternator typically runs between 13.8-14.1V. As it heats up the regulator drops the voltage, and running full tilt for 30 minutes in hot weather, the current will drop (for battery charging applications). For constant load applications (cooking, toaster oven, etc), the voltage will drop. If I exceed the alternators capacity with the inverter the current will stay mostly stable at the hot idle level, but the voltage will drop until the starter battery beings to supply the balance of the watts.

An alternators output current limit is set by the max field current that the regulator will supply (for specific RPM). This multiplied by the alternators output voltage is the max watts. If the balance load would create a current greater than the current limit, the result is the output voltage sags, but the current remains the same. So the thermal load (power dissipated inside the alternator) stays the same or actually declines. This same method is used to prevent alternator overheating by smart regulators, which reduce the field current as temperature increases. This is pretty standard behavior on any common vehicle alternator made in the last 15 years. Engine compartments can be cramped, and idling in hot weather with high loads from AC and electronics not unusual.

Bumping to a high idle helps by increasing cooling, and increasing available current. My 200A unit will supply 200A in cool weather at about 2k engine rpm. In hot weather its closer to 180A. I have not tested in extreme weather, say 120F yet, but I would expect something around 150A to the the max available current. My alternator is located fairly low in the engine compartment, so its cooling air flow is probably within 20F of ambient when moving, and 40F of ambient idling.

 

[john61ct]

As it heats up the regulator drops the voltage, and running full tilt for 30 minutes in hot weather, the current will drop (for battery charging applications). For constant load applications (cooking, toaster oven, etc), the voltage will drop. If I exceed the alternators capacity with the inverter the current will stay mostly stable at the hot idle level, but the voltage will drop until the starter battery beings to supply the balance of the watts.

That's the biggest advantage of converting to the external VRs I mentioned, or similar.

They allow the **current** to be adjusted (de-rated) according to temperature conditions

either by you manually in advance,

or automatically within the parameters you select, dynamically reacting to changing conditions.

All the while delivering the precise voltage setpoint you have selected, running all day long at the maximum amps within the context of protecting the alt from overtemp.

A stock alt/VR allowing too much voltage drop, in effect prevents charging from taking place, too rough an instrument.

Of course DCDC charger can play the same role, but then if high amps are needed, you need to parallel stack multiple units.

On the other hand, a small LFP bank say 200Ah should not be getting too high a charge rate anyway for longevity, maybe 100A is OK in hot weather, 60A when it's cool.

 

[ducktapeguy]

I don't doubt the stock alternator can output high power for some length of time, I would be worried about how long will it last doing it. Something designed to handle continuous duty is usually built much differently than something that is only designed to handle peak loads. A car alternator is meant to handle the electrical loads of the car (~30A as you measured). While it may peak at 200A, I doubt the car manufacturers even considered someone using it to run 2kw loads, so asking it to sustain 100A, 120A, or 150A continuous is well beyond what it was designed to do. If a small frame alternator were able to handle those type of loads, why would the continuous duty alternators be so much larger and heavier?

If alternators still cost $40 and could be changed in 5 minutes like on my old jeep, I wouldn't care too much and I'd probably give it a go. But a new OEM alternator for my vehicle cost approximately ~$600-$800, and takes a full set of tools, a lift, and half a day to change. Or if it goes out while travelling, it could cost up to $1500 to have it replaced at a mechanic. That's why I personally wouldn't risk it when a $500 generator could perform the same task with a lot less risk. Those things were designed to run 24/7, it would cost you less to buy, cost less to run, and if it breaks you go out and get a new one and not have to worry about your vehicle. I'm sure people have successfully modified their electrical system to make it work, I just wouldn't do it on my own vehicle when there are other viable options.

 

[luthj]

Vehicle electrical systems are much higher demand on the most recent crop of vehicles. many have 1000W electric heater elements to rapidly warm the cab in cold weather. Heated seats and mirrors, vented seats, multiple AC fans (or electric radiator fans). Charging electronics through a 200-200W inverter, etc. You can search for bench testing of various factory alternators. They can generally make at least 50% of their output at idle, though at max temp that could drop to 40%. Even at max operating temperature they will make 75% of rated power at ~2000rpm.

 

[john61ct]

But it is true, that the stress from **adding** another high-amp load, especially charging an LFP bank for hours,

can reduce reliability / lifetime of stock system components

if there is no mechanism in between letting you throttle the amps demanded to a gentler current rate.

There are many ways to do this.

When implemented properly, then there is no adverse impact on the system as a whole.

 

[steffen707]

12 volt ? In a Gladiator ? 200A is huge !
Of course depends what ones actual power needs are...
It maybe hard time getting physical room in a Gladiator (assume the current Gladiator truck?)
Prestolite 200 A alternator is about 8" dia. x 12" long. If its hingemount, about 10" to tabs bolt center.

if you get a rubicon, or a max tow sport, they both come with 240A alternator.....

 

[steffen707]

I don't doubt the stock alternator can output high power for some length of time, I would be worried about how long will it last doing it. Something designed to handle continuous duty is usually built much differently than something that is only designed to handle peak loads. A car alternator is meant to handle the electrical loads of the car (~30A as you measured). While it may peak at 200A, I doubt the car manufacturers even considered someone using it to run 2kw loads, so asking it to sustain 100A, 120A, or 150A continuous is well beyond what it was designed to do. If a small frame alternator were able to handle those type of loads, why would the continuous duty alternators be so much larger and heavier?

If alternators still cost $40 and could be changed in 5 minutes like on my old jeep, I wouldn't care too much and I'd probably give it a go. But a new OEM alternator for my vehicle cost approximately ~$600-$800, and takes a full set of tools, a lift, and half a day to change. Or if it goes out while travelling, it could cost up to $1500 to have it replaced at a mechanic. That's why I personally wouldn't risk it when a $500 generator could perform the same task with a lot less risk. Those things were designed to run 24/7, it would cost you less to buy, cost less to run, and if it breaks you go out and get a new one and not have to worry about your vehicle. I'm sure people have successfully modified their electrical system to make it work, I just wouldn't do it on my own vehicle when there are other viable options.

yeah for my truck i have no idea how long it would sustain 240amps.

I had no idea modern alternators could cost $600-$800, i'm still thinking of my honda civic alternator being $95 and easy to change......I'll take this into consideration.

 

[john61ct]

Just a quality VR fit for that purpose can be hundreds, not counting any labour costs.

But eBay does get some crazy good deals coming through if you know exactly what you're looking for.

$100 plus shipping can get pretty much anything, including models designed for outputting rated power continuously on emergency vehicles.

Getting one rewound / refurbished isn't too costly either, although getting harder to find local shops.

I'm looking for a truck that will drive a pair of ex-Humvee units, 15kW each. . .

 

[luthj]

For your usage you don't need heavy duty. The factory 240A will work fine.