# What is the best way to set up an alternator/battery system?

• Auto/Motor
Hello, I am a food truck owner and I recently had a situation which made me rethink my power needs for my kitchen on the food truck. I have a 2001 Workhorse forward control Stepvan and I wanted to run an alternator, batteries, and an inverter setup INDEPENDENT of the trucks own alternator and electrical system. I first thought of using a high capacity alternator and just running everything off of that because I was reading about how difficult it may be to couple two alternators together, however the best option for my needs would be to have two separate electrical systems. I am hoping someone can help me figure out the best and safest course of action. Thank you for reading and I thank you in advance for any advice.

## Answers and Replies

russ_watters
Mentor
[moved to DIY Projects]
Hello, I am a food truck owner and I recently had a situation which made me rethink my power needs for my kitchen on the food truck. I have a 2001 Workhorse forward control Stepvan and I wanted to run an alternator, batteries, and an inverted setup INDEPENDENT of the trucks own alternator and electrical system. I first thought of using a high capacity alternator and just running everything off of that because I was reading about how difficult it may be to couple two alternators together, however the best option for my needs would be to have two separate electrical systems. I am hoping someone can help me figure out the best and safest course of action. Thank you for reading and I thank you in advance for any advice.
Welcome to PF!

Could you explain more about your requirements (120V? kW required? How many kWh per day?) and the idea you have for meeting them? I see several ideas there that don't appear to go together well.

....the obvious choice, to me, would be to buy a normal stand-alone generator. It's certainly more efficient than an idling van. The only reason I could think of for using an inverter and batteries is if the daily requirements are so low you can get away with using one or two deep-cycle marine batteries to power the kitchen. I don't think that's likely, but it may be possible.

CWatters
jim hardy
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however the best option for my needs would be to have two separate electrical systems.
Simplicity is usually a good thing.
Separate systems eliminates need for interfacing them
but the physical task of mounting a second alternator is daunting to those of us without access to a machine shop.
Fortunately the audio guys with their preposterous subwoofer amplifiers have created a market for such a thing.

try a search on "dual alternator bracket"

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Joe591 and dlgoff
gleem
I agree with @russ_watters . a portable generator. 1KW is equivalent to 1.3 hp. You don't need to run a 200hp engine to produce a few kws of power. It is probably bad for the engine too.

jim hardy
jim hardy
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You don't need to run a 200hp engine to produce a few kws of power. It is probably bad for the engine too.
yep.

There do exist propane fueled generators for RV's
their exhaust is less annoying than gas or diesel
and you likely have propane on board for the kitchen anyway ?

russ_watters
anorlunda
Staff Emeritus
I'll fourth the vote for a separate generator.

Among other reasons, many localities forbid sitting with the vehicle engine idling.

But @gleem's reason was the best. Your $10,000 engine idling has about the same lifetime (measured in operating hours) as a$1000 generator. That makes it a no brainer.

(There is a counter-example of NYC Checker Cabs that got 700000 miles on their engines because they never allowed them to cool off. But I think that example is so ancient that its validity today is doubtful.)

russ_watters
I appreciate the feedback. I'm not saying what I wrote is correct or the actual parts I need. I have read articles of people who have used the idling engine, high capacity or coupled alternators, and battery banks to power their food trucks, many with solar panels to help supply power. I also will NOT be using a regular stand alone generator.. again. Seeing as the first one had an "internal failure" and burned down half of my previous food truck. That $1000 generator burned down 25,000 dollars worth of stuff and cost a year of work and "progress". Plus I need roughly 10kw to run the entire kitchen at any given time. The propane generators for RV's that I have found are roughly$1 per watt... $10,000 dollar generator will not work for me. I've read a few things on people that use the alternator, batteries and idling engine method and it works well for their purposes, and is MUCH quieter than the easy, traditional, and annoyingly loud generators sitting on a bumper. However all of these texts just say "high capacity alternator, or coupling alternators" but they don't specify where or how they had that accomplished. Maybe it was a converter and not an inverter? I'm not saying I have the proper terminology, I'm just inquiring about more detailed information on a system I know people use and works well. Last edited: anorlunda Staff Emeritus Plus I need roughly 10kw to run the entire kitchen at any given time. 10000 watts/12 volts = 833 amps. The biggest alternator I find online is 300 amps. You would need 3 of those, plus your existing alternator. 300 amp alternators are about$700 each. I'm skeptical that you could mount 4 of them in your engine.

Short answer, 10KW is too much for an extra-alternator solution.

I see on Amazon that you can buy a 12 KW propane/gasoline portable generator for $1059, not$10000.

Portable generators should be located outside the structure because of CO and fire hazards.

Are you running electric stoves? That is far less efficient and expensive than using propane stoves or ovens. Electric stoves/ovens are a poor match for mobile applications.

russ_watters
jim hardy
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I need roughly 10kw to run the entire kitchen at any given time.
sounds like you're using electric cookers ?
How do you power the present setup ?

The propane generators for RV's that I have found are roughly $1 per watt...$10,000 dollar generator will not work for me.
yeah, a fellow needs to find something that's made for the masses.

my first Google hit

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russ_watters
Mentor
Seeing as the first one had an "internal failure" and burned down half of my previous food truck.
Portable generators should be located outside the structure because of CO and fire hazards.
Not much to add except to second that.

...also, there is no battery+solar solution that can provide 10kW all day for a food truck. It's way too much energy. Perhaps people who have done that are using propane for the grilles and only using the electricity for the other appliances. I'd bet 80% or more of the energy a food truck uses is for the cooking surfaces.

jim hardy
CWatters
Homework Helper
Gold Member
Most mobile food vans in the UK use a free standing portable generator a few meters away from the van. One advantage is that if a power socket is available you just plug into that instead of the generator.

The other approach is to use batteries for lighting and gas cylinders for cooking.

russ_watters and jim hardy
CWatters
Homework Helper
Gold Member
10000 watts/12 volts = 833 amps. The biggest alternator I find online is 300 amps.
I think it would need to be at least a 48V system.

A 10kw continuous duty inverter won't be a super cheap item. Only one I could google was US $3000. I'm wondering if there are alternators for catering vans that produce 220V directly. No battery or inverter required. There would need to be some sort of throttle control. Think this route is a job for a specialist conversion company. anorlunda Staff Emeritus I think it would need to be at least a 48V system. A 10kw continuous duty inverter won't be a super cheap item. Only one I could google was US$3000.

I'm wondering if there are alternators for catering vans that produce 220V directly. No battery or inverter required. There would need to be some sort of throttle control.

Think this route is a job for a specialist conversion company.
That works too. Here is one that works from a power take off. About $1500. I presume it is an induction generator. For 10 kW, PTO sounds more practical than belt driven. #### Attachments • 44.6 KB Views: 336 Asymptotic and Tom.G gleem Science Advisor Education Advisor Regarding the failure of your first stand alone generator and the subsequent damage it caused. That should never have happened if you had proper breakers or fuses installed. What do you need 10KW for? Are you using an electric grill/stove? Another point I do not understand is the desire for batteries I assume for backup If you need 10kw and maybe need one hour storage you would need 9 - 220AH batteries with a total weight of over 1000 lbs. at an approximate cost of about$2700. not including inverter and cables/hookup. Even if you only need the battery for an orderly shutdown say of less than 7 minutes you still need about nine batteries to be able to deliver the 833 amps assuming you can only draw about 100 amps from each without damaging the batteries.

It is recommended for standard flooded cell batteries you do not discharge them more than 50% capacity in order to maintain the longest operational life.

I am using propane for the stove/oven, fryer and the water heater. I DID have a gasoline/propane generator that had what they said an "internal failure" and it burned down half of the old vehicle. The generator Jim Hardy suggested is the exact one that failed. Mounting the generator on the outside is NOT an option. No-one will be able to hear anyone order anything. We tried it with that last generator. The generators I am talking about roughly a dollar per watt are RV internal propane generators, RV...RV... not stand alone generators... Not the ones you wheel out and put next to your vehicle. Also with the information I was reading they converted the power to AC. (Hence the inverter or converter question.) Similar to a boat. CWatters I was reading about 48 volt systems. I hope people understand that I'm asking for what would work and not claiming that the idea I have is valid. I appreciate the concern but how about everyone please stop worrying about how much it costs, initially, and fuel costs. (Those are my problems.) I GREATLY appreciate all the feedback! Thank you everyone!

jim hardy
gleem
So what do you need 10KW for?

Chest freezer, freezerless fridge, hotbox, steamtable, heatlamp, hoodvent, fridge/freezer, sandwich table cooler, the small amount of power for the water heaters electrics (It's fuel is LP), lights, and 2 water pumps (one of which is gray water and won't be used when we are serving so I didn't count that. It works out to roughly 9,375 W with everything running peak (that is with the chest freezer in the higher amp "startup" and the hood vent motor on high which on our last vehicle we didn't need it on high) The grilltops/oven, fryers, and water heater are L.P. … So if I am running the system I wouldn't NEED batteries? I was planning on having them to provide at least a few minutes of battery backup if something should happen. (Planned on 3) Gives us a few more minutes to get the support truck there to empty the food. Plus, all the inspections and opinions I received before and after the fire from professionals and non-professionals on the generator claim that all the wiring, fuses and all were done properly throughout The pros determined it was a fault within the generator. Implying to me that it wasn't built 100% right.

gleem
Wow. Anyway you would want to carry on service for the current orders. Turn off all unnecessary appliance to take care of current customers re-figure your power requirement to determine the required back up batteries.

Getting back to adding alternators to your truck, something not mentioned is that the output of an alternator depends on the rpm. To get a decent output you would need to run the engine at a higher than idle rpm.

For a portable generator,a power management system that could prioritize the equipment's power use,would seem like an answer by inhibiting some units from starting up at the same time since start up current draw can be three to seven time greater than the running current. I do not know if such a system is commercially available. but if available could significantly reduce you power requirement.

I received before and after the fire from professionals and non-professionals on the generator claim that all the wiring, fuses and all were done properly throughout The pros determined it was a fault within the generator. Implying to me that it wasn't built 100% righ
Did they tell you that low voltage can burn up an AC induction motor. If you load a generator its voltage will drop. Listen to the a generator when you plug something into it. You would have needed an under voltage trip

Asymptotic, OmCheeto and russ_watters
anorlunda
Staff Emeritus
I still think the power-take-off generator sounds best. See #13.

It is located outside the vehicle; thus fire safety. (Alternators under the hood can start their own fire.) There is no external engine, so no audible noise to bother customers. It is AC, no inverter needed. It is disconnected while driving. It beats multiple alternators on simplicity.

Are there kits to add a PTO to a truck engine?

Edit: I added an AUTO/MOTOR tag to this thread. That might bring in some members more knowledgable on the AUTO aspects.

Asymptotic
jack action
Gold Member
All you need is the 'generator end' of a generator. This way you don't have to worry about what is the 'correct' electrical system, since it is already set up. Whether it is turned by the generator engine or your truck engine, it doesn't matter. You need to find the appropriate pulley ratio to match the idling rpm of your truck engine to the alternator designed rpm. The truck engines should try to maintain its idling rpm by adding more fuel as the alternator demand increases.

Edit: You may want to provide a way to disconnect the generator from the engine when you're on the road, i.e. not idling. As the generator will turn too fast in that condition.

As for a generator inside a food truck, one person died this year in my hometown because of that. Something to think about.

Wow. Anyway you would want to carry on service for the current orders. Turn off all unnecessary appliance to take care of current customers re-figure your power requirement to determine the required back up batteries.

Getting back to adding alternators to your truck, something not mentioned is that the output of an alternator depends on the rpm. To get a decent output you would need to run the engine at a higher than idle rpm.

For a portable generator,a power management system that could prioritize the equipment's power use,would seem like an answer by inhibiting some units from starting up at the same time since start up current draw can be three to seven time greater than the running current. I do not know if such a system is commercially available. but if available could significantly reduce you power requirement.

Did they tell you that low voltage can burn up an AC induction motor. If you load a generator its voltage will drop. Listen to the a generator when you plug something into it. You would have needed an under voltage trip

The generator did have a low voltage trip. The generator made numerous test runs on a full load during the months before the fire and everything was more than fine. That is why it was surprising to me. The "portable generator" will NOT be an option for our situation.

All you need is the 'generator end' of a generator. This way you don't have to worry about what is the 'correct' electrical system, since it is already set up. Whether it is turned by the generator engine or your truck engine, it doesn't matter. You need to find the appropriate pulley ratio to match the idling rpm of your truck engine to the alternator designed rpm. The truck engines should try to maintain its idling rpm by adding more fuel as the alternator demand increases.

Edit: You may want to provide a way to disconnect the generator from the engine when you're on the road, i.e. not idling. As the generator will turn too fast in that condition.

As for a generator inside a food truck, one person died this year in my hometown because of that. Something to think about.

What are you talking about "generator end"? and as for the last part. Generator inside a food truck? When and where was that said on my end? The only "generator" of power I am looking to use is the engine for the truck.

I understand the engine would need to be running a higher rpm and the pulleys and alternators and such will need to be calibrated to each other. I think there is room for a dual alternator bracket that I'm looking for. I've seen food truck running their engines and no other generators... maybe some solar panels to help. I thank all of those people who are telling me the physical properties and such of what I'm trying to accomplish versus those who offer the cheapest or easiest solution to just "half-ass" my problem. I'm hoping to find the way to give my customers and my crew the best experience. Even if it is a little more expensive or a little tougher to figure out. Thank You ALL for your input and imparting your knowledge my way.

jack action
Gold Member
What are you talking about "generator end"? and as for the last part. Generator inside a food truck? When and where was that said on my end? The only "generator" of power I am looking to use is the engine for the truck.
A generator is the combination of an internal combustion engine (ICE), an alternator and an electrical system to transform the current into something useful (voltage, for example). You need everything except the ICE. So if you can get the alternator and the electrical system from a generator that is known to work well and safely, all you have to do is connect this alternator to your truck engine while making sure the alternator will turn at the proper rpm. That's it. You don't have to customize your own system and wonder if you have the correct parts. The electrical system (alternator included) already works with the ICE, it will also work with the engine truck.

You may not have talked about a generator for the food truck, but others have mentioned it. I was just giving a real life example of a safety issue for anyone reading this thread and thinking it is a good idea.
I've seen food truck running their engines and no other generators... maybe some solar panels to help.
It all depends on your needs. A quick search shows that the largest alternator for a truck is 320 A @ 12 V. That is 3840 W (= 12 X 320) of power. Is that enough power for your needs? You still need some electrical system to convert that current to something useful. I doubt you are using equipment working with 12 V direct current, which is the alternator output. If so, great, you only need to change the current truck alternator to a bigger one!

jim hardy
Gold Member
2019 Award
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i found these guys' introductory page informative.
https://www.zena.net/htdocs/alternators/alt_inf.shtml

Typically, the largest single continuous duty alternator that can be fitted into the engine compartment of a large vehicle is one producing a maximum current of around 200-250 amps. Small vehicles seldom have alternators producing much more than a maximum of 100 amps.

Why? The waste heat that alternators can produce when heavily loaded increases dramatically as alternator output current increases. To deal with this heat, the alternator must become larger -- and, in some cases, also revert to liquid cooling.

For example: An alternator producing 100 amps produces four times the heat of one producing 50 amps. A 200 amp unit will produce four times the heat of the 100 amp model -- eight times more heat than the 50 amp model!

To deal with all this heat, a 300A air-cooled alternator balloons in size to be over a foot in diameter, and over eighteen inches in length -- much, much larger, and heavier, than a typical automotive alternator. This forces manufacturers of such ultra-large alternators -- typically used in busses and similar vehicles -- to resort to liquid cooling in order to make them small enough to fit into the very large engine compartment spaces found on this type of vehicle.

This is why most emergency vehicles resort to split electrical systems using two, or even three, large alternators -- one dedicated to the non-stock electrical equipment installed on the vehicle and one (or more) dealing with the load of the vehicle itself -- OR to very complicated isolation mechanisms that allow the output of multiple alternators to be combined to supply power to a single large load.
Woke me up to the cooling problem.
Might that be what burned up your first one? How was it ventilated ?

I think i'd investigate propane refrigeration, too.

jack action and russ_watters