How much gas does your genny use? And a charging question

[Naio]

After generous advice and hand-holding from folks here, I experimented with running my van engine to charge house batteries when dry camping, as I do not yet have a genny or solar. I used an MSW inverter and a 30 amp 'smart' charger. Now I have results to post and subsequent questions.

I did this for a total of 7 days at two campgrounds. At the first cg, I felt bad because my van engine was louder than the neighboring gennys. At the second cg, I did not, because some gennys were louder than my van, so I felt I was fitting in with social norms :).

It's hard to estimate, but it seemed to take about 1/2 gallon per hour, idling the van. Seems like a lot of wasted energy. How much does a small generator use? OTOH, the van gets nice and warm for sleeping at night!

Charging this way took a LOT longer than plugging in to 120v. I don't have an ampmeter yet, but it took around 3x as long. Same charger. Is there anything I can do to speed things up? My alternator is 105v, so I don't think that is the problem.

[Almot]

landyacht318 wrote:

... she won't be installing solar on her roof by herself. The labor to do this job, and how most paid installers do halfass jobs using halfassed wiring, is not a desirable route, though Solar itself is great at silently getting 80% batteries up and near to 100%, a job the alternator is Not good at, and neither is a grid powered charger hooked to a generator or a MSW inverter.

Installers are getting better, there is more of them to choose from. Even with the most stupid and lazy laborer there is an option to make them do it YOUR way, and this is what I would do if I were the OP. Do you research, ask, order most crucial parts and specify how it needs to be done - what panels, controller, panel mounts, wire gauge. Then just be there. Not much different from dealing with contractors in Mexico - you have to be there or they won't work or won't do it right (I would say, in Mexico almost never they would do it “right” because have no right tools or knowledge how to use it). Usually solar installers won't argue and will do what you tell them to.

So far I've heard of only one source for quality solar installers - www.amsolar.com. Some of their contractors are mobile, traveling all over. I don't endorse this company and didn’t buy any parts from them. Shop around for parts.

For DIY ideas, you can browse The list of completed projects
The very first link on the List is by Sleepy - on a small motorhome. Old post, panels are cheaper now and people install more and larger panels. As I see, the only time she needed help was to lift panels on the roof.

Yes, solar will often charge to 80% and near 100%.

Yes, solar does does a better yet job of charging “from” 80% to 100%, because these last 20% are slow, no matter what charging source, and it’s better to let solar do this after initial boost by generator or engine in the morning than running a generator for another 3-4 hours.

Yes, solar can charge from 50% to 100% as well. Energy conservation is the key, especially with a small solar. If you can make your coffee on propane, and reheat leftovers also on propane, a 200-300W solar in the South in winter will charge to 100% most of the time.

One other power hog is a furnace. Some people chose to replace it with Olympian catalytic heater from Amazon - those are non-vented, but apparently it works. I'm trying to get a vented cat heater for over 6 months now, from the only company that makes it, and am losing my patience already. But, with plenty of sun and nights above freezing, a furnace could still fit in the solar "energy budget".

Yes, bigger battery bank is important for off-grid, especially while on solar. Because you need to be able to ride through bad weather days. There aren't too many bad days in snowbirds destinations, but you still need to store at least 1.5 days supply. Which means - you need to do you "energy audit" - determine know how much you typically draw. Many people don't know. And - whether you can minimize this draw - a lot of people can't or don't want to.

If increased battery bank requires AGM due to space considerations - then get AGM, why not? They don't release fumes and can be mounted inside. Only Lifeline brand of AGM has very high charging rate, all other brands typically state that you should not exceed 0.3C charging rate, and this is about the same rate as with flooded. I recall reading 0.2-0.3C "recommended" rate in the manual of popular Troyan flooded batteries.

[JiminDenver]

There are people here that use the alternator both in a motorhome and like we did with the jumper cables. A hour or so a day didn't kill the truck which is quieter than a Honda 3000 but it did use a 1/8th of a tank of gas. Still much better than going home. Now it's solar first, generator if we have too and the cables as a last resort.

We all do things differently, well I know I do but sometimes that can lead to a better way of doing it. No one is right or wrong as long as their needs are met.

[pnichols]

I don't understand all this talk about being hard on vehicle alternators. Aren't they protected from burn-out regardless of how they're used?

It sure seems to me that's the way that they coulda/shoulda been designed in the first place. I assume that my RV's Ford 130 amp alternator can supply - if I spin it at high enough engine RPM - somehwere around 130 amps as long as I want it to, or until it's temperature protection and/or amperage protection kicks in .... whichever comes first. What am I missing here? :h

Per my Ford alternator's RPM versus amperage output curve, it can deliver around 60-70 amps at true engine idle. I assume it can do this forever, as the footnotes at the bottom of the curve say nothing about "intermittent use only".

Maybe alternators in the good old days could be burnt out - but modern ones have adequate protection? I can't anyway anyhow wrap my brain around being able to out smart the built in over-temperatue and/or over-current protection electronics in modern vehicle alternators.

Regarding long term idling of late model V8 and V10 engines .... I believe that Ford based (and probably Chevy based) ambulances and other emergency vehicles sit idling for hours at incident sites. And also, how about police cruisers .... they sit idling for hours along roads even in extreme heat with their air conditioners running, don't they?

[Naio]

Thanks, guys, for the thought you have put into my situation. You have given me lots to chew on! Driving today, so not typing a lot. But pondering!

@NinerBikes: Purse, really? It is INFO that I want. But I build houses not cars, and my level of ignorance about gas engines is often more than people here imagine, frankly :). I did not realise it was hard on my alt, if not overheating.

@landyacht: Good idea to compate prices... and hassle. I am not worried about build qualiry of a solar install. I have friends to help me as needed , and i now know to run cabling etc., choices by the folks here :).

[landyacht318]

The OP did not come here seeking sympathy for the plight of her hard working agm batteries, but solutions to recharge them. She is not in a large RV, or towing a fifth wheel, or towing a trailer, and space and weight are big considerations.

There is also an option of using less electricity, by not using battery power to make coffee or cook. I know lots of people have aversions to cooking with propane in a small vehicle, but adequate ventilation alleviates those concerns, at least for me.

In this fulltiming lifestyle we have 3 main charging sources available, grid power via the grid or a generator, alternator, or Solar.

We do not know the vehicle platform of the OP but it is a Van or a MiniVan, and we don't know what specific alternator is in the vehicle, nor how well it can stand the task of being forced into a job it was not designed for.

Generally it is recommended to use all charging sources available to keep the batteries in the highest state of charge as possible at all times.

The MSW inverter on the engine battery powering a regular 'smart' charger obviously works, but can it work as well as if there was a thick copper conduit between alternator and house bank? It depends on the alternator and the vehicles voltage regulator. Factors we do not know and can only guess at.

Say the VR allows mid 14s to be held, and some 2awg cabling between the two allows the AGM house battery bank to drink all it wants from the alternator, how well can the alternator handle this increased load it was not designed for? We do not know, and can only guess at it. Many apparently think it will vaporize instantly, cause a black hole to develop, and swallow the earth whole.

How difficult it it to replace an alternator on the OP's platform, and how expensive is a reman'd alterantor? We do not know. But could it be cheaper to kill an alternator prematurely than kill a pair of AGM batteries prematurely? Very possibly.

The OP has some physical issues so that she won't be installing solar on her roof by herself. The labor to do this job, and how most paid installers do halfass jobs using halfassed wiring, is not a desirable route, though Solar itself is great at silently getting 80% batteries up and near to 100%, a job the alternator is Not good at, and neither is a grid powered charger hooked to a generator or a MSW inverter.

Getting the batteries to a true 100% IS very important, and Solar is a great way to do this, however solar is low and slow, and AGM batteries seem to require higher charge rates when deeply cycled. So some high amperage from another source to get the batteries near 80%, then the low and slow solar can take over and try to top them off and keep them from discharging during daylight. This is a good method.

Running a generator to get the batteries up past 90% state of charge is also wasteful of gas, and annoying to listen to, or smell.

So to the OP, I'd recommend investigating the price of a new alternator and the labor to install it, and compare that to the price of a new set of batteries. I certainly would not use a MSW inverter on engine battery to power a battery charger on the house bank, in a Van, unless the vehicles voltage regulator is too timid to try and get the batteries to the mid 14's, or too timid to allow it to stay up at or near that level where max current will flow and do the most good for a depleted battery.

Solar is a great solution for many, but not all, and those for which it is not a good option, are most vociferous, and want everybody to agree with them. Same for the people who love solar and want everybody to do the same as them.

Some people love generators, others despise them, and those who pollute a quiet and clean environment by running them often.

You can't make everybody happy all the time, but consideration for others in the vicinity seems to have gone out the window too in recent times too, as if narcissism is a character attribute instead of a character flaw.

I use between 35 and 65 amp hours each night in my Van. I have 198 watts of solar on my roof, and park in the sun more often than not. My alternator is thickly cabled to my batteries, and it can easily be maxed out by my depleted batteries. If either of my batteries are depleted, there is no way I will not take advantage of this huge charging source.

Even if I use only 30AH overnight, an easy task for my solar to replensih the next day, if I drive in the morning, the battery gets everything it wants from the alternator as I drive from A to B. I've noticed these higher amperages, even briefly, allow the battery to hold higher voltages for longer during the next discharge cycle, compared to if the solar alone brought them to the high 90% range on its own.

My alternator is regularly maxed out and has been so for the last 8 years. I have no fear of killing it as I can replace it myself in 15 minutes, and I have a lifetime warranty on it from Kragen Autoparts, but do not know if Oreilly's will honor Kragen's warranty. Anyway a reman'd alternator is about 125$ on my vehicle, and my flooded deep cycle house battery ( not a marine or dual purpose)is $165 minimum. So for Me, in my rig, the alternator is not going to lead a creampuff pampered life and just replenish the engine starting battery, but will be whipped by a depleted battery over thick cabling, and I will be there every night whipping my battery down to the 70 to 50% range each and every night, and perhaps even lower when Peukert and capacity loss are factored in.

And I will use each and every charging source available to get that battery as close as possible to 100% before the next discharge cycle begins. But I will not use a generator, and in fact I could plug in anytime I want and not even cycle my batteries, but I want my solar to have work to do, I want my batteries to be worked, and I do not want to rely on the grid at all.

But When I do, I want my grid powered charger to do the best job possible, and through this forum, I'd learned the best way to do this, in my rig, with my intentions, was with an adjustable voltage power supply, to prevent premature efloatulation. That hideous and lawyerly ending of absorption voltages well before the battery would like that is the bane of all automatic charging sources.

So Naio, I'd recommend researching your alternator, and perhaps posting which one it is. Mexwanderer is intimately familiar with alternator design and can make a guesstimate as to how well it can handle a severe duty cycle from feeding depleted AGMS regularly. Knowing how hard it is to replace, both in labor and in unit cost, and weigh that against a new set of AGM batteries. Solar is great, but if stealthiness of your rig is desirable, solar panels on the roof detract from that, but not nearly as much as an idling vehicle with an inverter and cordage hanging out of the hood, or a stinky generator noisily allowing your 30 amp charger to underfeed the AGM batteries, which could likely accept 3 times that amount for 2 hours when depleted.

Also keep in mind the low and slow charge pattern of Solar is Not ideal for AGM batteries. They would prefer a higher am charging source when heavily depleted. Heck, all my flooded batteries seemed to like this too.
AGMs also differ in their recommended charge rates, some saying no more than 30% of capacity, and some others saying no less than 40% when deeply cycled, so knowing what AGM's you have and the manufacturer recommendations is also very important.

Any and all charging sources, whenever possible. Maximizing their effectiveness will maximize your battery life. This can be taken to extremes, so weigh those extremes against replacing the batteries a bit sooner from a less ideal recharge regimen.

Everything is a compromise, and always will be, knowledge is power, and the decision is yours.

[SoundGuy]

As an addendum to this discussion, because you now say you're "leaning towards solar but might just start with another battery" perhaps I can offer a couple of other observations ..... :W

Investing in another battery isn't a bad idea in itself, one I wouldn't particularly disagree with, even considered it myself - after all, if one G27 will get you through 3 days of camping without a recharge then two G27s would logically get you through 6 days. However, there is a catch ... it's generally accepted that one would want to not draw any 12 volt deep cycle battery down to any less than ~ 50% SOC or ~ 12 volts on a regular basis. Occasionally drawing it down a bit further is OK but make it a regular habit and you'll be replacing that battery sooner rather than later. That then brings up the question of timing your recharge, because the second generally accepted rule is that once drawn down you'd want to recharge that battery as soon as is practical, not just leave it sit for days or even weeks before you got access to shore power and could then properly recharge the battery. Solar is fine for what it is but if your system becomes ineffective because of unfavourable weather for days at a time your depleted battery is going to suffer for it. That's where a genset beats solar hands down as you're free to recharge as often as your battery needs it, and while you'd probably prefer to not run the genset so long that it can restore your battery to a full 100% getting it to a 90% SOC is easily achievable in 3 hrs or less of genset runtime. And that's where I see solar as best fitting in - allow it to do that last 10%, when it can ... if the weather doesn't cooperate, no loss, because at 90% SOC you're still good for another couple days of camping ... if the weather does cooperate and you do achieve 100% SOC then simply consider it a bonus.

[SoundGuy]

Naio wrote:
@SoundGuy:

But your aggressive, hostile, tone makes it harder for me to take the information you offer seriously. I am here for help, not a fight. When you are hostile, I feel like I want to just turn away.

Edit: Do you think I am a man?

My apologies, no intention to be hostile ... and I would have no idea whether you're male or female nor would I care. Regardless, it doesn't change the opinion of some of us that you're trying to use a tool (your vehicle's electrical system) for a job for which it was not designed to handle (charging your trailer batteries), which for some of us makes even less sense when there are tools such as a genset that are designed for the task at hand. Of course, what you ultimately choose to do is entirely up to you, I wish you well with it, but IMO you're reaching for the wrong solution.

[Almot]

Naio wrote:
I do generally park in the sun. I don't go to places where AC is required (don/t like humidity), and I don't hang out in the rig during the day, so I don't care if it gets hot in there except for the effect it has on my fridge/freezer. I don't think it gets above 90 in winter sun, with the windows cracked. Maybe not above 80.

I'm leaning towards solar, but might just start with another battery, first. I am cheap... and I don't really want another system to maintain, solar OR generator.

To me this all points to solar.
There isn't much to "maintain" with solar - nothing, in fact. After initial few weeks of curiosity and playing with voltage setpoints, you'll leave it alone.
Permanent installation does involve a great deal of planning and cable routing.
In a camper van or motorhome you can have charging from engine while on the road, with proper wiring from alternator to coach batteries.

[NinerBikes]

Naio wrote:
@SoundGuy: You are almost certainly more knowledgeable than I. And I don't know enough yet to always choose wisely between your advice and that of those who say the opposite.

But your aggressive, hostile, tone makes it harder for me to take the information you offer seriously. I am here for help, not a fight. When you are hostile, I feel like I want to just turn away.

Edit: Do you think I am a man? I notice that the aggressive attitude seems to come more often from guys who do, here. There is some subtle difference in gender roles at work that I do not understand -- the same post, when read by people who know I am female, often gets a very different response.

Would you use your purse to haul and carry boulders? Same thing with a car alternator used to do heavy recharging of a deep cycle battery. The alternator is designed to charge up your engines battery quickly after starting up the car, a very small, short usage of energy.

Recharging heavy duty deep cycle battery, stuff is best left to a generator set and a charge controller, designed for that purpose. It's going to cost money to have the right tools for the job at hand, no two ways about it. If money is tight, come back and ask when you have some money to address the project.

When my gal talks and has a problem... all she wants from me is someone that will listen, acknowledge her problem, and give sympathy.

The last thing she wants is for me to solve her problem with a workable solution, something that pisses her off to no end, because that's normally what young men do. Most of the men here are older, and wiser and have learned this, how to cope with women. We listen to women, but we don't attempt to solve their problems, best to just let them figure it out on their own. Otherwise we get grief from the whole incident, and end up in the dog house.

[Naio]

@SoundGuy: You are almost certainly more knowledgeable than I. And I don't know enough yet to always choose wisely between your advice and that of those who say the opposite.

But your aggressive, hostile, tone makes it harder for me to take the information you offer seriously. I am here for help, not a fight. When you are hostile, I feel like I want to just turn away.

Edit: Do you think I am a man? I notice that the aggressive attitude seems to come more often from guys who do, here. There is some subtle difference in gender roles at work that I do not understand -- the same post, when read by people who know I am female, often gets a very different response.

[SoundGuy]

Naio wrote:
@SoundGuy:

I don't know much about car and truck engines. What risks am I running by charging this way? I am talking about 7 days in 6 months, about 4 hours per day, sometimes less. Lengthy discussion in another thread left me with the impression that, as long as the engine does not get over-hot and I do not run down the chassis battery, it is ok. Is that wrong?

Sorry, I wouldn't claim to be an expert on the subject and I'm certainly no more qualified than some others who have already commented in detail in that other discussion you referred to as to why they thought that using your one and only way home for recharging your trailer batteries isn't a good idea. I would however add that to me it's just common sense that how much or how little you expect to subject your vehicle's electrical system to a load for it was never designed to deal with in the first place isn't sufficient justification for doing it anyway. That to me is no different than someone else rationalizing towing way over their vehicle limits because they're "only going 50 miles" ... the truck doesn't know how far it's going and whether it's going 5 miles, 50 miles, or 500 miles it's still subjected to a task for which it was never intended and would therefore also be subject to premature failure. Why this should be such a surprise to some is a mystery. :@

I'm leaning towards solar, but might just start with another battery, first. I am cheap... and I don't really want another system to maintain, solar OR generator.

My question in response would be - what makes you any different than the rest of us? I too would prefer the simples, least costly method of recharging my batteries but having examined all the possible options I still come up with the same conclusion - a mid-size, relatively "quiet", inverter genset that consumes a minimal amount of fuel, works anywhere at anytime regardless of the weather conditions, and will no doubt out live me. Judging from that aforementioned discussion initiated by lawrosa and many others like it that I've read over the years you're obviously not alone in thinking you can somehow bend the rules, using your vehicle's electrical system for a task for which it was never designed. I look at it this way - if doing so was such a proven and reliable method then why are all those who really are experts in the field of lead acid battery technology not recommending it, why are there also then not legions of other RV owners already doing it, and why haven't manufacturers like Honda, Yamaha, Champion, et al totally given up trying to supply the RV market with gensets that will easily do the job you're asking? :@ Perhaps you and others like lawrosa have stumbled on to a secret the rest of the world doesn't know about ... but I doubt it. 😉

[JiminDenver]

Our first trip in this trailer to the boonies we had to use the truck to get us through a week with sub freezing temps at night. After 2 nights I hooked up the truck and ran it a hour before bed.

The next year we bought a champion 3500/4000 and used it a few hours a day for charging primarily and five gallons of gas easily lasted us for two weeks under such low loads. Fire up the roof top air at 10.00 ft and it will guzzle a gallon a hour.

We don't take the generator for local trips but would for extended travel. Solar is nice but no guaranty.

[Naio]

@SoundGuy:

I don't know much about car and truck engines. What risks am I running by charging this way? I am talking about 7 days in 6 months, about 4 hours per day, sometimes less. Lengthy discussion in another thread left me with the impression that, as long as the engine does not get over-hot and I do not run down the chassis battery, it is ok. Is that wrong?

I do generally park in the sun. I don't go to places where AC is required (don/t like humidity), and I don't hang out in the rig during the day, so I don't care if it gets hot in there except for the effect it has on my fridge/freezer. I don't think it gets above 90 in winter sun, with the windows cracked. Maybe not above 80.

I'm leaning towards solar, but might just start with another battery, first. I am cheap... and I don't really want another system to maintain, solar OR generator.

[pnichols]

SoundGuy wrote:
I've been on / off with the genset / solar issue for several years now and came to the exact opposite conclusion - genset first, solar second. I did get my first EU2000i to run a 13.5 BTU A/C reliably until the temps got into the 90s (ironically when I'd want A/C the most), then concluded I wouldn't bother with it anyway as running A/C all day means running the genset all day which in turn means dragging along copious amount of fuel ... which ain't happenin'. OTOH I am very much interested in the freedom having a genset on hand provides in terms of being able to dry camp at any time, for as long as I want, a particular advantage here in Ontario where getting an electric site during the busy summer months of July / Aug is pretty well impossible without reserving months in advance. By dry camping I can get a last minute site, without reservations, with little difficulty at all ... but I need a way to recharge the battery. Yes, I did consider solar but there's no way I'm going to babysit a portable system to follow the sun and to avert theft issues ... a system permanently mounted on the rig wouldn't work either because we so often camp in deep shade, especially if we're dry camping and have to rely on fans for cooling. For sure, genset noise can be an issue, even with a so-called "quiet" inverter genset, but I think I've managed to dull that down to the point where I'm confident most people walking by our site would hardly notice. Pics and a couple of vids are here for anyone who may be interested.

X10! Excellent post.

I totally agree on generator first, solar second .... that is if you want your RV equipped to be ready for anything anytime anywhere so that you don't have to rely only on planning or lucking out. We're spontaneous campers and as such never know what situations we might find ourselves camping in. However, we've never added solar - which I consider a deficiency in our equipment list. We carry two generators - a large one for the A/C and emergency heating, and a small ultra quiet one for battery charging. The V10's 130 amp alternator is also a third electrical power source. If I finally add solar maybe this year, it most likely will be portable so as to continue to keep us flexible in choosing a camping site - however I won't babysit the panels - just put them out when I'm at the campsite. They'll just be another choice on the flexibility list.

P.S. #1 We have another generator, with fuel, at home for power outages anytime.

P.S. #2 BTW SoundGuy ... a great Honda generator installation as shown in your link. Now you're ready for anything.

[time2roll]

I tend to seek out sunny spots or just partial shade now that I have solar.
Deep shade I would be in conservation mode and need to move toward the sun about the fifth day(or hookups).
Worst case use jumper cables to charge from the truck similar to the OP.
Generator stays at home for some disaster style emergency.