800W Solar Powered Sprinter Conversion. (pics)

ickkii · Feb 21, 2013

Hello, I'm Keith - this is my first post here. I'm 22 years old and from Tampa, Florida. I've been playing with the idea since I was 15. My girlfriend and I have recently decided to take the plunge since we'd prefer to live our lives frugally instead of jumping headfirst into the rat race. My plan is to put an 800w solar array on top of a 144 WB Sprinter. While I'm 72 inches tall, I'm going with the smallest roof option (65") since it doesn't taper off - granting me the space I need. This array will power a 10kwh battery bank. While this may seem like awful lot of energy - I'm a software developer and need to power some devices. I'd also like to power a low watt fridge, and since I'm starting out of florida, AC is a must for me to do this comfortably. I'll also be powering a 45 watt dometic thermoelectric refrigerator, since I need cold red bulls to get me through my work cycle haha. I should mention the 3d model in this image was not created by myself, all credit to project sprinter - I just reused it because it accurately represents what I had in mind. So here's what I have planned! <img rel="lightbox" src="" class="bbc_img">

wagoneer · Feb 21, 2013

Hello, also my first posting. you did an amazing layout. Living in Ca. on the coast. My first choice was a sprinter as well to be exact the model you are using, this being out of my budget I chose a 2001 E350XL. One thing I have learned in my 45 years of vans and plans looking good on paper is really great and having the funds inline helps a lot. I would recommend a backup plan because all will not go your way. All the pieces seem to fit and excluding at any possible time the use of 110 volt or any luxury will assist in your power consumption. Dometic fridge run on LP is very efficient I picked up a small very portable new for $300 added to the fact that being very careful to not buy things you need to cool.The only brain will be a MacMini. Just be aware not to over-amp your package. I wish you the best you are on the right track and remember to have some fun while your at it... Wagoneer in SF will be posting some stuff in the near

ickkii · Feb 21, 2013

Well thanks, and welcome to you as well haha. I have a job and roughly $1000 saved so far. I estimate the project to be in the 15-20k range. I'm not making a purchase until I have at least 2/3 of that saved, then I'll trade my 2005 civic to a dealship as part of a down-payment on a $10-12k sprinter. The dometic fridge is mainly just for cold beverages and a ham & cheese sandwich to take to work, maybe a chef salad here and there. I realize eating out a lot can not only be expensive, but a lot of work if I just want something to snack on. As far as overamping goes, I feel that this is where I'll be investing most of my time on the project.  I have a mildly complex system and mainly need to make sure my regulators, converters, diodes, resisters, fuses, etc are positioned perfectly. I'm going to go without the alternator initially, I don't want to connect 160 amps to my system until I'm absolutely sure everything can handle it. Plus it gives me a chance to test out the solar powered system independently so I can get a feel for what solar power is capable of.

wrcsixeight · Feb 21, 2013

If you can get 800 watts on the roof, then you might not need to hook the alternator to the house batteries. But, too many people consider 800 watts on the roof as providing 800 watts all day long, where even in ideal conditions 720 watts around noon is more likely and significantly less before and after solar noon. A cloudy day and 1/10 the output is more likely.  Partial shading is not partial current, but a small fraction of the  shade free current An alternator rated for 160 amps, can only produce that, briefly, in lab conditions, when cool, at high rpm, with devices loads or batteries capable of asking for that much current and thick cabling that can pass it.  The stock wiring is not sufficient for this, and the alternator rating means little. The batteries themselves are big electrical filters. Utilize every charging source available, and keep in mind it is easier and cheaper to conserve electricity than it is to create and store it. Get yourself a Kill a watt meter and hook it to your devices to see how much battery capacity you will need to not go below 50% overnight. Most people vastly overestimate the storage capability of a battery and underestimate the electrical loads devices ask for.

ickkii · Feb 21, 2013

Well people typically say multiply your solar panel array's watts by 5 (hours of strong sunlight) and you get a rough estimate of your daily output from your array. I'm thinking I can get 4kwh per day of sunlight here in sunny Florida. My battery bank is 12v 900Ah, so about 10kwh. So if I don't exceed 4kwh my batteries shouldn't dip below 60% per day. There will be days I don't get that amount, so charging my batteries from a wall outlet through my inverter will pick up the slack - plus the alternator once it's properly installed. Now if I put five or six 2.5v 2600f ultracapacitors in series between my battery bank and the inverter, not only will my capacity increase a little- it will smoothen out heavy power draws on my batteries. So instead of dropping from 12.9v to 12.7v when a compressor from the refrigerator or ac kicks on, the ultracapacitors will eat the heavy load while the batteries tricke them back to full power. So this will increase my battery life some, in terms of capacity and health if I'm correct. The ultracapacitors are still pretty theoretical for me, they're affordable for a hybrid battery bank - but I need to research more into how I can implement them correctly into my system so I don't hurt anything or start fires. Over time they'll become so affordable that they'll be battery replacements, in 2013 this is an early adaptation. Their charge/discharge rate is much more fast, their capacity is still relatively low. They can also be cycled millions of times - compared to ~1500-2000 battery bank cycles. So getting back to what you said about the 160A max output of a 12v alternator, are you saying it won't be an issue to have that kind of power going though my banks/capacitors if I size the wire gauge appropriately? Basically because the batteries are only going to ask for so much of that while the rest of it just travels on unused? Another issue I'm facing is sizing fuses for the battery bank because I have 3 different power sources. Solar: 12v 45a AC outlet to DC inverter/Charger: 12v ???a Alternator: 12v 160a I'm probably going to have to implement some kind of switch system for doing this - with the appropriate fuse/regulator between each switch and power source. The issue this presented was only one power source can charge the battery bank at once. I've considered setting a ultracapacitor bank to run my dc load off ultracaps as the panels trickle charge them, while my battery bank charges from the inverter/alternator. There are still some problems due to the short capacity of the ultracapacitors, but if they're getting fed by the panels while they're putting out power - I don't think it will be an issue to run a few lights with a fan going. my apologies if this was a lot to read.

ccbreder · Feb 21, 2013

I hope you keep us posted on how the capacitors work with a surge load. Some are doing this with electric vehicles. I would have a means to quick charge the battery bank with shore power or a quiet generator as a Honda or something. Wiring any bank, solar, storage, or capacitor, try to lay things so all the units (ie: battery) connect with the same length (run) of cable so each unit faces the same resistance from charger or from draw. I like your use of zero position transfer switches.

ccbreder · Feb 21, 2013

"So getting back to what you said about the 160A max output of a 12v alternator, are you saying it won't be an issue to have that kind of power going though my banks/capacitors if I size the wire gauge appropriately? Basically because the batteries are only going to ask for so much of that while the rest of it just travels on unused?" The alternator has a regulator that will amp up the alternator to the load. The rest just is not there.

ickkii · Feb 21, 2013

Oh man you just made my day by telling me the alternator works like that. It's probably bad that I don't know so much about car electrical systems going into this, but everyone has to learn one way or another. The lengths I would have had to go to in order to account for 160 amps would have been nuts lol. For the capacitors I'm doing my fair share of research and asking around. I'll definitely keep this thread updated with my results. Since you mentioned electrical vehicles, an idea I had for the capacitors was to eventually use electrical car charging stations to charge the power banks. I've got a lot to focus on before I get around to that step, but if I can figure it out - just imagine the possibilities! here's some more documentation about hybrid battery-capacitor banks http://www.eetimes.com/design/power...ormance-for-many-solar-dependent-applications http://www.altestore.com/forums/Ren...To-Extend-Battery/index.php/topic,2402.0.html

ccbreder · Feb 21, 2013

thanks man. Please be careful with large capacitors, at least use eye goggles.

rokguy · Feb 21, 2013

Hi and welcome,  I personally would set my wiring up first with the heaviest cabling you can afford, with good battery storage capacity then start adding to the solar system as you find out what works and what doesn't. What is written in brochures doesn't always work in real life situation. On the alternator subject most class 8 trucks use 140+ amp 12v alternators but do not necessarily crank out that figure, you have to fool the alternator into thinking your aux. house batteries need that charge beyond the start batteries float charge. If your driving long distance or around all day (like trucks do) I can see the benefit of alternator solenoid charging but just starting up the engine to charge aux. batteries doesn't work. It does more harm to your engine idling in fact. (oiling up the valves, cylinder walls etc) Geoff

wrcsixeight · Feb 22, 2013

A large thirsty bank of batteries wired to the alternator can ask for everything the alternator can make at a given rpm, until the  vehicle's voltage regulator senses voltages 14.XX volts for some seemingly unpredictable amount of time before reverting to a lower voltage. My alternator is rated for 130 amps.  I have a Boat Battery Switch with a direct 11 foot 2awg feed from alternator to the the battery switch in addition to the stock Dodge wiring to the engine battery only.. I also have a slightly smaller pulley on my alternator so it turns faster.   I have a digital ammeter/ amp hour counter, 2 group 27 house batteries  115 a/h each when new.   Here's what I notice with my system: One old group 27 marine battery starts the engine, after about 10 seconds the engine battery voltage has already hit 14.5volts and the amps have already tapered to 10 (from about 28 amps right after engine start) or so and the rpm settles to 800. When My House batteries are thirsty with about 50 to 75 amp hours removed, and before the solar has been able to contribute anything back into the batteries, I turn my battery switch to Both.   The engine note/tone instantly changes as the alternator goes from putting ~8 amps into my engine battery, to making: ~56 amps into all three batteries at 800 RPM. Voltage rising from ~13.2 78 amps at 1200rpm  94 amps at 1600 rpm voltage at  14.1 105 amps at 1950rpm.  The alternator drive belt might start squealing from 88 to 105 amps, depending on the humidity. Then I let it go back to idle. 44 amps @ 800 rpm, 13.4 volts More RPMS follow the same pattern as above, just slightly lower output. Once 14.5v is reached, additional rpm produce no more amps The amps required to hold 14.5 steadily decreases with time. Once my van is at full temperature it idles at 550 rpm. Hot idle with still thirsty batteries, 13.6 volts, 32 amps 1200 rpm  56 amps and 14.3 volts 1800 rpm 62 amps at 14.5 At some point, my voltage regulator, located in my engine computer, decides that 13.7 volts is all the batteries deserve.  They can still be very hungry, 50+ amp hours from full, but the now the alternator is now making only 18 amps to hold the desiganted 13.7 volts. Removing my 98% charged engine starting battery from the alternator charging seems to prolong the amount of time the voltage regulator allows the alternator to make the amps needed to hold 14.5 volts, and the house batteries charge faster.   I do Not know much about capacitors.  I don't know how thirsty they are like a drained battery is, or if just accept a small amount of current at some predetermined rate. I do think they will be playing a big part in the future. Thanks for those links. Right back at you: http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/26699321/srt/pa/pging/1/page/1.cfm I have no idea how the capacitors would change what the alternator is asked to make, or how it will effect your vehicle's voltage regulator. I also have 200 watts of solar on the roof.  This contributes to the alternator current into the batteries until 14.5 is reached.  Sometimes it will still contribute something at 14.5 volts, usually the charge controller goes open circuit, and the alternator alone keeps the voltage at 14.5.  The solar might have something to do when the vans voltage regulator decides 14.5 was held long enough and reverts to 13.7 at any rpm and usually well before the the batteries would like, according to my amp hour counter anyway .  When the voltage regulator decides to allow 14.5 for a good while, and enough rpms are held to make 50+ amps, and the drive is long enough,  some good recharging goes on when the batteries are thirsty, if the cabling is adequate. But hot idle speed amps are poor with my system, and many systems, and whenever the voltage regulator decides to prematurely revert to 13.7, then much much less recharging takes place, and at some point I am better off removing the house batteries from the alternator, and let the solar bring them back up to 14.5. I do too much short trip driving and try not to start the engine with the house batteries providing any amps to the starter, for fear of frying my fridge's compressor controller.  The manual switch is less convenient in this matter, but I prefer to have a choice where the current comes and goes, and if my batteries are thirsty, I let the alternator feed them with as much as it can.  I think they like receiving 40 amps each briefly when they are hungry.  They hold voltage better that night when I feed them that much initially in the morning, compared to just the solar bringing them up slowly.  And generally the last 15% takes a long time to stuff back into batteries no matter the charging source.  A 300 amp alternator couldn't do it any faster after 14.xx is reached.  And the .XX is determined by your vehicle's voltage regulator.  Seems the lawyers have more say than the bean counters and engineers, as an undercharged battery, is a safer battery, from their point of view.

rokguy · Feb 22, 2013

Yeh agree, Once an alternator say no more thats it. Ultimately I would rather have more plug in solar or even wind power than rebuild a diesel engine due to charge idling. Ask any yachty. Geoff

ickkii · Feb 22, 2013

ccbreder Agreed, eye goggles are a must for this project. -Angle Grinder Sparks for cutting holes / resizing metal components -Battery Acid Splashes -Connecting numerous powerful electrical devices. I'll probably want some gloves too, I'm thinking some latex could work fine with 12v too. rokguy using 6g copper cable for the bulk of the project, the engine stuff I'll probably pick up some 2g cable for. Would you recommend a battery isolator / regulator? What about this? http://www.sterling-power.com/products-altbatt.htm It's kind of expensive compared to a more low-tech approach, but it looks like it would remove most of the guesswork that could kill my power system. wrcsixeight You seem like the right guy to ask about the effects of a battery bank on your starter battery - is there anything to concern myself with in regards to that battery being cycled while the alternator feeds a battery bank? It was a suspicion of mine, but it sounds like instead of going off the starter battery, the engine/alternator will look at all 9 batteries the same? I know about the last 10%, what makes me curious about your setup is that you seem to have a fair amount of current going for just 2-3 batteries. I read a few different places that amps should be 10% of the bank's total AH. In my case - 12v @ 900ah, I wouldn't exceed 90 amps total, solar power being 45 amps max. So basically thats about 9 hours of charging off solar from 0-90% I think, I could be wrong here. I've read some things that make me believe my bank could be charged in an hour, others that it could be 16 hours. I really need to take a day to sit down and go over some of the electric fundamentals again because I get these odd figures floating around in my head sometimes. I'd imagine the batteries would just use what it needs in any case. I have some additional control panel equipment like a portable oscilloscope and battery meters on the shopping list, didn't put them in the image because they're going to be a lower priority purchase. Still getting them, just going to use a voltage meter initially.

ickkii · Feb 22, 2013

also a question I forgot to ask anyone with solar panels on their rig - how do you handle bumpy roads? Someone recommended I use flexible solar panels, but their output seems to be half as much for their price compared to hardened panels. I was considering using strips of sheet metal to mount the panels to the tracks so theres a small amount of flex. Does this sound like a good idea, or should I go either 100% solid mounts or flex. I also redesigned the ventilation system for the battery bank just now, those 2 side pipes didn't seem to use space very efficiently, could intake condensation, and trap fumes. It could also be damaged. this is the new idea. <img rel="lightbox" src="" class="bbc_img"> The elbows will be placed underneath the van, mainly to prevent water from splashing up when driving over puddles. It's harder for condensation to travel up than it is horizontally. At 12v, .25A x 4, only a single amp will be consumed for much better airflow.

bee · Feb 22, 2013

Interesting build you have going on.  I am going to have to look into this capacitor thing, its the first I have heard about it. AGM batteries and dual alternators for ridiculously fast bulk charging would be my first thought.  Thats the best way I can think to replace the power draw from an air conditioning unit.  I am talking more amps then that sterling can put out.  200 amps easy and safely into your bank if they are lets say at 50% charge. You shouldn't have to worry about starter battery/ bank battery issues if you use a smart relay like the surepower 1314.  It will not hook up your bank batteries until the alternator has reached charge voltage.  It will auto disconnect with low voltage. You shouldn't have to worry about conflicting charge sources. At least that is what everyone seems to say. The risk would be that your solar charger would see high voltage from the alternator and switch into float mode since it would think the batteries are fully charged, then when you turn off the truck the solar charger will stay in float instead of switching back to bulk.  Its easy to test for once you are all set up so I wouldn't worry about trying to isolate the different setups right off the bat. You may have done this already, but I know that smaller solar panels tend to cost more then larger.  Its usually more cost effective to have fewer larger panels. Also consider finding a way to move the batteries as far forward as possible, they are heavy. I would highly suggest standing height rooftop.  I believe you said it is to narrow for the solar panels?  What about the nissan van?  Ford should have one out now or real soon as well.  Or  back to different panels. Here is a link to solar panel dimensions.  It will give you an idea on the common sizes they come in <a style="color: #000099; text-decoration: initial; font-family: Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif; background-color: #fafafa;" href="https://homepower.com/sites/default/files/uploads/webextras/HomePower_PVGuide_2013.xls" rel="nofollow" target="_blank">https://homepower.com/sites/default/files/uploads/webextras/HomePower_PVGuide_2013.xls</a> You can sort the excel sheet by columns.

ickkii · Feb 22, 2013

hello bee. Thank you for recommending that relay, searching for it in a new tab immediately! I'm avoiding AGM batteries due to lead-acid golf cart batteries having thick lead plates made specifically to be repeatedly charged and discharged. The charge speed may not be as great, but longevity is a higher priority for me. Ideally a LFP battery would be used, it's just not in the budget in 2013, maybe after 2020 comes and it's time to search for replacements the cost will have lowered enough to reconsider. But who knows really, 2020 could come and ultracaps will be efficient enough to spend 5 good years of savings on. Right now it just takes hundreds of them to store the same amount of energy, you'd need a trailer to carry them and about $200,000. For hybrid applications they're more feasible from what I've researched. I'll keep what you mentioned about conflicting charge sources in mind. It could be a burden to switch back and forth every time I start the vehicle, but until I know for sure I feel like it's the best way to insure nothing goes wrong with a relatively expensive power system I can't afford to replace. I have indeed looked at larger panels. The reason I've gone with multiple smaller panels is because I've did the math and it ends up being the most watts for the space taken. Some larger panels just won't utilize every bit of space available. It's going to be more expensive - but with the 32 cell 100w panels I am getting the most power I can possibly get for a slightly higher price. I started off with 250w, moved to 195w, then to 150w, and it was decided at 100w. I could build my own panels from solar cells to fit the dimensions, but I feel some comfort in getting something built by a trusted manufacturer. DIY cells can be very delicate, and carefully fitting 60 square feet of them is a chore I just don't have the patience for. 10 years down the line if I want to replace the system with higher efficiency panels, it'd be easier to do, and I'll get some resale value back (or I could use them with a homebase). I have had an ongoing battery bank dilemma like involving what you've mentioned, and I always end up going back to ventilating them and keeping them under the bed. I realize it'https://vanlivingforum.com/post/printadd?edit=1&pid=1277000604s not the most ideal thing to sleep on top of - but with a quarter inch thick steel plate around the enclosure, I think I could sleep feeling safe from anything short of a bullet. My reasoning is this, The 500lb battery bank must be centered so the van isn't thrown off balance to the left or right. So That gives me a 12 foot line to work with. I can't put it in the middle because it would obstruct movement, so that leaves me with the front or the back. the side doors are going to be the main exit from the vehicle interior, because opening the back door would reveal the bed. So since the side doors open behind the cab, if the batteries are to the front it would obstruct movement from the cab and side doors. So the only feasible place left to put them would be under the bed. There are some small risks with it being there, but for the most part those risks can be eliminated by making safety precautions. Concerning the high roof, I'm reeeaaalllyyyyyy close to the mark with my 1581mm wide solar array. I still need to measure the van models in the car lot to get a better idea of what the usable dimensions are on both the standard and high roofs, but looking at images gives me strong reason to believe they'll fit just right on the standard roof. With the high roof - I'm not so sure. I don't want to lose power over a 7 inch difference if it comes down to it. My girlfriend is 5'5" and she can still stand comfortably, I'm 6' so I may need to crouch some (my posture has me slouching most of the time anyway lol). Since I am going to be doing a fair amount of sitting to program, I don't think it's going to be very intrusive. The goal for me isn't really to stay in the van all day. I work and would like to be outdoors or at a coffee shop charging my devices. The van is not so much to live in, but mainly to chill / sleep in. The less I'm in it, the less power I'll end up using. I'll go ahead and check out the links you posted, maybe I'll find something better for the high roof.

blars · Feb 22, 2013

Unless you have lots of short pulse loads (or charges) I think the ultracapacitors would be a waste of money.  For an electric bus that stops every block and has reginerative braking, they make sense, for an air-conditioner with a soft-start capacitor, they don't. The money/effort would be much better spent on LiFePO4 batteries.  They can be had for not a lot more than the same usable capacity of AGM batteries, and they are smaller, lighter, and do not need to be vented.

wrcsixeight · Feb 22, 2013

I am not sure why you plan on cycling the engine battery, but if you plan on doing so, get a marine battery as they are a dual purpose.  Not quite deep cycle, not quite starting, but a compromise, and closer to starting. My Van says I only need a 550 CCA battery.  I have a group 27 marine battery in there with 650 CCA.  A regular Starting battery of that size would  have about 750+ CCA.  True deep cycle batteries rarely give CCA figures.  Trojan does, their 27 is 620 CCA.  As long as the deep cycle battery can exceed the minimum CCA, there is no danger in using it as a starting battery.   I try to not allow my house batteries to assist in engine starting, but when they do, I probably have about 1500 CCA remaining, and the slightest blip of the starter, the engine catches. I never discharge this engine battery.  All interior lighting,  stereo and ciggy receptacles have been moved to the house bank.  Its only overnight loads is the memory of the engine computer.  While it spent the first 23 months of its life being cycled shallowly, it has not been cycled since then, and will be 6 years old in July.  Pretty surprising as the 2 other matched batteries I bought at the same time failed at 12 and 23 months. My current batteries(Crown) when thirsty, do accept a LOT of current from the alternator, but for relatively short periods of time.  They really seem to behave better when fed these huge currents initially then have the solar top them off the rest of the day. And better than when my 25 amp Schumacher charger brings them to full.  I think the physical agitation of driving while being charged better destratifies the electrolyte and dissolved the sulfates back into the electrolyte. Just yesterday, My alternator made a big contribution morning and late afternoon but my battery monitor still read 15 a/h from full when I parked overnight.  At 11:30 at night at 38 amp hours from full they were still reading 12.5.  Without the driving I would see 12.4 or less, and that is even when they started out at 0 amp hours from full. I know the low and slow method of battery charging is touted as best for the batteries.  My observations do not agree.  I think longevity might increase with low and slow, but my observation is performance decreases, and I have no qualms about exceeding Crowns recommendation of 25 amps for bulk charging.  Let the batteries dictate how much they want from what is available is my opinion. I am lucky that my  vehicle's voltage regulator allows 14.5 volts,  Which is what My batteries specify as  bulk/acceptance voltages for 75 degrees F.  Unfortunately it does not allow them to stay there long enough.  No doubt some vehicles will behave better than others in this regard. With a bank of batteries tacked on to the engine battery with a solenoid/relay, or isolator, the fully charged engine battery(or nearly so) can reduce the amps to the house batteries, especially if the wiring is not very thick.  The thicker the wiring to the house bank, the more it will appear to the voltage regulator as if the engine battery is depleted and will allow the alternator to make maximum amps to bring the battery to 14.xx volts.  With my system I can remove the engine battery so that the alternator is feeding only the depleted house batteries, and this works noticeably better as 14.5 is allowed for longer and the amps required to reach it are higher, and not being shared with the engine battery. The DC to DC converters for a second bank of batteries are nice because they allow you to set the bulk and acceptance and float voltages.  But as you noted, are pricey. Some people power an inverter with the engine battery and use a large battery charger to the second bank of batteries.  This can be a case of robbing peter to pay paul though, the engine battery might get depleted, as the alternator might not be able to keep up except at highway rpms, and maybe not even then.  This is popular for travel trailers whose wiring to the alternator is very long and very thin. AC wiring doesn't suffer the same voltage drop as DC circuits.  Some chargers hate MSW inverters, and there is certain inefficiency in taking DC to AC, then AC back to DC again. One thing to keep in mind, it is nice and easy to prepare for huge loads and capacities to meet those loads, a whole different thing to pay for it.  My battery tray , below my floor, can only fit 2 group 27 batteries for 230 amp hours.  I am guessing I have about 50% of that capacity left, and it is more than enough to meed my overnight demands with a good buffer.  When these batteries need replacement, I might go with less capacity. I'd really have to be wasteful and have many cloudy days without driving before I'd be in danger of my compressor fridge not running overnight. Also note that solar panel performance degrades when panel temperature increases.  Florida summertime, expect only 80% of panels rating around noon, unshaded.  On a 60 degree day I might get 12.5 amps into my batteries at noon, in 85 degree day about 9.5.  MPPT charge controllers can take better advantage of lower temperatures, and lower battery voltages.  Higher voltage panels allow thinner cabling to the charge controller.  Usually 100 watt panels are nominally 12 volt rated. Consider getting a 1000 watt Honda generator and have less solar and battery bank. 800 lbs of batteries will really eat up your MPG.  Also it requires about 1 engine HP for an alternator to make 25 amps.  Asking the alternator to recharge a large bank of depleted batteries will noticeably reduce MPG, and alternator life.  The quiet Honda can power a charger and use less gas than your alternator would add to your engine's consumption. So many options....

ickkii · Feb 22, 2013

blars its barely $100 more to set up a hybrid capacitor bank - remember these can be bought used for cheap since they can handle millions of cycles. The ultracapacitors can receive charge in conditions that the batteries can not, like when under 12v of power is being produced. It extends the expected lifetime of the battery by load leveling. It's a good for the batteries to have balanced discharge rates regardless of the amount of surge. Even if the compressor is only dropping a tenth of a volt, on the batteries - the caps will still soften that out for the batteries. It's used on buses and trains because those applications have heavier power draw on the batteries,  just like mine do - although less rigorous. The braking uses capacitors for a slightly different reason - it needs a short & constant draw that the batteries can't deliver, making for more reliable brakes. While the goal is to be mindful of battery consumption, if I'm plugged in somewhere I want to be able to run heavier loads. Lithium-Iron Phosphorus batteries are substantially more expensive, in the range of double the cost of lead-acid for the same capacity. I intend to upgrade to these after the lead acid batteries have served their purpose and granted me the privilege of saving up more money. If you know of cheap LFP batteries please share! wrcsixeight I'm sorry to tell you I don't plan on discharging the engine battery after that long response. I was mainly curious if the alternator DID do that. I am thinking about getting a small generator as a 4th option for power, for rare circumstances that leave me thinking "man if I had a generator right about now", but no rush for the time being. The bank is 500 lbs, so not quite as bad as 800, but with the solar panels and ac it's about that. I'm not planning on doing much traveling for now.

rokguy · Feb 22, 2013

ickkii, On my motorhome.........I use a battery isolator on a single battery hooked up to the two 12v N70 truck start batteries but I do not trust it enough to rely on it and still manually disconnect it when I stop for the night. This battery is a 200amh 11 plate Century "truck and farm" super duty lead acid. Its not used to crank the engine (only in an emergency) It is used for the express purpose to run my frig and a strip LED. It is wired in to two cheaper mono 100w panels aswell. (soon to be replaced with 2 Canon 64w armouphous panels, why cause they work more efficiently) The other bank of two 150amh 11 plate Century "truck and Farm" are wired upto two 64w shade tolerate Canon armouphous panels **which on the subject of heat power loss** still perform over their rated power ouput in 25 C + temps of Australia. I have been using this same Canon panels, Century batteries and Morningstar solar module boxes on one truck, one yacht (+ air 403) (yes lead acids on a yacht) two motorhomes and my cabin for now going on 18 years. The batteries I replaced in each app after 12 years with exactly the same. I look at the old lead acid as a old big diesel engine that chuggs along reliably pumping out power, as long as you maintain it. With 5 batteries onboard my truck motorhome I still get reasonable diesel mileage, good hwy speeds and it still only weights in at 3.5 tons. Like I said a battery isolator charger is good if you do long miles every day. I still would not recommend charging batteries with a stationery road going engine. Thats why they introduced gensets. Even alot of OTR truckers are using them. The truck and farm batteries I use will not suit everyone as they are 500mm long X 250mm X 250mm high each. They are NOT a true deep cycle battery but I use them because of their large seperate plates and charge cap. You won't have any trouble with solar panels on your roof if you bolt them down properly yachts go to sea with these things (and like wind generators) do complete roll overs and still come up performing their duty. The sea is the ultimate proving grounds. I think the Merc Sprinter is a great van as there is heaps of conversions touring Aust. ickkii, you gotta do what you think works for you. Please don't overthink your plans otherwise you'll end up doing to much planning and not enough doing. Geoff

800W Solar Powered Sprinter Conversion. (pics)

Help Support Van Living Forum:

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Similar threads

Join the conversation!

Join today and get all the highlights of this community direct to your inbox. It's FREE!