Solar off while charging with alt. ?

[Redbearded]

Here is a video showing a neat setup for directional sensing to merge both systems. I do like the way that Lee thinks from the few videos of his rig I've seen!

 

[XERTYX]

I'm aware of the differences in battery types. What I meant was I had planned to use the vehicle power to use like say a crock pot while driving via an inverter but I'm not mechanically inclined so i have no idea how much juice an engine requires itself versus the output and I liked the idea of being able to keep the vehicle battery maintained if I had overdone it with the inverter. But if it's as simple as I've read in this thread to charge the house battery from the alternator I'd rather not even take that chance and just plug the crock pot for example into the house battery and let the alternator maintain the house battery while driving. I do still like the idea of floating the vehicle battery from the house battery as well.

 

[maki2]

Guess what....alternators come in different sizes. Some of them such as the one in my Honda Element are quite small, just enough output to handle charging the starter battery and run the radio, the blower for the heater, the headlights and charge a cell phone. Likely it would charge a laptop too from a very small inverter but I would not do that if I had the headlights on. Running a crock pot for a lot of hours...no way, that would kill my small alternator and result in a very expensive repair bill. My alternator would not even handle charging a house battery that got drained down to 60% overnight. It might do it for a few times but it will before long destroy the alternator. If I want a house battery in my vehicle I would have to upgrade to a custom built, larger alternator and between the price of the alternator and installation I would be looking at close to a thousand dollars. It does not make economic sense to me.

Of course you also don't need an electric hot pot to have a hot meal at the end of the day. I just found a thrift store bargain, a non electric, thermal slow cooker that is made in Japan. Before you hit the road in the morning you start the ingredients on the stove top in the inner pot, bringing it to a boil then place that pot inside the stainless steel thermal pot and it slow cooks all day.

You can get yourself out of the mindset where you think all appliances need to be powered with electricity. Remember that there are alternatives out there, inventions from the past and also more recent inventions. Insulated thermal cooking is old technology that is being revived with newly made products and processes. Keywords to explore for those units "insulated thermal cooker" youtube and other places on the internet have lots of recipes and directions for using them.

 

[flying kurbmaster]

Hi I have a marine switch that is hooked up to the batteries and the alternator. So If I want the alternator to charge my batteries I simply put it to both, I have options batt 1 batt 2 or both. if I need a boost I can also do the same and boost my strart battery from my house battery. If my house battery died I could use my starter battery for house power, that has never happened but is an option. I have 140 watts of solar and never use this option, the sun seems to work but if I had to I could. I used to use the switch when I only had 40 watts of solar. I have a Bluesky controller and I can charge my start battery with it as well, it has a trickle charge that goes to the start battery, every so often, not sure how it works, it is automatic, I just had to hook it up. That has worked for me for about 8 years.

 

[XERTYX]

Yes I actually read a post (I'm assuming yours) about the thrift store find on the thermal cooker and looked into it. Thanks for that by the way. I had never heard of one nor had I heard of thermos cooking which interests me greatly. I know there are beefier alternators and more minimal ones. I actually dont have the vehicle yet so it was speculative at best on my part but I do have experience with solar and scaling down my usage. When I lived on a boat I had to make do with only what I could generate but I still did manage being able to run a laptop every few days off of my excess power especially as I maintained its charge on my commute to work via an inverter. I knew it was possible to charge from an alternator as well as solar but thus far my research had lead me to thousands of dollars of equipment to do so and I liked the idea of capturing as much otherwise wasted energy as possible using the vehicle power while running but had not found a way to do so until this thread. Honestly I dont use much electricity even now but I like the idea of being able to if I wanted so I'd like to over engineer my system to accommodate this. I'll have to live without my convection toaster oven I've come to love I know but I still like to slow roast meats (perhaps with the new fangled hotlogic mini I've read about instead.) 

Sorry if my post came across as crass or defensive. I have no disillusions that I can run tons of household appliances in a dwelling i just like the flexibility to run one every now and then should I choose to. When I lived on the boat I learned quickly about having no lights because I'd killed my batteries playing solitaire on the PC. I want to avoid that type of scenario moving forward but still have the ability to use a coffee pot every now and then. Or a microwave once a day. That sort of thing.

 

[maki2]

Dreaming is good, it feeds you until you can turn dreams into reality.

 

[HalfShadows]

I had to buy a Sterling Battery to Battery Charger for my Vehicle. Solar charging is no issue while shore power or vehicle charging at same time. My issue was charging with my vehicles alternator via battery. Burned up my alternator. Using a lithium battery bank will do this. Lithium recharge demand with amps is ludicrous. Soon as i would switch to charge battery to battery my vehicle would increase the RPM dramatically and the alternator would whine. Now the charge is limited to 30 amps.While charging with my generator/shore power my generator would just scream as well.

 

[XERTYX]

Not an endorsement but I found this on the etrailer website. It helps me to see a picture of something as I'm a visual learner and I thought it might be useful to others. This is a diagram for a Redarc Smart Battery Isolator with dual sensing for around $130. Unless I find a better option I think this is the route I'll be taking. I looked at other battery isolators that were much cheaper (around $30-40) but required you to disconnect the positive lead from the alternator and install it in its place. I dont like that scenario. Also those only charge one battery at a time so while your house battery is charging your starting battery isnt and that seems like a recipe for disaster to me so I think I've found my solution. Using a dual sensing isolator like the one in the diagram.

 

[highdesertranger]

I am not being a smart ass but I think y'all are looking for a solution to a problem that doesn't exist. why again is this extra piece of equipment needed? highdesertranger

 

[XERTYX]

To be honest, for me. It's about being able to scale down my solar to 200 watts from 400 which was my target to start off with. I guess the same could be accomplished with just a disconnect switch (which I would also include) but I like the idea of a smart system making sure everything is running in the background without me being required to make sure it's doing its thing. Just my opinion.

 

[bullfrog]

I think as stated above people with minimum solar that are concerned that the alternator is charging their house battery with a profile that will actually harm their high dollar house batteries and also would like to maintain their starter battery with solar while doing extened stays. I personally don't like the idea of working the vehicle's alternator any harder than necessary plus when you do you are wasting fuel in my opinion. The new lithium batteries can be drained futher and demand large amounts of electricity to get recharged and everyone seems to want to go to these as they weigh less but don't want to buy enough solar to keep them charged and are now looking at the vehicles alternator to do so rather than a small efficient individual generator. I just cann't understand why everyone thinks electricity from a vehicle's alternator is free. I mounted an alternator on a stationary bike and bought a 12 volt television. The only way my kids could watch TV was to petal the bike, they got athletic scholarships in the end. It didn't take long on the bike to learn how much power it takes to make electricity.

 

[HalfShadows]

You can charge Lithium Battery Bank while your driving as long as you install a battery to battery charger. Otherwise new alternator will be in order Learned this from experience. Idling to charge a lithium battery bank is a waste of fuel. I am limiting current from alternator to 30 amps with battery to battery charger, otherwise the lithium battery bank will take everything your alternator can produce and still want more.

 

[frater secessus]

deleted. Will reedit.

 

[frater secessus]

I don't think we're overthinking here.  We're just thinking, and that's a Good Thing.  Doesn't mean we have to all buy Balmar products.

Balmar's quote is correct although incomplete.  The question is:  does it make a practical difference and if so how much?  For me it's "yes, in some situations" and "some, but I don't worry about it. "
 

Higher voltage sources do "win" in during constant voltage stages (Absorption and Float), but lead chemistries fill ~80% of their capacity in constant current stage (Bulk).  It's all hands on deck early on and all sources contribute what they can.  None has hit its setpoint yet.*

Here is an rvwiki article on multipoint charging that may or may not help folks wrestling with the topic.


* Higher-end charge controllers allow for networking parallel units so they can stay closely in sync and both provide power during those times where constant voltage charging is still a high-current affair.  Early Absorption is a good example of this.  So is the imposition of big loads in late Abs/Float but voltage sag tends to rope in the lower voltage sources again.

 

[wayne49]

That battery isolator is a solenoid. A magnetic switch that draws a load while holding the contacts opposite of normal. Normal Open, then Closed will draw amps. Normal Closed, then Open will draw amps.

There is no such thing as a free lunch. Especially when it comes to energy.

The vehicle's alternator is sized for the vehicle's needs as manufactured in normal driving. Not designed to charge at idle. Not designed to charge more than the number of batteries of the type the vehicle was built with at the automotive plant.

Your vehicle's battery bank's chemistry may NOT be compatible with a DIY house bank based on someone's experience and opinions.

Lead Acid, Gel, and Lithium, each has a different charging profile. They are incompatible. Gel requires a steady 13.7v. Any connection between a Gel system and a solar lead acid system is Trouble spelled with dollar signs.