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Old 02-15-2018, 06:13 PM   #1
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Alternate Battery Charging Source

If this post belongs in another thread; I apologize. I will post in the correct area if someone will let me know where to go.

We have a 2003 Chevy E3500 short bus that we're converting. We will be running 400 watts of solar with two 100amp LiFePO4 batteries. I'm wondering if we could connect the batteries to the alternator with a switch or something to keep it from charging all the time when we are running/driving the bus. We mainly want to know that if we unfortunately drain the batteries while we're boondocking if it's overcast for an extended period of time; we can at least be able to get them charged a bit while we're on the road or waiting for the sun to shine again.

Please please forgive my ignorance - especially if mess up terminology. I don't claim to be experienced in any of this. I am reading and learning as I go. But I know very little. Hence, my being here! That said, thoughts??

Thanks in advance for any feedback! I'll check back frequently!

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Old 02-15-2018, 06:16 PM   #2
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Using the vehicle alternator to charge the house batteries is a tricky thing to accomplish. It can be done but it often involves changing the alternator for one with a much higher output, and new wiring and switching. In addition to that, the voltage output of most alternators is regulated too low to fully charge many batteries, although it might be okay with those you mentioned.

A much simpler solution is to feed an Inverter/Charger with a small generator.
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Old 02-15-2018, 06:35 PM   #3
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I personally have gone out of my way to keep anything house away from my bus starting capacity.
If I have a problem in the house I can always start up and go home to figure it out and if my bus don't start then I can live in my house/bus until I get it started.
Just an opinion/thought/idea?
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Old 02-15-2018, 07:59 PM   #4
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Not really that complicated to tie the systems together so that if the "start" goes down, you can switch over to "house" and crank it up.
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Old 02-15-2018, 08:08 PM   #5
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We have our starting/house batteries cabled together with a disconnect switch between them so I can connect them together for emergency starting and, if needed, to give the house bank a quick alternator charge.

Starting and deep cycle batteries like to be charged differently so 99% of the time I keep the two banks separated. The starting bank gets charged by the alt. and the house bank gets charged by the converter three stage charger. That plan works fine for us.

The main problem with charging different types of batteries from the same source is that one type may take a full charge before the other and so become overcharged as the alternator stays at high output to charge the other bank.

The big question here is whether the lithium ion bank will take kindly to being charged by the alternator at the same time as the starting bank. I looked at the LifePO4 site and couldn't find anything on alternator charging.
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Old 02-15-2018, 08:17 PM   #6
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From what I have read (and very little of which I understand) if you go with AGM's for both, they charge evenly from either the alt or through a converter (?).
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Old 02-16-2018, 03:17 PM   #7
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Anyone have any idea why when I try to hit "quote" or "quick reply" and respond in this thread - nothing shows up? I'm really confused.
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Old 02-16-2018, 03:37 PM   #8
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Okay, after trying this twice already, I'm typing it in Notepad and then I'll copy/paste it. For some reason, if I hit "Quote" or "Quick Reply" and submit my info, it forces me to log in again and my response/post doesn't show up. (Very frustrating, ha!)

Thanks to everyone who has responded thus far. I'm going to respond generally in this post and hopefully everyone who's responded will see it. Sorry for not knowing how to work this website. I responded to multiple people but nothing is showing up.

Okay, so - I did reach out to the battery manufacturer (Battle Born Batteries) asking if I could connect my "house" batteries to the alternator and use a switch of some sort to manually connect/disconnect from the alternator. Here is their response:

"Our batteries are not designed to work as a start up battery. So it will not run your vehicle. You can charge off of the alternator but with that we recommend using sterling power:https://battlebornbatteries.com/ster...ttery-charger/ the reason why is because the lithium batteries will try to pull all the power that the alternator can give. This will stress and shorten the lifespan of the alternator. Putting in the Sterling will lessen the load."

So, I'll have to look into this "sterling power" they're referring to and see if I can figure how how to do this and if it'll be a feasible option for me. As stated earlier, we don't intend to manually engage the alternator to charge the batteries on any regular basis. It would really be only if we had no "house" power and truly needed it. It may have been a good thought, but just not something we will be able to do. And that's alright. If we have to boondock for another day or something while we wait for a storm to pass or the clouds to clear so we can get some sun on the solar panels to charge up the batteries - great. It'll do. We're just trying to be prepared and plan for various scenarios that we could see possibly happening?

To give everyone an idea: we do not intend to live inside the bus 24/7. At all. We are tentatively planning to hit the road on May 1st this year and our thought is that we will actually only be in the bus when we're driving (of course, haha) and then at night to sleep. The only other time we really anticipate being in the bus for lengths of time is if there is inclement weather and we require shelter. Otherwise, we plan to be outdoors doing as many activities and just keeping life as simple and free as possible.

We have looked into a generator, but to us (preference only of course) - it seems the cons outweigh the pros. Generators seem to be bulky, quite quite loud, and if we went that route we'd have to rig something up on the back exterior of the bus to haul that generator and a jug of gasoline around. I'd like to try to avoid this IF possible. It sure would be nice though to have a fallback to charge the "house" batteries should we need to.

Originally we were going to purchase a third one of these specific batteries and place that third one under the hood replacing the existing lead acid battery. Apparently, according to the battery manufacturer, this is not an option. They are not made or intended to be used as an engine battery. I have to say, that is terribly disappointing. I would've been willing to spend the money on a great battery like this to replace the old one in there. I suppose I'll just have to replace the old lead acid battery with another of it's kind before May 1st when we take off just to make sure we have a brand new, good-to-go battery in place. I was really looking forward to having that awesome new LiFePO4 batter under the hood though. :/

IF we decided to go with a generator - are we talking a generator like this?

https://www.northerntool.com/shop/to...xoCw48QAvD_BwE

I copy/pasted a link to a random generator from a quick google search. I just want to confirm that what I'm calling a "generator" is actually the correct type we might consider getting.

Thanks again for all the help. I am certain you will see a bunch more posts coming from me asking for help or thoughts and feedback. This Skoolie website is incredible. I am so glad I came across it online! Thanks for all the help and feedback!
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Old 02-16-2018, 04:43 PM   #9
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You'll find that this type of generator is much quieter and possibly more efficient.

https://www.amazon.com/Honda-EU2000I...case+generator

There are many brands of suitcase models. Honda is of course the most expensive comparison for a similar sized generator. Other brands are less expensive. Try to get a sinewave generator so it's safe for your electronics.
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Old 02-16-2018, 07:20 PM   #10
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After a bit or quick research and reading; I think for now I'll hold out and just see if my 2x 100Ah LiFePO4 batteries will be enough. Unfortunately, I won't know for another month or so until the build is complete.

Thanks again for all the replies and feedback. Really appreciate it!
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Old 02-17-2018, 12:59 PM   #11
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Quote:
Originally Posted by Robin97396 View Post
You'll find that this type of generator is much quieter and possibly more efficient.

https://www.amazon.com/Honda-EU2000I...case+generator

There are many brands of suitcase models. Honda is of course the most expensive comparison for a similar sized generator. Other brands are less expensive. Try to get a sinewave generator so it's safe for your electronics.
Actually, Robin I do have a question. If you know how these generators work:

This particular link you included shows a 2000w generator. I assume this is the output? Meaning, it will provide you up to 2000w while it's powered and running? If so, what is this in comparison to my solar panels? If I have 400w worth of solar panels that's the most it can pump out and recharge into my batteries. But if I have this 2000w generator does that mean I will get 2000w of power going into my batteries? That would seem to me that it would recharge my batteries almost instantly right?

Also, I have a 10k watt inverter that I purchased earlier on in this project. Do I need that inverter if this generator has one built in??

Lastly, can I power all my stuff with something like this? If I said to heck with the solar panels and just used the generator - is that an option?

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Old 02-17-2018, 01:28 PM   #12
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Quote:
Originally Posted by msearslive View Post
Actually, Robin I do have a question. If you know how these generators work:

This particular link you included shows a 2000w generator. I assume this is the output? Meaning, it will provide you up to 2000w while it's powered and running? If so, what is this in comparison to my solar panels? If I have 400w worth of solar panels that's the most it can pump out and recharge into my batteries. But if I have this 2000w generator does that mean I will get 2000w of power going into my batteries? That would seem to me that it would recharge my batteries almost instantly right?

Also, I have a 10k watt inverter that I purchased earlier on in this project. Do I need that inverter if this generator has one built in??

Lastly, can I power all my stuff with something like this? If I said to heck with the solar panels and just used the generator - is that an option?

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Well it's 1600W continuous, but yes, that will go into your batteries via your Inverter/Charger.

Good question about the solar ... Solar is expensive and not always there when you need it, but if I had the cash I would put in 1500W of solar and keep the genny for top-ups as needed. Generators need fuel, and they do make noise (even the quiet ones).
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Old 02-17-2018, 02:03 PM   #13
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Well it's 1600W continuous, but yes, that will go into your batteries via your Inverter/Charger.

Good question about the solar ... Solar is expensive and not always there when you need it, but if I had the cash I would put in 1500W of solar and keep the genny for top-ups as needed. Generators need fuel, and they do make noise (even the quiet ones).
Heavens yes. If we had the money we would love to just cover the top of the short bus with solar. That'd be preferred. But man this electrical side of the bus conversion is no joke.

It's very expensive (IMO). Very. Especially if you want quality products. (What am I saying though - that's with almost anything I suppose.)

We are looking online and so going to go to Lowes and places like that to look at some and get some ideas.

Any tips or suggestions on specifically what to look for as we shop? Someone mentioned somewhere that I should try to find a "sinewave" generator or something?

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Old 02-17-2018, 04:00 PM   #14
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I know a little bit about generators but practically nothing about solar.

My theory is you need whatever system you want to use (solar in your case) and you need to have a backup plan. Sometimes your backup plan needs a backup plan. Solar is great, but you don't have much power from your particular setup yet. You can improve your system to have the potential under the right weather conditions to be capable of charging your house batteries each day. Yes, expensive to set up but you're part way there already. Alwys a good idea to have a generator backup, which is also an added expense to get a nice quiet generator.

That Honda generator was just a quick example that was similar in output to the 1800 watt generator you spoke of earlier in this thread, but would likely be 1/4 the noise. I'm unaware of how much power your charge controller can use for charging your house batteries. I'd size the generator to handle the charge controller plus an appliance or two.

Also the sine wave generators apparently don't damage your fine electronics. My generator is just a plain little suitcase 1000 watt Yamaha generator. I've been running my electronics on it whenever the power goes off for years with no apparent issues. Sine wave is supposed to be better for protecting your electronics.

That 10,000 watt transformer you bought will eat up a lot of power from your house batteries. I know that was an expensive item, but smaller transformers eat less power. Some people even dedicate a 200 watt transformer to certain appliances because the large transformers continue to waste power even to run a small electrical output. It's often said to be about a 15% loss in the transfer of power. Its about do you want a 15% loss on 10,000 watts or do you want a 15% loss on 2000 watts, or whatever size you need?



Quote:
Originally Posted by msearslive View Post
Actually, Robin I do have a question. If you know these generators work:

This particular link you included shows a 2000w generator. I assume this is the output? Meaning, it will provide you up to 2000w while it's powered and running? If so, what is this in comparison to my solar panels? If I have 400w worth of solar panels that's the most it can pump out and recharge into my batteries. But if I have this 2000w generator does that mean I will get 2000w of power going into my batteries? That would seem to me that it would recharge my batteries almost instantly right?

Also, I have a 10k watt inverter that I purchased earlier on in this project. Do I need that inverter if this generator has one built in??

Lastly, can I power all my stuff with something like this? If I said to heck with the solar panels and just used the generator - is that an option?

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Old 02-17-2018, 11:23 PM   #15
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Quote:
Originally Posted by msearslive View Post
Also, I have a 10k watt inverter that I purchased earlier on in this project. Do I need that inverter if this generator has one built in??

Lastly, can I power all my stuff with something like this? If I said to heck with the solar panels and just used the generator - is that an option?
The inverter in the Honda generator (as I understand it) does an AC-DC-AC conversion inside the generator electronics which converts square wave generator AC current into sine wave AC current. You can't hook up your battery bank to it.

A 1600 watt generator will power a lot of stuff. During power outages we run 2 refrigerators, a gas furnace, a sump pump, the TV and a bunch of lights and the Honda rarely comes off eco mode.

Without knowing what stuff you need to power it's impossible to know whether your proposed system will handle it. It's best to figure out what you want to power then build a system that will handle it. Anything that uses resistance heat (electric coffee pots, hair dryers, electric stoves, etc) draws a LOT of power.

Your two 100 amp batteries aren't a lot of power to begin with and the batteries can be killed by drawing them down past 10 volts so your available power may be less than you think. Post up what appliances you want to use and we can give you a better idea what will work.
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Old 02-17-2018, 11:38 PM   #16
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I have found it easiest to figure the number of amp hours I need over, say, two days.

Design the system, and battery bank, to cope with that and everything else you add like solar or a generator is merely to charge, or keep charged, those batteries.

The Solar and generator requirements are then easy to see, with the generator having the added benefit of helping with peak load.
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