Charging from Alternator via Renogy's DC to DC Charger

[DanDweller]

Do you already have the lithium battery?

If not, just buy a lead acid AGM to power the fan.... and charging it with your existing infrastructure becomes much easier. A super simple and cheap solenoid or switch will keep that house battery happy, it will allow you to charge it with the engine alternator, no worries, and a ventilation fan plus an LED or two is NOT a heavy drain on any reasonably sized lead acid battery.

I have the Battle Born 100ah battery.  In my roadtrek I killed multiple lead acid batteries with my vent fan.

 

[maki2]

DC to DC charging. I won't attempt anything more than trickle charging in my Honda Element. The OEM alternator in it is a real wimp. One of these years I might have a more powerful alternator custom built for it. Not in the budget anytime soon though.

 

[Cajunwolf]

I have the Battle Born 100ah battery.  In my roadtrek I killed multiple lead acid batteries with my vent fan.

Sweet! I'd love to have about 300ah of Battleborn batteries myself, but too rich for my blood. Don't take this the wrong way, okay, but the root of your problem seems to be a vent fan that's killed several Lead Acid Batteries. I'd rethink that fan. I had a 5000 BTU air conditioner on my sailboat that pulled right at five amps at full load, but once things were cool, I set it on low, and it came on every now and then but never used over two amps. I could run that AC two nights on my 300ah battery bank with no problems. What kind of fan is it?

 

[DanDweller]

Sweet! I'd love to have about 300ah of Battleborn batteries myself, but too rich for my blood. Don't take this the wrong way, okay, but the root of your problem seems to be a vent fan that's killed several Lead Acid Batteries. I'd rethink that fan. I had a 5000 BTU air conditioner on my sailboat that pulled right at five amps at full load, but once things were cool, I set it on low, and it came on every now and then but never used over two amps. I could run that AC two nights on my 300ah battery bank with no problems. What kind of fan is it?

Not sure what model vent fan is in my old Roadtrek.  But I think the problem was more in the constant usage without properly maintaining the batteries.  I too frequently drained the lead acid batteries way below threshold and also hooked up those batteries to a stupid charger and left it on too long.  That is why I am trying to get it right in the Transit Connect I am converting.  With a lithium battery and smart chargers combined with built-in battery management system, my bad habits should be less of a problem.  Anyway, the fan I purchased for the new van is a Maxxair fan.

 

[Cajunwolf]

@DanDweller

Cool, makes sense. Yeah, I can understand you wanting to be careful with that battery. Keep plugging; you're on the right track. Trial and error have taught you well, young man!

 

[MrAlvinDude]

Why does it seem so difficult to figure out which components I should get? 

I think there are two parts to this question/answer.

One. The concept of the function of each component/device - and on this one I think you are very much on the right track.

Two. Selecting the specific brand/device for each function.  And trying to predict how well and for how long that specific device will be able to deliver/live.  And it seems to me that this is the one causing frustrations right now. 


It might seem like it has all been done before, but because you have switch to a different (and very new) battery technology, your are actually among the early adopters of devices that combine new and old battery systems.

And one of the new requirements for a lithium based battery is, to be able to manage/limit the charge rate of the battery (or to beef up the alternator system). As the balance between power needs, capabilities and limits are typically tuned to fit a lead acid system. and was typically centered around the natural internal resistance of a lead acid battery.

With lithium based technology this changes. As the internal resistance in a lithium based battery is much lower that that of a lead acid battery. 


As for being able to charge the lithium battery from the alternator, there are several ways to do that.

The energy optimal way is using a DC-DC charger (with limited amp capacity, so nothing gets overheated or over loaded).

But it is also possible to use a small cigi-plug 100-150 watt inverter, and a small 110V battery charger. This method is not as energy efficient, but in a pinch, it can (slowly) get the job done. 
And perhaps you already have a small (as in somewhat low amp) shore power lithium battery charger. And perhaps you already have a small inveter that can be plugged into a 12V-cigi-plug. Again a 12V-cigi-plug is not ideal for things over 50W, but they can be supervised, so they do not overheat, and the job will get done.


So what I hear is, that you experience the frustration that is only very common among early adopters of fairly new technologies and fairly new devices.


But all in all, I think you are doing exactly the best thing you can do - by asking in forums where several people with actual and specific experience and observations can guide you.
So please be patient, and give the details time to settle. Okay?

 

[DanDweller]

I really am curious who are these Ford people and alternator mechanics that it is suggested I talk to. I have never had luck trying to ask questions of the guys at the Ford dealers (much less the 800 number). If I am not there to purchase something, they don't like to give me the time of day. Also, regarding auto mechanics, in ny experience, walking into a shop the first thing they want to do is schedule an appointment for them to earn some money doing routine work, not answer some oddball questions from left field. I'm not trying to be rude, but you guys make it sound so easy when in my experience I tend to just hit a brick wall trying to make calls or drive to these places.

So I would like to take a different tack and simply ask: Does anyone here know of someone on these forums with experience and who lives in Utah (I am in Salt Lake City) and would be willing to help me design anf install my electrical system for a fee? I mean, I haven't even gotten to questions about fuses and wiring yet. I am not here on the forum because I like DIY electrical--I hate it. But what I can do is keep going to work every day, buy some components and then leave my van for a week with and throw money at someone willing and able.

 

[DanDweller]

I think there are two parts to this question/answer.

One. The concept of the function of each component/device - and on this one I think you are very much on the right track.

Two. Selecting the specific brand/device for each function.  And trying to predict how well and for how long that specific device will be able to deliver/live.  And it seems to me that this is the one causing frustrations right now. 


It might seem like it has all been done before, but because you have switch to a different (and very new) battery technology, your are actually among the early adopters of devices that combine new and old battery systems.

And one of the new requirements for a lithium based battery is, to be able to manage/limit the charge rate of the battery (or to beef up the alternator system). As the balance between power needs, capabilities and limits are typically tuned to fit a lead acid system. and was typically centered around the natural internal resistance of a lead acid battery.

With lithium based technology this changes. As the internal resistance in a lithium based battery is much lower that that of a lead acid battery. 


As for being able to charge the lithium battery from the alternator, there are several ways to do that.

The energy optimal way is using a DC-DC charger (with limited amp capacity, so nothing gets overheated or over loaded).

But it is also possible to use a small cigi-plug 100-150 watt inverter, and a small 110V battery charger. This method is not as energy efficient, but in a pinch, it can (slowly) get the job done. 
And perhaps you already have a small (as in somewhat low amp) shore power lithium battery charger. And perhaps you already have a small inveter that can be plugged into a 12V-cigi-plug. Again a 12V-cigi-plug is not ideal for things over 50W, but they can be supervised, so they do not overheat, and the job will get done.


So what I hear is, that you experience the frustration that is only very common among early adopters of fairly new technologies and fairly new devices.


But all in all, I think you are doing exactly the best thing you can do - by asking in forums where several people with actual and specific experience and observations can guide you.
So please be patient, and give the details time to settle. Okay?

 Thanks for putting it in perspective!

 

[DanDweller]

@DanDweller

Cool, makes sense. Yeah, I can understand you wanting to be careful with that battery. Keep plugging; you're on the right track. Trial and error have taught you well, young man!

And thanks for the encouragement.  I'll be so happy to be on the road again!  Being in a Salt Lake City winter was never and will never be my plan, but because I didn't get started on the conversion project earlier this summer, here I am.

 

[Cajunwolf]

I never said anything about a Ford mechanic, that's an oxymoron, chuckle, joking, I said a reputable alternator repair shop and I bet you a shiny quarter there are two or three in the Salt Lake area, there are alternator and starter shops in town of any size.

 

[willprowse]

I agree with HDR...both of us (and a few others here) have had to clean up the mess of misunderstandings that Will leaves in his wake. 

Too little info, too much info-tainment.

And I seriously doubt that he would have the ability to predict whether a Ford Transit Connect alternator will overheat or fail if loaded down with an extra 20 amps.

As to whether the B2B chargers will work OK if hooked to the same battery as a typical solar controller, yes, they will work fine, if all the parameters on all devices are set properly.

Please do explain. What was I incorrect about?

 

[DanDweller]

I never said anything about a Ford mechanic, that's an oxymoron, chuckle, joking, I said a reputable alternator repair shop and I bet you a shiny quarter there are two or three in the Salt Lake area, there are alternator and starter shops in town of any size.

Yeah, not you, but someone said it.  So does FORD mean Fix or Repair Daily, or Fail on Research and Design?  So far in my experience it's been more the latter (poorly designed transmission and stupid so-called "courtesy lights" that come on when you open a door.  On the bright side, with the help of a mechanic, I did manage to find and permanently ground the leads going from the body control module to  all the doors so now my van's dumb brain always thinks the doors are closed and stops telling the whole neighborhood about it every time I enter or exit the vehicle.  That was fun.)

 

[willprowse]

Let me clarify a bit more:

Lots of information presented by youtubers can be wrong, out dated, erroneous, misleading, etc. There is no 'vetting' of the information for the most part. They have no fact-checkers on staff. And, they do not get paid for presenting truth anyway. They get paid for presenting titles and content that is 'ad-friendly' and that people will click on. 

Content is EASY...but 100% correct, provable, well-researched, hard technical content is hard. 

The everyday youtuber presents opinions, not necessarily facts. You have no way of knowing what level of fact-checking, research, experience, or knowledge they have beyond opening a box and hooking up some wires to a new toy. 

I'm not saying Will gets it wrong while everyone else gets it right, what I'm saying is that the content is presented in a pleasant way, so people think that by golly, he MUST have this all figured out. And there is a mix of good and not-so-good information. Or, things that get left out so we end up explaining the details to the newbies that come on board here. 

And its a never ending, thankless job. 

Just make sure to be skeptical when the presenter is being paid to promote him or her self, or endorses a product for money.

Hey can you please tell me SPECIFICALLY what information that I have presented that is erroneous? Waiting for your reply. 

And unlike other youtubers, I am not on any contracts or corporate sponsorship. When a video is "sponsored" it is because they sent me the product for free. And I have given my harshest reviews to the nicest companies. I don't care who makes the product, or how nice the people who own the business are. I give equipment a real world test and try to break it, and that's it. I have learned a lot from destroying solar equipment over the years, and I love to educate others on my findings. 

And what information do you feel that I have left out? I would really appreciate a list of specific examples. I do not want a vague judgment without evidence. If something in my video is incorrect, it is taken down. Please let me know exactly what is incorrect and these videos will be taken down tonight.

 

[DanDweller]

Please do explain. What was I incorrect about?

I personally don't know--I'm the novice here just trying to learn as much as possible.  But now that I've got your attention, would you mind giving me your two cents on using that Renogy device on my 2015 Ford Transit Connect--not the Transit, but the smaller, 2.5L, 4 cylinder Transit Connect?  Would its alternator be too wimpy?  And also, how has that device worked out for you since you first reviewed it?

 

[willprowse]

Does anyone here have actual experience using the 20 amp version of the device mentioned in this video on a smaller van (eg, Ford Transit Connect) or a similar device by another brand?



Unfortunately, the reviewer does not mention whether this device would be compatiblw with the solar charging system I plan on using with an MPPT controller.  I have talked to Renogy's "technicians" and only received conflicting and hesitant answers.  I am trying to get a definitive answer on whether the additional 20 amps draw would be too much for my alternator to handle and whether this will work in tandem with a solar system.

20 amps is fine to pull from your alternator. The bigger question is what type of battery are you charging with it? You could charge a small FLA or SLA no problem with a traditional voltage sensitive relay system for a few years, without problem (which is why many people think that its ok to do this).

Problems occur when you have a solar battery with low internal resistance and you try to charge it with an alternator. What factors decrease the internal resistance of a battery? Hot temperatures, large batteries, various cell designs, and of course lithium. Any lithium battery has a MUCH lower internal resistance compared to FLA or SLA. And one WILL burn out their alternator if they do not use some form of external regulation. Also, a alternator will not have temp coefficient compensation or multi stage charging algorithm. So even if you use a FLA or SLA, its life will be decreased drastically. 

The marine crowd runs into this problem a lot. Charging a massive 48v battery with a boat alternator without an external regulator will cause issues. Check out this useful article: https://stevedmarineconsulting.com/alternator-charge-regulation/

 

[willprowse]

I personally don't know--I'm the novice here just trying to learn as much as possible.  But now that I've got your attention, would you mind giving me your two cents on using that Renogy device on my 2015 Ford Transit Connect--not the Transit, but the smaller, 2.5L, 4 cylinder Transit Connect?  Would its alternator be too wimpy?  And also, how has that device worked out for you since you first reviewed it?

Biggest issue I have seen people have with it is wiring it up (its difficult) and understanding the settings in the manual. Thats about it. It works as advertised and has some great features, but its not for everyone. I would look at the manual before attemping to install it. If the manuals instructions make sense, you should be good to go. Its a dead simple device and everyone NEEDS regulated alternator charging (current limiting, temp coeff. comp./multistage charging etc), so do not go without one. 

Let me know. Let me know if any of this was confusing and I can re-word it

 

[DanDweller]

20 amps is fine to pull from your alternator. The bigger question is what type of battery are you charging with it? You could charge a small FLA or SLA no problem with a traditional voltage sensitive relay system for a few years, without problem (which is why many people think that its ok to do this).

Problems occur when you have a solar battery with low internal resistance and you try to charge it with an alternator. What factors decrease the internal resistance of a battery? Hot temperatures, large batteries, various cell designs, and of course lithium. Any lithium battery has a MUCH lower internal resistance compared to FLA or SLA. And one WILL burn out their alternator if they do not use some form of external regulation. Also, a alternator will not have temp coefficient compensation or multi stage charging algorithm. So even if you use a FLA or SLA, its life will be decreased drastically. 

The marine crowd runs into this problem a lot. Charging a massive 48v battery with a boat alternator without an external regulator will cause issues. Check out this useful article: https://stevedmarineconsulting.com/alternator-charge-regulation/

I have the Battle Born 100ah lithium battery.  So when you say a form of external regulation is needed, is that what this battery to battery device by Renogy does?

 

[DanDweller]

 Its a dead simple device and everyone NEEDS regulated alternator charging (current limiting, temp coeff. comp./multistage charging etc), so do not go without one. 

Let me know. Let me know if any of this was confusing and I can re-word it

So I guess all those things are what this device does, right?  Sorry, very novice.  Also, am I correct in understanding that I can use this battery to battery device in the same system which also has solar panels and an MPPT controller?  I understand that the battery to battery device would not wire up to the MPPT controller but directly to the battery, and that, if I am driving down the road and voltage is being sent from the front to the back battery, the MPPT controller will sense the voltage difference arriving at the back battery and adjust its output voltage accordingly.  Is this correct?  
Thanks for chiming in!

 

[highdesertranger]

Dan get a hold of Jimindenver. he is not in Utah per se he is all over the west,

https://www.jimindenver.com/

you might recognize him from Bob's youtube channel.

highdesertranger

 

[bullfrog]

This electrical section of these forums has always been a difficult area to get a consensus on what works best as the tech changes often and the products quality, specs, and prices often change as well. As every situation changes with the user and no two systems will be used exactly the same what is recommended for one person may not work for another. Many highly qualified people have attempted to help others here as well as not so qualified experminters that made things work for them but eventually they all become frustrated and leave or stop advising. Currently jimindenver is recognized as one of the most knowledgeable and most sought after advisors. I enjoyed watching Will when he first started out 10 years ago and I'm sure he has learned a lot since his first videos where he was wiring using speaker wire due to costs. As stated above all the posters here want to help you but having someone, if you can afford it, to work with you individually and custom design your system as jimindenver will do is best if you can not take the huge amount of time (as Will stated it has taken him 10 years) it takes to learn what you need to do it yourself. Thanks to everyone who takes the time to educate others!!!