Second alternator vs. solar panels???

[Troutbum]

So if I didn't want any solar panels on the roof would I be able to consume about 50 amp/hours per day from 300 amps of lithium batteries by just charging off a dedicated and SEPARATE alternator in a Ford Transit if I drive an average of 2 hours per day? 

If so would I gladly spring for the extra 150 or 250 amp alternator.

What charging system would be able to charge at the highest charge rate from this set-up and would it be better to get 2 150ah batteries in series for 24v or get 1 300ah battery in 12v?    I am good with normal battery charging but never used an alternator in this scenario before.

I will be making the battery with something like these depending on using 12 or 24 volt system.

https://www.ebay.com/itm/Brand-New-...764582?hash=item1f0587afa6:g:bF0AAOSwNq9dycRv

https://www.electriccarpartscompany.com/Fortune-100Ah-Aluminum-Encased-Battery

 

[DLTooley]

This is a new area. A lot of folks here are two Trojan die hards. These are good questions and though I can’t answer them definitively I do think I can contribute.

LiFePo4 is a good candidate for alternator charging as they accept full power easily and don’t have the long tail of lead acid. Why do you think you need a second alternator? I don’t know about Transits but as I recall with Econolines there was an upgrade option available. I’d suspect that a standard alternator would have no problem generating 50ah in two hours.

That is a lot of driving, is that your daily work requirement? I hope you aren’t van dwelling and commuting two hours a day. Solar is cheap.

Both of the products you list don’t have built in BMS and that’s a factor in their cost. Better controllers have programmable charge voltages and temperature shut off might also be possible, but there’s still the cell balancing function.

A built in BMS might not be necessary, but I’d like the warranty that comes with same. A naked battery supplier that also provides tech support would be a big plus, but I’m not holding my breath.

Costs of these will continue to come down. Utility scale costs are at $156 per KWH, not much less than the useable power off a 100 ah battery. They are forecast to be at $100 in a year or two.

I’m still limping along on my existing lead acid setup.

12v systems are generally simpler. As I understand it the advantages of higher voltages are on the solar charging and transmission distance aspects. There are also increased safety risks.

 

[Troutbum]

I really like the lithium numbers since I can use almost twice the capacity from the same a/h battery and they are a fraction of the weight so I can have 300ah for about the weight of 2 agm's and still have an extra 150 ah of extra usable capacity (rough numbers). 
The lithiums sure cost alot more but if they last twice as long in my hot van than regular batteries do (about 3 years and they are done) like they are supposed to then it's worth it to me especially with carrying about 100 less pounds of battery.

The Ford stock alternator is rated 150 amps but the van uses around 100 when driving and more running the heater or cranking the radio so there is not alot of headroom left for my comfort level.

  My main question boils down to how many amps can I pull from a dedicated alternator since the batteries say you can charge at 1C rating which I think is 300 amps but if I could charge at even 50 amps it would be great and eliminate my need for a solar panel.

I could use a $75. BMS or just keep the cells balanced manually once in a while and I know not to charge hem below freezing temps so not too worried about that. Once balanced by the charge controller they should stay balanced by themselves for 6 months or more. A good bms is under 100 bucks anyways.

 

[ckelly78z]

Are you actually planning on driving for 2 hours every day ? What about when you are stationery/boondocking ?

 

[Troutbum]

I think with 300 amps of lithium that's good for 6 days even with no driving. But I usually  tend to move around alot and cover ground so 2 hours daily driving is just an average.
Having one of those flat folding solar panels for backup would be ok if necessary.

It all depends on how much juice I can grab from the alternator. They even sell a 300 amp alternator but I don't know how to get it to the battery.

 

[highdesertranger]

it's ALWAYS a good idea to use the alternator as a secondary charge source.

it's NEVER a good idea to rely on an alternator as your only charge source.

highdesertranger

 

[tripper]

Watch the video by victron regarding alternator charging lithium batteries. It is very informative and shows that a large alternator charging a lithium battery at max power while idling can catch the alternator on fire due to not enough cooling and too much current output. Lithium Battery Charging via Alternator YouTube link

 

[Troutbum]

That's a great video Thanks for posting it. The smoking alternator is exactly what I am trying to avoid Lol.

Also I just found out that you need a special aftermarket kit to add a second alternator for $1800. so that plan is out the window.

So I don't know how everybody gets away with sticking in the usual Renogy battery-to-battery charger that draws 60 amps from the van battery.
 must be alot of smoking going on.

 

[Van-Tramp]

I would not recommend this for a few reasons

First, an auto alt will not charge a lithium to 100%. Also, an auto alternator will burn themselves out trying to bulk charge for hours on end. They just aren't intended for that. And, you will take a big hit to your MPG, which means you will pay more for this setup then solar.

If you are planning to drop 3k+ on 300a of lithium, then $400 on some solar isn't a huge deal and will save you money over time.

If you must go this route, look into marine Balmar alternators ($600+) which are intended to bulk charge for hours on end and will regulate their temp

 

[Cammalu]

A ton of batteries and no solar and want to be stealth. I don’t know how they are charging this battery bank. I don’t get it. I must be missing something.



https://www.youtube.com/channel/UCpP1y-e7xQzD8S0bQaIdgZw

 

[Trebor English]

When Ford built your transit they did that to make profit.  If the alternator they put in could run all the van systems and still spare 50 more amps they would have put in a cheaper alternator. 

A 150 amp alternator can put out 150 amps as long as you keep it cool.  Usually that means stopping the current 2 out of every 5 minutes while the fan keeps blowing.  An a vehicle the full charging current to refill the starter battery after an engine start doesn't go on very long.  Then the current goes way down.  If you turn the high beams on and set the air conditioner to the maximum fan speed and put it in reverse to turn on the backup lights and turn on the interior lights and the CD player and turn on the 4 way flasher that will take enough current to keep the alternator hot.  If you drive with the headlights off there are 10 amps that aren't going to the headlights that you could take plus another 5 for the tail lights that are off.  If you want 15 amps to charge a phone and a laptop that is feasible.  All the energy a small home can use delivered in just a couple of hours is not likely.

 

[chris84]

A ton of batteries and no solar and want to be stealth. I don’t know how they are charging this battery bank. I don’t get it. I must be missing something.



https://www.youtube.com/channel/UCpP1y-e7xQzD8S0bQaIdgZw

[quote pid='484005' dateline='1580831142']
That is exactly what I have, only 600AH of lithium batteries and no solar. They charge off the alternator while I drive, I use a Sterling battery to battery charger that limits the draw on the alternator to 60 amps, so if the battery is completely dead I would need to drive 10 hours to fully charge it, but I have never gone below 30% and don't feel compelled to charge the batteries all the way back to 100% either.

I have a solar controller and everything except the panels, with the idea that if I needed solar in the future I will just add the panels. In the 8 months since the 'build' I have not yet felt compelled to add the solar panels yet. I say 'build' because it is never finished, completely livable, but never finished.
[/quote]

 

[highdesertranger]

wow, you must do a lot of driving. don't you ever sit in one place for a few weeks? highdesertranger

 

[Van-Tramp]

I guess if you don't consume much power then you could rely only on the alt charging. But then if you don't use much, why such a big battery bank?

Kerri and I consume about 1kw per day in power. That is a lot of running the motor, each and every day, to make up for the power we use. The cost if fuel would add up quickly.

 

[chris84]

wow,  you must do a lot of driving.  don't you ever sit in one place for a few weeks?  highdesertranger

No, I stay in mine for work and can't always park close (not do I really want to) so I generally drive about 20 miles each way to somewhere better to stay, this is quite sufficient to keep the batteries charged most of the year. A few fans, phone chargers, a few hours of TV, none of it is really a big draw. The only large draw is the AC in the summer for a few hours in the evening, during the summer I get a campground and top up once or twice a week. The van is just a tool to save rent or hotels and sadly not much of a vacation tool (but I still manage to sneak in a little fun)

That said I don't generally drive all that far, less than 7000 miles the first year I've had it.

 

[Ticklebellly]

....... the van uses around 100 when driving and more running the heater or cranking the radio................

How sure are you of that figure?    Seems like a lot to me but I have no experience with a Transit so checking..

 

[riptorn]

Just curious. wouldn't a good DC to DC charger be simpler? I'm poor so I just plug a Battery Tender into the elc outlet on my dash to charge as I drive down the road. 
One 100ah agm, only runs a 13 yo ARB fridge.

 

[Troutbum]

I read it draws around 100 amps with everything running lights, stereo etc but hard to find any good facts.