Possible Dream Crusher- Need Help w/ A/C & Solar Please!

[Brewerbob]

Originally Posted by Robin97396

I love the idea of a large battery bank but I'd want to charge the batteries from a generator. It would be nice to be able to feed the battery bank from the bus alternator while driving if it wouldn't tax the alternator to much.

Here's an idea... How about adding a second alternator that does nothing but house batteries? If the bus did NOT come with AC but has teh option, there's obviously a place to mount a compressor and pulley. Repurpose that space for an alternator instead. Has anyone one done that?

[Brewerbob]

Originally Posted by superdave

you can not properly charge deep cycle batteries from a alternator, you will ruin them in months. when building a F L A battery bank its best to design it with the least amount of cells. when you design your system you need enough solar to put your batteries thru the recommended charge cycle and run your ac or you will ruin your batteries.

Um, ... what about every internal combustion engine that is on the road (hybrids excluded) that start every morning for roughly 5 years with a battery before the battery dies?

[cadillackid]

Originally Posted by Brewerbob

Um, ... what about every internal combustion engine that is on the road (hybrids excluded) that start every morning for roughly 5 years with a battery before the battery dies?

they arent deep cycle batteries... but I do wonder about today's alternators since they do have electronic voltage regulators that do a good jiob of pushing a constant voltage at a battery vs the old school magnetic regulators that used to seem to pulse a battery up and down with charge...

I do suppose a true charge controller can push a set Amperage at a battery. vs a set voltage and maybe thats the ticket..

I do know my Chevy Volt charger did exactly that... a normal plain battery charger like you buy at wal mart for $20 oushes a constant voltage up to a maximum current... as the battery charges the current reduces... in the beginning of a dead battery recharge that battery will eat up all the current you can give it.. and heat up quickly...

a regular car battery is rarely ever run down... most times you are simply topping off a mostly charged battery.. when you start the car you maybe kill a few % off the charge.. vs a person running on their solar battery system each night and depleting it 50% or even 100%.. then needing to charge it back up.. an alternator will hit it Hard .. day in and day out i could see this shortening the life of the batteries...

I dont have any scientific testing of this im only going on theory of how hot a dead battery gets when you first start to charge it with a powerful souirce vs a current-controlled source..

-Christopher

[JDOnTheGo]

Originally Posted by Brewerbob

Why use 6V batteries?

In general terms and as a rule of thumb, 6 volt batteries are better for typical RV style use (deeper/longer discharges). Most 12 volt batteries are more of a starting battery. I am not a battery expert so it's best to Google the subject for the technical jargon and scientific details. All that said, 12 volt batteries have served people well in the RV world. It seems that most batteries are destroyed by overcharging/not being cared for long before one might see a lifespan difference.

Originally Posted by Brewerbob

I don't know what the 6V cost but I think I'd rather run 8 of the 12V batteries instead. Two banks of 4 in series. These are "only" 86 lbs each. Call it 100 with some wiring and it's lighter than sixteen 60lb batteries.

There are a LOT of different types of batteries available. Allow me to limit our discussion to the typical and commonly available automotive and golf cart lead acid batteries. Of those and assuming similar physical size, there is no significant difference in capacity between two 6 volt (golf cart) batteries and two 12 volt (starting or "deep cycle") batteries. Much confusion is caused by many 12 volt automotive batteries not being rated at the typical 20 hour rate. Without that, one can only know "capacity" by testing/measuring.

Originally Posted by Brewerbob

It seems they have 305W panels and 250W panels. Their biggest system uses the smaller panels which makes no sense to me either.

Yes, there are many different types and sizes of solar panels. 12(ish) volt panels are "easy" as a pretty simple and inexpensive charge controller is all that is needed (or maybe not even needed).

I prefer the big, high voltage residential panels. However; no installer will sell you these as the warranty will be voided (installed on a bus/RV). They can also be difficult to source and are simply too large for many vehicles (with limited roof space). However; they pack some serious punch and MPPT charge controllers (while semi-expensive) are really quite magical. My real world experience is ONLY with the residential panels and comparing notes with those who have typical RV (12 volt) panels.

[JDOnTheGo]

There are a couple of products available that will "combine" battery banks for charging purposes. I have the Smart Battery Combiner from Magnum Energy. It is very flexible and set points can be set by the owner. It doesn't solve every world problem but I have found it helpful.

[JDOnTheGo]

Originally Posted by Brewerbob

Um, ... what about every internal combustion engine that is on the road (hybrids excluded) that start every morning for roughly 5 years with a battery before the battery dies?

An automotive starting battery is not a "deep cycle" battery. Even the batteries labeled "deep cycle" are not really "deep cycle" like we would like to think.

A "good" lead-acid battery bank for an RV/bus is built with components that can handle the discharges to near 50% capacity (lower than that is damaging). When working with a 220 Ah battery (at the 20 hr rate), you have 110 Ah of usable capacity.

I'm not exactly sure how modern alternator regulators work but a good RV battery charger will charge a battery bank at close to the ideal "charge acceptance rate" depending on the state of the battery and will then go into a float mode to avoid overcharging/cooking it.

[Brewerbob]

I assumed the big truck batteries are deep cycle. They are 12 volt but double the physical size of a car battery. Sure they have a higher CCA rating but not much higher these days. Add to it that you have 2 in most disiels.

I know that my battieries are currently under 50% since I have to jump start the bus. I need a quick, dirty, and CHEAP solar version for just the batteries. This one sounds good but is about twice what I'm willing to spend just to "throw away" later.
BatteryMINDer Solar Battery Charger/Maintainer/Desulfator — 12 Volts, 15 Watt Panel, Model# SCC-015 | Battery Maintainers| Northern Tool + Equipment

This is more cheaperer.
https://www.tractorsupply.com/tsc/pr...er-kit-8500020

[JDOnTheGo]

Originally Posted by Brewerbob

I assumed the big truck batteries are deep cycle. They are 12 volt but double the physical size of a car battery. Sure they have a higher CCA rating but not much higher these days. Add to it that you have 2 in most disiels.

I don't "think" they are but I have no facts. Real deep cycle batteries (like golf cart batteries) have much thicker plates (as I understand it).

Originally Posted by Brewerbob

I know that my battieries are currently under 50% since I have to jump start the bus.

That is very bad for the battery and will shorten it's life.

There is nothing wrong with those products you listed but be aware they produce a maximum of 15 or 18 watts (ideal sun and all that). At a charging voltage of 13.5 volts, that translates to 1.1 and 1.3 amps - not much. Maybe not enough to actually charge the battery, maybe not enough to even keep up with phantom loads (if you have any).

[Brewerbob]

Originally Posted by JDOnTheGo

That is very bad for the battery and will shorten it's life.

Also bad for my mood.

There is nothing wrong with those products you listed but be aware they produce a maximum of 15 or 18 watts (ideal sun and all that). At a charging voltage of 13.5 volts, that translates to 1.1 and 1.3 amps - not much. Maybe not enough to actually charge the battery, maybe not enough to even keep up with phantom loads (if you have any).

That's all a trickle charger is supposed to put out. Worse case I drive the bus for a couple of hours then slap the charger on it?

There's no electric at the lot so it's something small like this or nothing. If you know of something bigger for under $100 please pass it along. I liked these in the even that they acutally work, they won't overcharge the batteries.

I'm also considering putting in a switch to kill any leakage current but I don't know how many amps the starter draws.

[JDOnTheGo]

Originally Posted by Brewerbob

Also bad for my mood.

HA!! Indeed it is!! Mine too!

[mmoore6856]

Originally Posted by superdave

The point of having a skoolie is it being mobile . move it so your not dealing with temperature extremes And save yourself alot of money and hassle . were doing more with less. This is a forum. Its my comment. My opinion.

the point of being mobile is to be free to go where you want to despite weather not to be confined to a temperate zone my choice is to stay away from the east part of the usa as i been trucking too long there and it sucks

[jrtroubleshooter]

We have a couple of these setups that we are happy with
$129 and you can always find a 25% off coupon

https://www.harborfreight.com/45-wat...kit-68751.html