M380 Solar - An All-Electric Conversion

[DW SD]

Kev and Van-
How many amps does an AC unit draw on average?

Thanks,

Doug

[NoGas]

I’ll be doing a two year update to this thread shortly (a few tweeks but it’s all still working great! ). Is water under the bridge, but just noticed Mike’s post above and wanted to answer:

Originally Posted by rtpn60

BUT, most over the road transit buses are 24v systems. They also have 24v starters, etc... So in our buses you'd have to deal with 24 to 12 volt converters and that's not a good direction, especially for large current items like starters

Had I not already owned an almost new 12v inverter/charger, I would definitely have gone with a 24v Magnum instead. Mikes converter point would’ve been easily solved with a simple wiring addition. My coach has two 12v -31 AGM engine/chassis batts. Going with 12v parallel to the chassis/engine and 24v series from the charger to that battery pair (it’s rarely used to charge the engine batts) would’ve solved the problem. Same principle for the coach batts, though the number of 6v L16’s mightve been changed to either 4 or 8 (something divisible by 12). Instead, I would likely have stayed with six batts and used an inexpensive DC-DC converter for the small number of 12v DC low load items in my coach. The advantage of less voltage “sag” (technical term ), when under heavy load with a 24v vs 12v inverter supplying 120v AC is significant.

Doug - Between 10 and 13 worst case when compressor is running. With just the fan in between it’s much lower, of course. There is a momentary spike to more than 20 on initial compressor start. However that settles down almost immediately and the micro air easily compensates, preventing an inverter fault. At this point had I to do it again, I probably would’ve just stayed with a soft capacitor upfront. That’s because I so seldom use my generator and providing BOTH ac units when traveling provides a good opportunity to do so. When bonondocking, I do occasionally run the front AC unit off the inverter mid-day, when solar is at its most productive.

[badandy]

Originally Posted by DW SD

Kev and Van-
How many amps does an AC unit draw on average?

Thanks,

Doug

They are 10-15 amps running. My new Atwoods are about 10-12a depending on temps. My old clunker original Dometics would take 15-18a, but one died and the others weren't far behind.

I installed a Microair on the middle Atwood and I've been running it pretty much nonstop without issues. I need to put my meter on it to see what the peak came down to, but you can even hear the difference when it's starting up.

[DW SD]

Thank you, Amigos!
I was noodling on the idea of a soft start on my front AC unit and running it for an hour or two in the heat of the day from battery and inverter.

I'd have to see how well the solar compensates. Seems like @ 13A, that translates to 100 amps DC. I'm guessing solar could make up 40 to 50 amps of that.

Then again... it probably just makes sense to run the generator for an hour or two if need be. That only costs $2 in diesel if it burns 1/2 gallon / hour.

Back to your regularly scheduled programming.. Van's kick a$$ upgrade channel.

Best,
Doug

[NoGas]

Originally Posted by DW SD

...I was noodling on the idea of a soft start on my front AC unit and running it for an hour or two in the heat of the day from battery and inverter...

Before trying AC off batts/solar, go back and read Micro-Air’s post (#28 on Page 3, this thread). It’s the initial compressor locked rotor startup spike not the running amp draw that creates a problem for the inverter. That huge fraction of a second startup slam typically “red light” faults a 3,000 watt inverter. Not a good way to ensure it’s longevity. M-A’s product solves that issue completely. Naturally, they recommend their product over a soft start cap. The PT100’s charger output by itself can’t quite keep up with one A/C’s draw. However, I can confirm it works if one rewires the rear AC CB panel such that the front A/C feeds off the inverter and they limit their other AC draws. Again when it’s HOT, I usually run the geny and both A/C’s.

Someday, I’d like to see and be dazzled by Andy’s coach .

[DW SD]

Hi Van,
When I wrote soft start, I meant something like Micro-Air (not capacitor - only) solution.

In this case, I think I can better spend my $ on Diesel when I need AC here and there.

Doug

[nbedinger]

Originally Posted by rtpn60

Aaron, Not sure I understand your statement.
<snip>
The only time I've run my generator in the last 2 years was to power up the 3 AC units in Arizona while travelling during the day in the summer heat... because I could.

Michael

������

The temps and humidity here on the edge of The Dismal Swamp are truly oppressive—so hot and humid I am soaked with sweat sitting here. The house has central AC but I’m in the SP with just ceiling fan on. I know a couple of weeks is what’s needed for my body to adjust, then I will be cool to do a little work outdoors or sit comfortably inside without AC. The body gets in tune with the climate if you give it time. But I’m looking forward to AZ winter, it’s the COLD that I can’tt abide!

[MRPutz]

Good update guys!

I am tempted to play with the idea of running a front AC unit off solar/alternator/inverter while travelling. But I'm still on a 2000w pure sine wave, live in AZ where one AC just isn't going to cut it. So IF I were to play with this setup it would be with a 24v 3000w inverter but then again, stuck with one AC in Arizona.... On top of all that I've upgraded all 3 AC units to 15,000 BTU units so just doesn't seem to be a logical solution for this old bus.

[badandy]

Originally Posted by rtpn60

Good update guys!

I am tempted to play with the idea of running a front AC unit off solar/alternator/inverter while travelling. But I'm still on a 2000w pure sine wave, live in AZ where one AC just isn't going to cut it. So IF I were to play with this setup it would be with a 24v 3000w inverter but then again, stuck with one AC in Arizona.... On top of all that I've upgraded all 3 AC units to 15,000 BTU units so just doesn't seem to be a logical solution for this old bus.

You might be surprised - did you measure the running current of the new A/C's? If it's under 15 amps, which I bet it is, you could probably run two of them on that 3000w 24v inverter if you put Microairs in them.

[NoGas]

This post has been moved here from JimB’s original 2V Battery Installation thread. If you are considering a total upgrade to your batteries and are thinking 2V liquid lead acids, check that thread out HERE. If you’re an M380 Owner, also see #5 below...

To Dean, Anthony and others from Jim B’s 2V Battery Installation thread...

If you go back and read my All-Electric M380 thread from the beginning, there are some important lessons to be learned. This thread starts out with me totally convinced about lithium’s operational advantages (I still am) and I was in the process of making that conversion happen. The scooter I’d converted several years earlier meant everything I’d learned there could've been applied. However at the time, lithiums were even more expensive than they are now and they were not quite ready for the mass market from a simplicity of installation standpoint. Their sketchy operation in high heat conditions was the proverbial straw for me. So I elected to install AGM’s for all the reasons stated in that thread. Over the past 3 years my FullRiver AGMs have exceeded every expectation. Conversions like Jim’s, Doug’s, Andy’s, mine and a few others are generally not “cost effective”. That said, with our batteries and our solar, long term off-grid “camping” is a totally transparent non-event compared to having hookups and it just works. It’s a want vs need thing! To gain the inherent charging and weight advantages lithiums offer is why I was still tempted to switch when I saw Battle Born’s excellent product on-sale at this years Q. Will I pull the AGM plug and go Lithiums? Someday but not right now.

Last night I pulled into a National Forest off-grid CG. It’d been a long day so turned in early (entertainment center & TV OFF with outside temps that encouraged open windows & no heat/AC). This morning’s total overnight draw showed -130 Ah at 7 am. With the capacity of our stock Bluebird coach battery packs, they could do this in their sleep with no modifications! The problem found in ALL BB’s is they were not designed to off-grid and their crazy phantom draws make off-grid stays a challenge. That’s especially true if one adds a house fridge. So before you spend the $$$ on giant battery packs and solar, you should systematically go through your coach to eliminate all the phantom draws! You might be pleasantly surprised how well your stock coach does off-grid when given a fighting chance.

I believe that some in Jim’s thread have the wrong impression about batteries. Batteries do not make power, they store it in a bank account! Hence the term “bank” . As long as your battery bank “account” can support the lifestyle you choose, life is good. But if you overdraw your account, a bank will charge you a big fee and perhaps close the account. It’s the same with batteries! A large enough battery bank can support A/C for a limited period but only until your battery bank account energy balance drops below a certain point. Then that balance must be restored using shore power, generator, engine alternator and/or solar. This morning my solar was finished restoring that measly 130 Ah deficit by 10 am . However unless your solar array is huge it almost certainly will NOT support running even one roof top A/C unit for even a short period without help. To do that the A/C unit would get its AC power from your inverter (Micro-Air equipped if need be) and the inverter would “invert” DC battery power into AC power as needed, obtaining that DC power from your batteries. If you happened to be running off grid at the time with a sun bathed solar array but without a Geny running, your solar charge controller would see this HUGE demand and make every effort to refill the batteries at the same time. That’s because the Solar charge controller “sees” you trying draw the batteries down to run your A/C. If your solar panel setup cannot refill the battery bank with an amount = to what you are using, your battery State of Charge (SOC) will drop. A/C units suck ALLOT of juice so even with a small solar supplement, your batteries are likely to be “bankrupt” in short order. When driving and if wired right, your engine alternator can also supplement Coach A/C use. However, engine alternators aren’t cheap so it’s best to limit that type of use unless you are absolutely certain doing so will not “smoke” your alternator.

It’s the relationship between each of the different parts that everyone needs to understand BEFORE they start making changes or spending big money to (perhaps unnecessarily?) update their systems.

Now to a few questions...

1) Switches to Pos or Neg side? - I installed my rotary control switches on the Positive side. As long as one reduces their circuit loads to zero before actuating, a switch wired this way should not cause a problem.

2) One BIG battery bank or two separate, one for Chassis and one for Coach? Initially I planned to wire mine such that I would be able to join the two packs. I also purchased AGM batteries for both banks from the same manufacturer, with the exact same charging profile. The plan being that the charger would charge them all as one big bank and if I was ever dumb enough to let them run down to zero, I could still start my generator with its own battery and recharge everything using that, then start the big engine. While I was trying to figure out how to connect them without destroying Bluebirds original battery connect system, I discovered the big 1,260 Ah coach bank of batteries are more than enough to satisfy our needs without connecting the engine start chassis batteries. So I removed the still unwired separate starting switch already installed, and now use the original battery interconnect system. Like Jim and except when on shore power, I usually run the Coach and Chassis battery systems separately. However, I use BlueBird’s stock interconnect system as needed instead of a manual switch.

3) If someone is contemplating installing lithium batteries, it helps with the cost if they are already running a Magnum or Vectron inverter/charger set up. New inverters can be configured to support lithium‘s and therefore one can avoid the cost of buying a new one.

4) Running a roof AC off of one’s inverter is not recommended unless appropriate steps have been taken to ensure that the inverter will not be damaged and that it’s power use is supportable.

5) Lastly, I’ve been asked would I do it again? In short YES! However, if were I doing my huge battery upgrade TODAY instead of three years ago, I would likely go with Battle Born’s. Everything about them except INITIAL cost is superior, and in the long run that is better also. Supposedly, even lithiums notoriously poor HOT temperature performance has been addressed by Battle Born. Though I would have to see that during a Phoenix summer to believe it. For the M380 guys, changing your three 4D’s out to 4, 5, 6, 7 or even 8 Battle Born’s depending on your needs would be easy except for their initial cost. That would also address the front axle weight issue, while providing superior quick recharge capability. LOVE having my battery bank in the new rear bay I created where the propane bottle used to be. I can put 6 plastic storage bins in that former battery location! Plus I really do not like having propane on the coach. So I would likely still remove my propane bottle and create that new rear “battery bin” and then add even more storage above the new lithiums. Long term, that’s a good option for me when my AGM’s die. However, with Battle Born’s “drop-in” swap-out form factor you wouldn’t HAVE to do that. You could keep them in that stock BB plastic battery tub if you really wanted to, or not & create a nice slider in the same space if you desired. With the huge weight saving lots of flexibility there. All it would take is some serious pocket change up front

If anyone has questions, PM your phone number to me and I’ll call you back.

Pics below of coach in its off-grid element. Willing to bet even Andy would have a hard time seeing her solar panels
.