Thoughts on this trailer power system.

[OllieChristopher]

Watch the video in my other post.
I'm going to install a LiFePo4, chuck the stock WFCO, install a PD4045KA.

That is an eye opener Bill!! I'll continue to use my dual AGM's under the bonnet of my truck. But for aux power for RV or camper you are making a good argument for using Lithium for true back up power when parked. Thank you for taking the time to post and share your knowledge. My only concern for cost per amp hour and discharge cycles is the vibration and banging around batteries go through.

 

[Buddha.]

Watch the video in my other post.
I'm going to install a LiFePo4, chuck the stock WFCO, install a PD4045KA.

I’ve watched a few of his videos. There’s an older one where he installs part of a Tesla battery pack in his fifth wheel camper. Seems like an interesting option, don’t know how practical it is to the average individual.

 

[Hilldweller]

I’ve watched a few of his videos. There’s an older one where he installs part of a Tesla battery pack in his fifth wheel camper. Seems like an interesting option, don’t know how practical it is to the average individual.

A dude in the office next to mine built-out an old church bus as his new "home" at the start of COVID. He used Tesla batteries --- headed out from here for Canada. Haven't heard from him since...

 

[228B]

1500W inverter on [in this case 225 Ah battery bank] is a waste of $$. The battery pack is way too small. The standby (ghost load) on the Go Power is 1.8 amp...

Sincere question, no disrespect intended: What if the user of a 200 Ah battery bank used a 1500W inverter simply for the deliberately-planned luxury of a quick, convenient cup of coffee? I plan to install a system like this is in a very small camp trailer.

In my case, this setup uses the small Keurig Mini that uses +/- 1300 watts. The process is roughly 3 minutes duration (say, three or four times per day). And then for five minutes, once or twice in the morning, a 1200 watt toaster? System battery bank is two 100 Ah Group 31 AGM wired parallel and charged with 12-13 amps solar (with a separate, 120V shore power 3-stage charger as backup).

While these appliance loads may be some sizeable amp hits (+/- 120 amps 12VDC) on the small battery bank, the run time is certainly short enough to use very little amp hours relatively speaking. Either way I guess we'll know soon enough because I am also installing a device that cannot lie: a Trimetric TM-2030RV battery monitor/recording meter. I may have to add a battery (and perhaps a third 100W panel), which can be done since the two extant are brand new and the supplier has more available from the same pallet...

 

[Alloy]

Sincere question, no disrespect intended: What if the user of a 200 Ah battery bank used a 1500W inverter simply for the deliberately-planned luxury of a quick, convenient cup of coffee? I plan to install a system like this is in a very small camp trailer.

In my case, this setup uses the small Keurig Mini that uses +/- 1300 watts. The process is roughly 3 minutes duration (say, three or four times per day). And then for five minutes, once or twice in the morning, a 1200 watt toaster? System battery bank is two 100 Ah Group 31 AGM wired parallel and charged with 12-13 amps solar (with a separate, 120V shore power 3-stage charger as backup).

While these appliance loads may be some sizeable amp hits (+/- 120 amps 12VDC) on the small battery bank, the run time is certainly short enough to use very little amp hours relatively speaking. Either way I guess we'll know soon enough because I am also installing a device that cannot lie: a Trimetric TM-2030RV battery monitor/recording meter. I may have to add a battery (and perhaps a third 100W panel), which can be done since the two extant are brand new and the supplier has more available from the same pallet...

Check the battery specs and find out what the max discharge (C) rate is.

 

[228B]

Thanks for your reply.

Can't find that exact specification, but there are other specs listed.

Specifications

Voltage

12

Pulse (5 second) Hot Cranking Amps (PHCA)

2150

Cold Cranking Amps (CCA)

1150

HCA

1545

MCA

1370

20Hr Nominal Capacity (Ah)

100

10Hr Nominal Capacity (Ah)

92

Reserve Capacity Minutes

205

Terminal

SAE

Torque Spec in-lbs (Nm max)

N/A

Internal Resistance

2.2

Short Circuit

5000

 

[228B]

For the sake of easy math, let's say these 12VDC amp dumps are 150 amps each totalling 30 mins per *day*.

What does that do to the 100 amp hours capacity (50% of 200 Ah)? I can't get into a position mentally to figure that example. Hah! ******.

 

[228B]

Let me start over... and thanks, Alloy, for getting me to think.

Average of the appliance amperage is 11.5 amps @ 120V which translates, roughly, to 127 amps @ 12VDC totalling 30 mins run time.

30 mins = .5 hour | 127 amps X .5 = 63.5

Is that 63.5 amp hours' consumption of the a 100 Ah capacity (50% of 200 amp hours battery bank)? That's a busy day for those batteries...

 

[Rando]

Let me start over... and thanks, Alloy, for getting me to think.

Average of the appliance amperage is 11.5 amps @ 120V which translates, roughly, to 127 amps @ 12VDC totalling 30 mins run time.

30 mins = .5 hour | 127 amps X .5 = 63.5

Is that 63.5 amp hours' consumption of the a 100 Ah capacity (50% of 200 amp hours battery bank)? That's a busy day for those batteries...

The better battery manufacturers will provide a table with run time vs current the captures the Peukert effect. Here is an example from Odyssey:

https://www.odysseybatteries.com/docs/us-ody-tm.pdf

If you scroll down to their 100Ah battery you will see that it will provide 1hr of run time at a 73A load, so the effective capacity at such a high load is about 70% the rated capacity at 5A (20-hr rate). You should do a little better that this as this assumes a continuous draw of 73A and you will be using an intermittent draw, and the battery will recover (somewhat) between loads.

Also, how do you plan on charging? Will it get recharged between loads? Either way you should be OK, if you can charge every day.

 

[Grassland]

I'm starting to question only having two 6 volt batteries now after seeing the above consumption pattern math.

But then again other than charging phones and the iPad, using lights and using the fan a bit, we've gotten by on a single 12 volt with 45ah usable, and a 90 watt peak portable solar panel.

I guess I'll be leaving the inverter off 99% of the time.

 

[228B]

Thank you Verskstad, Rando, Grassland.

V, yes, Puekert's Law. Thank you for reminding me. d'oh! Certainly something to factor.

Rando, they are Odysseys, and I'm glad you found that chart. I had been looking elsewhere on their site. If you go to the 30- [Edit: minute] amp load line, the wattage shown is roughly the higher rating of the two appliances I wish to use.

Yes, the batts will have time to recover between hits and they'll be charging in camp with 200 watts of panels. I see at least 6 amps from each panel. I had experimented and connected the panels in series for a nominal 24V into the charge controller and saw an additional amp output, but it was an MPPT Sunsaver and this was five years ago. I am going to use a Trimetric SC2030 this time around (PWM). The 200 Ah bank needs at least 6 amps to charge it, so I could get by with one panel but charge times would be too long for anything but summer days. Too, I'll have a genset and shore charger as backup for times I'll want to bulk charge to speed the process, then let solar do the absorption phase...

Grassland, I too am rethinking how "convenient" this setup will be and will more than likely use the luxury of the inverter loads less often and brew two of the four daily cups the old-fashioned way using my Coleman 500 Speedmaster single-burner stove. There's just no getting around electric incandescent camp toast! though, so the toaster will be used at least once and then twice if DW is along on that particular trip.

Thanks again for being here and for your responses. Helps greatly to put everything into perspective. I'm still quite excited about this system, though. Imagine when on the road and you want a cup... rest stop, open the back of the trailer, touch two or three switches, pour 6 or 7 ouces of water, drop in a pod, touch another button, and bang! Fresh-brewed French roast, black. Ymmmmm.

I bought a smaller size Chemex I had never seen so I'll be using that, too, along with the 1947 Speedmaster stove.

 

[Rando]

Two related notes - Odysseys are good batteries that are great for high loads, but not really great for deep cycling, so you definitely want to keep them above 50% as much as you can so as to get your moneys worth. Secondly, unless you are reusing the Trimetric and already have it, there are much better options out there for the same or less money, I wouldn't buy one new.

 

[228B]

Thanks Rando. I wouldn't know what those better options are, and the Trimetric has already been acquired, but not yet installed. It will be fine for what I'm doing, and no deeper than 50% is always the goal, even less DoD whenever possible.

That said, I would be interested in reading anything about these better options anyone might care to link in this thread. ??

 

[Rando]

For battery monitoring:

BMV-712 Smart - Victron Energy

Communicate wirelessly between products and simplify system installation and enhance performance using the BMV-712 Smart. Find a dealer now.

www.victronenergy.com

For Charging:

BlueSolar MPPT 75/10, 75/15 & 100/15 (12 / 24 Volt + load output) - Victron Energy

Maximize the energy-harvest, driving it intelligently to achieve full charge in the shortest possible time using the BlueSolar MPPT 75/10, 75/15 & 100/15. Find a dealer nearby.

www.victronenergy.com

If the trimetric is returnable, I would consider it. They are ancient tech.

 

[228B]

Thanks again, Rando. I appreciate the links.

Tell me, though, why, in your opinion, is the Trimetric TM2030 "ancient" tech?