2019 Acela 4x4 with full expedition build - Sold
- Thread starter varythings
- Start date
varythings
Member
@GENX Thanks. To clarify your question for others... We're talking about the truck batteries, not the lithium house batteries.
Yes, the military originally had 4 12v batteries for the truck.
Essentially 2 groups of 2 with a 12v center tap:
Each group is 2 12v-batteries in parallel for 12v, 2 of these groups wired in series for the 24v.
The setup here is one 12v-battery in each group (flooded commercial grade 8D size). 2 batteries in series for the 24v.
When you center tap a series pack you must somehow maintain cell balancing for the entire series. The military (and most anyone else who deals with these trucks) doesn't really address the cell balancing. The military puts in a diode polarity protector to prevent damage when the inevitable happens: when the 12v tap draws down one half of the series pack there can be a polarity swap on the 12v side when there's a high current demand on the 24v pack (ie cranking the engine). This can severely damage any electronics on the 12v system.
Acela didn't address the issue either, they tell owners to disconnect the truck batteries if the truck is not running to prevent parasitic draw.
Okay that's the why, here's how we addressed the problem to have a reliable and redundant solution.
There are 12v draws on the battery that we want to maintain while parked: mainly the security system and dash cameras, and occasionally radio coms and lights. Solution 1: There is a solar system dedicated to the truck batteries that charges the series pack at 24v and uses excess solar on sunny days to perform a full cell balancing. Solution 2: The noco charger can be plugged in to the camper and utilize the inverter output to maintain the truck batteries. Because this is a 12v x2 charger it keeps the series pack balanced. We do this if we're stationary for several days without sun or in the shade.
When on shore power we let the noco do it's thing.
When storing the rig, the noco can be plugged in separately to maintain the truck batteries and keep the alarm and cameras on. (For extended storage you don't want to keep the lithium system on shore power charge, so it is important these are independent systems).
Woah, that was a long answer! Sorry about that. Hope I got the answer to your question in there
Yes, the military originally had 4 12v batteries for the truck.
Essentially 2 groups of 2 with a 12v center tap:
Each group is 2 12v-batteries in parallel for 12v, 2 of these groups wired in series for the 24v.
The setup here is one 12v-battery in each group (flooded commercial grade 8D size). 2 batteries in series for the 24v.
When you center tap a series pack you must somehow maintain cell balancing for the entire series. The military (and most anyone else who deals with these trucks) doesn't really address the cell balancing. The military puts in a diode polarity protector to prevent damage when the inevitable happens: when the 12v tap draws down one half of the series pack there can be a polarity swap on the 12v side when there's a high current demand on the 24v pack (ie cranking the engine). This can severely damage any electronics on the 12v system.
Acela didn't address the issue either, they tell owners to disconnect the truck batteries if the truck is not running to prevent parasitic draw.
Okay that's the why, here's how we addressed the problem to have a reliable and redundant solution.
There are 12v draws on the battery that we want to maintain while parked: mainly the security system and dash cameras, and occasionally radio coms and lights. Solution 1: There is a solar system dedicated to the truck batteries that charges the series pack at 24v and uses excess solar on sunny days to perform a full cell balancing. Solution 2: The noco charger can be plugged in to the camper and utilize the inverter output to maintain the truck batteries. Because this is a 12v x2 charger it keeps the series pack balanced. We do this if we're stationary for several days without sun or in the shade.
When on shore power we let the noco do it's thing.
When storing the rig, the noco can be plugged in separately to maintain the truck batteries and keep the alarm and cameras on. (For extended storage you don't want to keep the lithium system on shore power charge, so it is important these are independent systems).
Woah, that was a long answer! Sorry about that. Hope I got the answer to your question in there
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@varythings
That's a pretty elegant and fine solution, as you say redundant and multi-use for field and storage. Thank you for sharing.
Did you keep the stock alternator or does it charge at only 24V now or if it puts out the 24v and 12 v just disregard the 12v? Just curious on this idea this is one clever set up.
That's a pretty elegant and fine solution, as you say redundant and multi-use for field and storage. Thank you for sharing.
Did you keep the stock alternator or does it charge at only 24V now or if it puts out the 24v and 12 v just disregard the 12v? Just curious on this idea this is one clever set up.
varythings
Member
varythings
Member
This rig is still available and ready for adventure.
Looking4Boulders
New member
approx mpg@hwy speeds?
varythings
Member
I have good data for mixed driving, see below. Instantaneous highway mpg (displayed on the scanguage) is between 7mpg and 11mpg. You can do better or worse depending on how you drive. We set the cruise control around 60mph on long hauls.
Overall fuel efficiency is 7mpg +/-
With 40,000 miles of data over 30 months, we averaged 7.47 mpg (fully loaded, mixed driving).
varythings
Member
Price drop to $255,000
MsRandiCook
Member
I am surprised not a small AC for the living area.... Any way to add easily?
varythings
Member
The habitat is very well insulated and ventilated so we found that if the outside temperature cooled down at night (like in the desert) we were able to stay very comfortable without an air conditioner.
If you wanted to add AC I think a unit like the Ecoflow Wave would be adequate. Link: Ecoflow Wave
This could easily be placed in the storage garage area and ducted into the living space.
A more complex system like a minisplit could also be added, but that would be more BTU's than is necessary to keep this size habitat cool in my opinion.
If you wanted to add AC I think a unit like the Ecoflow Wave would be adequate. Link: Ecoflow Wave
This could easily be placed in the storage garage area and ducted into the living space.
A more complex system like a minisplit could also be added, but that would be more BTU's than is necessary to keep this size habitat cool in my opinion.
MsRandiCook
Member
I was going through your website and was surprised it didn't have one. Ok, I have to ask, what was the reasoning on the cab color? It's very unique to see a vehicle of this caliber!
Also, how does the toilet work. I think I know, but not sure.
Also, how does the toilet work. I think I know, but not sure.
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varythings
Member
The color was thoughtfully chosen. For daily life of domestic travel as well as boarder crossings we wanted to avoid the "tacticool" aesthetic, we did not want to look like a first responder vehicle, we wanted a friendly color that was not too 'loud'. Perhaps it doesn't translate well in the photos, but in-person we've received a lot of compliments on the color.
There are good reviews online that talk about the function of the Separett Tiny. Basically it's a liquids/solids separation that allows disposal of solid waist into the normal garbage and urine can be disposed of easily. There's active ventilation that exhaust from the toilet to the exterior. We think it's a much better solution than a composting toilet, and is not a disgusting chore to maintain like a cassette toilet can be.
varythings
Member
92" between the large hatches allow easy access from both sides of the box. 36" height is enough to fork-mount most bikes on the floor.
113 cubic feet, very spacious, largest gear storage we've seen in any expedition vehicle of this size.
There's L-track mounting hardware throughout the gear garage. Also, it has heat, ventilation, DC and AC power, LED lights and ambient temperature is displayed on the main control panel.
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Wow, that's a lot of storage for gear and extras! Is there access to the main living area from the gear garage?