New Road Trek Battery Bank...

powderhound

Member
Hey There,

I had a look at a new RT Recently....so nice..so efficient. I noticed the "house batteries" are under the hood and the cranking battery is under the drivers seat. I'm guessing this was V6 model.

My question is, what is Road Trek putting in there late-model Sprinters i.e. - Number of batteries, group size, and total Amp-Hours in the house battery bank and what type of battery chemistry (Wet, Gel, AGM)?

My Wife and I went with an 8D AGM battery from Deka for a total of 245 Amp Hours. We are now questioning the value (if any) of such a spacious battery foot print. In fact, we are questioning the footprint of our entire electrical system when considering a packaged AC/DC load/distribution center like those sold my Progressive Dynamics and WFC.

Thanks for your help,

-Rich

 
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Carolann

New member
The Sprinter based Roadtreks like the RS Adventurous or Agile come standard with two 6 volt AGM batteries, for a total of 220Ah. You can add two more as an option for a total of 440 Ah. The E-Trek (and CS with e-trek option) come standard with eight 6 volt AGM batteries, for a total of 1800Ah. My E-trek has two large 24 volt Lithium Batteries rated at 200 Ah each and a single 12 volt Lithium battery in the engine compartment rated at 200Ah.
 

K-9 SPRINTER

Well-known member
The Sprinter based Roadtreks like the RS Adventurous or Agile come standard with two 6 volt AGM batteries, for a total of 220Ah. You can add two more as an option for a total of 440 Ah. The E-Trek (and CS with e-trek option) come standard with eight 6 volt AGM batteries, for a total of 1800Ah .
:thinking:
You say... it comes standard with two 6 volt AGM batteries, for a total of 220Ah (two 6 volt
You can add two more as an option for a total of 440 Ah. (four 6 volt
..........:hmmm:
So... if you double that (eight 6 volt batteries)..........
........................its 880, NOT 1800
 
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casdclassb144

New member
as you say - 440 for 4 - 880 for 8 , your connecting 2 6 volt batteries in series to = 12 then connecting in parallel

Chuck
SS Agile
SD CA



:thinking:
You say... it comes standard with two 6 volt AGM batteries, for a total of 220Ah (two 6 volt
You can add two more as an option for a total of 440 Ah. (four 6 volt
..........:hmmm:
So... if you double that (eight 6 volt batteries)..........
........................its 880, NOT 1800
 

Uncle Dave

2013 3500
:thinking:
You say... it comes standard with two 6 volt AGM batteries, for a total of 220Ah (two 6 volt
You can add two more as an option for a total of 440 Ah. (four 6 volt
..........:hmmm:
So... if you double that (eight 6 volt batteries)..........
........................its 880, NOT 1800
I was looking at that 1800 number myself. 1800 is a small house sized bank.

seems an error.

UD
 

Carolann

New member
Should be 1600 not 1800. This from their website: "Batteries - auxiliary - AGM deep cycle - eight 6V, 1600 total amp-hrs." I guess that some batteries are just larger than others.
 

chromisdesigns

New member
Should be 1600 not 1800. This from their website: "Batteries - auxiliary - AGM deep cycle - eight 6V, 1600 total amp-hrs." I guess that some batteries are just larger than others.
IIRC, that number is wrong -- there was a discussion about this in several forums when the e-trek was first announced. I believe they are using 200 AH, 6 volt AGM batteries, in which case it's 800 AH total for the bank at 12 volts.

Appears they have an ad copywriter that does not understand electrical systems very well.
 

Carolann

New member
It appears that Roadtrek advertises Ah ratings based on the individual battery size and voltage like the eight batteries in the E-Trek, all 6 volt 200Ah. Maybe they don't convert all to a 12 volt equivalent because in the case of the E-trek only two are used in the 12 volt system. My E-Trek has two large 24 volt lithium batteries, 200Ah each, and they are only used for AC outlets and appliances. They aren't part of the 12 volt system.
 

chromisdesigns

New member
It appears that Roadtrek advertises Ah ratings based on the individual battery size and voltage like the eight batteries in the E-Trek, all 6 volt 200Ah. Maybe they don't convert all to a 12 volt equivalent because in the case of the E-trek only two are used in the 12 volt system. My E-Trek has two large 24 volt lithium batteries, 200Ah each, and they are only used for AC outlets and appliances. They aren't part of the 12 volt system.
Without saying what the system voltage is, it's all apples and oranges. Do you know what voltage the inverter circuit and chargers are on e-trek without the lithium option? Do they still run 24 volt equipment? If so, then with 4 six-volt, 200 AH batteries connected in series, there is still only 200 AH total at 24 volts, of which only about half is actually useable.

In addition, comparing lead-acid and lithium by AH capacity doesn't take into account that the lithium cells can be drawn down much further in percentage terms than lead acids. In your case, with 400 AH of 24v lithiums, you have about as much USEABLE electrical capacity as someone with 1600 AH of 12-volt lead acid batteries (which would be 16 of those 200-amp 6 volt units).
 

Carolann

New member
That was just a wild guess on my part as to how they have it set up. My E-Trek has two 24 volt lithium batteries attached to a 6000 watt inverter in the rear, and under the hood there's another lithium battery, but it's 12 volt. Roadtrek uses a similar layout in their E-treks with 6 volt AGM batteries. Two in the engine compartment, six in a tray at the rear next to a 5000 watt inverter. I see that most everyone here says that amp hours should be calculated at 12 volts, but shouldn't they be calculated based on the output of the battery bank? As in my case, one battery bank outputs 24 volts? In my previous post I pointed out that Roadtrek listed a total amp hour figure of 1600 at 6 volts for the E-Trek. Maybe they did this for simplicity or to avoid confusion. To be precise, If their agm battery setup is similar to mine then they'd have to break it down by battery bank, 400Ah at 24 volts and 200Ah at 12 volts.
 

chromisdesigns

New member
That was just a wild guess on my part as to how they have it set up. My E-Trek has two 24 volt lithium batteries attached to a 6000 watt inverter in the rear, and under the hood there's another lithium battery, but it's 12 volt. Roadtrek uses a similar layout in their E-treks with 6 volt AGM batteries. Two in the engine compartment, six in a tray at the rear next to a 5000 watt inverter. I see that most everyone here says that amp hours should be calculated at 12 volts, but shouldn't they be calculated based on the output of the battery bank? As in my case, one battery bank outputs 24 volts? In my previous post I pointed out that Roadtrek listed a total amp hour figure of 1600 at 6 volts for the E-Trek. Maybe they did this for simplicity or to avoid confusion. To be precise, If their agm battery setup is similar to mine then they'd have to break it down by battery bank, 400Ah at 24 volts and 200Ah at 12 volts.
The problem is that AH capacity is not a measure of energy content or power, unlike watt hours or kilowatt hours. It just tells you how much **current** the battery is capable of delivering at a certain draw rate, over whatever the rating period is (typically 20 hours). The higher the voltage, the more work the same amount of current can do.

To exaggerate for the purposes of clarity, if you had a one kilo-volt battery pack rated 100 AH capacity, it would be capable of delivering 100 KW of power, at least in theory. You could call it a 100KW battery pack, reasonably. In fact, that is typically how electric vehicle battery packs are rated, in KW of capacity.

However, you could have a 12 volt pack, also rated at 100 AH, that could deliver at most 1.2KW of energy over the same time period.

See the difference?

I assume the RT ad copy is just the result of a copywriter not understanding electrics. But if it's "deliberate" on the part of RT, then it's sort of like the old HiFi power wars, where makers were rating their amplifiers at "maximum peak power", even though many of them could only deliver that for a fraction of a second. So a "200 watt" amp might actually be only capable of 20 watts "continuous power", which is the only meaningful measurement of power when discussing amplifiers. It's very deceptive and the same is true of publishing amp-hour ratings without specifying the voltage or total energy capacity of the banks.
 

GeorgeRa

2013 Sprinter DIY 144WB, Portland OR
The problem is that AH capacity is not a measure of energy content or power, unlike watt hours or kilowatt hours. It just tells you how much **current** the battery is capable of delivering at a certain draw rate, over whatever the rating period is (typically 20 hours). The higher the voltage, the more work the same amount of current can do.

To exaggerate for the purposes of clarity, if you had a one kilo-volt battery pack rated 100 AH capacity, it would be capable of delivering 100 KW of power, at least in theory. You could call it a 100KW battery pack, reasonably. In fact, that is typically how electric vehicle battery packs are rated, in KW of capacity.

However, you could have a 12 volt pack, also rated at 100 AH, that could deliver at most 1.2KW of energy over the same time period.

See the difference?



I assume the RT ad copy is just the result of a copywriter not understanding electrics. But if it's "deliberate" on the part of RT, then it's sort of like the old HiFi power wars, where makers were rating their amplifiers at "maximum peak power", even though many of them could only deliver that for a fraction of a second. So a "200 watt" amp might actually be only capable of 20 watts "continuous power", which is the only meaningful measurement of power when discussing amplifiers. It's very deceptive and the same is true of publishing amp-hour ratings without specifying the voltage or total energy capacity of the banks.
Very good explanation, I would add that the common denominator of amphours battery rating in the automotive world is 12V.

A simple table to remember:
100 amphours at 6V = 600 watthour
100 amphours at 12V = 1200 watthour
100 amphours at 24V = 2400 watthour

Connecting 2 batteries in parallel doubles their energy – so two 100 amphours @12 V = 200 amphours @12V or 1200 watthour x 2 = 2400 watthour

Connecting 2 batteries in series doubles their total voltage and energy – so two 100 amphours @6V = 100 amphours @12V or 600 watthour x 2 = 1200 watthour

Amphours and watthours math is the same in Lead Acid or Lithium batteries, the differences is maximum discharge state while keeping batteries healthy and lithium batteries unquestionably lead but they do require carefully engineered charging and discharging schemes.

George.
 

Mein Sprinter

Known member
Very good explanation, I would add that the common denominator of amphours battery rating in the automotive world is 12V.

A simple table to remember:
100 amphours at 6V = 600 watthour
100 amphours at 12V = 1200 watthour
100 amphours at 24V = 2400 watthour

Connecting 2 batteries in parallel doubles their energy – so two 100 amphours @12 V = 200 amphours @12V or 1200 watthour x 2 = 2400 watthour

Connecting 2 batteries in series doubles their total voltage and energy – so two 100 amphours @6V = 100 amphours @12V or 600 watthour x 2 = 1200 watthour

Amphours and watthours math is the same in Lead Acid or Lithium batteries, the differences is maximum discharge state while keeping batteries healthy and lithium batteries unquestionably lead but they do require carefully engineered charging and discharging schemes.

George.
Aye....:thumbup:

cheers....
 

icarus

Well-known member
Just to add a bit to the above. It should also be noted that any give AH capacity battery bank will not deliver that many AH, or at least not very effectively. Discharges below ~ 50%SoC will prematurely kill a battery, and below 50% the ability of the battery to deliver power, especially t higher currrents diminishes quite rapidly.

So when designing a battery bank, gross AH capacity is important, but the more important number is the expected load, the duration, and the total expected draw between charging cycles.

Routinely drawing more than 50% (in the solar world, we try to design for a maximum discharge of ~25%) will lead to shorter battery life.

Icarus
 

chromisdesigns

New member
Just to add a bit to the above. It should also be noted that any give AH capacity battery bank will not deliver that many AH, or at least not very effectively. Discharges below ~ 50%SoC will prematurely kill a battery, and below 50% the ability of the battery to deliver power, especially t higher currrents diminishes quite rapidly.

So when designing a battery bank, gross AH capacity is important, but the more important number is the expected load, the duration, and the total expected draw between charging cycles.

Routinely drawing more than 50% (in the solar world, we try to design for a maximum discharge of ~25%) will lead to shorter battery life.

Icarus
All true for any type of lead acid batteries, but since this was in the context of a discussion of the e-trek, they also offer lithium packs as an option. Most lithium batteries can deliver well over 90% of their rated capacity without harm for 1000's of cycles, as long as the appropriate battery monitoring system is used that keeps track of individual cell voltages.
 

casdclassb144

New member
ok, Would a fair judgement be ? 2 6 volt AGM batteries 210 AH in series = 12 volts you could run 100 watts for 20 hours but at to be safe 10 hours = 50 %

so 10 - 6 volt agm 210 AH batteries in series would supply approximately 500 watts for 10 hours for 50 % discharge

My Magnum Hyrbrid manual actually says to recharge at 80% discharge, I imagine this is lead acid and not AGM , To be safe I would set my generator to turn on at 60 % I guess

Chuck
Roadtrek SS Agile Modified
SD CA


All true for any type of lead acid batteries, but since this was in the context of a discussion of the e-trek, they also offer lithium packs as an option. Most lithium batteries can deliver well over 90% of their rated capacity without harm for 1000's of cycles, as long as the appropriate battery monitoring system is used that keeps track of individual cell voltages.
 

chromisdesigns

New member
ok, Would a fair judgement be ? 2 6 volt AGM batteries 210 AH in series = 12 volts you could run 100 watts for 20 hours but at to be safe 10 hours = 50 %

so 10 - 6 volt agm 210 AH batteries in series would supply approximately 500 watts for 10 hours for 50 % discharge

My Magnum Hyrbrid manual actually says to recharge at 80% discharge, I imagine this is lead acid and not AGM , To be safe I would set my generator to turn on at 60 % I guess

Chuck
Roadtrek SS Agile Modified
SD CA
Right, basically you don't want to cycle any lead-acid deep cycle battery, whether flooded, gel, or AGM to more than 50% discharge on a regular basis. Many will tell you even that's too low, but remember you trade off useful capacity for battery life. They will last much longer if you keep them above 75%, but then you only have a quarter of the rated capacity available. You pays your money and takes your choice!
 

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