Amp hours to kWh (for a Tesla guy)

[StuM]

Originally Posted by LoudMusic

I wish we could all go to Wh or KWh since there are beginning to be more 24v boats.

I was watching a Delos video and Bryan kept talking about how many Ah they'd installed and I kept thinking "Wow I expected it to be nearly twice that much". Turns out they use a 24v system. It was twice that much!

And then we get the people with 2 x 6V 200Ah Trojans in series that think they have 400 Ah

[mikedefieslife]

Originally Posted by LoudMusic

I wish we could all go to Wh or KWh since there are beginning to be more 24v boats.

I was watching a Delos video and Bryan kept talking about how many Ah they'd installed and I kept thinking "Wow I expected it to be nearly twice that much". Turns out they use a 24v system. It was twice that much!

Delos weren't great on their technical video about their power. They didn't even set up and install their own LFP bank they had a guy from the UK install "drop in" style batteries for them.

[Frankly]

They do have 400 AH it is just at 6 volts if I put a 12V to 6 V DC to DC converter in the system.


What you describe is an honest mistake, part of the obligation of all of this here is to get them on the right rode/road.

If everybody knew everything, the world would be a miserable place. Discovery is what makes it all worth while.


Frankly

[valhalla360]

Originally Posted by Frankly

Ampere hours is in some ways a meaningless term. It is a piece/ part of an electrical unit that refers to energy. What makes it useful is that we all/ most assume it in reference to a 12 volt system. If your battery bank is 600 AH and mine is 300 AH then a pretty safe bet is yours has twice the energy as mine. Kind of a gentlemen's convenience.

When we include the actual voltage (Volts X Amps X time) now we have a real measure of energy (sometimes referring to storage capacity, sometimes referring to usage).

Because a Tesla has such a large energy storage battery we refer to kilowatt hours whereas for us boat types watt hours is more appropriate. Both indicating energy just differing by a factor of 1000.


Frankly

Correct usage is AH @ V but since for many decades 98% of boats were at 12V, common usage assumed the voltage. With the voltage defined, it's a perfectly acceptable term. Where WH makes sense is if you start shifting between voltages. 24V, 48V, 375V...are all still fairly rare in the boating world.

Teslas don't use AH because they are large battery banks but because they don't use 12V batteries (I believe they are 375V) and it would be confusing for people accustomed to 12V systems unless you get very specific. KWH vs WH are interchangeable and either is perfectly acceptable for reference to either vehicle (many newer cruising boats do have battery banks in the multiple KWH range. Like any other metric unit the kilo- is just a multiplier to avoid having to count zeros. You can legitimately measure a single AAA battery in GWH it's just hard to keep track of the decimal point.

[canyonbat]

Does all this still apply if I am using dilithium crystals as a power source?

[Dockhead]

Originally Posted by LoudMusic

I wish we could all go to Wh or KWh since there are beginning to be more 24v boats.

I was watching a Delos video and Bryan kept talking about how many Ah they'd installed and I kept thinking "Wow I expected it to be nearly twice that much". Turns out they use a 24v system. It was twice that much!

I'm going to defend the use of amp hours here.


I'm a 24v boat, but like most others I think of power in terms of amp hours. In my opinion this is the correct terminology to be used against your battery capacity, which is so specified. Even if it doesn't directly tell you about power -- as has been noted, you need to factor in volts to get that. But we measure current draw in amps, and most of us have ammeters showing the momentary draw on our batteries. We know our battery capacity in amp hours. We have power budgets in terms of amp hours. So it is natural to think in terms of amp hours and I don't think there is anything in the world wrong with it.



When I'm writing about something in amp hours, I always specify "* 24v" so that no one is confused that any figure represents double the power of the same figure for a 12v boat.

[StuM]

Originally Posted by Frankly

They do have 400 AH it is just at 6 volts if I put a 12V to 6 V DC to DC converter in the system.


What you describe is an honest mistake, part of the obligation of all of this here is to get them on the right rode/road.

If everybody knew everything, the world would be a miserable place. Discovery is what makes it all worth while.

Frankly

That's a stretch!

If the batteries are in series, you don't have 6V, you have a 12V system. Ergo 200 Ah. The people making that sort of error never have a "12V to 6V DC to DC converter" in their systems.


Yes, it's a mistake resulting from a lack of understanding of the basics of electricity. AI nd make it a point to try to educate such people.

[StuM]

Originally Posted by Dockhead

I'm going to defend the use of amp hours here.


I'm a 24v boat, but like most others I think of power in terms of amp hours. In my opinion this is the correct terminology to be used against your battery capacity, which is so specified. Even if it doesn't directly tell you about power -- as has been noted, you need to factor in volts to get that. But we measure current draw in amps, and most of us have ammeters showing the momentary draw on our batteries. We know our battery capacity in amp hours. We have power budgets in terms of amp hours. So it is natural to think in terms of amp hours and I don't think there is anything in the world wrong with it.



When I'm writing about something in amp hours, I always specify "* 24v" so that no one is confused that any figure represents double the power of the same figure for a 12v boat.

I agree completely. You may notice that I regularly include "@12V" when using Amps or Amp hours if there is any potential ambiguity about the voltage