Volvo incompetence

[Chiquita1]

I run a 7kw electric drive on a 48 volt system using 4 agm 210 amp batteries. Range at full throttle is 5.1 knots for about 3.5 hrs. At half throttle at 3.5 knots range is 12 hours or 42 nm. If I go cruising I take along a portable 2Kw Honda generator. If I run at half throttle the generator will both run the electric drive and charge the batteries, thus giving me more range than I had with the original Atomic 4.

Although solar and/or wind generators are options for charging, because I still club race, I have yet to put them on my boat, because they would take a beating from my crew. I plug in at the marina and am fully charged within 4 hours.

[TreblePlink]

Originally Posted by Chiquita1

I run a 7kw electric drive on a 48 volt system using 4 agm 210 amp batteries. Range at full throttle is 5.1 knots for about 3.5 hrs. At half throttle at 3.5 knots range is 12 hours or 42 nm. If I go cruising I take along a portable 2Kw Honda generator. If I run at half throttle the generator will both run the electric drive and charge the batteries, thus giving me more range than I had with the original Atomic 4.

Although solar and/or wind generators are options for charging, because I still club race, I have yet to put them on my boat, because they would take a beating from my crew. I plug in at the marina and am fully charged within 4 hours.

I'm having some trouble with the math here; let's say half throttle is 3Kw draw, and the Honda generator is supplying 2Kw maximum. This appears to remain a deficit charging mode, and cannot be sustained, let alone top up the batteries ...

[Three Sisters]

Originally Posted by Pete7

I like the way I can pop into the local Volvo dealer unannounced and pick up a spare part for my 30 year old engine knowing he has it on the shelf. Try that with a Ford motor car.

Pete

Huh ?

[billknny]

Originally Posted by TreblePlink

I'm having some trouble with the math here; let's say half throttle is 3Kw draw, and the Honda generator is supplying 2Kw maximum. This appears to remain a deficit charging mode, and cannot be sustained, let alone top up the batteries ...

When somebody starts talking about solar or wind charging for en electric powered boat you can be pretty sure they don't really understand the power being used... BUT....

When somebody talks about "half-throttle" that's not a very clear term. I'll give the poster the doubt and assume he means 1/2 of full RPM. Remember, a propeller power curve is close to cubic. Power increases with the 3rd power of the rotational speed. So half the rotational speed is no where close to half the power--actually about 1/4. So what he describes is within the real of possibility.

Of course if he really gets 3.5 hours at 7kW, thats 24.5 kW total... to recharge that in a day would talk about 3800 Watts of solar panels. And that's being optimistic...

[kmacdonald]

Originally Posted by TreblePlink

Note to self: Never buy a boat with a Volvo engine.

I think most of problems with Volvos are self inflicted. Lack of proper maintenance. Parts are outrageous but they are rarely needed and all marine diesels are getting that way. If you have a choice, Yanmar or Beta would be a better option IMHO, especially if you are in the US. Location will also play a role in the best choice.

[kmacdonald]

Originally Posted by billknny

When somebody starts talking about solar or wind charging for en electric powered boat you can be pretty sure they don't really understand the power being used... BUT....

When somebody talks about "half-throttle" that's not a very clear term. I'll give the poster the doubt and assume he means 1/2 of full RPM. Remember, a propeller power curve is close to cubic. Power increases with the 3rd power of the rotational speed. So half the rotational speed is no where close to half the power--actually about 1/4. So what he describes is within the real of possibility.

Of course if he really gets 3.5 hours at 7kW, thats 24.5 kW total... to recharge that in a day would talk about 3800 Watts of solar panels. And that's being optimistic...

Agreed. Electric motors are not an option for cruisers.
That said, there a plenty of ships that are diesel electric. Electric propulsion engines driven by diesel generators. I don't know how that would scale down to pleasure boats but I am not aware on any being produced commercially.

[billknny]

Originally Posted by kmacdonald

I think most of problems with Volvos are self inflicted.

Not always... A Volvo story:

A new catamaran was delivered on her own bottom from the factory in France to San Francisco where she was put into charter service. Shortly after delivery one of the saildrive transmissions blew up and needed to be replaced.

Local Volvo dealer says, "These units had SAE30 oil in them. Per the manual, they are only supposed to have ATF. That's why they failed. Warranty claim DENIED." The delivery crew, the boat owner, and the charter service crew all claimed "Not me! We didn't change the transmission fluid!" With no obvious culprit, eventually the bill was split three ways... Of course nobody was happy--except of course the local Volvo dealer.

Fast forward 6 months... An emergency service bulletin from Volvo USA: "Do NOT put ATF in these saildrives! Only use SAE30 oil." It then became clear that the oil was put in these units in France, where they were notified sooner of the "emergency" change by Volvo AB.

An appeal on the warranty claim was filed with Volvo USA--and DENIED.

[kmacdonald]

Originally Posted by billknny

Not always... A Volvo story:

A new catamaran was delivered on her own bottom from the factory in France to San Francisco where she was put into charter service. Shortly after delivery one of the saildrive transmissions blew up and needed to be replaced.

Local Volvo dealer says, "These units had SAE30 oil in them. Per the manual, they are only supposed to have ATF. That's why they failed. Warranty claim DENIED." The delivery crew, the boat owner, and the charter service crew all claimed "Not me! We didn't change the transmission fluid!" With no obvious culprit, eventually the bill was split three ways... Of course nobody was happy--except of course the local Volvo dealer.

Fast forward 6 months... An emergency service bulletin from Volvo USA: "Do NOT put ATF in these saildrives! Only use SAE30 oil." It then became clear that the oil was put in these units in France, where they were notified sooner of the "emergency" change by Volvo AB.

An appeal on the warranty claim was filed with Volvo USA--and DENIED.

That's what law suits are for. A slam dunk triple damage win.

[TreblePlink]

Originally Posted by kmacdonald

[...]
That said, there a plenty of ships that are diesel electric. Electric propulsion engines driven by diesel generators. I don't know how that would scale down to pleasure boats but I am not aware on any being produced commercially.

Diesel locomotives do the same - I understand this arrangement improves low-speed torque.

Question for you marine engineer types on CF: Why is it done on ships?

[newhaul]

Originally Posted by TreblePlink

Diesel locomotives do the same - I understand this arrangement improves low-speed torque.

Question for you marine engineer types on CF: Why is it done on ships?

actually on locomotives it is done for a more basic reason . There is no other way to efficiently put the torque to as many as 16 drive wheels at the same time.
Cruise ships do it for placement of equipment and redundancy . ( you are providing many mw of power to light the ship so it just makes sense to use it for primary propulsion.as well)

[kmacdonald]

Originally Posted by TreblePlink

Diesel locomotives do the same - I understand this arrangement improves low-speed torque.

Question for you marine engineer types on CF: Why is it done on ships?

Electric motors did away with reduction and reverse gears.

[Paul L]

Originally Posted by kmacdonald

I think most of problems with Volvos are self inflicted. Lack of proper maintenance. Parts are outrageous but they are rarely needed and all marine diesels are getting that way. If you have a choice, Yanmar or Beta would be a better option IMHO, especially if you are in the US. Location will also play a role in the best choice.

Did you ever own in a 2000 series Volvo? They have some interesting engineered in issues.

[Seymore]

Originally Posted by TreblePlink

Diesel locomotives do the same - I understand this arrangement improves low-speed torque.

Question for you marine engineer types on CF: Why is it done on ships?

I understand that diesel locomotives do so because it's impossible to design a clutch for this application.

Ships do so for the efficiency. Design a diesel engine for a wide range of speeds. like for automobiles, and it's relatively inefficient. Design it to run at a constant speed and it's much more efficient.

I think so....

[cyan]

Originally Posted by newhaul

you are providing many mw of power to light the ship

Many Many mw

[Chiquita1]

Originally Posted by TreblePlink

I'm having some trouble with the math here; let's say half throttle is 3Kw draw, and the Honda generator is supplying 2Kw maximum. This appears to remain a deficit charging mode, and cannot be sustained, let alone top up the batteries ...

Electric drive graph curve amps to speed, is not linear but rather more exponential. On my system for my boat running a 48 volt system, full throttle draws about 87 amps x 48 volts = 4.1kw. At half throttle I draw 35 amps (x48volts= 1.6 Kw)

As to the 7Kw size reference, vendors take the highest possible rated power of the motor for classifying & sizing reference. Perhaps more correctly they should use the continuous rated power which for my drive is rated at 5Kw. Four fully charged AGM batteries will start at 52V x 87 Amps = 4.5Kw (some loss of efficiencies do occur, prop selection, marine growth on the bottom)

My main reason for posting was to offer a possible vastly reduced maintenance alternative for powering your craft. It may not be for everyone but for inshore cruising and club racing as stated previously it has sure worked for me.

Good sailing!