Removing alternator on Yanmar 2YM15

J

jeromsam

.
Aug 23, 2018
3
Columbia Carbon 32 60449 Marina Del Rey
Dear all,
I have a race boat, with 2 lithium batteries. I want to keep the weight down and keep the system simple. The boat doesn't require much power (electrical) so I have no need to run the engine to charge the batteries. Being lithium batteries, I have to keep a starter battery on the boat as a "buffer"...Long story short, does anyone know if it ok to run the engine without the alternator, and how? I understand that my engine may actually get 20% extra HP (which I don't really care, but that's a nice gain). I want to remove the starter battery, start the engine with either lithiums, which will also be used as 2 house banks.

Thanks!

Jerome
 
Last edited:
mermike

mermike

.
Nov 21, 2012
598
Yamaha 33 Port Ludlow, WA
Depending on the BMS in your Lithium batteries, you might be able to start the engine, but more likely not. Do you know the max current allowed?
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,674
Canadian Sailcraft 36T Casco Bay, ME
jeromsam said:
Dear all,
I have a race boat, with 2 lithium batteries. I want to keep the weight down and keep the system simple. The boat doesn't require much power (electrical) so I have no need to run the engine to charge the batteries. Being lithium batteries, I have to keep a starter battery on the boat as a "buffer"...Long story short, does anyone know if it ok to run the engine without the alternator, and how? I understand that my engine may actually get 20% extra HP (which I don't really care, but that's a nice gain). I want to remove the starter battery, start the engine with either lithiums, which will also be used as 2 house banks.

Thanks!

Jerome
Click to expand
Your alternator belt drives the fresh water pump on the engine if you physically remove the alternator the engine will overheat.protecting from a BMS load dump needs to be done very carefully and a starting battery can be kept as a buffer., How this is wired is critically important. Be aware that many of these drop in lithium batteries are not designed to start engines. You can destroy the BMS inside them by doing so. Be sure you have batteries/BMS that can handle the inrush current for the starter motor. The inrush current can be six times what the average cranking current is.please read the specifications on your lithium batteries very very carefully. Also be aware that if your batteries are not ABYC TE-13compliant, and many are not, or you may not be insurable

this customer destroyed a drop in lithium iron phosphate battery using it to power his windlass

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J

jeromsam

.
Aug 23, 2018
3
Columbia Carbon 32 60449 Marina Del Rey
mermike said:
Depending on the BMS in your Lithium batteries, you might be able to start the engine, but more likely not. Do you know the max current allowed?
Click to expand
The battery can output 900A peak, then approximately 250A for one minute and 150A continuously.
 
J

jeromsam

.
Aug 23, 2018
3
Columbia Carbon 32 60449 Marina Del Rey
Maine Sail said:
Your alternator belt drives the fresh water pump on the engine if you physically remove the alternator the engine will overheat.protecting from a BMS load dump needs to be done very carefully and a starting battery can be kept as a buffer., How this is wired is critically important. Be aware that many of these drop in lithium batteries are not designed to start engines. You can destroy the BMS inside them by doing so. Be sure you have batteries/BMS that can handle the inrush current for the starter motor. The inrush current can be six times what the average cranking current is.please read the specifications on your lithium batteries very very carefully. Also be aware that if your batteries are not ABYC TE-13compliant, and many are not, or you may not be insurable

this customer destroyed a drop in lithium iron phosphate battery using it to power his windlass

[/IMG]
[/IMG]
Click to expand
Thanks you both so much for the reply. I wasn't sure about the belt driving the fresh water pump (not being at the boat at the moment). The battery can output 900A peak, then approximately 250A for one minute and 150A continuously. With that in mind, is there a way to disable the alternator?
Thanks again.
 
Davidasailor26

Davidasailor26

.
May 17, 2004
5,079
Beneteau Oceanis 37 Havre de Grace
jeromsam said:
I understand that my engine may actually get 20% extra HP (which I don't really care, but that's a nice gain)
Click to expand
The HP consumed by the alternator depends on the amperage it’s putting out, which depends on the batteries’ state of charge. Nigel Calder says to figure that generating 100 amps consumes about 5 HP. That would be a big percentage of your HP, but your alternator is probably nowhere near that size, and depending on your battery use you probably can’t absorb that for very long.
 
TimFromLI

TimFromLI

.
Jan 7, 2014
401
Beneteau 45F5 51551 Port Jefferson
I ran my engine fine without an alternator for a few days. My alternator was in the shop so I bought an Accu-Link belt at HF and made it fit so I would not miss race night. You don't need the alternator but you do need the water pump which is also powered by the same belt. You will need to find a belt that will power your water pump and without the alternator as a "tensioner" not sure how you will get the right tension. The accu-link belt was a temporary solution, I made it tight and held it on the pulley while I had my son crank the engine to pop it on the pulley, then I counted my fingers. I leave it on the boat as a spare to my spare belt. I assume you have shore power to top up your batteries.
 
NYSail

NYSail

.
Jan 6, 2006
3,064
Beneteau 423 Mt. Sinai, NY
As was said, what is the point of disabling / removing the alternator and starting battery? Couldn't be more than 50 lbs all together....
 
JoeWhite

JoeWhite

.
Mar 6, 2008
1,099
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
To remove the counteracting load on the alternator, rather than removing it simply disconnect the cable that supplies current to charge the batteries. Place a 50 AMP switch on this cable so that you can turn it on or off as you need it. Your engine and ignition must be off when using the switch to prevent damage to the alternator. When off the tac may not operate aswell.
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,674
Canadian Sailcraft 36T Casco Bay, ME
JoeWhite said:
To remove the counteracting load on the alternator, rather than removing it simply disconnect the cable that supplies current to charge the batteries. Place a 50 AMP switch on this cable so that you can turn it on or off as you need it. Your engine and ignition must be off when using the switch to prevent damage to the alternator. When off the tac may not operate aswell.
Click to expand
If the alternator is self exciting,many are you can destroy the alternator by doing this.
 
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