Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 05-01-2015, 15:13   #31
Marine Service Provider

Join Date: May 2011
Location: PDX
Boat: Gulfstar 50
Posts: 895
Re: Need dedicated starting battery?

So the primary issue is space (and thus size of the house bank).

Odd thing happened this last summer....

We were tied to a remote dock -

The dedicated start battery was old and gave up the ghost after 8 years use. It would not start the engine (4.236 perkins).

No problem just switch in the house bank. Ah, but of course the house bank was old and I just wanted it to last till the end of the season. Ran the fridge and lights fine but would not start the engine. (4 T105s)

Oh ****....

With luck I has a fresh windlass battery that I un hooked and brought back to the engine room which started the engine.

of course you say - doom on me - I was running with batteries that I knew to be at end of life and got caught.

But, I say to you that a dedicated start battery is not about having a way to start your engine when the house battery is fine. It is about starting your engine when the house cannot.

The upshot is that I new have a new agm for starting and 700 AH LiFePO4 house and the "old" lead acid for the windlass. Charging is set to 13.8 bulk, 13.2 float for the house bank.

At some point the windlass battery will become AGM (or perhaps LiFePO4).

Charging of the start and windlass is sourced via a small inverter driven 10 amp charger and echo charge for isolation. (still thinking that through) This is manually activated.

Actual draw for the start battery is around an AH or 2 depending on the cranking time. The windlass is up to 5 AH consumed.
__________________

__________________
evm1024 is offline   Reply With Quote
Old 05-01-2015, 15:22   #32
Senior Cruiser
 
colemj's Avatar

Cruisers Forum Supporter

Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,049
Images: 12
Re: Need dedicated starting battery?

Quote:
Originally Posted by evm1024 View Post
But, I say to you that a dedicated start battery is not about having a way to start your engine when the house battery is fine. It is about starting your engine when the house cannot.
But your example was of a dead start battery?

Actually, the only lesson I can take away from your misfortune is to not trust batteries that you know are at their end of life.

The necessity of a dedicated start battery is not born out by your example.

Changing the subject, I am interested in how you are charging mixed chemistries. I understand the 13.8V for the LiFePO, but is that also the charging voltage on the AGM? Also, I though Li was not supposed to be float charged?

Edit: oops, I think you added a bit more to your post while I was writing mine.

Mark
__________________

__________________
www.svreach.com

You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Old 05-01-2015, 15:57   #33
Marine Service Provider

Join Date: May 2011
Location: PDX
Boat: Gulfstar 50
Posts: 895
Re: Need dedicated starting battery?

Quote:
Originally Posted by colemj View Post
But your example was of a dead start battery?

Actually, the only lesson I can take away from your misfortune is to not trust batteries that you know are at their end of life.

The necessity of a dedicated start battery is not born out by your example.

Changing the subject, I am interested in how you are charging mixed chemistries. I understand the 13.8V for the LiFePO, but is that also the charging voltage on the AGM? Also, I though Li was not supposed to be float charged?

Edit: oops, I think you added a bit more to your post while I was writing mine.

Mark
My example was of SNAFU - FOOBAR - TARFU and that having a good battery that was just sitting around saved the day. Of course I should have had a good start battery, of course I should have had a good house bank. And of course if nothing goes wrong (human error or otherwise) you only need one bank.

My example was of a real world event where human error trumped and a spare battery (dedicated windlass) saved the day, or at least a long dinghy ride.

Not to hijack the thread. The LiFePO4 is the main bank and fed with 13.8 in bulk mode and then 13.2 in absorbtion/float. 13.2 v is below the resting voltage of a LiFePO4 bank and thus current is supplied (for the most part) by the LiFePO4 bank and not charging it. This is per MaineSail's recommendation.

The start and windlass batteries are both fed from a 10 amp trucharge battery charger and echo charge for isolation between the 2 batteries. The charger is powered by the main inverter and is manually activated. Not a well thought out configuration for automatic use.

An improvement would be to get a small sine wave inverter and only power it when the engine is running. Let the small charger and echo charge handle the charging profile for the AGM and LA batteries. I should add that this is built from what I had lying around.

The point about the Ah draw for the start and windlass batteries is that they would typically consume less than 5 Ah total and are quickly restored to full charge even with the 10 amp charger and the losses in the inverter, etc.

As MaineSail said (and place any errors, mis-statements on my shoulders) the trick is to get the AGM fully charged once in a while.

As a side note I'm playing around with using a HP Proliant 60 amp 12 V supply for charging the LiFePO4 bank. Other areas I'm looking at is to make a 16 v charge bus and use point of need charger converter at each battery bank. But that is for a different thread.
__________________
evm1024 is offline   Reply With Quote
Old 05-01-2015, 18:16   #34
Registered User
 
malbert73's Avatar

Join Date: Jun 2008
Boat: Tartan 40
Posts: 1,032
Re: Need dedicated starting battery?

Thanks everyone. Much food for thought.

My engine starter circuit fgoes through a 1-2-both switch. What if 1 is 315 Ah house bank (3 AGM house banks) and 2 is generator start battery as backup? That way I don't have to rewire engine alternator output to the generator battery. I'll make sure generator battery is sized appropriately.
My Yanmary 4jhe has always fired with less than 1 second of crank. Does anyone think that this short burst of draw will affect that size house battery bank, or will draw down voltage enough to affect basic electronics?

Sounds like most people here's main concern is having a backup starter battery rather than any problem with using adequate house bank to start engine.



Mike


Sent from my iPad using Cruisers Sailing Forum
__________________
malbert73 is offline   Reply With Quote
Old 05-01-2015, 22:28   #35
Registered User
 
Agility's Avatar

Join Date: Sep 2006
Location: Colorado
Boat: Chris White A47 Mastfoil
Posts: 310
Images: 6
Re: Need dedicated starting battery?

I just spec'ed my new project with a LiFePO4 house bank and no starter alternators or start batteries. If I lose my house bank, which I never did in years or cruising, I'll wait for the solar or wind power to charge the house bank.

No alternators and no start batteries and no extra cabling and parallel switch save my considerable weight and enough to buy an extra house battery to increase the house capacity by 50%.
__________________
Agility is offline   Reply With Quote
Old 05-01-2015, 23:45   #36
Registered User
 
Suijin's Avatar

Join Date: Feb 2013
Location: Annapolis MD; currently in Oriental NC
Boat: Valiant 40
Posts: 2,912
Re: Need dedicated starting battery?

The old way was that you'd have two banks and alternate use of them. Then the new way came along with dedicated starter batteries.

I think the old way faded out because of too many stories of people turning the switch through the off position while the engine was running and toasting the diodes on their alternators. A separate start battery is a more idiot proof arrangement. And we can all be idiots sometimes, or have someone inadvertently do a bad thing on our boats.

That said, I have two house banks and I'm in no great hurry to reconfigure. I don't use a lot of juice on my boat, and the size of each bank lends itself to a good depth of discharge and recharge cycle. I will, however, likely add an automatic voltage relay somewhere down the road when I get around to it.
__________________
Suijin is offline   Reply With Quote
Old 06-01-2015, 01:36   #37
Registered User
 
DumnMad's Avatar

Join Date: Mar 2012
Location: Nelson NZ; boat in Brisbane
Boat: 45ft Ketch
Posts: 1,247
Re: Need dedicated starting battery?

Interesting thread.
We have a separate starter battery, large house bank, two alternators and a spare starter motor.(which I haven't tested yet.)

How many have a spare starter motor?
__________________
DumnMad is online now   Reply With Quote
Old 06-01-2015, 06:51   #38
Senior Cruiser
 
colemj's Avatar

Cruisers Forum Supporter

Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,049
Images: 12
Re: Need dedicated starting battery?

Quote:
Originally Posted by Suijin View Post
the size of each bank lends itself to a good depth of discharge and recharge cycle.
This is actually bad for battery life.

Mark
__________________
www.svreach.com

You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Old 06-01-2015, 06:52   #39
Senior Cruiser
 
colemj's Avatar

Cruisers Forum Supporter

Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,049
Images: 12
Re: Need dedicated starting battery?

Quote:
Originally Posted by DumnMad View Post
How many have a spare starter motor?
We have an entire spare engine!

Mark
__________________
www.svreach.com

You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Old 06-01-2015, 07:05   #40
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Need dedicated starting battery?

Quote:
Originally Posted by Agility View Post
I just spec'ed my new project with a LiFePO4 house bank and no starter alternators or start batteries. If I lose my house bank, which I never did in years or cruising, I'll wait for the solar or wind power to charge the house bank.

No alternators and no start batteries and no extra cabling and parallel switch save my considerable weight and enough to buy an extra house battery to increase the house capacity by 50%.
Wow, on so many levels........
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 06-01-2015, 07:44   #41
Registered User
 
Agility's Avatar

Join Date: Sep 2006
Location: Colorado
Boat: Chris White A47 Mastfoil
Posts: 310
Images: 6
Re: Need dedicated starting battery?

Although it is a cat with two high output balmar alternators for the house back so we have a fair amount of redundancy.


Sent from my iPhone using Cruisers Sailing Forum
__________________
Agility is offline   Reply With Quote
Old 06-01-2015, 08:25   #42
Registered User
 
Exile's Avatar

Join Date: Sep 2010
Location: Land of Disenchantment
Boat: Bristol 47.7
Posts: 2,961
Re: Need dedicated starting battery?

Maine Sail -- I recall a short video you made awhile back showing how little draw there is on house batts. when using them to start an engine. Although I see the merit in having a dedicated engine start batt., your vid seems to bode well for what the OP is trying to do.

I have a similar set-up, with an entire 225ah 8D dedicated solely to starting my 80hp Westerbeke. Seems wasteful, and one of these days I'd like to parallel it in to my other two 8D's which comprise my house bank. The challenge for me it seems is making sure my 2 alternators continue to properly charge the 3 batts. in the new configuration.
__________________
Exile is offline   Reply With Quote
Old 06-01-2015, 08:49   #43
Don't ask if you can't handle it
 
sailorboy1's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: On the boat somewhere
Boat: Hunter 410
Posts: 12,312
Re: Need dedicated starting battery?

My house battery will start my engine just fine. I know because I once left the start battery switch off after doing some electrical work and started the engine because the house bank feeds into a common line (the start battery can not feed the house if the breaker is off). I don't really even know if the start battery itself is good and can start the engine since if if it is low the house would just do it.

So my vote is to just combine the batteries.
__________________
jobless, houseless, clueless, living on a boat and cruising around somewhere
sailorboy1 is offline   Reply With Quote
Old 06-01-2015, 08:57   #44
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29 49.16 N 82 25.82 W
Boat: Pearson 422
Posts: 12,379
Re: Need dedicated starting battery?

Quote:
Originally Posted by Exile View Post
Maine Sail -- I recall a short video you made awhile back showing how little draw there is on house batts. when using them to start an engine. Although I see the merit in having a dedicated engine start batt., your vid seems to bode well for what the OP is trying to do.

I have a similar set-up, with an entire 225ah 8D dedicated solely to starting my 80hp Westerbeke. Seems wasteful, and one of these days I'd like to parallel it in to my other two 8D's which comprise my house bank. The challenge for me it seems is making sure my 2 alternators continue to properly charge the 3 batts. in the new configuration.
Maybe playing with semantics here but starting an engine is a very large current draw, say 100-150 amps for a typical sailboat engine. However, the total amp hours used from your battery is not much since the draw only lasts for a few seconds.

Another issue is the voltage. Even if you have a huge house bank with lots of amp hours, if the bank is partially discharged and voltage is low you might have trouble starting the engine. Also I don't think it's good for the long term health of a starter motor to run it on low voltage.

I do agree that an 8D is not the best fit for starting your engine. Something smaller rated for cranking instead of deep cycle would be much better.
__________________
The water is always bluer on the other side of the ocean.
skipmac is offline   Reply With Quote
Old 06-01-2015, 09:01   #45
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 3,060
Re: Need dedicated starting battery?

Quote:
Originally Posted by Agility View Post
Although it is a cat with two high output balmar alternators for the house back so we have a fair amount of redundancy.


Sent from my iPhone using Cruisers Sailing Forum
Ah that makes more sense. Still with all the ways LFP can go awry a small reserve bank is a decent idea...
__________________

__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Reply

Tags
battery

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
High Amp Alternator - Dedicated Double Pulley Belt dadidoc Electrical: Batteries, Generators & Solar 48 28-10-2011 06:34
Charging a Dedicated Starter Battery and House Bank Ericsn25Chespk Electrical: Batteries, Generators & Solar 8 02-09-2010 08:44
Dedicated Electronics Battery ? Healer52 Marine Electronics 4 08-07-2010 05:53
Dedicated Genset Start Battery Questions Hyprdrv Electrical: Batteries, Generators & Solar 13 01-02-2010 04:25
dedicated starting battery salty_dog_68 Electrical: Batteries, Generators & Solar 8 24-01-2007 10:31



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 02:21.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.