Battery Size

[NYSail]

Hello all,

Quick one here... what is the smallest battery one can use as a back-up / starter battery. Have a large house bank of 3 group 31 and #2 and want to just an adequate spare for bank #1. I have a Yanmar 3HM35F... no glow plugs or preheater

Thanks

 

[Maine Sail]

Hello all,

Quick one here... what is the smallest battery one can use as a back-up / starter battery. Have a large house bank of 3 group 31 and #2 and want to just an adequate spare for bank #1. I have a Yanmar 3HM35F... no glow plugs or preheater

Thanks

Any of the small form factor car batteries will work...

 

[Steve Dion]

Take a look at the Optima. We have one for our dedicated starter.

 

[Warren Milberg]

Group 24.

 

[Benny17441]

I use one of those rechargeable automotive battery packs with jumper clamps and it starts the diesel quite well. They are meant to be used as boosters in automobiles but are able to start the small auxilliary diesel by itself if need be.

 

[NYSail]

Thanks all

I do have and always carry an emergency jumper. Just wanted a fixed dedicated back-up to the house in case I drain down to far to start. I bought 3 Group 31 AGM's last season that are my house. Group 24 sounds good for a back-up....

Thanks

 

[Maine Sail]

Hello all,

Quick one here... what is the smallest battery one can use as a back-up / starter battery. Have a large house bank of 3 group 31 and #2 and want to just an adequate spare for bank #1. I have a Yanmar 3HM35F... no glow plugs or preheater

Thanks

BTW I just finished a conversion on a 36-2 a few weeks ago. Owner wanted a 400+/-Ah house bank and a "reserve" bank of 160-200Ah...

He got two Trojan L16's in the lazarette:

And two group 31's in the factory battery box location:

The factory location was simply too small for the capacity he wanted..

 

[Benny17441]

Why for backup? If you are installing a Group 24 starter battery why don't you just dedicate it to the starter circuit and relieve the house bank from such duty. Nice house bank. I bet those 3 Group 31 when deeply discharge could probably suck the power out of a group 24 before you hit the starter button. It is better to exercise a battery rather than just let it sit around between charges.

 

[NYSail]

Maine, I put the 2 extra batteries behind the factory battery location where the factor waste bladder was. One stands up perfect... the other on a slight angle. Another reason for the AGM's from Sams! I removed the bladder when bought the boat and put a regular tank in the lazarette.... so that area has been vacant. Better holding tank set up as well in my opinion. Benny, rather than rewire I figure if I ever do need the spare I will switch to 1 and not to both.... I understand the drain that would cause. I never get in a situation where the house is drained so much it wont start off house.... The 24 is just in case. But let me ask this... if I were to use "Both" all the time with 3 31's and a 24 what affect would that have on the 24? Thanks all for the input!