Battery Terminal Short-Circuit Protection

[Maine Sail]

I have been asked numerous times what the rules are about protecting battery terminals and how I do this. A lot of my images do not show them because I may be trying to show physical wiring connections.

#1 If the battery is in its own dedicated compartment, separated from the rest of the vessel, this compartment can count as your terminal protection.

#2 If your batteries are in protective battery boxes, with lids, this can count as your terminal protection.

#3 If the batteries are not in a dedicated locker or do not have battery boxes, AGM's don't require acid containment, then you should protect the terminals with "terminal hats", as I call them, "cable caps" or "terminal boots" as they are most often refereed to.


To most boaters this would be a good complete battery installation. It is not;

For batteries with this type of bolt terminal I use this type of terminal hat:

This is how they come out of the package:

One trick I do is to slit the bottom side so the hats can be taken on/off without needed to fit them over the cable ends. Most cable hat makers have totally forgotten that adhesive shrink wrap makes the cables bigger near the terminal thus a terminal hat for 2/0 wire does not slide over 2/0 wire once properly sealed.

For series or parallel wiring fit the hat and then mark where the series or parallel cable will exit the hat. Make two slits the width of the cable:

The exit flap you just made creates an excellent place for another wire tie:

An installation is not complete until the battery is well secured, acid containment is in place (for flooded batteries), cables are labeled, cables are well secured, terminals use locking washers or nyloc nuts & the terminals are protected via numbers 1-3 above.

This bank is in its own dedicated battery compartment thus it is not required to use terminal hats. You can always add them, if you wish, for additional protection.

If you are utilizing MRBF fuses, and lack sufficient stud length for good cap grip, I find it best to physically wire tie the hat onto the fuse.

Not all terminal hats will work for all batteries so choose what works best for your banks.. On this boat (negatives disconnected & secured for winter storage) you can see that the start battery uses one type of hat and the 4D battery utilizes another type.

Note: I usually use 1" or 1.5" river raft / kayak straps (source NRS) for battery hold downs and stainless steel footman's loops by Hayn or Suncor for securing the batteries in place. I do not and will not use plastic footman's loops or the cheesy straps that come with plastic battery boxes.

 

[edcarter517]

Comment

Excellent review and presentation.

 

[Jim 5757]

hey, thanks for the detailed pix! I've often thought about what'd happen to the batteries if we were to be knocked down. Definitely food for thought!

 

[Maine Sail]

hey, thanks for the detailed pix! I've often thought about what'd happen to the batteries if we were to be knocked down. Definitely food for thought!

I think the better question is what happens to those cheesy plastic footman's loops and the crappy sub standard plastic buckle battery straps, that we see on thousands of boats, when you actually need them to work?

 

[Dan_Y]

Maine-
Your consistently high level of craftsmanship is inspiring and comparable to fine art!

 

[pieyed]

I'd go down to my local tire shop and pick up an old inner tube (free), cut two bands from it about 4" wide, stretch each band around the the battery and over a post, call it good. It is cheap, a lot easier, and just as effective. HTH JD

 

[The Garbone]

Good stuff.

I think the better question is what happens to those cheesy plastic footman's loops and the crappy sub standard plastic buckle battery straps, that we see on thousands of boats, when you actually need them to work?

My motor has resided in my garage for the past year and with it the start battery and its box. I have toted the start battery out to the lawn mower ( I really should get a new battery for it) in its box using said sub standard strap as a handle about once a week and it has held up fine. Of concern is the metal component of your tie down. Somebody gets a little inattentive and leaves one loose and you now have a metal buckle adrift in your battery space.

 

[Maine Sail]

Good stuff.



My motor has resided in my garage for the past year and with it the start battery and its box. I have toted the start battery out to the lawn mower ( I really should get a new battery for it) in its box using said sub standard strap as a handle about once a week and it has held up fine. Of concern is the metal component of your tie down. Somebody gets a little inattentive and leaves one loose and you now have a metal buckle adrift in your battery space.

In my experience, over many hundreds of vessels, perhaps no other item has as high a failure rate as the chintzy battery straps and plastic footmans loops. A solid 40%+ of the plastic footman's loops I come across are cracked and a solid 55-60% of the straps have broken buckles. If they don't have broken buckles the owner could not figure out how to secure/lace them, and did it wrong, so the battery is no longer secured anyway. Heck the vast majority of batteries I come across, using the straps that come with battery boxes, are not secured in anyway what so ever..

If someone can find me a plastic cam buckle that can be cinched easily, won't fail or become brittle and is as bullet proof as the NRS/Ancra type buckles please do. Currently I have found no more durable, easy to use or robust battery strap than the river raft straps that use the Ancra type cam buckle. I have used them on my vehicles for multiple winters in the North East getting pounded with road salt and have yet to have one fail.

I am also not concerned about the buckle in the battery space as it can not contact both terminals simultaneously. Also once I install the batteries there is often no need for the owner to remove the straps.. Because these straps are so easy to use you would really need to fudge it up to have a loose buckle...

 

[CarlN]

Mainsail,

So what do you think of that Firefly battery pictured? - besides the snazzy paint scheme

Are they an reasonable option for a house bank if you want to give lithium batteries a little longer to mature?

Carl

 

[Maine Sail]

Mainsail,

So what do you think of that Firefly battery pictured? - besides the snazzy paint scheme

Are they an reasonable option for a house bank if you want to give lithium batteries a little longer to mature?

Carl

Carl,

I tested a whole slew of AGM batteries over about a 5 month period under a PSOC operation (partial state of charge) test protocol for Practical Sailor (see May 2015 issue) and the Firefly certainly was the stand out winner in terms of fending off the effects of sulfation. Based on those tests and seeing it for myself I will likely be installing a lot of them. Nigel is also using the Firefly on his own boat and been very happy. He never went above 80% SOC all last year and at the end of the season they revovered 100% of their as new capacity. He is so confident in them that he left them at 50% SOC while on the hard in Scottland and came home to Maine. I am waiting for an email to see how they recovered from that abuse.. If they do this could be a lead acid game changer as most any other lead acid battery, sitting at 50% SOC for 6 months, is a goner....

I can't speak to long term projections but the PSOC test we set up should be a good predictor of future performance for boats where PSOC operation is the reality. The batteries are not cheap by any means, about $425.00 for a Group 31, and case sizes are limited, but for me they bridge a gap between AGM acceptance performance, GEL cycle life and still lead acid so a drop in replacement is easy. This is a small company and demand is currently slightly ahead of production so they can be a bit tough to get.

Like any batt only time will tell but I think these should easily outlast most current AGM's on a boat where PSOC use is a realty.

I will still install Lifeline & Odyssey too depending upon boat owner budget....

Oh and the reserve bank on my own boat will be a Firefly by Saturday....

 

[Charles Erwin]

You can make these straps and obtain genuine Ancra 1" cam buckles from many places. That way you can be sure to get polyester webbing which is acid resistant - and the straps will fit instead of having to account for too long tails.

We actually use them for raft trips - but I row McKenzie boat instead of a raft.

Charles

 

[Maine Sail]

You can make these straps and obtain genuine Ancra 1" cam buckles from many places. That way you can be sure to get polyester webbing which is acid resistant - and the straps will fit instead of having to account for too long tails.

We actually use them for raft trips - but I row McKenzie boat instead of a raft.

Charles

I have thought about making them myself and I also found some stainless cam buckles but for what NRS charges for a 1.5" 2000 pound rated polypropylene strap that has dual SS springs in the cam buckle, it is just a lot easier & cheaper labor wise, to order them through NRS or pick them up at Hamilton Marine. No matter what size I buy I am always trimming them to the correct length... I have also soaked these straps in battery acid with no noticeable degradation...

 

[Charles Erwin]

Stainless buckles are $7 each whereas the standards are $2. So one could give a customer 3 straps for the price of one stainless.

You could embroider "Compass" on every one, go with standard buckle alloy, and still make out.

Oh and by the way - I never had one quit on me in countless battery tie downs in trucks, boats, cars and just about anything else that moves using standard buckles.

Charles

ps I promise not to digress further.

 

[Maine Sail]

Mainsail,

So what do you think of that Firefly battery pictured? - besides the snazzy paint scheme

Are they an reasonable option for a house bank if you want to give lithium batteries a little longer to mature?

Carl

Firefly Battery UPDATE!!

Carl,

I just got an email from Nigel this morning about his Firefly batteries and this is the summary.

Last August he discharged his Firefly bank to 38% SOC and came home to Maine. After 9 months at 38% SOC he arrived on the boat a few days ago, charged the batts, cycled them a bit, and then capacity tested them at the C/20 rate. They were charged at 14.4V and this voltage simply held over night. Nothing really special he just held them a bit longer at absorption voltage. They are 110 Ah rated batteries and after sitting at 38% SOC since last August (NINE MONTHS) as of yesterday May 20th 2015 they delivered 110Ah's of capacity!!!!

Wow!!!!! I am sure I don't need to explain that this type of abuse would have been guaranteed death for any other lead acid battery....

So yes I will continue to install these batteries even if they are a bit pricey...

 

[Solstice]

Firefly Battery UPDATE!! Carl, I just got an email from Nigel this morning about his Firefly batteries and this is the summary. Last August he discharged his Firefly bank to 38% SOC and came home to Maine. After 9 months at 38% SOC he arrived on the boat a few days ago, charged the batts, cycled them a bit, and then capacity tested them at the C/20 rate. They were charged at 14.4V and this voltage simply held over night. Nothing really special he just held them a bit longer at absorption voltage. They are 110 Ah rated batteries and after sitting at 38% SOC since last August (NINE MONTHS) as of yesterday May 20th 2015 they delivered 110Ah's of capacity!!!! Wow!!!!! I am sure I don't need to explain that this type of abuse would have been guaranteed death for any other lead acid battery.... So yes I will continue to install these batteries even if they are a bit pricey...

Maine,
Given this real world feedback as well as your article, it occurs to me that given these batteries break the 50% SOC rule of thumb, then you actually get more useable AHs per battery?
I've been trying to get as close to 400 AH into a space that is custom sized for 2 4Ds plus 1.75" of additional height. Trying to get away from 4Ds, but my default will be LLs if I can't make G31s work. However the FF may be my salvation??

 

[Maine Sail]

Maine,
Given this real world feedback as well as your article, it occurs to me that given these batteries break the 50% SOC rule of thumb, then you actually get more useable AHs per battery?
I've been trying to get as close to 400 AH into a space that is custom sized for 2 4Ds plus 1.75" of additional height. Trying to get away from 4Ds, but my default will be LLs if I can't make G31s work. However the FF may be my salvation??

Yes 3 of them would be 330 Ah's and at 80% DOD you'd have 264 usable Ah's keep in mind though you're still only getting back to about 85% SOC (they are still lead acid) so the real "usable capacity" is about 65% of 330Ah's or 214.5 Ah's when off cruising and cycling between 20% SOC and 85% SOC. It would take a 610 Ah bank of standard lead acid batteries at 50% cycle depths to equal what the Firefly can do at 80% DOD.

Certainly makes the cost perspective a bit better too.....

 

[Solstice]

Yes 3 of them would be 330 Ah's and at 80% DOD you'd have 264 usable Ah's keep in mind though you're still only getting back to about 85% SOC (they are still lead acid) so the real "usable capacity" is about 65% of 330Ah's or 214.5 Ah's when off cruising and cycling between 20% SOC and 85% SOC. It would take a 610 Ah bank of standard lead acid batteries at 50% cycle depths to equal what the Firefly can do at 80% DOD. Certainly makes the cost perspective a bit better too.....

Sounds like I have a solution! The reason I am looking at 400 AH is because I try not to get below 70% and based on my amp requirements, that gets me 2 days before running the engine. We are usually out for two weeks at a time and hooked up to shore power the rest of the time. Also need to talk to him about solar panels...thanks Maine!