Why two batteries are a good idea

boristhebold · 26 July 2010, 12:49

Returned from a week in Devon last weekend so decided to take my rib out for a spin on Sunday as I had been having withdrawal symptons. All was going well until shortly after going through Poole Harbour Entrance the electronics started playing up, VHF buzzed loudly and died, then the GPS went down, then the sterio system started sounding strange, then the engine started misbehaving, noticed the battery indicated was showing around 12.2V when usually it shows 13.8V. Shut everything off once out of traffic and switched to my second battery and everything came back fine. So I strongly expect my first battery which is old (had second fitted with a switch last year when I bought the RIB) needs retiring.

I am so very glad I had the second battery fitted.

MarkWildey · 26 July 2010, 12:55

Have suffered that myself a couple of times over the years and it's always nice when the backup plan works!

HUMBER P4VWL · 26 July 2010, 13:12

glad it worked. though curious as to why you only use one when out and about.

We have two, but run on both when out and about, then switch to one when we leave the boat. Then both get fully charged when out and about and when we leave it, if the bilge sticks for example and flattens the battery, we have the other to start up the engine and charge them both again.

Just a thought. Though there are many ways to skin a cat.

Cookee · 26 July 2010, 13:23

Quote:

Originally Posted by boristhebold

Returned from a week in Devon last weekend so decided to take my rib out for a spin on Sunday as I had been having withdrawal symptons. All was going well until shortly after going through Poole Harbour Entrance the electronics started playing up, VHF buzzed loudly and died, then the GPS went down, then the sterio system started sounding strange, then the engine started misbehaving, noticed the battery indicated was showing around 12.2V when usually it shows 13.8V. Shut everything off once out of traffic and switched to my second battery and everything came back fine. So I strongly expect my first battery which is old (had second fitted with a switch last year when I bought the RIB) needs retiring.

I am so very glad I had the second battery fitted.

I would check the wiring, especially the earth and have the battery checked at a garage or similar before spending any money - you never know!

boristhebold · 26 July 2010, 14:54

Quote:

Originally Posted by HUMBER P4VWL

glad it worked. though curious as to why you only use one when out and about.

We have two, but run on both when out and about, then switch to one when we leave the boat. Then both get fully charged when out and about and when we leave it, if the bilge sticks for example and flattens the battery, we have the other to start up the engine and charge them both again.

Just a thought. Though there are many ways to skin a cat.

Mark - I use battery 1 on one weekend and battery 2 on the next weekend, dont ask me why, I think I do it so I could tell if one battery went bad and obvisouly every other weekend one gets charged off the engine. Im sure there is some logic in that but cant pinpoint it. laughing out loud. Hey it worked, if both had been used I may not have spotted the bad one until too late as they are not connected to any seperate battey monitors.

willk · 26 July 2010, 15:32

Cookee is right - test your battery and cables first. I'd physically swap the batteries over and see if the problem moves, a handy, free test.

A thorough wiring check is essential in these situations.

jyasaki · 26 July 2010, 15:49

Quote:

Originally Posted by HUMBER P4VWL

glad it worked. though curious as to why you only use one when out and about.

Just a thought. Though there are many ways to skin a cat.

There are indeed.

Personally, I usually try to run on one battery on the way out, and the other on the return. The only time I have the switch set to BOTH is when one battery has trouble cranking the motor (the batteries are slightly undersized per Yammie's specs.)

I usually pop them on a 6 amp charger for an hour or two prior to leaving home.

Works for me.

jky

Mollers · 26 July 2010, 16:04

Maybe a Devon Pikey nicked the elecerric.

Bedajim had a about 5mm of wear material nicked off of his clutch plate whilst down there this weekend.

HUMBER P4VWL · 26 July 2010, 16:09

All make sense. Beauty of the forum, you learn what different people do and why, then apply the best logic to your own circumstances/needs.

Happy boating!!

BruceB · 26 July 2010, 16:45

I have two batteries operating via a VSR so no switching and batteries are always both fully charged and drain protected.
Worked fine for over two years now and never had a problems with batteries.

Hightower · 26 July 2010, 20:35

I run both my batteries together (as one large battery). During pre flight checks I check the voltages seperatly just to compare the condition of each of them. Then if anchored up and using depth gauge, radio, GPS etc I then switch back to one battery, keeping the other as an emergancy starter one if needed.

I like to keep things really simple, so don't have any VSR.

Searider · 26 July 2010, 22:04

Quote:

Originally Posted by BruceB

I have two batteries operating via a VSR so no switching and batteries are always both fully charged and drain protected.
Worked fine for over two years now and never had a problems with batteries.

Me too.

BruceB · 26 July 2010, 22:59

Quote:

Originally Posted by Hightower

I run both my batteries together (as one large battery). During pre flight checks I check the voltages seperatly just to compare the condition of each of them. Then if anchored up and using depth gauge, radio, GPS etc I then switch back to one battery, keeping the other as an emergancy starter one if needed
I like to keep things really simple, so don't have any VSR.

I switch on and leave on all day, the VSR does all the above for me. I personally decided a slight increase in equipment complexity was worth simpler operation and one in which it is not possible to leave switched to "both" by mistake!

Horses for courses as usual..........

HUMBER P4VWL · 27 July 2010, 00:24

Bruceb. VSR? excuse my ignorance. Guessing, variable something resistor

Don't get too techie but what is it and what's it do?

Hightower · 27 July 2010, 00:54

Quote:

Originally Posted by BruceB

I switch on and leave on all day, the VSR does all the above for me. I personally decided a slight increase in equipment complexity was worth simpler operation and one in which it is not possible to leave switched to "both" by mistake!

Horses for courses as usual..........

That's fair comment. When I was building my RIB years ago I remember taking some advice from someone that operates Canal narrow boats. He suggested that these pieces of tech were more trouble than they're worth, so I decided to take his advice.

I understand that there are a few people on here that use "Voltage Sensitive Relays". Perhaps they would like to comment if they've had any problems with theirs?

Hightower · 27 July 2010, 00:59

Quote:

Originally Posted by HUMBER P4VWL

Bruceb. VSR? excuse my ignorance. Guessing, variable something resistor

Don't get too techie but what is it and what's it do?

Volage sensitive relay. Basicly charges whichever battery is in the poorest condition. Kind of like a modern "split charge system" but has built in overcharging protection etc.

See here: http://www.power-store.com/?id=197

jwalker · 27 July 2010, 02:17

Bloodyell. I could buy two batteries for the price of one of them! I think ma diode cost about 20p.

Cookee · 27 July 2010, 09:47

Quote:

Originally Posted by Hightower

Volage sensitive relay. Basicly charges whichever battery is in the poorest condition. Kind of like a modern "split charge system" but has built in overcharging protection etc.

See here: http://www.power-store.com/?id=197

Actually it doesn't!

It will charge the main (starter) battery first, and when it has reached a pre-set voltage signifying it's full, the relay will trip and charge the second (house) battery - they usually come in a cluster of four with switches for both batteries and an emergency switch to link the two together.

As far as I know there is no overcharging protection either but I've been wrong before!

We have fitted them to several boats and they work very well.

Searider · 27 July 2010, 09:54

Quote:

Originally Posted by Hightower

That's fair comment. When I was building my RIB years ago I remember taking some advice from someone that operates Canal narrow boats. He suggested that these pieces of tech were more trouble than they're worth, so I decided to take his advice.

I understand that there are a few people on here that use "Voltage Sensitive Relays". Perhaps they would like to comment if they've had any problems with theirs?

Had mine fitted for 5 years with no problems.

Cookees right on how they operate.

9D280 · 27 July 2010, 12:49

Quote:

Originally Posted by HUMBER P4VWL

Just a thought. Though there are many ways to skin a cat.

Indeed, and here is another:

One battery, and a bit of suitable length rope with a knot one end & a toggle the other.

Electronics wise there's a handheld VHF under the seat, which gets discharged & recharged the nights before I go out, and a Garmin 12 full of a heap of "tactical" waypoints which sits on the console being powered off the boat battery (gives a "get you home" trail), but has a heap of AAs inside which will give it a further 12 hrs should the boat battery die. Nav. lighs taken care of in the instance of the main engine failing (no charge) by switching from ">7knts" to "<7 knots" mode, i.e one 10W lamp, which at some point I plan to replace with an LED bulb. What's left of the main batt should keep that alive long enough to get to a place of safety. If not, I have a battery ARW that can be gaffa'ed to the frame.

Or, in summary, anything vital hanging off the boat battery has a low power, aux or fully manual backup.

And I have had to use the manaul start option when my main batt switch decided not to play after a particularly bad soaking.......