Leisure batteries..

[wazza]

My question is..
Can I change JUST my leasure batteries or must I change them all..
I have 2 x 75ah leasure batteries, plus a 75ah starter battery as well as another battery just for the windlas and bow thruster.
My leasure batteries drain all too quickly, but I have no problem starting the engine, and of course both the windlas and bow thruster run only when the engine is going, so would it be ok to just change the leasure ones??

 

[sailorman]

My question is..
Can I change JUST my leasure batteries or must I change them all..
I have 2 x 75ah leasure batteries, plus a 75ah starter battery as well as another battery just for the windlas and bow thruster.
My leasure batteries drain all too quickly, but I have no problem starting the engine, and of course both the windlas and bow thruster run only when the engine is going, so would it be ok to just change the leasure ones??

just change the domestic bank

 

[Spi D]

Agreed, and get two identical if your charging system see them as one bank. May go bigger if you like.

 

[Hugh Foulis]

Nike - just do it.

Whatever the charging arrangement, your leisure and start batteries will be independent of each other.

There will be pureists (sp) along to explain why you cannot, but I have a cocktail of batteries on my boat 1 I bought new off a bloke in a unit in Manchester back of the railway,1 I bought in a scrapyard and 1 that was left on the boat when I bought it. This year after 7 months over winter I switched on, gave the heaters a bit longer and then fired up. Domestics were OK too. I think there is a lot of hand-wringing about batteries that is unnecessary. When was the last time you had to buy a battery for your car? How old was the last one? The battery on my caravan came off the old van, it must be 10 years old.

HF

 

[AIDY]

Nike - just do it.

ADIDAS - All day I dream about Sailing or is it Sax

 

[sarabande]

it might be worth thinking about why the batteries run out of charge so quickly, before putting new ones into the same environment.

Perhaps you need more charging capability, or bigger battery capacity.

 

[Spi D]

Whatever the charging arrangement, your leisure and start batteries will be independent of each other.

Connect more batteries to form one bank and they will be charged independently? Please explain.

While at it, explain why multi stage, multi channel chargers and dedicated battery types are not better than any random mix of batteries charged by any charger?

 

[wazza]

Jolly good then, it'll be two 100ah batteries for the leasure side. As to why they run down so quickly, must be because they are dead. Accept a full charge quick and die quite quickly..

 

[rick-lamb]

Answer to the original question: Yes you'll be fine just changing the leisure batteries.

However it does sound like you have done some damage to them, so in case you didn't already know...

Car batteries last forever because they are never(very rarely) totally discharged before re-charging.
Leisure batteries that are used when the engine isn't running need to be 'deep cycle' so they can tolerate being totally discharged.

This article explains the difference between starter and deep cycle batteries pretty well.
http://batteryuniversity.com/learn/article/lead_based_batteries

It boils down to the fact that a 'starter' battery could be dead after 10-20 complete discharges and a deep cycle battery will allow 10 times that.
(They'll last much longer if they are discharged less than 50% but that's easier said than done.)

PS. IMO the easiest way to tell a quality deep cycle battery is weight, it should be around double the
weight of a starter battery. E.g. starter battery 30lbs, deep cycle battery 60 lbs.
Marketing seems to be blurring the lines of what a true deep cycle battery is and there are also many in-between compromise batteries likely labeled 'marine' or something,
but since you have a distinct leisure bank then you should stick with real deep cycle.

 

[Hugh Foulis]

Connect more batteries to form one bank and they will be charged independently? Please explain.

I dont believe I said that. I said that leisure and start would, for the purposes of charging, be independent of each other and therefore there would be no need to change all at the same time

While at it, explain why multi stage, multi channel chargers and dedicated battery types are not better than any random mix of batteries charged by any charger?

Again, I didnt say they were not better, I did say that my random mix have been perfectly satisfactory and there was a lot of unnecessary worry about batteries and charging.

HF

 

[William_H]

Jolly good then, it'll be two 100ah batteries for the leasure side. As to why they run down so quickly, must be because they are dead. Accept a full charge quick and die quite quickly..

How do you know they are accepting a full charge quick? I would suggest that if you have 2 batteries in parallel that you disconnect one at a time to check performance of each battery. I would never trust a charger to tell me when a battery is charged. Use a multimeter and clock. If it seems flat then you need to make sure you put in about 20% more amp hours than the size of the battery. ie about 120 amp hours or 5 amps for 24hrs to be sure it is charged. Then do a discharge test. If you can't get 5 amps for 10 hrs then throw it away. You can decide on this figure. Even less might be useful to you. But never expect more than about 80% of capacity out of a new battery. Use a volt meter to check the apparent state of charge and don't let it go below 11.3 volts or so.
As I said when you divide the batteries you may find one much worse than the other In which case change it or both. (how rich do you feel). You cana see I think an amp meter is very desirable in dealing with batteries charging etc. good luck olewill

 

[Bobc]

Another suggestion for you

Why don't you get a couple of Trojan 6v (225Ah) batteries and connect them up in series.

This will give you a total of 225Ah at 12v, and IMHO is a better solution than a pair of 100Ah 12v batteries.

 

[VicS]

Another suggestion for you

Why don't you get a couple of Trojan 6v (225Ah) batteries and connect them up in series.

This will give you a total of 225Ah at 12v, and IMHO is a better solution than a pair of 100Ah 12v batteries.

Trojan are deep cycle but what is the advantage of two six volt in series over two twelve volt in parallel?

A disadvantage is that if one fails you are cream crackered but with two twelve volt in parallel you would still have one good one..

 

[William_H]

Trojan are deep cycle but what is the advantage of two six volt in series over two twelve volt in parallel?

A disadvantage is that if one fails you are cream crackered but with two twelve volt in parallel you would still have one good one..

Vic is right but for me I would be deciding on 2 x 6v or 2x12v purely on price as i suspect the 12v would be more commonly used so cheaper. good luck olewill

 

[Richard10002]

Vic is right but for me I would be deciding on 2 x 6v or 2x12v purely on price as i suspect the 12v would be more commonly used so cheaper. good luck olewill

2 x 110Ah 12V Varta £200-£220

2 x 225Ah 6V Trojan £234 or so.

So not much to differentiate on price.

Personally, I'd prefer the Trojans, but their footprint is different to the normal 12V battery, so there might. E an issue with fitting in an existing space.

 

[oldbilbo]

I've been bemused by qualified and experienced advice in these pages before and, no doubt, will be again. Having knackered one of the 2 x 110Ah batteries that came with my small and 'very last century' ( no bow thruster, no 12v TV ) sailing cruiser, I was persuaded to buy one, then two, then three AGM deep cycle batteries to replace the dead one. That's 212Ah, if my sums are right! I still have the 'good' original 110Ah conventional wet thingy.

I suspect you may have been over-stressing your weebly 75Ah service(s) or domestic battery..... taking rather more out than was being put back in. Frequently.

Now, it may be truly stuffed. Or it may be capable of regeneration. An effective multi-stage charger ( not necessarily expensive - Aldi sell them for the price of a bottle of wine ) could well recover this to a sound level of charge. This could easily take two days to come right. Or it may be too late and your battery may be defunct/deceased/stuffed/knackered. ( I don't know what the Swedish vernacular is for this state of affairs.... )

In which case, buy one or two new, with about double the capacity of the old one. If the old one regenerates, buy another one to ensure 'double the capacity'.