Domestic Battery

[Stemar]

My domestic battery is showing signs of fatigue after it got knocked down to about 3v a few weeks ago. It charged up OK, but was very tired after only 36 hours of light use, when it usually lasts the best part of a week. It’s a few years old, so it doesn’t really owe us anything, but I’d like to get the best replacement for my setup.

The boat’s a Snapdragon 24 with a 55 amp alternator and a dedicated 35AH starter battery. The current domestic battery’s a 85AH “leisure” battery charged by a simple relay run off the wire between the charge warning light and the field coil. I haven’t got any sort of clever charge booster, but do have plans to add a 20w or so solar panel next year. I’ve space for a bigger battery, probably up to 120AH and could find more space, but on a small boat, weight starts to become an issue – we already get a list to port when we’re both sitting at the dinette and a heavier battery isn’t going to help!
Needs are modest. Lighting, mostly LED, a car stereo, water pressure pump and a tiller pilot are about it, but I do want to retain the option to start the engine (VP2003) from the domestic battery in case of problems with the starter battery. I have an electric cold-box, but don’t usually plug it in unless the engine’s running.

Current thoughts are to get the biggest battery I can afford. I understand that AGM or gel batteries aren’t going to give their best without a clever charger and I’m not sure of cost effectiveness of one on a little boat like mine.

I understand the theoretical difference between car batteries and deep cycle ones, and leisure batteries appear to be a cross between the two, but are they Jacks of all trades and masters of none, or are they a good compromise? One such advertised on the internet claimed 300 recharge cycles compared with 100-150 from the competition, but even 300 cycles doesn't seem much unless it's down to almost flat.

I see that lot of true deep-cycle batteries don’t quote CCA capacities. Is this because it’s irrelevant to their application, or would they be damaged by the demands of starting the donk occasionally? Even with the correct cold-start procedure, it can take a lot of churning on a cold day, which is, according to Sod’s Law, when the starter battery’s most likely to need help.

Final question. Is a Varta or Trojan battery worth the extra compared with a middle of the road one, or even a Halfords special? I could throw away a couple of cheap leisure batteries and still be in pocket compared with a top of the range one.

Any thoughts, especially from folk with expert knowledge appreciated.

Thanks

Confused of London

 

[Plevier]

.

Current thoughts are to get the biggest battery I can afford. I understand that AGM or gel batteries aren’t going to give their best without a clever charger and I’m not sure of cost effectiveness of one on a little boat like mine.

#### I agree (but some may not!)

I understand the theoretical difference between car batteries and deep cycle ones, and leisure batteries appear to be a cross between the two, but are they Jacks of all trades and masters of none, or are they a good compromise?

#### Can be. From a reputable manufacturer likely to have (slightly) thicker plates and better separation. Helpful but as you say no sub for real deep cycle. But is your use going to be cycle limited or years limited?

One such advertised on the internet claimed 300 recharge cycles compared with 100-150 from the competition, but even 300 cycles doesn't seem much unless it's down to almost flat.
#### NO lead acid is OK to run nearly flat. 50% discharge is a reasonable rule of thumb.

I see that lot of true deep-cycle batteries don’t quote CCA capacities. Is this because it’s irrelevant to their application,
#### yes
or would they be damaged by the demands of starting the donk occasionally?
#### no (or only if very badly designed) but they won't do the duty well.
Even with the correct cold-start procedure, it can take a lot of churning on a cold day, which is, according to Sod’s Law, when the starter battery’s most likely to need help.

Final question. Is a Varta or Trojan battery worth the extra compared with a middle of the road one, or even a Halfords special?
#### Varta definitely worth more than stuff of unknown provenance such as Halfords and they are expensive anyway. Trojan i would say only for liveaboards. I wouldn't touch cheap own brands that probably come from a different manufacturer every batch. I think I'm going to need new batteries next year. I shall go for Varta if feeling generous at the time and probably Numax if feeling the pinch! Numax seem to have a decent name, they come from a distributor (Manbat) with a long association with Varta and there are persistent rumours they come from the same factory. That doesn't necessarily mean they are identical but it's common practise in many fields to have a back door brand for extra volume. The battery company I was with manufactured under many names. (Varta by the way is now a brand of Johnson Controls Inc battery division who also make the v expensive Optima battery. They also use the Bosch brand name, Bosch and Varta batteries appear to be identical.)

#### Final rule of thumb if two batteries seem to have the same spec go for the heavier one. There is no substitute for lead!

 

[Stemar]

Thanks, Troubador.

I knew about the 50% discharge rule, but thought (hoped) it applied to starter batteries, while deep discharge jobs could handle a bit more. If it applies to both, what's the advantage to the deep cycle ones? Is a starter battery going to suffer with less than 50%, or do you just get more amp hours for your money & battery size?

 

[Chalker]

A starter battery in normal use hardly gets discharged at all. It simply has to provide a high current for a short time. 200 Amps for 10 seconds is less than 1 Amphour.

A proper deep discharge battery will be capable of far more discharges to 50% than a starter battery doing the same job.

 

[Plevier]

A starter battery in normal use hardly gets discharged at all. It simply has to provide a high current for a short time. 200 Amps for 10 seconds is less than 1 Amphour.

A proper deep discharge battery will be capable of far more discharges to 50% than a starter battery doing the same job.

Exactly.

 

[Mistroma]

I bought Numax from ManBat years ago and they were very cheap at that time (not true now). They lasted very well and were as good as the Varta's I'd used previously.

They did a Caravan range and a Yachtie range so I asked what the difference was before buying. Guy behind the counter said "the label (& price)", so I bought the Caravan ones.

Things change so they might be rubbish now but they certainly were excellent for normal weekend use 5-6 years ago.

I now live on board for 6-7 months and have a larger boat. Guess what? I now have 6V Trojan's. However, I only paid £120 each and that wasn't hugely more than "good quality leisure" batteries. I say only but it was still a chunk of change, just seemed like a better investment for heavy use than leisure type.

 

[rafiki_]

I buy from the Battery Megastore. Their advice is good and prices better.

 

[Stemar]

I buy from the Battery Megastore. Their advice is good and prices better.

I can't speak for their advice, but I certainly like their prices!

I'm tempted by their Alphaline DC31, which gives me 125 AH and a 4 year warranty for £94.50 including delivery. It doesn't give a CCA value, but I can't imagine that it won't give the 120 amps my donk would need in an emergency.

Anyone with any experience of that battery? I'd love a Trojan, but they only give 115 AH for £150. Ouch!

 

[VicMallows]

I'm tempted by their Alphaline DC31, which gives me 125 AH and a 4 year warranty ........

I'm sure their batteries are just as good as any other similar type. However I would not put any value on the so-called warranty. When you read the small print you may find terms like:

'you must submit a report by an approved service facility that the alternator is in full working order'

'you must return the battery at your own cost'

'any refund will be proportionate to the typical life, and will only be applied against the full retail value of a replacement'

Of course you would have your normal sale-of-goods rights, but are you REALLY ever going to bother?

 

[Plevier]

I can't speak for their advice, but I certainly like their prices!

I'm tempted by their Alphaline DC31, which gives me 125 AH and a 4 year warranty for £94.50 including delivery. It doesn't give a CCA value, but I can't imagine that it won't give the 120 amps my donk would need in an emergency.

Anyone with any experience of that battery? I'd love a Trojan, but they only give 115 AH for £150. Ouch!

Varta 105Ah 26.9kg
Alphaline 125Ah 23.4kg

Here's the Alphaline even cheaper £86 http://www.ebay.co.uk/itm/DEEP-CYCL...ies&hash=item41696cd875&_uhb=1#ht_2468wt_1186

 

[Stemar]

Varta 105Ah 26.9kg
Alphaline 125Ah 23.4kg

Point taken.

A nose round the web suggests I can get the Varta for much the same price as the Alphaline and, as I have plans to add a solar panel next year, absolute capacity is, perhaps, less of an issue. Even with a "summer" like this year I'd expect a 30w panel to give me close to 15 AH a day, which isn't far from my usage.

The only thing to decide now is whether to stretch the old one out and buy fresh for next year or go for it now. I'll be out of the water and have access to mains to keep it charged up during the winter, so it won't take take too much of a beating, which means the only consideration is the likelihood of a significant price increase between now and next March.

 

[Plevier]

This is from PerformanceBatteries website http://www.performancebatteries.co.uk/page/faq/ (Battery Megastore is another of their names)

Alphaline Leisure Batteries
The warranty of Alphaline Leisure Batteries is reduced if used for the following applications.
Live Aboard usage: 1 Year
Commercial and Industrial usage: 1 Year
Electric fence usage: 6 Months

also you have to pay all the costs of any testing to prove it's faulty.

TBH you'll find similar getouts from most manufacturers! Most battery warranties are full of holes but the cheaper the battery the more they will squirm.

I have nothing specific against Alphaline. There are certainly worse (and cheaper) batteries around but I distrust own brand ones when they are cheap, underweight and I can't find out who makes them. You might like to look at the Numax ones (and various others) at www.manbat.co.uk as well as Performance Batteries, Battery Megastore and Tayna.

You generally get what you pay for, and if it looks too good to be true, it probably is. Boring but true!

Your choice.

Regarding timing, it used to be the case that production concentrated on car batteries through spring and summer to build stock ready for the rush with the first frosts, and other lower volume types tended to be built over the winter with lower car battery production. Also leisure batteries are more likely to be bought in spring whether for boats or caravans. If you buy in the spring, you might get a much newer battery. I would personally only buy now if unavoidable.

 

[BabaYaga]

Even with a "summer" like this year I'd expect a 30w panel to give me close to 15 AH a day, which isn't far from my usage.

A solar panel is a very good idea, but that expectation is too high in my opionion.
I believe there is a rule of thumb that gives around 25 percent in daily AH of the panel wattage. This is an average for a panel mounted flat during the summer months. For a panel that can be redirerected to follow the sun I have seen figures of around 35 percent.

Regarding battery type I agree with others that a good quality leisure battery probably gives the best value for money.

 

[VicS]

A solar panel is a very good idea, but that expectation is too high in my opionion.
I believe there is a rule of thumb that gives around 25 percent in daily AH of the panel wattage. This is an average for a panel mounted flat during the summer months. For a panel that can be redirerected to follow the sun I have seen figures of around 35 percent.

Regarding battery type I agree with others that a good quality leisure battery probably gives the best value for money.

Maplin have at present a 145watt panel on offer bundled with a basic regulator for £280.
http://www.maplin.co.uk/12v-145w-solar-panel-kit-623195

They estimate a typical daily output of 32.6 Ah ( stupid degree of precision!) Not far adrift from the 25% rule of thumb.

I guess a more sophisticated regulator could improve on their 32Ah figure a little

 

[alan_d]

Current thoughts are to get the biggest battery I can afford.

A sensible plan, but don't forget weight and size. Although, other things being equal, heavy batteries are good, don't forget that someone is going to have to get it aboard and manoeuvre it into position. Also, when thinking about whether it will fit your chosen site, consider the height as well as the other dimensions, and the location of the terminals.

 

[elhix]

alphalines - pretty good

I've used an Alphaline DC31 on my boat for two years, it's been pretty good. I accidentally discharged it one night whilst crossing Biscay (autopilot discharged it to well below 50%), it wasn't quite the same again but remained usable. A good buy for the price for certain.

 

[VicS]

My new one is a Varta

My new battery is a Varta and is described as a "Professional Deep Cycle Leisure battery" ..... its a Leisure battery!

Its sealed, but nearly all are now, but not AGM.

Size / proportions influenced my choice.

Best price for the chosen battery was from Tayna. Ordered one day and delivered first thing next morning.

Only time will tell if it was a good choice or not .