Battery needed - Which one ?

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Mike_S

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Chaps I'm looking for some help from the forum collective.

I need to pick up a new battery for our boat, after going down to it last night and getting a series of clicks from the starter before she finally (and very slowly) turned over and kicked into life. Considering it was only used last Sunday, 4 days isn't great for it to die. Now, hunting through the swindlery websites I can see different battery options for marine and otherwise. Marine seems to mean it's £££significantly more than what I'd class as a 'car battery', so I'm looking for a bit of enlightenment as to the differences.

When we bought this boat 18 months ago the brokerage apparently fitted a new battery for the seatrial (there wasn't one fitted when we first viewed the boat) and to be honest, I've always thought that a) it wasn't new and b) it's perhaps not big enough, as it struggles to turn the engine over and it's always needed the solar panel to keep it topped up otherwise after a couple of weeks it's useless.

My boat's got a 5 litre V8 and the current battery is a 70Ah type. Would anyone happen to know if this is the right size battery or should I be putting something with a bit more whap in there ? Cost isn't an issue, I just want to make sure it's the right battery for the job, last thing I want is to be stuck out at sea wondering how I'm going to bump start it /forums/images/graemlins/tongue.gif

Cheers

Mike
 
If you are running the battery flat while not on the boat, you probably have some voltage drain somewhere. Check all the connections and earths and make sure there is nothing on that shouldnt be.

I had a similar problem earlier in the year and it took two batteries and about 4 hours of looking around to find the culprit was a faulty battery master switch.

70ah sounds like enough for a dedicated engine start battery. Do you have another battery that does your domestics and navigation lights/electonics etc or do you rely on the same battery for everything?

If it is just one battery, I would invest in a second for non engine stuff, and install it with a cross over so you have a second back up in an emergency you can use to start the engine.
 
Thanks Jez

There's just the one battery for everything, no room at the back for another one to be honest as it's only a smallish boat (Regal 2150) but I could fit one slightly larger than what's in there at the moment, hence the question really.

The voltage drain is the auto bilge pump, given the rain we've had over the last few months and the fact Regals aren't great at keeping the rain out we get some water in the bilge. I've had the sparky check everything as I had the same thought as you, but all he could find was the auto bilge pump kicking in. He did find a load of rotten wiring but that's all been cut out and replaced.
 
Buy the best quality you can afford. Cheap batteries are rubbish and are a waste of money. I bought two cheapies earlier this year and they were useless at turning over the same engine as yours after about a week or two and never seemed to have much power!
 
Go to a specialist supplier such as Merlin or Barden (among others) and get a dedicated engine start battery, or a dual purpose "leisure" battery if you are running other things off the same battery.
 
70Ah sounds tiny to me if you are using it for domestic load too. Bit of a "mondeo" battery. It's possible the dealer shortchanged you by saving money on a smaller battery? All water under the bridge now. Anyway, I'd want the biggest you can fit, depends on size of box. I'd stick a 220 in there if space (they're 50cm long) but if not try to get 140+ in there. Also, I agree with others who say get a good quality one, as a cheapie is false economy. A 220 is perhaps £400ish (i bought 4 of them last month, ouch)
 
I had both my domestic 200AH batteries replaced this year. Not cheap! Anyway, stupidly I left the boat for 3 weeks without charging and they no longer get to a full charge. Lead acid's take so much looking after to keep in tip top condition, i.e. ensure they're fully charged before you leave them standing for any period etc.

I was thinking this week wheteher you could get a Nikel/lithium battery in a decent size these days. Quick search in google found a 100AH Nikel weighing just 2.9Kgs, no info on pricing though or availability. Anyone know if this is feasable? Must be so much better suited to boating
 
Thanks everyone for the answers / advice. It's more a starter battery than anything else given it's just a small cuddy dayboat. Aside from starting duties we're not running anything major off it, only a radio if anchored up and the auto bilge pump so I'd guess a requirement for about 40Ah ? The GPS / VHF / lights are only on when the engine's running, so I'd think the load is taken by the alternator for those.

I'll look to fit a bigger battery though given the consensus of opinion pointing in that direction.

jfm I'd say you were correct about the cheap battery from the broker, they weren't exactly brilliant (lost all the service history amongst other things).
 
I would nip over to marine scene and pick up one of their 110ah batteries. Thats where i bought our last two they lasted and were reasonable too.
 
Yep, just rung them David. They've got a couple left so I'll pick one up tomorrow. Sods law of course, had it not been for the decent forecast this weekend I'd have ordered a bigger one online for delivery next week, I'm loathed to take it out this weekend without a new battery though so marinescene will have to do.
 
Before you pick up the batteries make sure that the poles (+ and -) are the same way around as yours or you might find that you have to change the lead lengths. As a price guide I've just bought from Costco two Bosch 110Ah Marine batteries for £85 each
 
Our local chandlers want £80 for a 110Ah, so Costco are quite competitive there. I'll remember that though as I have to drive past the new Costco on my way home, so it might be worth dropping in tonight to see if they have any.
 
Thanks for all the help and the problem is now sorted. The biggest I could lay my hands on from the chandlers was 110Ah, it's also the biggest case I could get in the back of the boat once I took the battery tray out. It's made a huge difference though, the engine spins over no trouble now (not comparing it to the dying battery that was in there, but to when we first bought the boat) and we spent the weekend out on her in the comfort of knowing it was actually going to restart. Consequently it cost me £150 in petrol as well /forums/images/graemlins/cool.gif /forums/images/graemlins/cool.gif

Cheers all

Mike.
 
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