Roderick

Our batteries have month and year of installation on the top, corresponding to the date our boat was first floated and sent for fitting out. This weekend we ran the engine for 6 hours, then got 2 hours of running the fridge through the inverter before it bleated. I disconnected the battery positive terminals and checked the voltages - ranged from 9.5V down to 7.5V - so it is pretty evident that they must have sulphated badly whilst the boat was at the brokerage. Starting up the engine immediately revocered the voltage to 14.5V so I'm certain the alternator is delivering the goods! She's at a boatyard at the moment to sort out other problems of "boat arthritis" from sitting unused for a year however the boatyard electrician came up with a shocker. He asked for the safety cert and I explained that there was not one because she's less than 4 years old and has the CE certification. Well, it seems it should be a case for Trading Standards, because the battery wiring is apparently pathetically inadequate and could easily have gone into meltdown. I'm glad I found out now, not when she fails her safety inspection on her 4th birthday. My new 5000W inverter comes with the beefiest cables I've ever seen, but apparently even these are not up to the job of delivering the 800 amps the inverter will be able to draw under peak load. So, it looks like I'll be forking out for rather a lot of copper as well as new domestic batteries, however, I'm sure I'll be glad I did. Cheers, Roderick

I think that running the engine in gear for battery charging purposes is a waste of fuel, a safety hazard and a pointless churning of mud. On the other hand, increasing the revs above tick-over whilst in neutral will dramatically improve alternator charging performance - compare for example, to the speed at which diesel generators run. I suspect also that this will cause the engine to run a little hotter - probably no harm in this following the discussion about glazing. If your boat is anything like mine, increaseing the revs will also stop everything in the galley from rattling due to the low frequency resonances of the tick-over speed I would not mind betting that the extra fuel used for these extra revs is marginal and certainly much less than when causing unnecessary movement of water! Cheers, Roderick

Hi, This is really useful feedback. Our boat, which we bought last month, was previously used as a live-aboard and I reckon almost always had a shore line, so the 1800W inverter was never really tested. The wretched thing invariably goes into overload when both fridge/freezer and microwave oven are on, which is an unacceptable bore and with just the fridge/freezer on overnight the battery voltage ( 4 x 110 Ah) drops and alarms at about 3am, even after 8+ hours of charging from the engine, duly waking us up. I'd figured that high start-up currents were an issue, so I have struck a bargain on a 5000W continuous / 10000W peak inverter to eliminate this and hopefully turning on appliances will no longer cause any problems. I realise I am now moving the weakest link to the bank of batteries (and then maybe to the alternator, if I beef up the batteries) and I don't want to be overly hasty to replace the batteries, though they are 3 years old. Swatting up on deep cycle batteries, I read about a crofter who has 1470 Ah of battery that provides 2 to 3 days of power for his croft through a 4500W inverter. It would thus seem to me that 6 x 110 Ah on a boat should be perfectly adequate for 24 hours without recharging and the 4 x 110 Ah we have at the moment should be more than enough to allow the fridge/freezer to run through the night. Thus, my gut feel is that our batteries are shot. I'd like to think we could run the fridge/freezer for 24 hours off battery alone but I don't know at this stage whether this is realistic or pie in the sky, as I don't have a clue what its average load is. I'd appreciate your thoughts on this. Cheers, Roderick