1agos Posted December 21, 2015 Report Share Posted December 21, 2015 Advise please I installed new batteries last month - maintenance free lead acid types. We are leaving the boat in a marina for 6 weeks should I pay for shore power and leave them on charge via the mastervolt charging system. Or can they just have the isolation switches turned off and leave them alone. They will get a small charge through the 250w solar panels while we are away. Andy Link to comment Share on other sites More sharing options...
Sea Dog Posted December 21, 2015 Report Share Posted December 21, 2015 Leave the Mastervolt to look after them. It's designed to do just that and will protect your investment for about a fiver a month. Outside the winter, the solar will do the job, and it might even do so now, but why take the risk whilst you get to know your new equipment? Link to comment Share on other sites More sharing options...
Graham.m Posted December 21, 2015 Report Share Posted December 21, 2015 Advise please I installed new batteries last month - maintenance free lead acid types. We are leaving the boat in a marina for 6 weeks should I pay for shore power and leave them on charge via the mastervolt charging system. Or can they just have the isolation switches turned off and leave them alone. They will get a small charge through the 250w solar panels while we are away. Andy I would leave them with the solar charge running. If they are fully charge they will survive well for several months. I think the major thing to do when you get back is to give them a boost charge. So I would pay a bit for leccy and make sure they are full charged when you leave and boost them when you get back Link to comment Share on other sites More sharing options...
Boat&Bikes Posted December 21, 2015 Report Share Posted December 21, 2015 I alwys run my charger through winter, can't do any harm can it. Best add its very unlikely to cause any problems anyway. Ian. Link to comment Share on other sites More sharing options...
Graham.m Posted December 21, 2015 Report Share Posted December 21, 2015 I alwys run my charger through winter, can't do any harm can it. Best add its very unlikely to cause any problems anyway. Ian. I always leave mine on solar panels and get over 4 years out of standard batteries Link to comment Share on other sites More sharing options...
ditchcrawler Posted December 21, 2015 Report Share Posted December 21, 2015 I would leave them with the solar charge running. If they are fully charge they will survive well for several months. I think the major thing to do when you get back is to give them a boost charge. So I would pay a bit for leccy and make sure they are full charged when you leave and boost them when you get back I go along with that. I never use our shore supply unless I happen to be staying in the marina for a couple of days. The other week a substation caught fire in Lichfield knocking our marina out, I wonder how many boats were being kept warm with electric heaters fed by inverters and batteries. Link to comment Share on other sites More sharing options...
bottle Posted December 21, 2015 Report Share Posted December 21, 2015 Classic forum, arguments for either way. I recently (last weekend) left my boat for five days, batteries were 95%SOC when left and 100%SOC when I returned. All isolators turned OFF only the solar panels (400 watt) connected to batteries. Batteries have different 'self discharge' rates depending on temperature. All batteries should be OK after six weeks even if not being charged You just need to replace the self discharge and that is very small. Check your battery manufacturers website for your particular battery and its specification. Link to comment Share on other sites More sharing options...
Robbo Posted December 21, 2015 Report Share Posted December 21, 2015 Advise please I installed new batteries last month - maintenance free lead acid types. We are leaving the boat in a marina for 6 weeks should I pay for shore power and leave them on charge via the mastervolt charging system. Or can they just have the isolation switches turned off and leave them alone. They will get a small charge through the 250w solar panels while we are away. Andy They will lose around 10-15% of SoC over the 6 weeks. If it was for longer (like 3 months) I would say use the shore power, but for 6 weeks it's not worth it unless your just paying just for the electric usage as this will be small (around 5p a day). Link to comment Share on other sites More sharing options...
Sea Dog Posted December 21, 2015 Report Share Posted December 21, 2015 I go along with that. I never use our shore supply unless I happen to be staying in the marina for a couple of days. The other week a substation caught fire in Lichfield knocking our marina out, I wonder how many boats were being kept warm with electric heaters fed by inverters and batteries. The decent Mastervolt stuff can be switched to charger mode to prevent that. The inverter can be also set to cut in in the event of a power failure, etc, but not when in charger mode. Why have a couple of grand's worth of battery charger and conditioner and switch it off in the winter when it's needed most? Link to comment Share on other sites More sharing options...
matty40s Posted December 21, 2015 Report Share Posted December 21, 2015 With 250W of solar, I wouldn't bother with landline unless you are going to leave something on. You will find that if everything is isolated, your batteries will be fully charged on your return. Link to comment Share on other sites More sharing options...
WotEver Posted December 21, 2015 Report Share Posted December 21, 2015 I'd pay for the shore power if only to have a tube heater sat in the boat on a thermostat just in case the temperature plummets. And while you have it there's no problem having the charger switched on as backup to the solar. It's what I do but that doesn't make it right, just my preference. Tony Link to comment Share on other sites More sharing options...
1agos Posted December 21, 2015 Author Report Share Posted December 21, 2015 Thanks for the advise guys. Link to comment Share on other sites More sharing options...
peterboat Posted December 21, 2015 Report Share Posted December 21, 2015 i am with the solar it works you are bound to get more than enough power over the six weeks to fully charge and maintain the batteries Link to comment Share on other sites More sharing options...
ditchcrawler Posted December 22, 2015 Report Share Posted December 22, 2015 The decent Mastervolt stuff can be switched to charger mode to prevent that. The inverter can be also set to cut in in the event of a power failure, etc, but not when in charger mode. Why have a couple of grand's worth of battery charger and conditioner and switch it off in the winter when it's needed most? I know that, you know that, but I have heard of more than one boater who has come back a week later because the power had gone off and the fridge had been trying to run all week. Link to comment Share on other sites More sharing options...
trackman Posted December 22, 2015 Report Share Posted December 22, 2015 If everything is switched off by the isolators then 250W of solar will more than compensate for self discharge unless you've a huge battery bank. We found that our original 68W panel easily coped with keeping our 440Ah bank fully charged in winter when the isolators were off. Now we have over 200W it's well more than enough to do the job in any weather. The only risk might be heavy snowfall cutting off the light, but that seems unlikely this winter! Link to comment Share on other sites More sharing options...
Top cat Posted December 22, 2015 Report Share Posted December 22, 2015 (edited) I've got a 130W panel that is even now easily keeping up with the self discharge on our 4 x 110Ah 3yr old battery. The boat is moored at the bottom of the garden shaded by trees much of the day. I check it frequently (while down there for other jobs) and the batteries have been on float at 13 and a bit V and trivial Amps for weeks now. So I unless you are moored in deep shade I would go with the solar charging. Top Cat Edited December 22, 2015 by Top cat Link to comment Share on other sites More sharing options...
Sea Dog Posted December 23, 2015 Report Share Posted December 23, 2015 I know that, you know that, but I have heard of more than one boater who has come back a week later because the power had gone off and the fridge had been trying to run all week. Mine would do that too, but that's cos my fridge is 12V. I take the fridge fuse when I leave the boat in winter. Link to comment Share on other sites More sharing options...
tosher Posted December 23, 2015 Report Share Posted December 23, 2015 Seem to remember Gibbo saying some where that the self discharge rate of batteries is less in cold winter weather than in the warm summer which is opposite to what you might think. Is that correct???? Link to comment Share on other sites More sharing options...
Graham.m Posted December 23, 2015 Report Share Posted December 23, 2015 Seem to remember Gibbo saying some where that the self discharge rate of batteries is less in cold winter weather than in the warm summer which is opposite to what you might think. Is that correct???? Yep the cold slows down the reaction Link to comment Share on other sites More sharing options...
cuthound Posted December 23, 2015 Report Share Posted December 23, 2015 Seem to remember Gibbo saying some where that the self discharge rate of batteries is less in cold winter weather than in the warm summer which is opposite to what you might think. Is that correct???? Yes, batteries are chemical devices so temperature affects the chemical reactions. That's why battery life is very much shortened when they are kept at high temperatures, and your car is reluctant to start at very low temperatures. Link to comment Share on other sites More sharing options...
Sea Dog Posted December 23, 2015 Report Share Posted December 23, 2015 That's why battery life is very much shortened when they are kept at high temperatures, and your car is reluctant to start at very low temperatures. Well, mine won't start because the starter motor is sitting on the bench, but otherwise you might be right. Link to comment Share on other sites More sharing options...
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