charging and fridge use advice please
- Thread starter Falcoron
- Start date
jrudge
Well-Known Member
I would leave it on.
My freezer just went bang ( 2 years old) and i believe had it just been left on like in a house it would have been fine.
My freezer just went bang ( 2 years old) and i believe had it just been left on like in a house it would have been fine.
ARE
Well-Known Member
If it is a compressor fridge, it is important to have the correct size cables running to it as the start current is considerable and if the voltage drop is to great the fridge will cycle on and off flattening the batteries quickly.
I am surprised if the current setup is switched by the alternator as unless the engine is run constantly the fridge will begin to warm up once the engine stopped. Does the fridge light stay on when the engine is not running?
My current setup uses 2x 110ah batteries powering 110 L Dometic compressor fridge/freezer. The batteries are charged by a 35A Victron charger and this also split charges to the engine battery via a cyrix split charge relay. The cyrix relay then charges the leisure batteries once the engine is running.
I also have 2×120 W solar panels that top up the batteries when no sure power is available. The Cyrix relay also operates to trickle charge the engine battery from the solar panels in the leisure batteries come up.
As you stated you can also link the two sets of batteries with the cyrix relay to jump start the main engine if required.
Anthony.
I am surprised if the current setup is switched by the alternator as unless the engine is run constantly the fridge will begin to warm up once the engine stopped. Does the fridge light stay on when the engine is not running?
My current setup uses 2x 110ah batteries powering 110 L Dometic compressor fridge/freezer. The batteries are charged by a 35A Victron charger and this also split charges to the engine battery via a cyrix split charge relay. The cyrix relay then charges the leisure batteries once the engine is running.
I also have 2×120 W solar panels that top up the batteries when no sure power is available. The Cyrix relay also operates to trickle charge the engine battery from the solar panels in the leisure batteries come up.
As you stated you can also link the two sets of batteries with the cyrix relay to jump start the main engine if required.
Anthony.
Falcoron
Well-Known Member
No light in the fridge, it does run off the alt when engine running then switches off when engine stops via a rely. I want to charge all batteries when on shore power and run another live and Earth to the fridge via a fused link and on off switch. So it gets cold without engine running. So it's on all the time with charger keeping it going and keeping batteries topped up.
boatingdave
Well-Known Member
If it were me....
I'd remove the fridge relay (the relay will have the trigger wire off the alternator - just take the relay away and the battery supply and the fridge supply connect together with a switch). Connect a DVSR (digital voltage sensing relay) between the starter batter and the domestic batteries. Run the charger (single output) to the starter battery.
This will mean when the engine is running OR you are on shorepower with a charger - the starter battery has priority for charging and once the voltage increases above 13.3V the charge is then made available to the domestics (but cuts out at approx 12.5V). This works OK on both single and multple engines too as most combinations will charge the batteries and use any 'spare' capacity from the alternators (the domestic batteries tend to service the 'other' engine' i.e. one engine always has its own . You can expand this if you have, as an example, a separate generator battery, just put in another DVSR. I don't think this is the most efficient for the larger vessels as the elctrics are more complicated but for something reasonably cheap and simple for most of us sub 50'. Also useful - if you run the domestics flat (on a twin engined boat) just start up the engine with the dedicated battery and it will quickly charge the domestic batteries enough to start the second engine. Just a suggestion, always worked fine for me - in fact I fitted this set up on my 'new' boat last weekend and had the same thing on my previous boat for many years. It made it almost idiot proof.
I'd remove the fridge relay (the relay will have the trigger wire off the alternator - just take the relay away and the battery supply and the fridge supply connect together with a switch). Connect a DVSR (digital voltage sensing relay) between the starter batter and the domestic batteries. Run the charger (single output) to the starter battery.
This will mean when the engine is running OR you are on shorepower with a charger - the starter battery has priority for charging and once the voltage increases above 13.3V the charge is then made available to the domestics (but cuts out at approx 12.5V). This works OK on both single and multple engines too as most combinations will charge the batteries and use any 'spare' capacity from the alternators (the domestic batteries tend to service the 'other' engine' i.e. one engine always has its own . You can expand this if you have, as an example, a separate generator battery, just put in another DVSR. I don't think this is the most efficient for the larger vessels as the elctrics are more complicated but for something reasonably cheap and simple for most of us sub 50'. Also useful - if you run the domestics flat (on a twin engined boat) just start up the engine with the dedicated battery and it will quickly charge the domestic batteries enough to start the second engine. Just a suggestion, always worked fine for me - in fact I fitted this set up on my 'new' boat last weekend and had the same thing on my previous boat for many years. It made it almost idiot proof.
Falcoron
Well-Known Member
If it were me....
I'd remove the fridge relay (the relay will have the trigger wire off the alternator - just take the relay away and the battery supply and the fridge supply connect together with a switch). Connect a DVSR (digital voltage sensing relay) between the starter batter and the domestic batteries. Run the charger (single output) to the starter battery.
This will mean when the engine is running OR you are on shorepower with a charger - the starter battery has priority for charging and once the voltage increases above 13.3V the charge is then made available to the domestics (but cuts out at approx 12.5V). This works OK on both single and multple engines too as most combinations will charge the batteries and use any 'spare' capacity from the alternators (the domestic batteries tend to service the 'other' engine' i.e. one engine always has its own . You can expand this if you have, as an example, a separate generator battery, just put in another DVSR. I don't think this is the most efficient for the larger vessels as the elctrics are more complicated but for something reasonably cheap and simple for most of us sub 50'. Also useful - if you run the domestics flat (on a twin engined boat) just start up the engine with the dedicated battery and it will quickly charge the domestic batteries enough to start the second engine. Just a suggestion, always worked fine for me - in fact I fitted this set up on my 'new' boat last weekend and had the same thing on my previous boat for many years. It made it almost idiot proof.
is this ok to keep attached all the time when engine running and when on shore power? ( obviously the charger wont be connected to 240v when sailing)
would you have a simple wiring diagram?
boatingdave
Well-Known Member
Absolutely - fit and forget. I can get a diagram if you need it but its very simple. The DVSR has two lugs and one wire. I made short tails (16mm welding wire with 8mm crimps) to bolt on to the lugs on the DVSR. That then gives you three cables now coming out of the DVSR. The lug marked 'starter battery' connects to the +ve on the starter battery, the other 16mm cable marked 'domestic' obviously then connects to the +ve on one of the domestic batteries (they should all be in parallel so it doesn't matter which one) and the thin (third) black cable connects to the -ve. It is common for all the -ve's to be connected together across the whole bank but if in doubt connect it to the -ve on the starter battery as it is then on the same supply as the 'trigger' to turn the relay on. If you want I can send you a parts list from Amazon so you can see pictures of everything you need to buy? I also bought my own crimping tool which you will need unless you know someone who has one but it was only about £12 and saved me the hassle of having to ask anyone (and you keep it and can use it for various other applications on the boat wiring as the one I bought was adjustable).
Dave
Falcoron
Well-Known Member
Superb Dave!
Thanks a million chum, very helpful. If you dont mind the list from amazon would be great, what size charger do you have? one supplkier said i needed a 30amp one said i need a 10a and another said 6a! So if they can't agree im stumped LOL! Aslo the leisure batteries are about 1.5 to 2mtrs away from starter battery does that affect the size of the cables i should use?
Thanks again
Ron
Last edited:
boatingdave
Well-Known Member
Hi Ron - the charger depends on the battery capacity. I would suggest a 'smart' charger so it can be left on. It will self regulate the current from the maximum. It should be approx 10% of the batery capacity i.e. for 3x110Ah batteries - about 30Ah will do. You can charge at a higher capacity that this on occasions but not good to do it all the time long term.
The cable (below) is 175Ah so distance is fine, there will be no appreciable losses at that distance.
Parts are:
https://www.amazon.co.uk/gp/product/B00N8P975S/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
https://www.amazon.co.uk/gp/product/B00904IIKG/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1
https://www.amazon.co.uk/gp/product/B015ZIA146/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1
https://www.amazon.co.uk/gp/product/B00E1GH76E/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
Good luck
Dave
Falcoron
Well-Known Member
Perfect,
Thanks again and if you are ever around Co Fermanagh give me a shout i owe you a few pints
cheers
