Battery Chargers

[sailinglegend420]

Don’t use an automotive charger on a boat - why?

1. You need a high current device that will happily charge a boat service battery that is maybe 400Ah or over. This would require a charger that can deliver 100 amps. It should also have an external voltage sensor to measure the actual battery terminal voltage, and a temperature sensor to measure the battery temperature and automatically adjust the charge voltage. This is especially important if the batteries are in the engine compartment.
2. You need a good Smart Multi-stage charger to properly charge and maintain a deep cycle battery bank.
3. You need a charger that is designed for safe marine use where the AC side is electrically insulated from the DC side.
4. You want a charger with a dedicated three pin plug, including an earth wire, not a two pin that could be plugged in with the Live and the Neutral reversed. This could kill swimmers in the water around the boat.

 

[dom]

You need a high current device that will happily charge a boat service battery that is maybe 400Ah or over. This would require a charger that can deliver 100 amps. It should also have an external voltage sensor to measure the actual battery terminal voltage, and a temperature sensor to measure the battery temperature and automatically adjust the charge voltage. This is especially important if the batteries are in the engine compartment.

Agree with using proper marine gear. However, I think the OP sails a 33' ketch and a full-suss 100A marine charging system is going to set him back the thick end of a grand. Overkill?

I wld have though a 30A or even 20A would almost certainly sort him out.

 

[PaulRainbow]

Don’t use an automotive charger on a boat - why?

1. You need a high current device that will happily charge a boat service battery that is maybe 400Ah or over. This would require a charger that can deliver 100 amps.

1. 
   
   No you don't. 10% of battery ah is considered the norm. My charger is 30a, my batteries are 110ah engine and 220ah domestic. As i said earlier, fridge and heating are currently on 24/7, along with other stuff on and off. Batteries currently on float and the charger is maintaining them and running the boat.
   
   

   It should also have an external voltage sensor to measure the actual battery terminal voltage,

   
   Why ? The charger itself is connected directly to the batteries.
   
   

   and a temperature sensor to measure the battery temperature and automatically adjust the charge voltage. This is especially important if the batteries are in the engine compartment.

   
   I have one of those, good idea but not absolutely vital (mine hasn't been fitted yet, had to fit the charger in a hurry when the old one gave up the ghost over Christmas).
   
   
   

   You need a good Smart Multi-stage charger to properly charge and maintain a deep cycle battery bank.

   
   Doubt many on here have deep cycle battery banks, but a good multi stage charger is essential for any battery bank on a boat, IMO.

 

[sailinglegend420]

....I would have though a 30A or even 20A would almost certainly sort him out.

It's the principle that is important. Most battery manufacturers recommend 20% (Trojan recommend 10-13%) so divide the Ah capacity of the Service bank by 5 (20%) and add 5% to cover the load the boat is taking. So 20% - so yes he needs a 30 amp charger, certainly not a 4 amp charger.

....It should also have an external voltage sensor to measure the actual battery terminal voltage....

You need an external voltage sensor because the charge may well be connected via several buss bars switches and fuses, all of which will eventually corrode and produce voltage drops. More importantly if there are split diodes for charging the Service AND Starter batteries then there will be a 0.7 volt drop across the diodes.

 

[PaulRainbow]

You need an external voltage sensor because the charge may well be connected via several buss bars switches and fuses, all of which will eventually corrode and produce voltage drops. More importantly if there are split diodes for charging the Service AND Starter batteries then there will be a 0.7 volt drop across the diodes.

The charger should be connected directly to the batteries, no switches or bus bars and certainly no diodes. If multiple banks need to be charged then a charger with multiple outputs should be used.

Not sure which, if any, of the major manufacturers make mains chargers with battery sensing facilities. Sterling don't, their charges are designed to be connected to the batteries, as above.

 

[pvb]

You need a high current device that will happily charge a boat service battery that is maybe 400Ah or over. This would require a charger that can deliver 100 amps.

The OP has already said he only has a single 110Ah domestic battery, so talk of 100A chargers isn't perhaps helpful or relevant.

 

[sailinglegend420]

The charger should be connected directly to the batteries, no switches or bus bars and certainly no diodes. If multiple banks need to be charged then a charger with multiple outputs should be used.

I agree - no switches should be in circuit, but I have seen a 30 Amp switch in circuit with a 120 amp charger, and the switch melted.

Split Diodes are very common in old installations and shouldn't be used because of their voltage drops which causes all sorts of other problems. Today VSRs or Battery to Battery chargers do a better job. I could have written 10 pages on each of my 4 reasons for not using automotive chargers.

Not sure which, if any, of the major manufacturers make mains chargers with battery sensing facilities. Sterling don't, their charges are designed to be connected to the batteries, as above.

I'm not sure either, but my Viltron has an external battery sensor, and Balmar alternators and some regulators have the facility.

 

[VicS]

Don’t use an automotive charger on a boat - why?



3. You need a charger that is designed for safe marine use where the AC side is electrically insulated from the DC side.

I'd be very worried if I found any battery charger where the DC side is not insulated from the AC side

4. You want a charger with a dedicated three pin plug, including an earth wire, not a two pin that could be plugged in with the Live and the Neutral reversed. This could kill swimmers in the water around the boat.

I am struggling with this concept rather.

You would also need a battery charger fault that made the DC output live, the onboard RCD to fail to trip, the supply RDC to fail to trip and to be in a freshwater marina.

 

[pvb]

You would also need a battery charger fault that made the DC output live, the onboard RCD to fail to trip, the supply RDC to fail to trip and to be in a freshwater marina.

Could happen, Vic, could just happen.

 

[VicS]

Could happen, Vic, could just happen.

For Christ's sake don't try crossing the road!

 

[sailinglegend420]

...You would also need a battery charger fault that made the DC output live, the onboard RCD to fail to trip, the supply RDC to fail to trip and to be in a freshwater marina.

It only takes a very very small AC current to paralyse a swimmer. This could be below the trip currents. Freshwater marinas are indeed more dangerous than saltwater.

 

[CalicoJack]

Thanks for all the replies. I have contacted Ring today and they could see no problems, apparently they have tried this with the 25amp version, but could see no reason why the 12 wouldn't work; their only comment was that it might turn itself off after perhaps 24 hours, but it could be reset.

As someone guessed it's a pletier (spelling)type fridge so no wonder it likes its power. Also we are a centre cockpit layout and have a very compact engine compartment. I don't want the charger in a hot compartment and want to mount it in the aft cabin, but space is an issue. I know that the 25 amp simply won't fit, but the 12 will.

I'm looking for a cheap simple solution, one such as, to hell with it I won't drink cold beer, I will simply open some more red. The sort of sailing that we do means that we are in port/Marina every couple of days so buying more food is not too difficult.

 

[VicS]

Thanks for all the replies. I have contacted Ring today and they could see no problems, apparently they have tried this with the 25amp version, but could see no reason why the 12 wouldn't work; their only comment was that it might turn itself off after perhaps 24 hours, but it could be reset.

As someone guessed it's a pletier (spelling)type fridge so no wonder it likes its power. Also we are a centre cockpit layout and have a very compact engine compartment. I don't want the charger in a hot compartment and want to mount it in the aft cabin, but space is an issue. I know that the 25 amp simply won't fit, but the 12 will.

I'm looking for a cheap simple solution, one such as, to hell with it I won't drink cold beer, I will simply open some more red. The sort of sailing that we do means that we are in port/Marina every couple of days so buying more food is not too difficult.

I thought I'd do a bit more experimenting.

I'd assumed you had a compressor type fridge because you said it cuts out when it gets cold enough ... I thought Peltier ones ran continuously!

When I tried the effect of a load previously I had the battery on charge then switched the load on (car lights!). The charger went into recondition mode.

Therefore I have now tried putting the load on first ( single headlamp bulb ) for a minute or so then switching the charger on and setting it to 8 amps max output. ( fairly new battery by the way)

No problems 8 amps output soon falling to about 4 amps ( which is what the bulb would have been taking) I left it like this for a short while but I am sure the charger would have coped with that indefinitely.

I then disconnected the load and the charger immediately went into its float mode. ( It has a strange pulsed pattern to its float mode)

I watched that for a while and all seemed to be normal so I reconnected the load .

After a short delay, while the charger completed one cycle of its pulsed float mode, it went into recondition mode, as I thought it would.

( By this time the brass monkeys were beginning to feel the cold so I packed up and came back into the warmth indoors)

Conclusion: The charger is happy with a steady load but if that is switched off and then back on again... like a fridge will do on its thermostat... the charger does not like it, thinks there is problem with the battery and attempts to recondition it!

It will be interesting to know if the current range of Ring Smartchargers behave the same or differently. At least if you find it goes into recondition mode it wont be entirely unexpected .

BTW named after the French physicist, Jean Charles Athanase Peltier.

 

[CalicoJack]

Thanks Vic for all your efforts. I'm not sure what to do with this one, I will have to have a bit of a think.