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Battery charging systems

Manxcat54
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David Mack Veteran II

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To keep it simple:

Lead acid batteries. Tried and tested solution, relatively cheap. Use a VSR to link the systems if you have one alternator; with twin alternators the systems can be completely separate, although a VSR would enable one solar setup/generator/mains charger to keep both batteries topped up.

If you don't keep on top of the charging routine you can wreck LA batteries very quickly.

Lithium batteries. As far as I am aware there are no (affordable) lithium batteries capable of starting a diesel engine, so you need a lead acid starter battery. 

Domestic lithium bank can be charged from dedicated alternator, but you very quickly get into complex and expensive kit to do the job properly. £6k installation cost has been quoted here previously.

Hybrid system where the alternator is connected to the LA starter battery which in turn charges the lithium domestic battery can vary from simple DIY lashups to more complex and expensive electronic charging (B2B) systems. Note that the DIY lashups contravene battery manufacturers' advice and emerging technical standards, and may render you uninsured. Doing it by the book will be significantly more expensive. 

If you have the mindset and the technical understanding you can implement your own solution, as some on here have done, but don't expect it to be cheap and simple.

Edited by David Mack
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magnetman Veteran II

magnetman

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Dynastarts could make a comeback.

 

If one could have a belt driven starter/generator designed for lithium batteries it could work. 

 

Quite hard to start a Diesel engine with a belt without decompressors but could be feasible with a toothed belt and a good ratio. 

 

 

 

I'm sure I heard a Volvo XC90 Diesel starting silently recently. 

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Manxcat54 Contributor

Manxcat54

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11 hours ago, David Mack said:

To keep it simple:

Lead acid batteries. Tried and tested solution, relatively cheap. Use a VSR to link the systems if you have one alternator; with twin alternators the systems can be completely separate, although a VSR would enable one solar setup/generator/mains charger to keep both batteries topped up.

If you don't keep on top of the charging routine you can wreck LA batteries very quickly.

Lithium batteries. As far as I am aware there are no (affordable) lithium batteries capable of starting a diesel engine, so you need a lead acid starter battery. 

Domestic lithium bank can be charged from dedicated alternator, but you very quickly get into complex and expensive kit to do the job properly. £6k installation cost has been quoted here previously.

Hybrid system where the alternator is connected to the LA starter battery which in turn charges the lithium domestic battery can vary from simple DIY lashups to more complex and expensive electronic charging (B2B) systems. Note that the DIY lashups contravene battery manufacturers' advice and emerging technical standards, and may render you uninsured. Doing it by the book will be significantly more expensive. 

If you have the mindset and the technical understanding you can implement your own solution, as some on here have done, but don't expect it to be cheap and simple.

To be honest I wish to keep it simple, I have read all the comments and take much of it onboard, I built myself a campervan, I have 2 x 120Ah leisure batteries and 2 x starter batteries (not sure of rating) in the van I have probably as many 12v LED lights as a 55ft narrowboat would need, I also have a 12v fridge, a 12v TV, a water pump and ignition for the cooker, I also have a stack of USB points, and as I described I use a C-TEK unit, I think it was about £385. When on the move the batteries will charge, I have seen probably over 14v displayed, however once the engine stops (only one alternator) the voltage will drop to maybe 13v and shortly afterwards settle around 12.9v they will maintain this for an hour or so, and then drop to 12.7v then a bit later 12.6v. I can run everything until I go to bed still retaining a good voltage (the fridge is the killer) and so I have fitted a switch to turn it off overnight) it's noisy too. When I wake the next morning the batteries are still about 12.5v and following some breakfast I am normally away and the process repeats.

And so with this in mind I ask why should I go overboard on my narrowboat (which I have only just started to fit out) there may well be a few more gadgets on the boat, but there will be 3 x Leisure batteries (I have probably changed my mind and will go with lead acid sealed type) I also have an inverter onboard, it is only a 1800w but I will upgrade that, I also have 230v hook-up which as in my camper I probably won't use, but you never know, I have been watching blog after blog and reading lots, and I have come to my conclusion that having a massive bank of Victron equipment simply is Narrowboat snobbery, and like I have said there is too much to go wrong and if it does I myself won't be able to fix it (just like cars) so I am keen on finding out a little more about the Stirling system, I might also add that my engine on the boat has 2 x alternators and the stirling system accepts two alternators, and figures out what goes where....comments please guys.

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Tony Brooks Veteran II

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So, assuming from the voltages the van is using lead acid batteries, the rested voltages show that you are doing everything correctly and are fully charging the domestic bank, while not discharging to below about 50% (about 12.2 to 12.3 rested voltage). Apart from the fact that you have to allow for staying in a pleasant spot for a few days, that should be fine if you stay with lead acid batteries.

 

However, as you do not seem to specify the Sterling system you are talking about (B to B, or split charge system) it seems difficult to advise.

 

1. Simple system - One alternator charging each bank, with any solar just charging the domestic bank. Nothing extra to buy.

 

2. A little more complicated - As 1 above but with an external controller on the domestic alternator.

 

3. Less simple system, but with the potential to increase the charge to the domestic bank for much of the engine run time -  As 1above but with a VSR between the banks, that will allow the solar to charge both banks. Note - when the batteries are getting well charged, one alternator may shut down and put its warning lamp on, but the batteries will still be taking all the electricity they want. (If you used an alternator controller, we could all but guarantee the engine alternator would shut down.

 

4. Yet more complicated - Use an Alternator to battery charger or a battery to battery charger but, as you say, that is more difficult to understand.

 

LA batteries should be considered consumables, like oil and oil filters, with engine batteries lasting many years (say 8 o 12)  and domestic ones far less time, but I had a set of leisure (Exide) batteries last six years when I sold the boat and all it had was a 14.5V regulated alternator and a bidirectional VSR, with solar input to the domestic bank. I just kept an eye on the rested voltage and tail current to ensure they were properly charged, and you seem to be doing both those at present.

 

 

 

 

 

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Alan de Enfield Veteran II

Alan de Enfield

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1 hour ago, Manxcat54 said:

I can run everything until I go to bed still retaining a good voltage (the fridge is the killer) and so I have fitted a switch to turn it off overnight) it's noisy too.

 

It sounds as if you have bought the 'wrong' sort of fridge - is it one of the 3-way types (typically Electrolux) ?

These do not have a thermostat on the 12v side (only on the 230v side) and use between 4 and 5 amps so, require something around 100Ah per day.

It will be noisy as it is running continuously rather than the 1:3 on-off ratio of a modern thermostatically controlled fridge.

 

A 'modern' 12v fridge (eg Dometic ) uses around 30Ah per day when left running 24/7.

Mine generally only 'clicks on' for a couple of minutes during the night as the temperature is generally cooler and no one is opening the fridge door

 

The number of Ah used will vary depending on how often you open the door, and the ambient temperature.

 

If it is a 3-way then run it on gas overnight - silent.

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Tony Brooks Veteran II

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17 minutes ago, Alan de Enfield said:

 

It sounds as if you have bought the 'wrong' sort of fridge - is it one of the 3-way types (typically Electrolux) ?

These do not have a thermostat on the 12v side (only on the 230v side) and use between 4 and 5 amps so, require something around 100Ah per day.

It will be noisy as it is running continuously rather than the 1:3 on-off ratio of a modern thermostatically controlled fridge.

 

A 'modern' 12v fridge (eg Dometic ) uses around 30Ah per day when left running 24/7.

Mine generally only 'clicks on' for a couple of minutes during the night as the temperature is generally cooler and no one is opening the fridge door

 

The number of Ah used will vary depending on how often you open the door, and the ambient temperature.

 

If it is a 3-way then run it on gas overnight - silent.

 

But the three-way fridges are normally absorption fridges so that can work on gas, and they are silent in operation. I think the OP has an old compressor fridge that has seen better days and may need regassing.

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Alan de Enfield Veteran II

Alan de Enfield

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8 minutes ago, Tony Brooks said:

 

But the three-way fridges are normally absorption fridges so that can work on gas, and they are silent in operation. I think the OP has an old compressor fridge that has seen better days and may need regassing.

 

 

I did suggest that if it is a 3-way he run it on gas ...........................

 

 

28 minutes ago, Alan de Enfield said:

If it is a 3-way then run it on gas overnight - silent.

 

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Manxcat54 Contributor

Manxcat54

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No it is a specific campervan fridge (forgot the make) it is 12v only, it does have a thermostat, but as any fridge it is on/off all the time and it can disturb my sleep, so I knock it off at night, it never loses any chill and the freezer box is still minus something or other.

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Alan de Enfield Veteran II

Alan de Enfield

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22 minutes ago, Manxcat54 said:

No it is a specific campervan fridge (forgot the make) it is 12v only, it does have a thermostat, but as any fridge it is on/off all the time and it can disturb my sleep, so I knock it off at night, it never loses any chill and the freezer box is still minus something or other.

 

If it is on & off throughout the night then there is something wrong with it - maybe Tony is correct and you've had a gas leak.

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Tony Brooks Veteran II

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20 minutes ago, Alan de Enfield said:

 

If it is on & off throughout the night then there is something wrong with it - maybe Tony is correct and you've had a gas leak.

 

That is the refrigerant gas, not the bottle gas used for cooking etc.

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LadyG Veteran II

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Posted
Posted (edited)
3 hours ago, Manxcat54 said:

No it is a specific campervan fridge (forgot the make) it is 12v only, it does have a thermostat, but as any fridge it is on/off all the time and it can disturb my sleep, so I knock it off at night, it never loses any chill and the freezer box is still minus something or other.

I now have a small 12v  fridge with a freezer. Designed for sailing, i bought it at £699, but its available at £1200!

It's pretty quiet, it does not need a lot lot of power if I have no frozen foods.

Using it as a larder fridge it could be turned off overnight. My ambuen5 temp inside boat is high, ie butter goes soft.

My ancient 12v fridge was very noisy., power hungry, I only used it to chill my G&T.in summer,  a waste of space

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truckcab79 Proficient

truckcab79

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21 hours ago, Manxcat54 said:

I think I will tackle it myself, you lot are too smart for me.

Join up to the 12volt boating group

on Facebook. In fact there are two of them one lower and one upper case if I recall.  Both very good. Lots of sensible down to earth advice without anyone trying to overload you with more info than you need.  

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Tony Brooks Veteran II

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29 minutes ago, Manxcat54 said:

The fridge is perfect

 

Except it is allegedly noisy and keeps running on and off throughout the night. Never mind, it must be perfect and all those that run quietly and infrequently at night must be faulty.

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