'alternator to battery charger' Question?

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mjb666
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Joined: August 23rd, 2014, 5:07 pm
Location: Surrey. M3-Junction 4.

'alternator to battery charger' Question?

Post: # 16883Post mjb666
February 15th, 2017, 12:48 pm

I noticed this comment on another site and wondered if anyone on here 1. Has this set-up on their Demountable & 2. Can explain what is all does in plain terms, i got a bit confused reading Sterling Power Products site.

I have a stand alone leisure battery at the rear of my Demountable which i periodically charge before setting off, apart from that, i have no other means of power. I have wondered what is the best way forward for me as i plan on keeping the demountable for a few more years.


" I've been using Sterling Power 'alternator to battery charger' for years. It's a 4 stage charging device that sits between an alternator and the two banks of batteries (starter/leisure). It's by far the most efficient use of energy I've found and that's whilst having solar on board too. I can charge a 100ah leisure battery (and properly) in a couple hours. Nothing else come even close. Solar in the UK is a bit pants because of lack of sun and panel efficiencies being around 17% still. The Sterling isn't cheap but it's fit and forget and I've spend a good few years living in trucks."
2005 Mitsubishi L200 Single Cab 4x2
Unknown Demountable

keeflester
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Joined: August 24th, 2014, 8:23 pm
Location: Carradale Argyll and Bute Scotland, beside the sea

Re: 'alternator to battery charger' Question?

Post: # 16890Post keeflester
February 16th, 2017, 2:17 am

mjb666 wrote:I noticed this comment on another site and wondered if anyone on here 1. Has this set-up on their Demountable & 2. Can explain what is all does in plain terms, i got a bit confused reading Sterling Power Products site.

I have a stand alone leisure battery at the rear of my Demountable which i periodically charge before setting off, apart from that, i have no other means of power. I have wondered what is the best way forward for me as i plan on keeping the demountable for a few more years.


" I've been using Sterling Power 'alternator to battery charger' for years. It's a 4 stage charging device that sits between an alternator and the two banks of batteries (starter/leisure). It's by far the most efficient use of energy I've found and that's whilst having solar on board too. I can charge a 100ah leisure battery (and properly) in a couple hours. Nothing else come even close. Solar in the UK is a bit pants because of lack of sun and panel efficiencies being around 17% still. The Sterling isn't cheap but it's fit and forget and I've spend a good few years living in trucks."
I'm using a Sterling B2B (battery to battery) charger in my recent project. It does the same for my leisure battery. I can go from 12.3v to fully charged in about an hour as soon as the engine is started and the alternator is supplying current. My vehicle has two batteries, the starter-only battery is kept charged at all times. All the vehicle auxiliary power is taken from the auxiliary battery, which is permanently live to things like 12v sockets, satnav, radio, interior lights. When the ignition is switched on the aux battery is switched in parallel with the starter battery to provide extra cold cranking amps (CCA), then it remains in parallel while the vehicle is being driven. The feed for the Sterling B2B is taken from a fused output off the aux battery. I'll be fitting a 240v charger which will supply the aux battery with a maintenance charge while I'm parked up at home, so the B2B will automatically look after the leisure battery at the same time. This would also work if I fitted a solar panel and used that to supply the maintenance charge to the aux battery. The Sterling is a very useful bit of kit.
2003 Ford Ranger 2.5 TD 109 Supercab, sold to Simon
Tandy Pony, sold
Northstar 750, sold
K33F-built Penthouse Pee Pod, sold to Simon with the Ranger
Built the lozenge for my wee sister, its now finished and in regular use
Now converting a blue Tranny.

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sabconsulting
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Location: High Wycombe

Re: 'alternator to battery charger' Question?

Post: # 16906Post sabconsulting
February 17th, 2017, 9:39 pm

Batteries

Regular starting batteries provide high current for engine starting but cannot be discharged much or they will fail. Leisure batteries are starting batteries that are a bit more tolerant of being discharged by more than a few percent, but still maybe only a few dozen times before they are toast, and certainly no lower than 50% charge. Deep cycle and AGM batteries are much more expensive and can be discharged much more each time and can tolerate deep discharge hundreds of times. I use an AGM battery that can be discharged down to 20% hundreds of time, but cost about £300 :o

So don't expect to buy a cheap leisure battery, charge it at the start of your trip, run it down and expect to repeat that process many times. Hence having some method of charging from your truck alternator is a good thing to recharge the battery as you drive.

Charging off your alternator

Traditionally you could just use a permanent 12v wire from your truck battery (charged by the alternator) through the caravan socket on the back of your truck, and then through the camper wiring to the battery (usually at the front of your camper, though I see yours is at the rear). The first problem is that without any form of isolation as you run down your camper battery you are also running down your truck battery so may not be able to start it in the morning.

This can be solved with a relay fitted under the bonnet that only connects the camper battery when the engine is running.

The next problem is voltage drop. Your alternator will provide a healthy voltage to charge the truck battery maybe a foot from it (connected via nice thick cables). But now you are running a probably thin wire through a charging relay, the whole length of your truck and back and through a connector. The thinness of the wire and its length will cause a voltage drop, as will the charging relay and connector. So what you actually get at your camper's battery is too low a voltage to charge it properly and certainly quickly.

DC to DC chargers

These are the solution. Sterling Power and CTEK both sell these, though they aren't that cheap. You install them near your camper battery and they do the following:

They take the now inferior voltage they receive all the way from the truck alternator and using clever electronics can increase the voltage to one reasonable for charging at the expense of amps. They are also 'intelligent' and that means they go through various stages of charging, adjusting the charging voltage and current to provide optimal charging for a lead-acid battery.

This means they charge your battery more quickly and help elongate its life.

Some also come with a 2nd input which you can wire up to solar panels. On my one if the camper battery is full and the solar panels have sun it will send voltage back down the wire to the truck battery to top that up,

The catch

My truck is 10 years old. Being old-school the alternator runs all the time the engine runs. I have heard that new vehicles have cleverer alternators that disconnect themselves to save fuel once the truck battery is charged. If you have one of these you need to do more research because it might be the alternator won't provide sufficient power to charge an auxiliary battery.

Other ways of charging

I have a DC to DC charger on my camper. In addition it takes an input from the solar panels on the roof, so whenever there is sunlight it is charging the battery, e.g. when parked during the day. Finally I have a multi-stage intelligent mains charger that fires up as soon as I plug the camper into the mains, e.g. on a campsite where I have paid for full hook-up. So that is 3 different sources of power. However, I have a compressor fridge that is power hungry unlike 3-way propane fridges, so I have to maximise my battery charging.

Keeping an eye on your battery

Unfortunately you are usually in the dark about the state of charge of your battery. If you know how much charge remains in your battery you can better ration that power out to preserve the life of the battery, e.g. turn off some lights, unplug your laptop or phone from the 12v socket, etc.

If you isolate the battery you can then measure its voltage and work out the state of charge from that. I believe you are really supposed to leave it a while unplugged in order to get an accurate reading. Clearly this is inconvenient if you want to check the state of charge half way through watching TV or simply in the winter when you need the lights on to see.

So you can buy battery meters that you wire in-line with the cables to the camper battery. These will keep a running total of the amps going into and out of the battery. I have one made by Victron. Like the DC-to-DC chargers these are not cheap, but being able to see you are at 83% battery charge at the press of a button gives you so much more peace of mind and allows you to plan better.

Steve.
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mjb666
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Re: 'alternator to battery charger' Question?

Post: # 17056Post mjb666
March 1st, 2017, 5:22 pm

Thanks Keith & Steve.

When i got my new pick up it was fitted with a split charger

Imagepost images

and fitted with a 13pin Euro socket

Imagephoto upload

My leisure battery is in a compartment at the back of the Demountable

Imagephoto uploader

Is there a simple way of checking if this set up will actually put a charge from the alternator to the leisure battery?

I do own a multimeter, which i use to check the state of charge in the leisure battery, but too be honest, i wouldn't know much else to do with it, i'm useless at DIY.
2005 Mitsubishi L200 Single Cab 4x2
Unknown Demountable

keeflester
Posts: 538
Joined: August 24th, 2014, 8:23 pm
Location: Carradale Argyll and Bute Scotland, beside the sea

Re: 'alternator to battery charger' Question?

Post: # 17057Post keeflester
March 1st, 2017, 5:50 pm

If you measure the leisure battery at rest and it gives you better than 12.5v, then it's getting a good charge. After you've established the base voltage, start the engine and watch the voltage at the leisure battery to see it get a boost when the split charge relay cuts in. Just for your own peace of mind and fire safety, there should be a fuse in the positive feed to the leisure battery as close to the terminals as is feasible.
Further to that, the cables look a little light. But plenty of folk get by with similar. If your usage is high and you need the fullest charge, the reduced voltage drop from fatter cables will help. That needs to be all the way through from the relay. It's a bit problematic as there's not really room in the caravan connector for a fatter cable.
This is where B2B chargers score highly, as they boost the voltage at the leisure battery - at the cost of some more current draw - and charge the leisure battery fully, in less time, and with the correct charge profile for the battery. It's no accident that they cost as much or more than the battery they're designed to charge.
Hope this helps.
Kind regards, K33F
2003 Ford Ranger 2.5 TD 109 Supercab, sold to Simon
Tandy Pony, sold
Northstar 750, sold
K33F-built Penthouse Pee Pod, sold to Simon with the Ranger
Built the lozenge for my wee sister, its now finished and in regular use
Now converting a blue Tranny.

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Toshbins
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Joined: October 22nd, 2015, 12:12 pm
Location: Between Reading and Oxford

Re: 'alternator to battery charger' Question?

Post: # 17062Post Toshbins
March 1st, 2017, 9:29 pm

Looking at the quality of the connection to the leisure battery, you could add hundreds of pounds worth of kit to it and not get much improvement. Crimp connectors are great for a quick fix, but going through them all with a soldering iron and some shrink insulation will make them reliable and able to carry full voltage - then yes, money spent on a quality battery and charge system will let you stay longer in one place without needing to drive for three hours just to get the battery back up to charge. If you are always plugged in when you stop, or drive a couple of hours each day then it won't gain you much.

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TrueDink
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Re: 'alternator to battery charger' Question?

Post: # 17063Post TrueDink
March 1st, 2017, 10:52 pm

I went for the Ctek 250S Dual which does the same as the Sterling but its also an MPPT solar controller.
Nissan NP300 Navara Tekna double cab
S.Karosser EC6L-2.0

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Gary W
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Re: 'alternator to battery charger' Question?

Post: # 17091Post Gary W
March 3rd, 2017, 10:05 am

mjb666 wrote:I noticed this comment on another site and wondered if anyone on here 1. Has this set-up on their Demountable & 2. Can explain what is all does in plain terms, i got a bit confused reading Sterling Power Products site.

I have a stand alone leisure battery at the rear of my Demountable which i periodically charge before setting off, apart from that, i have no other means of power. I have wondered what is the best way forward for me as i plan on keeping the demountable for a few more years.


" I've been using Sterling Power 'alternator to battery charger' for years. It's a 4 stage charging device that sits between an alternator and the two banks of batteries (starter/leisure). It's by far the most efficient use of energy I've found and that's whilst having solar on board too. I can charge a 100ah leisure battery (and properly) in a couple hours. Nothing else come even close. Solar in the UK is a bit pants because of lack of sun and panel efficiencies being around 17% still. The Sterling isn't cheap but it's fit and forget and I've spend a good few years living in trucks."
Your have lots of answers already, but you might still find this useful....

http://sbsadventurecampers.com/wp/charg ... e-campers/


Best wishes

Gary

SBS Adventure Campers

Mobile: +44 (0) 7595 368 422
Desk: +44 (0) 1305 305 900

Web: sbsadventurecampers.com
Web: djangocampers.eu



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TrueDink
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Re: 'alternator to battery charger' Question?

Post: # 17092Post TrueDink
March 3rd, 2017, 11:34 am

Which battery to battery chargers do you fit Gary?
Nissan NP300 Navara Tekna double cab
S.Karosser EC6L-2.0

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Gary W
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Re: 'alternator to battery charger' Question?

Post: # 17104Post Gary W
March 3rd, 2017, 4:53 pm

TrueDink wrote:Which battery to battery chargers do you fit Gary?
Sterling if it's going in the truck, Votronic or Mastervolt if it's going in the camper. We''ve heard good things about Ctec too but we've not tested them yet.

Best wishes

Gary

SBS Adventure Campers

Mobile: +44 (0) 7595 368 422
Desk: +44 (0) 1305 305 900

Web: sbsadventurecampers.com
Web: djangocampers.eu



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