Lesure battery charging

[jtr rhyl]

Now before I go and buy a split charger for 2 x 100 amp batterys, I have read that the Berlingo Multispace 2011 Hdi Xtr 1.6 has a smart alternator, these do not work with normal split chargers.
Could anyone tell me if its true or not, I was told that they only give 13.5v out, and the split charger needs 13.8 to switch to the lesure batterys.

[malgpz900]

The split charger I fitted to my Peugeot 407 could be adjusted. There was a procedure to adjust for the voltage to switch it on. I did not need to use it though.
Malcolm.

[jtr rhyl]

I will look out for the adjustable type, would make life easier and cheaper.

[dumdum]

The split charger I fitted to my Peugeot 407 could be adjusted. There was a procedure to adjust for the voltage to switch it on.  I did not need to use it though.
Malcolm.

That’s a caravan split charger and if there’s any extra load on the battery and it is to be present when the vehicle is running then it is very little use... it’s ok for a caravan and maybe keeping a fridge alive in a caravan, but if there’s any more load than maybe 10-15a ideally you would use a proper decent sized relay and switch that with the smaller caravan item...

[hawaiianblue]

Doesn't a caravan split charger charge the caravan's leisure battery from the car anyway? That's what they're for. 10 amps is a massive load, most leisure batteries only need 3 or 4 amps max to charge them.

The genuine Citroen trailer ECU will have a split charger in it, so if you have factory towing electrics just tap in to the caravan charging line.

[GraemeT]

Doesn't a caravan split charger charge the caravan's leisure battery from the car anyway? That's what they're for. 10 amps is a massive load, most leisure batteries only need 3 or 4 amps max to charge them.

The genuine Citroen trailer ECU will have a split charger in it, so if you have factory towing electrics just tap in to the caravan charging line.

Hi - yup they do, I have one of these  in both our Berlingo and the Renault Master and they trickle charge a 110 Ah battery in the caravan. They have the adjustable voltage screw previously mentioned. Cheap as chips but not very durable.

For the two batteries listed this setup would take a heck of a lot of time to charge - have a look at https://www.ebay.co.uk/p/Durite-0-727-33...777&chn=ps states it kicks in at 13.3 volts - there's fully crimped kits on eBay for about £60 that include this Durite relay - If you measure across your battery terminals when the engine is running you'll (hopefully) see around 14 volts - the system runs on that value and is independent of the ignition/alternator systems.

[hawaiianblue]

For the two batteries listed this setup would take a heck of a lot of time to charge

That's pretty much going to be the case with anything hooked up to a car. Car alternators aren't that great at charging batteries, they'll top one up, but charging from flat takes forever. I remember reading in the handbook for my Range Rover, it would take over 8 hours to fully charge the car's battery from flat with the alternator, and that was running the 4.4 litre v8 at a constant 2000RPM without any other loads on the electrical system for the full 8 hours. It had a massive water cooler alternator on that!

[jtr rhyl]

I have 14.4 volt so should work and at that price iits worth a try.

Thanks for the comments every one.

[dumdum]

You guys know very little about charging battery’s, allow me to explain

If an alternator is for example 90a, if you for example flatten a 110a leisure battery, not beyond the realms of you leave a light on or something, the battery will allow whatever current you can give it, but it gets limited by current limiting with a battery charger for example, that’s why you use something like a ctek, take a 15a charger

The battery current is first limited to 15amps and the voltage it puts out will reflect this, the voltage will slowly rise from whatever a current limit of 15a will provide, so it may cap current at 15amps and increase the voltage from maybe 12v and slowly as it charges the battery will increase voltage until it hits 14.4v, then it keeps the voltage at 14.4v as the current slowly drops, once it hits a minimal amount of current, the charger then drops to a maintenence level of 13.6v, this is enough to keep the terminal voltage of a battery just above the point where it self discharges and so it stays ready to go, if it sees a bigger amount of current to stay at that level it then works out something is drawing from it and switches to 14.4v fixed voltage mode and gives whatever current it can upto 15a once more or fixed current mode if it’s a big draw

Now what you have in your vans is just a fixed voltage supply to a degree, it can also modulate its voltage on big demands, but either way it’s capable of dropping 90-150a depending on its size, and all it wants to do is keep voltage at 14.4v by switching on and off the field inside the alternator (an alternator in itself without a battery connected if it can self excite and once you’ve started it will have an output that looks like a sawtooth, varying around 14.4v, so maybe 14.3 to 14.5v

So your out and about and you flatten your battery camping, you then start your vehicle and boom your split charge relay drops in, first thing that happens is the alt decides it wants to get the leisure battery to 14.4v... from my previous explanations the alternator will then do as much current upto and including its full output if more than one battery is connected... I have seen two 210a alts connected to a battery bank in a car stereo car doing 400+a and the owner thought his alts were screwed as the voltage was 12.4v, it wasn’t until I dropped the clamp on he believed that his 6 leisure battery’s were massively flat!

So the thing we learn from this is that an alternator doesn’t care if you put a 30a relay in situe, it’s gonna try and charge the battery’s with whatever it can, personally I’d rather have a relay and fusing appropriate to my alternator rather than what’s cheap and seems to work, in my campervan I have a 200a relat swithed from the alternator light wire as my two leisure battery’s will take whatever charge the alt can give

So no it doesn’t take 3-4a to ‘charge’ a leisure battery, it takes way more if it’s flat, if you believe otherwise you need your head read, it may take that much current if it’s charged to trickle it, but any Accesory off a lewisite battery with the vehicle running will also draw current through the relay from the alternator

So when you have lights, laptop charger and a heater say, all running and dragging that battery voltage down your relay will let your alternator pass all the current to keep the voltage up to whatever it’s preset is, the little relays are not really ideal for what they are sold for, do they work? Yup, but in lots of scenarios they are very dangerous and not really upto the job

The average caravan while travelling they tick the fridge over and also the battery topped up, that’s less than ten amps, but a caravan is also designed to go on mains which then will have a 15-30a power supply/ 3 stage charger fitted like a ctek, this will generally keep the battery charged and nice so when you plug your car in to come home the alternator has a nice easy time... guess what happens when you plug it into a flat battery... both ends of the charging cable should have 30a fuses and one end or the other will then pop, not a lot of good when you have no indication of it

Do it right with appropriate cable and fusing and your charging system will cope very nicely with whatever you throw at it and won’t cost you a great deal more than half arsing something that gets you by with plastic tat that is sold for doing a job and sold for caravan towing electrics...

[old son]

I know it is slightly different but I have a narrow boat with 4 135amp leisure batteries and 1 starter battery. I have 2 alternators, 175amp for leisure and 90 amp for starter. With leisure batteries at 60% I see 90 plus amps of initial charge that drops to around 2 after 6 hours or so. We use split chargers but they direct both alternators to the leisure bank when the starter battery is charged. It is the batteries that dictate the charge, once nearly charged they will only accept very low amps.