Technical New Ducato Stop Start Alternator

[Reg 65]

Hi, Looking for help
I'm needing to get a new van for a camper, where the only source of electricity will be the vans alternator. On older models I have fitted a second battery through a voltage sensing relay using 25mm2 cable so the X2/50 standard 150amp alternator charges both batteries really well, providing enough power for the living accommodation. Even on tickover its 14.4v so can charge the batteries without even moving the van. I use a normal battery rather than leisure battery for the secondary battery so it will accept fast charge and can be used to jump start the van if the engine battery fails
Can anyone tell me how to get the new fangled Ducato start stop alternator to work as normal and charge the secondary battery like this please?
PS: I don't have the new van yet so can't look at it, may have to stick to the old Ducato if I can't solve this problem.

 

[Reg 65]

or failing that maybe just connect both batteries through a simple 100A relay activated by the ignition switch?

 

[Communicator]

Reg65,


I think that this is as much a motorcaravan problem as a Fiat one, and is similar to that posed by smart alternators.

The accepted fix for smart alternators in motorcaravans, is to fit a battery to battery charger (B2B) between the two batteries. This approach should provide an optimum charge profile for the second battery, however the extra load taken by the habitation system may prevent the stop start system from working.

For safety, when connecting between batteries, the cables should be fused as close possible to each battery. However, if this is applied to the simple ignition controlled relay and one battery is in a discharged state, the fuses could blow when starting.


I am interested in the use of starter batteries for the habitation supply. Has the battery life suffered due to the deeper discharging in the habitation role? An alternative would be to use dual purpose batteries, which offer substantial starting currents together with deep discharge capability. The Varta LFD95 is a popular example.

 

[Reg 65]

Thanks for the reply
Yes I guess a 200A - 500A relay would be better.
A you tube video I saw said you need a B2B charger to reduce the current to the batteries as the high current produced under regenerative braking may damage Leisure / GEL AGM batteries. He didn't mention using batteries able to cope wth it - but then he was selling B2B chargers.
I like to keep things as simple as possible so there is less to go wrong, and I can understand and maintain them.
And I don't want to waste alternator current in the B2B charger when it could be used to charge the secondary batteries. Especially when parked up without doing much driving. So want to make the most of the alternator current to charge the secondary battery without obstructions in the way like B2B chargers which can only consume power.
So the simple solution of connecting them through a hefty relay and cables, activated by turning on the ignition appeals to me. If the secondary battery was flat I would know about it and disconnect the ignition switch feed wire to the relay before trying to start the van.
But would it work?

 

[mikefitz406]

You need a B to B charger because with the 'smart' alternator charging for start stop, the voltage is regulated NOT to fully charge the engine battery. This leaves 'room' in the engine battery so regen braking has somewhere to put power.

If you add a leisure battery with a simple relay to connect to the leisure battery then the leisure battery will never fully charge and fail within a short time.
Even with a non smart alternator, a B to B charger will charge the leisure battery more effectively and quicker than a relay.
Its unusual to only have engine charging for a camper, and if this is the case its more important than ever to have both a true deep cycle leisure battery and an a efficient and fast charging method. Keep in mind that even with powerful chargers, to completely charge from half full , a lead acid battery, it will take 5 hours.
Using a typical starter battery in a leisure application will give a very short service life.

Mike

 

[Reg 65]

If you add a leisure battery with a simple relay to connect to the leisure battery then the leisure battery will never fully charge and fail within a short time.

Thanks for the reply
But I'm a simple soul and don't understand the above.
Why wouldn't the secondary battery get fully charged during regenerative braking like the starter battery?
Why doesn't the starter battery fail in a short time?
If both batteries are in parallel why wouldn't they both get charged to the same level - including fully charged with regenerative braking?
The starter battery must be kept charged enough to start the van, why wouldn't that be enough for the secondary battery?

 

[chris3234]

Thanks for the reply
But I'm a simple soul and don't understand the above.
Why wouldn't the secondary battery get fully charged during regenerative braking like the starter battery?
Why doesn't the starter battery fail in a short time?
If both batteries are in parallel why wouldn't they both get charged to the same level - including fully charged with regenerative braking?
The starter battery must be kept charged enough to start the van, why wouldn't that be enough for the secondary battery?

Why are you mentioning regeneration braking?
That's only on electric cars a smart alternator does not have the ability to do regenerative braking
While it will charge more heavily while your foot is off the pedal it's nothing like the power of regen breaking

 

[Reg 65]

Why are you mentioning regeneration braking?
That's only on electric cars a smart alternator does not have the ability to do regenerative braking
While it will charge more heavily while your foot is off the pedal it's nothing like the power of regen breaking

OK - but, whatever its called, its enough to charge the starter battery, and both are connected together so they get the same, why would it not be enough for the secondary battery?

 

[RS3100]

Why are you mentioning regeneration braking?
That's only on electric cars a smart alternator does not have the ability to do regenerative braking
While it will charge more heavily while your foot is off the pedal it's nothing like the power of regen breaking

But the charge supplied by the alternator is reduced or even cut-off under open throttle, and increased on overrun or during braking. Nothing to do with a charge being obtained from the brakes themselves, but vehicle manufacturers still refer to it as regenerative braking.

Volvo say that my ICE car has regenerative braking, but it is purely ECU controlled smart-alternator charge variation according to throttle and brake monitoring as above. Common on vehicles with start/stop, petrol, diesel, electric or otherwise.

The system is usually also programmed to maintain the vehicle battery at around 80% charged, so that it has the spare capacity to absorb charge generated under "regenerative braking". The additional capacity is used to support electrical systems on the vehicle when start/stop is engaged at a standstill, and the electrical system on the vehicle will always attempt to return ther battery to around 80% charge in use, even after fully charging it with a battery charger overnight for instance.

 

[Reg 65]

The system is usually also programmed to maintain the vehicle battery at around 80% charged, so that it has the spare capacity to absorb charge generated under "regenerative braking". The additional capacity is used to support electrical systems on the vehicle when start/stop is engaged at a standstill, and the electrical system on the vehicle will always attempt to return ther battery to around 80% charge in use, even after fully charging it with a battery charger overnight for instance.

Could maybe just get a bigger secondary battery then?

 

[Reg 65]

Or maybe a Fiat Dealer could programme the alternator to charge as normal?
Unless they are not allowed to as it affects emissions with the engine using a drop more fuel to charge the battery instead of vehicle momentum?.

 

[Reg 65]

Why are you mentioning regeneration braking?

Because I don't know what else to call it when the alternator is used as a brake to generate power.
What do you call it?

 

[Nappulakenka]

Hi all,

Could the CTEK Smartpass 120S do the job for you? My apologies, I was going to share the link, but I am "unqualified" for that, "You are only allowed to post URLs once you have at least 5 posts".

It can be used with cars with smart alternators, it supports many different types of battery types and can automatically give extra crank power(from leisure battery) if start battery voltage have dropped to low.

 

[rayc]

In the motorhome world manufactures are fitting battery to battery chargers to ensure habitation batteries are charged when smart alternators are fitted.
https://www.12voltplanet.co.uk/auxiliary-battery-charging-in-vehicles-with-smart-alternators.html

 

[RS3100]

As said 3 times above, you need a B2B charger that is compatible with, and wired correctly for use with smart alternators. That means it should be triggered by a D+ input from the alternator rather than operating simply from voltage sensing of the vehicle battery circuit and be designed to work correctly with Eu6 vehicle charging systems. Fiat provide a simulated D+ controlled by the BCM at the conversion socket in the RH B-pillar if your motorhome has that option fitted. The B2B charger simulates a heavy load on the vehicle battery in conjunction with monitoring the state of the leisure batteries, causing the smart alternator to continue to generate a charge when the base vehicle systems would have otherwise told it to cut out, until the leisure batteries are charged.

Although my van is not Eu6, I have a Votronic B2B fitted which is also Eu6 compatible and I have been very happy with it. Output is substantially higher than the standard split charge relay fitted by the original converter.

 

[Reg 65]

As said 3 times above, you need a B2B charger that is compatible with, and wired correctly for use with smart alternators.

Thats what the salesmen tell us.
Cynic that I am, I suspect they would rather sell a £400 B2B system than a £10 relay. I get they are fitted to some motorhomes, but they have things I don't need, like mains hookup, solar charging, electric fridge, etc etc. I just have LED lights, Chromebook, DVD, and Chinese diesel air heater. (with an ice box cooled by supermarket ice cubes)
But I like to keep things simple enough for me to understand and maintain them.
So I just wondered if anyone knew why you couldn't use the simple old fashioned method of connecting both batteries together by a relay controlled by the ignition switch.
Only reasons I have heard is
1) It may only get 80% charged like the engine battery - solved by getting a bigger battery?
2) Charge rate may be too fast for some batteries solved by getting a battery that will take a faster charge.
Does anyone know if there is another reason please?

 

[RS3100]

Does anyone know if there is another reason please?

It will charge significantly more slowly due to interruptions to and reduction of the charging current caused by the vehicle's default smart-charging algorithm. Even without a smart alternator, I see approximately 3x the current being fed to the leisure batteries from the B2B than through the split-charge relay.

You also mention charging your battery by running the van whilst stationary. I hope you realise that the practice of idling or revving an engine for any length of time whilst it is not under load is bad for the longevity of the engine, and the likelihood of prematurely blocking the particulate filter on an Eu6 or other vehicle with an emission control system including a DPF may well result in a cost to you far greater than the fitment of a B2B charger.

 

[rayc]

A good B2B is half the price of the £400 quoted.
https://www.ebay.co.uk/itm/19229849...ughtOfCoviewV2&_trksid=p2563228.c101113.m2108

 

[RS3100]

Or even less Ray, but I'm assuming the price he's being quoted includes installation by the converter. Basedon things I have fitted to my van myself - additional solar panel cost me £125. The same panel supplied and fitted by the converter £499. Washroom roof vent fan £250 ordered with the van. The same Heki without the fan kit is fitted by default though. I bought the fan kit for £70 and spent a couple of hours connecting it to the fusebox.

 

[Reg 65]

A good B2B is half the price of the £400 quoted.
https://www.ebay.co.uk/itm/192298499267?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20200818142055%26meid%3Da1c1695392674800b2dac8525310c521%26pid%3D101113%26rk%3D1%26rkt%3D3%26mehot%3Dpf%26sd%3D174723260658%26itm%3D192298499267%26pmt%3D1%26noa%3D0%26pg%3D2563228%26algv%3DSimplAMLv5PairwiseWebWithBBEV2bAndUBSourceDemotionWithUltimatelyBoughtOfCoviewV2&_trksid=p2563228.c101113.m2108

In my experience you rarely get the figures quoted from these things. Like if they quote the range for an electric wheelchair you are lucky if you get half. But even if you do get the 30 amps quoted, thats less than I have been getting from the standard 150 amp alternator in my X250 with a cheap and basic split charge relay through 25mm2 cables. I had 2x100Ah secondary batteries in parallel - 300Ah with the starter battery. The voltage in the secondary batteries dropped to 12v, I started the engine, and within a few seconds it was up to 14.4v just on tickover.