Technical Alternator amp size

[Bigbear52]

Does anyone know how to find out what size amperage alternator I have?
I want to fit a 60amp battery to battery charger and want to make sure I don’t overload it.
Looking online they seem to vary between 140amps and 180amps that will all fit my van but I would like to know what I actually have.
Thanks for any help

 

[Communicator]

Does anyone know how to find out what size amperage alternator I have?
I want to fit a 60amp battery to battery charger and want to make sure I don’t overload it.
Looking online they seem to vary between 140amps and 180amps that will all fit my van but I would like to know what I actually have.
Thanks for any help

The rating of the alternator will be shown on the alternator label, which is effectively the rating plate. As an alternative to crawling underneath, you could try inputting the VIN number into ePER. (For ePER see top of any of this forum's pages.

 

[Bigbear52]

The rating of the alternator will be shown on the alternator label, which is effectively the rating plate. As an alternative to crawling underneath, you could try inputting the VIN number into ePER. (For ePER see top of any of this forum's pages.

Hi thanks
I did try the ePER but it doesn’t seem to cover my vehicle unless I’ve done something wrong it appears to be just older vehicles

 

[Reg 65]

ePer won't accept my VIN number either (2021 Ducato smart alternator)
Whatever, the standard alternator for your 2019 Ducato is Bosch 150 amp, ( 180amp for smart alternator.)
Either one should be ok for a 60 amp B2B
Most of the stuff you read from the experts will tell you to fit a B2B because they are selling them!
But I have never bothered with one
I have 4x019 100ah secondary batteries - 2 under each seat.
I have tried them connected directly in parallel with the main battery, and through a 200amp relay activated by the ignition switch, or by the D+ on the alternator
All 3 ways worked well enough
But I found that having 510ah of capacity I never came anywhere near to discharging them to the point where the engine wouldn't start.
The heaviest users are my inverters, and they cut out when the battery voltage drops
So now I have them all connected directly in parallel with 25mm2 cable - sometimes the best way is the simplest way!
So all 5 batteries are getting equal charge and wear.

 

[Communicator]

With lead acid batteries the charge current soon drops back from an initial maximum, as the cells aquire surface charge. I suspect that the OP is considering lithium batteries, which can take high charging voltages over much longer periods of time. This could make the alternator overheat. A B2B will place a limit on the current taken from the alternator, and can also provide the correct charging profile for optimum charging of lithium batteries.

 

[Bigbear52]

Update
I have a full Victron charging system with 315amp lithium batteries.
I have a Victron 30amp dc to dc charger and I want to add another one hence the reason for my original question.
Thanks for your help

 

[Reg 65]

With lead acid batteries the charge current soon drops back from an initial maximum, as the cells aquire surface charge. I suspect that the OP is considering lithium batteries, which can take high charging voltages over much longer periods of time. This could make the alternator overheat. A B2B will place a limit on the current taken from the alternator, and can also provide the correct charging profile for optimum charging of lithium batteries.

Fair comment yes - I didn't know the OP had Lithium batteries, and should have said all mine are conventional flooded lead acid. So connecting them all together in the simplest way I get the efficiency and environmental benefits of smart alternator charging, and charging/discharging them all equally.

 

[Communicator]

Fair comment yes - I didn't know the OP had Lithium batteries, and should have said all mine are conventional flooded lead acid. So connecting them all together in the simplest way I get the efficiency and environmental benefits of smart alternator charging, and charging/discharging them all equally.

Yes the OP was economical with relevant information in his initial post.

I hate to think as to what the possible fault current is on your installation. I have two dual purpose nominal 100Ah batteries used in the habitation role. They have a CCA rating of 1000A each. Short circuit current would exceed that. I am becoming concerned about the fault rupturing capacity of the maxi blade fuses that I have as individual battery fuses. Mega fuses are under cosideration, but there are space/mounting difficulties, and the easy disconnection facility would be lost.

 

[Reg 65]

I hate to think as to what the possible fault current is on your installation.

So do I - so I have connected them together with double insulated 25mm2 tinned welding cable running inside reinforced rubber water hose for good measure. People will say you need fuses at each battery terminal but we never used to. Our lorries came with 2 x hefty 12v batteries wired in series running straight through to the starter motor - or an electric tail lift at the other end of the trailer and no fuses. The cables weren't as well insulated as they are on my van. But we never had any fires in the whole of the fleet. (As always I am not advising anyone else to do this - just saying this is what I have done successfully, but if you do it you do it at your own risk same as me)

My 5 lead acid batteries wired in parallel (510ah) has been working well for over 4 years now. Taking advantage of smart charging and no current loss - More efficient and environmentally friendly than any B2B. But now I am thinking about getting a fridge that would need a solar panel to keep the batteries topped up. Does anyone know of anything that could be used just to regulate the current from the solar panel to the battery bank?

 

[Communicator]

I cannot see why you consider a B2B to be unfriendly to the environment. A B2B would limit the maximum current delivered by alternator, should your battery bank become significantly discharged. An MPPT solar regulator should control the solar input to your battery bank, by limiting the maximum voltage.

 

[Reg 65]

I cannot see why you consider a B2B to be unfriendly to the environment. A B2B would limit the maximum current delivered by alternator, should your battery bank become significantly discharged. An MPPT solar regulator should control the solar input to your battery bank, by limiting the maximum voltage.

Thanks for the info on MPPT solar regulator - that side of things is all new to me.
As I understand it B2B would absorb current (some claim to be super efficient even when they need fins or even a fan to cool them down!), and they wouldn't utilise the free power from smart alternator regenerative braking. Nor would they make full use of the available power - some are only rated at 30 amp (and in my experience you seldom get the figures manufacturers claim Like the range of an electric mobility scooter or car). Seems a waste to have all that Smart alternator technology just for one of the five batteries.

I realise the professionals always say you need a B2B. But I have managed very well without one for 20 years. And, as warren Buffet says, Never ask a Barber if you need a haircut