Can a T25 run an alternator charger?

[tomrussell94]

Hi all,

I currently run my T25's power (lights/fridge etc) through a bluetti power station (AC180) as it saved the hassle and space of a leisure battery/inverter/solar controller plus I already had it from a previous self-build.

In the summer, it has been great as I have solar on the roof however, I am keen to use the van over winter and concerned the lack of sun will be an issue with my preference of being off-grid.

I have seen Bluetti now sell these: https://bluettipower.co.uk/products/cha ... or-charger which seem ideal as I would drive enough per day to keep the power station's charge up.

However, my concern is whether or not my van's alternator would handle the power draw? I have a 1981 2.0 Air Cooled CU with what I would imagine is the original (or similar replacement) alternator...

Bluetti FAQ say: "Charger 1 can be used with any vehicle with a 12V or 24V starter battery, including RVs, vans, and trucks" but google AI seems to think an alternator of 150+ amps would be needed.


Thoughts or has anyone done something similar?
(Thanks in advance for any advice )

[hotpod]

The specs say this:INPUT:   Input Voltage: 12V -14V / 22.5V - 28V
             Input Amperage: 50A - 12V / 25A - 24VSo I would have thought a standard alternator should be fine. You might want to prioritise charging the starter batter first though maybe so perhaps you could run it through a VSR of high enough amperage?

[shepster]

I have a Victron b2b (dc to dc) or whatever you prefer to call it on my van, although its a wbx with 90amp alternator and it works just fine. Pumps around 27amps into the battery according to the Fogstar app.

[cobblers]

You're right to come and ask here... Do not use AI to answer any technical questions - It'll very confidently give you totally incorrect and often unsafe answers (however in this case it wasn't miles off, really)

The bluetti charger claims that it draws 50A when used on a 12V system. That's quite a lot.

Most early T25s have <70A alternators, in which case it's an absolute no.

Even if your van had the 90A alternator and the charging system is all in fine fettle, you would get away with it, But it doesn't leave a lot of overhead, on a cold winters day with the lights, wipers and blowers on there would be precious little current left to actually charge your starter battery.

Maybe there is some setting that will allow you to limit the charging current?

On a electrically simple vehicle like a T25, you should aim to have at least 50A spare capacity if you want the OE charging system to function without having to keep an eye on it. So if your alternator is only 60A then you'd need to find a DC-DC charger that only draws 10A.


There are other ways round it if your charger has configurable input voltage thresholds to allow you to only charge the leisure battery when the starter battery is 80% full, but they're quite application dependant.

[Rosie n' Jim]

If the Haynes air cooled manual is to be believed, the alternator is 45 amp or 65 amp. No explanation of why two outputs, maybe 1.6 CT is 45 and 2.0 CU is 65? But that was 40 years ago, how much might it put out now?
​​​​​I use a Renogy 20 amp dc to dc charger as back up to 200w of solar into a 100ah lithium battery. The dc to dc charger can be switched remotely to half power, 10 amps in this case. At 20 amp charge and only the radio playing and at cruising revs, the starter batter does not get more that 13v. But it's only there for back up, and so far has not been used except for testing.