Smart Alternator

Chas

Full Member

Messages
8
I recently had to have my alternator replaced in my Hobby Siesta. I had previously replaced the leisure batteries. I’m now finding that the leisure batteries never reach full charge, even after a long run of a couple of hours or so. I have a 150 watt solar panel, and the batteries charge normally when plugged in to mains.
is the problem that the alternator cuts off when it senses that the engine battery is fully charged? My electrical knowledge is limited so can I please ask for any advice on how to resolve my problem.
Thanks, in anticipation, Chas.
 

trevskoda

Full Member

Messages
2,143
Wildbus knows a way round this, or as I have, a switch and 200amp relay to connect all ats up when driving and disconnect when parked up, I don't have a smart alt but this will work for you too.
 

wildebus

Full Member

Messages
3,824
Wildbus knows a way round this, or as I have, a switch and 200amp relay to connect all ats up when driving and disconnect when parked up, I don't have a smart alt but this will work for you too.
I recently had to have my alternator replaced in my Hobby Siesta. I had previously replaced the leisure batteries. I’m now finding that the leisure batteries never reach full charge, even after a long run of a couple of hours or so. I have a 150 watt solar panel, and the batteries charge normally when plugged in to mains.
is the problem that the alternator cuts off when it senses that the engine battery is fully charged? My electrical knowledge is limited so can I please ask for any advice on how to resolve my problem.
Thanks, in anticipation, Chas.
The best way to deal with this is to fit a B2B - Battery to Battery - Charger. The basic split-charge relays don't operate correctly.
In actuality, the relay charge method will never fully charge a lead acid battery anyway regardless of if you have a smart OR a standard alternator

A bit of a workround to stop the Alternator disconnecting that I understand people do (I say it like this as it is not something I have tried myself) is to turn on the lights. That extra load on the electrical system keeps the alternator outputting. I would still get a B2B however as the lights trick will sort one thing but not fix the bigger issue of not fully charging the batteries
 

ActiveCampers

Full Member

Messages
232
What age/model van?
Was it OK before the alternator swap?

I doubt they've added a smart alternator if you had a basic one before - its not *just* the alternator thats smart, it links to ECU in a big way (e.g. regen when braking/easing off) - so they would not swap types.

You'd need more diagnostics for an accurtagte answer, but as Wildebus, B2B is the way to go...
 

Chas

Full Member

Messages
8
What age/model van?
Was it OK before the alternator swap?

I doubt they've added a smart alternator if you had a basic one before - its not *just* the alternator thats smart, it links to ECU in a big way (e.g. regen when braking/easing off) - so they would not swap types.

You'd need more diagnostics for an accurtagte answer, but as Wildebus, B2B is the way to go...
The van is 2014. It is a Hobby Siesta V65 GE. The original alternator failed and was replaced by my local service station whom I have dealt with for well over 20 years.
Ross always gives me the best there is, but he is not a Motorhome mechanic. It was only after the leisure batteries were replaced by a Motorhome specialist, and I found the they were not being fully charged, that I discovered that it was a smart alternator.
The van is always plugged into mains with the 12 volt system switched off when I’m at home, so the leisure batteries are fully charged.
it was only when I’m travelling that I discovered they were never being fully charged, and I begun to investigate why.

i like the suggestion of the B to B charger idea, i didn’t know that was possible, but will investigate now that it has been suggested.
Thankyou everybody for taking the time to respond to my question.
 

ActiveCampers

Full Member

Messages
232
2014 will not be smart.
May be worth seeing what the voltage at the VB is - should be >14v - if not the alternator/regulator may not be right.
The rest is devil in detail... You may have simple relay or voltage sensitive relay, and/or fuses inbetween that may fail. So with engine running, check VB > 14v - then check voltage at LB - should be fairly similar whilst being charged.
(of course, check LB when solar and hookup is turned off).

Sounds like it could be possible its not being charged at all from the engine?

Worth doing some basic tests first. (My old van had basic relay which worked fine for 10y - B2B needed for smart alternator but just nice to have now - but I'd check basics first)
 

nabsim

Full Member

Messages
2,550
A B2b can fully charge your battery’s regardless of alternator where a split charge will get to around 85% charged. Plus the b2b is a proper smart charger so worthy upgrade for any age motorhome
 
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