Better to upgrade existing alternator or add an extra one for leisure batteries.

[collectors]

Hi, just at the start & planning of this project on a sprinter van "box luton" & was wondering if! Better to upgrade existing alternator or add an extra one for the leisure batteries & also put the tail lift on this lesure bank of batteries X 4 = 440 amp hour total.

Thanks,

Chris

[Mike90250]

My prime choice, is add an alternator. But is there room under the hood for another high power alt ?

Another suggestion, use 4, 6V 200ah batteries. Golf cart batteries are cheap and rugged. They will give you 400ah with only 2 parallel strings instead of 4, which is an improvement in equal charge/load of the battery bank

if you upgrade the OEM alternator, you will need a good Battery Isolator. http://www.balmar.net/ makes good ones http://www.balmar.net/products/digital-duo-charge/

[collectors]

Some good ideas to think about. Not sure on the golf batteries as the 12v x 110 ah seem to be quite a bit cheaper. What i also wasn't sure on, was the drag on the alternator on a long trip. Not sure if you can get free wheeling ones. You can on water pumps & this saves on engine drag. Thanks for the reply.

[Mike90250]

There are no clutch type / freewheel alternators that I've ever heard of. Even the viscus clutch cooling fan in my truck, has some parasitic load until it's 200F under the hood.

[bcroe]

The drag on the alternator is because it is delivering power, you can not
get something for nothing. When the battery is charged or the load removed,
alternator output no longer required, most of the drag will go away.

Bruce Roe

[collectors]

Hi, there are actually 2 types of clutch on some alternator's, "or should i say disconnection" its not a clutch in the same as you would have on a gear box, but an electronic part of the system that disconnects the coils on the alternator to save any drag & a free wheeling pulley that lets the alternator run free on deceleration. https://www.knowyourparts.com/techni...-do-they-fail/

[Mike90250]

Hi, there are actually 2 types of clutch on some alternator's, "or should i say disconnection" its not a clutch in the same as you would have on a gear box, but an electronic part of the system that disconnects the coils on the alternator to save any drag & a free wheeling pulley that lets the alternator run free on deceleration. https://www.knowyourparts.com/techni...-do-they-fail/

Those look like one way ratchet clutches and only activate at extreme low or high RPM's They are OEM equipment and I don't think I have the engineering skills to divine which one would fit any specific application. And another part to go bad. Replace a pulley with a complex sprag clutch - not for me.

https://en.wikipedia.org/wiki/Sprag_clutch

[Mike90250]

Some good ideas to think about. Not sure on the golf batteries as the 12v x 110 ah seem to be quite a bit cheaper. What i also wasn't sure on, was the drag on the alternator on a long trip. Not sure if you can get free wheeling ones. You can on water pumps & this saves on engine drag. Thanks for the reply.

The sprag clutches you speak of, are not electrical devices, they are mechanical, and prevent engine & belt damage under novel engine operating conditions. No application here. Either your vehicle has one by design, or it does not. you don't get to pick and chose if you want one.