Thread: Alternator output

Ive fitted a few of these as replacements for the kings 40A DC/DC units that have died just out of warranty.

fit it as per the instructions, use 2x fuses one near the start battery, one near the aux battery.

Set it up to the battery you have (lithium) and cross reference the charge profile page of the DC/DC manual and your battery data sheet. IF the numbers line up its now time to forget about the whole thing and enjoy the amps in the aux battery.

If the charge profile doesnt line up to the data sheet, in the monitoring app on your phone adjust the required paramaters and refer to the last half of the previous instructions.

Maximum input draw Ive seen on a 40A dc/dc was 70 amps and it was kicking 45amps into the aux battery the battery was big and flat after about half an hour or so the unit was running hot but the rates dropped off to more reasonable number . This was neither a kings or renogy unit

Normaly input draw for a kings 40a is in the 45A range for about 35 out (Ive never tested it to limits) in rush is upto 65 although that might have a slight meter lag on it.

The only renogy IVe tested pulled very similar numbers.

So long as your alternator can produce more demand than all the loads combined it doesnt matter what its maximum output amps are so long as it can maintain voltage, your start battery will take care of any short term drops caused by the smart alternator going to a reduced voltage state. So long as you hook up correctly and the smarts that drive the alternator can see the load of the DC/DC trying to charge the battery and run your accessories it will sort itself out.

That said...

be careful how you earth the accessories and the aux battery. I've heard tell of AUX appliances upsetting the apple cart for the smart alternator smarts, Never seen it and dont put much faith in it but most stories start somewhere. My reccomendation is currently anything that runs on the AUX battery gets connected to the earth of the aux battery and not chassis earth. (this doesnt apply for the current kings unit as its a common earth unit.)

Originally Posted by Blknight.aus

Ive fitted a few of these as replacements for the kings 40A DC/DC units that have died just out of warranty.

fit it as per the instructions, use 2x fuses one near the start battery, one near the aux battery.

Set it up to the battery you have (lithium) and cross reference the charge profile page of the DC/DC manual and your battery data sheet. IF the numbers line up its now time to forget about the whole thing and enjoy the amps in the aux battery.

If the charge profile doesnt line up to the data sheet, in the monitoring app on your phone adjust the required paramaters and refer to the last half of the previous instructions.

Maximum input draw Ive seen on a 40A dc/dc was 70 amps and it was kicking 45amps into the aux battery the battery was big and flat after about half an hour or so the unit was running hot but the rates dropped off to more reasonable number . This was neither a kings or renogy unit

Normaly input draw for a kings 40a is in the 45A range for about 35 out (Ive never tested it to limits) in rush is upto 65 although that might have a slight meter lag on it.

The only renogy IVe tested pulled very similar numbers.

So long as your alternator can produce more demand than all the loads combined it doesnt matter what its maximum output amps are so long as it can maintain voltage, your start battery will take care of any short term drops caused by the smart alternator going to a reduced voltage state. So long as you hook up correctly and the smarts that drive the alternator can see the load of the DC/DC trying to charge the battery and run your accessories it will sort itself out.

That said...

be careful how you earth the accessories and the aux battery. I've heard tell of AUX appliances upsetting the apple cart for the smart alternator smarts, Never seen it and dont put much faith in it but most stories start somewhere. My reccomendation is currently anything that runs on the AUX battery gets connected to the earth of the aux battery and not chassis earth. (this doesnt apply for the current kings unit as its a common earth unit.)

Its already on the way back, I wasn't prepared to take the risk, even the input of that 70 amps you talk about is way more than their limit of 720 watts. I am going to leave it go for now, we went to town yesterday with a fully charged battery, did some shopping and a bit of running around and it used 10% so I might just recharge when it gets down to about 30-40%. On longer trips we can just run it off the power socket in the back and change over to the battery if we stop for any length of time. Town and back is about 50 ks.