This is where a B2B can be very good for limiting the load on the alternator even when the leisure battries are low (or if you have Lithium, which will take a high current even when just a little down).Two 90ah units when connected to my starter with a switch/relay will hammer the alt if they are lowish, broke a belt last week as the alt stalled at tickover, ok when driving at 2500rpm.
Any link to the ablemail current regulator, sounds like a good cure.This is where a B2B can be very good for limiting the load on the alternator even when the leisure battries are low (or if you have Lithium, which will take a high current even when just a little down).
I run the Ablemail AMC 60A B2B which is good as internally it is a dual 30A unit and you can configure each half differently. I have one half only coming on initially and the other half once the alternator voltage increases a bit more to help straining the alternator at tickover speeds.
Link on my shop is here - https://www.wildebus.com/product/ablemail-b2b-chargers/ .Any link to the ablemail current regulator, sounds like a good cure.
Whether you have an alternator overload problem with adding a other battery to an extent depends on the thickness and length of the wiring.hi i have an autotrail comanche with 2x 130ah lead acid batterys what are the implications of me fitting a third 130ah lead acid battery ? ie engine alternator size ??????????????????????????????????????????????????????
The most likely issue Compo would have in his scenario is not with the cabling, but the actual charging unit. A battery bank of that size is much larger than the recommended maximum and the charger could overheat as it would be running at its (very low) maximum for so long.Whether you have an alternator overload problem with adding a other battery to an extent depends on the thickness and length of the wiring.
I have 2x100ah lithium and an 120a alternator and 16mm wiring 3m long, return by chassis. This is with a victron cyrix lict battery combiner. I have never as yet seen more than 40ah instantly on bms switch on to one battery only dropping quickly to 35 and only 66a into both together. My fiat alternator seems to respond to double batteries by charging more but by no means not double charge. It is much quicker to charge my batteries this way than my previous 30 amp b2b, which charged at 30 for a short while then dropped away to a long tail. But a lot of that is the response of lead acid compared to lithium.
Sounds like a plan.Two things with my van is first, the alt is an old 75/90ah I think, second thing is its the old thin v belt where as the later iveco engines run the flat ribbed belt giving a better grip and with a 120ah alt, what happened is the mot chaps switched the batteries in and wore out the belt at tickover only to snap a few days later, me I don't switch them in until I'm well under way and at 2500rpm, I have never had a problem in 9 years to the dipstick got hold of it.
Mine is like this using battery cable and 200amp relay, it also means I can use all the batteries to start or help someone jump start a dead engine.Sounds like a plan.
My B2B is voltage sensing as mentioned, but the sensing is not on the main supply cable like most VSRs or B2Bs, but on a voltage sense wire. I have that sense wire going though a switch by the dash like your switch is, and can have it switched on (so purely voltage sensing), ignition (so stops it kicking in if I am charging the starter battery from mains), or off so an override like you have.
Belts and Braces with the different programming, but I think it is a good idea to provide protect the original electrics which were not designed to have a big constant load stuffed on while also having charging on the go.
I was suggesting that the cabling could be part of the solution to overuse of the alternator. I did not see it as the problem.The most likely issue Compo would have in his scenario is not with the cabling, but the actual charging unit. A battery bank of that size is much larger than the recommended maximum and the charger could overheat as it would be running at its (very low) maximum for so long.
Derek, my reply is regarding the OPs question primarily. Hence my posting of charging profiles of Lead-Acid of a similar size back to that proposed - again,of Lead Acid batteries, if if he were to bypass the current charging setup. Not talking lithium.I was suggesting that the cabling could be part of the solution to overuse of the alternator. I did not see it as the problem.
I would dispute that a modern alternator works in a more intelligent way than a 120a set voltage supply, so that your vsr test is not real world? For example if you repeated my test, one 100ah battery then a 2nd at the same Soc surely with a your voltage supply the current would nearly double restricted only by the cabling resistance. My alternator only allowed 50%?
Just Maybe a vsr works better with lithium. I certainly have a very fast recharge now, seemingly within safe limits, that would have cost me much more with a b2b.
My system reaches my full charge cut off point still at around 12a charge rate per battery.
Nope. It is a self-contained unit which is really designed for caravans but been adopted by many British Motorhome manufacturers. I think the EBL was designed up-front as a more versatile unit.Is the Sargent unit anything like an EBL where you can attach an additional charger to allow a second battery?