Its a voltage amplifier which provides a rapid 4 step charge to your leisure battery whilst your engine is running.
It will charge your battery 5 times faster and 20% more than the original split charge system.
Is it worthwhile investing in? I have 3x 110watt batteries total 330 watt and I have run out of batt only once. We full time wild camp so depend heavily on the batts as a long time between electri hookups. also 180 watts solar panels.
We use ours like you might use a gennie. If Sian is going to hammer the batteries through our inverter by using a 2kw hairdryer or Katie using straighteners then I start the engine while they are using them and the B2B ensures we essentially lose no charge.
We park up in the Alps for a weeks skiing.
There is little daylight because we are in a valley and it is winter. The roof is covered in snow, so solar is a waste of time (and bad for your batteries anyway, but that's another story).
We have the heating running 24/7 to stop things freezing, use the hairdryer a little, charge tablets, phones, etc and use the TV and lights as required.
After 2 days, the batteries are a bit discharged so I run the engine for an hour and a half whilst we have dinner. The habitation batteries are now fully charged and we wait another two days before running up the engine again.
Our battery bank is 345Ah and the Sterling Alternator to Battery charger charges at 90 amps on tickover.
A 50 amp battery to battery charger would take twice as long, but you get the idea.
so...........we have a 110a/hr battery with a 2k inverter (hairdryer and andrew james griddle thingy), so it seems like the dobrey that tricks the alternator into giving some serious juice is the answer.
so how easy/hard/friggin' impossible are they to fit, bearing in mind i'm quite happy to strip a motorcycle gearbox to bits................and get it working again
If slow charging was best for batteries, our fleet of rental forklift trucks would need 6 batteries each to keep up with their shift patterns!
Our habitation batteries are now over 6 years old with full capacity still remaining. They have always been charged by a fast charging Sterling product.
Fast charging is only bad for batteries if you don't or can't keep the electrolyte topped up.
Open lead acid batteries lend themselves best to fast charging, sealed, AGM and gel types cannot be charged as rapidly, but certainly faster than with a conventional split charge system.