Good Morning,
I hope the following answers your questions with regard to the GrippaPower smart charge relay system.
Obviously the following information is in connection with our systems and the specific kit we use, and may not apply to the batteries or systems you have installed, if they are not a GrippaTank supplied kit.
All of our systems are fitted with the Lucas/ Numax range of batteries which are sealed. These days, this range of the car and leisure batteries are all basicly exactly the same I.e they are sealed. The difference being the plate design.
The car battery is designed to withstand a massive and sudden draw of power on start up (I.e vehicle startup) and then be recharged by the alternator. This is where Robert's question comes to mind the battery you have is designed for a very high rate of sudden draw when called upon (ie to start a vehicle).
A leisure battery is deep cycle which means the plate design allows for a slow and prelonged draw of power over a long period of time. This means a leisure battery is better suited and indeed designed for the continuous drain / recharge / drain / recharge etc. Thus the leisure battery is the recommended for use in our industry, as most of the systems require relatively little power in comparision to a vehicle battery it just needs to be drawing pretty much continuously over the course of a day / night.
A bench charger will also charge at a lower rate to an alternator. There are two factors to this 1/. the quality of the charger (as a very lose guide, the cheaper the charger, the less power it will be able to give the battery), and 2/. most bench chargers are designed to be trickle charge hence a maximum of 13.9v / 10-15amps. Some bench chargers do however have a boost button, which will give a battery a charge of 30 40 amps.
Our split relay is capable of charging upto 100 amps, but obviously is limited by how much power the alternator is capable of giving you (which on older vehicles may only be about 30 40 amps). The split relay has a smart trigger which will always 1/. put your vehicle battery and power first, 2/. then once this has been done, will supply the system battery the full charge required. Because of the processor in the split relay it will then calculate weather a full power charge is required (I.e the full 30 40 amps = a boost) or weather a low trickle charge is required (I.e 10amps). So if you upgraded your alternator on your vehicle, and the alternator was kicking out 80 or 100 amps for examplle, which can be found for example in HGV's, larger LCV'S or marine applications, the leisure battery will accept the full charge.
The key being the processor, which is always calculating what is required for the vehicle and what is required for the system.
As Robert says, our split relays really do work. We always have been of the thought, that where possible, the systems should always be a fit and forget from a power of view (Not refering to maintenance, as this should always be done of course. However, lifting a battery in and out of a van every day shouldnt be part of a professional system routine). We have had a large amount of customers in the past who were very nervous of split relays, because maybe in the past they have tried them and they do not work etc. However, once changing over to our split relays, they have found this has answered their issues. In fact, our engineers often fit our power packs to competitors systems in order to solve the power issues.
We have one customer, who literally works in the next street from his house, his regular daily journey being about 30 40 seconds to work (this has been timed by the customer!). So obviously in this case, the customer is recommended to bench charge at the weekends as well, as the alternator barely kicks in before he arrives at his job!
However this is the first and only customer who has to do this, every other customer we supply, never has to worry about power, even with our HydroHeat kits, because the split relay takes care of the batteries.
I hope that answers the questions!