TreeSeeker wrote:
The Cyrtix-ct is $51 US on Amazon.
So, the price is a bit better (less) than the m-ACR. (Still going with the m-ACR for the boat but have shifted to the Cyrtix-ct for MLP.)
TreeSeeker wrote:
It does seem considerably better than the old battery isolators these RVs came with. This one is two-way, where the originals are only one way.
However, these types of things seem to just be making a battery bank out of two dissimilar batteries which is not recommended. Especially if the two batteries are not of the same size, age, and type.
So I do wonder what the long term effects of this will be.
Ideally, I would think, each battery needs its own multi-stage charger. This is even more complicated since they need multi-stage charging both when on shore power and engine alternator power. And maybe even solar and generator power too. Yikes!
It is all hard to grasp.
The questions you've raise and concerns you've expressed are entirely valid and on-point. These are also issues that have concerned me for a long time and have spent well over a decade seeking answers. As I mentioned previously, I've had lengthy discussions with experts, on this topic specifically. (In this case, 'experts' means electrical engineers and technicians, kept in companies' back rooms out of reach of the general public.)
The 'old battery isolators' tended to create more problems than the solved. For this reason, I rip them out and throw them away whenever I encounter one.
While not ideal, the Cyrtix-ct and m-ACR are the best available today for this purpose. (I'm still looking ... and will report if I find something better.)
I
know what would be ideal for our purposes and have laid out draft conceptual and functional design. However, limited application means low market demand and significantly greater cost to the consumer.
I won't go into my background, other than mention one senior commander told me, point-blank, "You have an annoying tendency to be right."
Having said that, I encourage you to go over the same ground I've covered. I would be remiss if I didn't encourage independent research, both for confirmation and conflicting information and views.
ABS Alaskan is a good place to discuss your concerns and questions. Their previous name was Alaska Battery Systems and they have a lengthy track record and reputation for reliable systems like those in our motorhomes. (They started out focusing on RV systems and expanded to off-grid systems that integrate battery banks, inverters, solar panels, and gensets.)
(I haven't been in contact with ABS Alaska recently so they may have new/additional information I haven't encountered.)
Dissimilar batteries is an issue I've explored extensively. m-ACR includes design and testing criteria for the probability of dissimilar batteries, verified through discussions with a Blue Sea Systems engineer/technician. (I'm confident Crytix-ct is identical in this respect.)
The charging systems in our older motorhomes are effectively automatic single-stage battery chargers, like the chargers that existed in the late 1960s and 1970s. The systems in new vehicles are capable of performing the first and second stages. To the best of my knowledge, no vehicle has a system capable of three-stage charging.
(The characteristics of the third -- 'float' -- stage makes it arguably impossible in a motor vehicle.)
Note: Some newer OEM-type voltage regulators for our older motorhomes actually have two-stage charging capability. (Some are closer to OEM and still single stage. Others have been updated to better-than-OEM two-stage operation. Which are which is almost to tell, with price probably being the best indication.)
The limitations of motor vehicle charging systems is the reason I regularly (at least monthly) connect a three-stage charger to vehicle batteries, even when it's apparently not necessary.
The adverse effects on the battery due to vehicle charging systems is partially offset by the engine's electrical system cycling (i.e., exercising) the battery during operation.
Every electrical system, with multiple power sources, tries to reach voltage equilibrium. In particular, a discharged battery will act as a circuit load, drawing power from the more fully charged battery.
The worst case is a significantly discharged deep cycle battery sucking enough power out of a SLI (engine) battery to damage the SLI battery due to excessive discharge.
Ideally, I would think, each battery needs its own multi-stage charger.
Very valid and something I've advocated extensively.
The m-ACR and Cyrtix-ct should only be used when the engine is running. They're both designed to be used in other situations but limiting use to when the engine is running is best.
(There's a means of automatically turning off either when the engine isn't running ... I will describe it in a later post.)
