Mex's 20% AGM Rule Sucks.
Mex says deep cycle AGMs need to be recharged at a 20% of Bank AH rate even if they are not Lifelines (which do specify that). My AGMs are not that brand, and no mention is made of a minimum charg...
Forum Discussion
That specific Ctek product is a DC to DC converter which is supposed to take whatever voltage the vehicle is allowing, and transform it to 3 stage charging for house batteries, and also be a MPPT solar controller.
It is not simply a take whatever voltage supplied and provide 14.4v to house bank always converter.
I imagine a 14.4v always DC to DC converter could be done for much cheaper and a member here has done so on his 7 pin trailer harness.
Either way, absorption at absorption voltage takes considerable time, and more time as the batteries accumulate cycles.
So simply driving and supplying 14.4v is not the end all be all answer, as it might take 6 hours at absorption for amps to taper to 0.5% of capacity, and driving simply to supply 0.6 amps to a 99% charged AGM battery is insane.
Also note than unless equipped with the "$martpass" that Ctek is limited to 20 amps output so would only meet the 20% minimum, on a single 100Ah or less battery.
Beware of marketing, and the physics defying claims that marketers like to employ in their quest to separate you from your money.
The Ctek product might be OK in a small rig whose vehicle voltage cannot be manipulated for better battery charging, and whose house battery bank is small, but it is very pricey for what it is, and is by no means a solution to the AGM's 20%+ 'rule', or the fact that it requires a bunch of time to properly absorb a hard working daily deep cycled AGM.
If it holds a 85% charged battery at 14.4v rather than 13.7v, well that certainly is an improvement, but is it worth 300$?
A dedicated inverter on engine battery powering a grid powered charger, or a Megawatt or Meanwell power supply set to 14.4v, could easily be more effective for less$$, and the powersuppy can also be used on the grid when that is available for top charging.
I have a meanwell rsp-500-15 that I use as a converter, and bulk charger, and portable charger, and it is capable of 40 amps at any voltage from 13.12 to 19.2v. Rated for 500 watts It regularly outputs 600.
I've never run it from an Inverter though.
It is not simply a take whatever voltage supplied and provide 14.4v to house bank always converter.
I imagine a 14.4v always DC to DC converter could be done for much cheaper and a member here has done so on his 7 pin trailer harness.
Either way, absorption at absorption voltage takes considerable time, and more time as the batteries accumulate cycles.
So simply driving and supplying 14.4v is not the end all be all answer, as it might take 6 hours at absorption for amps to taper to 0.5% of capacity, and driving simply to supply 0.6 amps to a 99% charged AGM battery is insane.
Also note than unless equipped with the "$martpass" that Ctek is limited to 20 amps output so would only meet the 20% minimum, on a single 100Ah or less battery.
Beware of marketing, and the physics defying claims that marketers like to employ in their quest to separate you from your money.
The Ctek product might be OK in a small rig whose vehicle voltage cannot be manipulated for better battery charging, and whose house battery bank is small, but it is very pricey for what it is, and is by no means a solution to the AGM's 20%+ 'rule', or the fact that it requires a bunch of time to properly absorb a hard working daily deep cycled AGM.
If it holds a 85% charged battery at 14.4v rather than 13.7v, well that certainly is an improvement, but is it worth 300$?
A dedicated inverter on engine battery powering a grid powered charger, or a Megawatt or Meanwell power supply set to 14.4v, could easily be more effective for less$$, and the powersuppy can also be used on the grid when that is available for top charging.
I have a meanwell rsp-500-15 that I use as a converter, and bulk charger, and portable charger, and it is capable of 40 amps at any voltage from 13.12 to 19.2v. Rated for 500 watts It regularly outputs 600.
I've never run it from an Inverter though.
