Hopefully wasn't being too concise. I am technical by nature and by profession ( Electrical Engineer ) so do tend to cover more detail than necessary sometimes.
The overview of the post was for someone with an older C&C, original wiring and alternator considering a newer AGM large house bank. It was to point out that the design has some significant challenges if part of the upgrade was to have optimal bulk charging. The section that you refer to was in the context of optimal bulk charging, which is usually done in three stages. Given a barely discharged smaller starting battery and a moderate or fully discharged larger house bank the optimal charging profiles are very different. The start battery will need a small top off. maybe of 2 - 5 AH and a voltage of around 13.4 V for a flooded battery. Depending of the type of house bank, flooded - AGM - Gel, the voltage may ramp up to 14.4 V for bulk charging. An echo charger has no control over the input side voltage, though the smarter units will choose when to operate and charge the battery on it's output, and may also protect a charged battery from over current. The better units do help, and are worth the price. They do not, in the context of charging profiles, create different profiles for two different batteries. If properly installed ( yes, they can be install wrong ) in normal use they will do exactly what you say - no flat or overcharged starting battery. My term "solution" was in reference to providing a fast bulk charge to the house bank, which as earlier commented on was not what the original C&Cs were designed for. Charging rates up to 30 amps might be possible, but above that wiring, alternator, belt and temperature concerns need to be considered. I see some boats that have upgraded to a high output marine alternator, serpentine belt kit, external three stage regulator and upgraded wiring. That is definitely a solution, albeit may be costly. With that setup an echo charger for the starting battery is pretty much required to get the best life out of it. My post pointed out that the DC - DC chargers are also worth a look at, particularly if the boat does minimal longer trips and bulk charges a year. Less money, possibly less rewiring. I like the echo chargers, do a great job for the money. I was on one boat "for a beer" and "take a quick look" at the charging setup. Nice high end alternator with a three stage external regulator. Never got the batteries fully charged. Took a while to figure out but the starter battery was connected to the house bank when the engine was running. Took a few beers to trace everything. I asked the owner if he has to add water to the starter battery much. He said no, maybe a few cups every week. Effectively the flooded lead acid starting battery was absorbing a lot of the charging current and boiling away. Fixed everything with some slight re-wiring and telling the owner to add an echo charger. Rich - what brand do you use? Michael Brown Windburn C&C 30-1 Rich Knowles <[email protected]> , 5/8/2014 10:23 AM: Michael: Can you please explain why you say the Echo Charge is not a solution? I have had one on my boat for 11 years now with never a flat battery and no overcharging problems. Ditto all the boats I have installed them on. Rich On May 7, 2014, at 12:11, Michael Brown via CnC-List <[email protected]> wrote: There is no single charging profile that works when you are trying to charge a barely discharged smaller starting battery and a large fully discharged house battery in parallel. Workaround - see solutions below. Note that a Voltage Sensitive Relay or Echo Charger can help a bit but is not a solution.
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