PD or Iota for my upgrade?
I'm thinking about a converter and battery upgrade. The batteries will be wet cell lead acid 6 volt Possible T-105s or the 230AH, EGC2 from Sam's club. I'll probably go for four. (Does nayone have...
Forum Discussion
You got a lot of questions. Let's see if I can resolve some of them.
1. There's no guarantee Iota starts in bulk. Unlike other converters, Iota monitors battery voltage when converter ac supply is off. Don't know where the threshold voltage is, but if battery is below (perhaps) 12.9V it will start in bulk.
2. If the battery requires bulk, the converter will charge at the specified current limit. As battery voltage rises, Iota's output voltage keeps pace, maintaining max current. As voltage within the converter reaches 14.6V, a 15 minute timer is initiated. Bulk mode will end after 15 min. During this time the output voltage can still rise up to 14.8V.
3. I think Iota's charge algorithm does a good job knowing when to switch from bulk to absorption. Once batteries get to about 80% SOC they can't accept high charge rates any longer. Battery resistance and battery voltage dramatically increase. At this point Iota switches to absorption to prevent excessive battery boiling. You don't need SG data to know when to exit bulk.
4. Here's the Iota charge plot when battery (2 6V's) was discharged to 50% SOC. Charging current is a solid 55A. Current doesn't remain constant during the final 15 min of boost. I suspect the Iota is suffering from ac low voltage at this time. My garage ac is a long way from the main breakers.
1. There's no guarantee Iota starts in bulk. Unlike other converters, Iota monitors battery voltage when converter ac supply is off. Don't know where the threshold voltage is, but if battery is below (perhaps) 12.9V it will start in bulk.
2. If the battery requires bulk, the converter will charge at the specified current limit. As battery voltage rises, Iota's output voltage keeps pace, maintaining max current. As voltage within the converter reaches 14.6V, a 15 minute timer is initiated. Bulk mode will end after 15 min. During this time the output voltage can still rise up to 14.8V.
3. I think Iota's charge algorithm does a good job knowing when to switch from bulk to absorption. Once batteries get to about 80% SOC they can't accept high charge rates any longer. Battery resistance and battery voltage dramatically increase. At this point Iota switches to absorption to prevent excessive battery boiling. You don't need SG data to know when to exit bulk.
4. Here's the Iota charge plot when battery (2 6V's) was discharged to 50% SOC. Charging current is a solid 55A. Current doesn't remain constant during the final 15 min of boost. I suspect the Iota is suffering from ac low voltage at this time. My garage ac is a long way from the main breakers.
DryCamper11 wrote:
So what does it mean to say that the Iota does bulk at 14.8? If the Iota charger is really at 14.8, then the charge current will be well above 80A (at least on my batteries). That would burn something out if the charger isn't rated above 80A. If it's not really at 14.8, and it's at some lesser voltage to limit the current, and only charges until the battery reaches 14.6, then the charger would never reach 14.8 ???
Didn't I read that the Iota always starts in bulk mode (perhaps at 14.8 regardless of the battery voltage) and stays there for at least 15 minutes? If that's the case, are you saying it will go as high as 14.8 in that first 15 min window, then drop out if the voltage is 14.6 or above?
From the reading I have done, the ideal charger would use constant current in the bulk mode, no matter how high the voltage rose. It would stay at constant current until it reached the desired SOC (as determined by the SG) and then it would switch to constant voltage for the topping/absorption, followed much later by float mode.
No chargers do this, since they have no way of knowing the true SG and SOC and thus, no way to know when to switch out of the constant current mode into the absorption mode. This isn't really a problem until the voltage at the battery has reached 14.4 or so, However, above that voltage, although it may be perfectly OK to supply the same current, it may not be OK. One can only tell from the SG/SOC, which is info not available to the charger.
