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
mena661 wrote:DryCamper11 wrote:The IOTA does indeed do this and the other converters do something similar.
I don't know much about the Iota charge algorithm, but it would seem very odd to me if they drop to 14.2 at the start of the absorption stage. Usually absorption is constant voltage.
Yes, you are right. I phrased my comment very poorly. I was trying to figure out what the Iota does when the current flow out of the charger is below the charger's current limit and the charger is still in boost/bulk mode at its maximum voltage.
When a charger is in bulk/boost mode and the battery is sufficiently discharged, and the cables are sufficiently fat/short, the charger will supply its full rated current at some voltage below its maximum rated voltage for that mode. As the battery charges, eventually, the charger will be unable to supply that full rated current (without increasing its voltage - which the charge profile does not allow).
All the charger knows at this point is that it can't supply full current. This is not necessarily a sign that the battery is ready to enter absorption mode. It would be an unusual design for a charger to immediately drop its voltage just because it can no longer supply its maximum rated current when in bulk/boost mode. Instead, chargers use some other method of deciding when to leave bulk/boost mode. Most use time. If they've been in bulk/boost mode for long enough according to the profile set by the charger designer, they switch out of that mode and enter absorption/topping/normal mode.
The criteria and method used by the charger designer to decide when to leave the bulk/boost mode and enter the absorption/normal/topping mode is one of the major differences between chargers.
I should have been more clear that I was talking about whether the charger uses the fact that it can't supply full current in boost/bulk mode voltage as a sign to enter the next mode. None do that, that I'm aware of. If you look at this:
you see two drops in current. One is the asymptotic decay in current at about 2 hours (dark blue current plot) due to the fact that the charger is not allowed to increase its output voltage. It is still in boost/bulk mode at that point. The other is the vertical drop at 4 hours where the PD enters the 13.6 volt absorption/normal/topping mode.
Sorry for the confusion.
