Originally posted by rgourley@... on the RailPro Users Yahoo! Group on Jun 12, 2015
My assumption is that Ring is using NiMH batteries, which can range from 1200 mAH to 2600 mAH, for an AA cell. Therefore, if Ring went with lower capacity cells, 1200-1350 mAH, then you could easily double the capacity by switching to 2400-2600 mAH cells. If Ring is already using the higher capacity cells, then increasing the number or size of the cells would be the only option. That would involve modifying the battery holder. I would not recommend switching to a different battery chemistry, as that could be extremely hazardous. The cell voltages can be different (higher for LiPo), which if not accounted for, could damage the throttle. Also, if not charged properly could result in a fire.
Without knowing how long it takes to recharge a throttle, I really can't speculate on what method Ring is using. If they went with a low fixed current method, then it might not be possible to reach the full potential of the increased capacity. This is due to the fact that the charging current used, is usually based on the capacity. Also, since NiMH batteries can be damaged by overcharging, some chargers have a time limit, as well. This might further impede the chances of the larger capacity cells reaching full charge. If they used a delta V or delta T method, then there is a good chance that the increased capacity would be fully charged. However, since the delta in voltage is not as pronounced, as with a NiCd battery and could be slightly different for a different brand or capacity, there could be a risk of overcharging. Hopefully, Ring took into account potential increases in battery capacity and designed the charger accordingly. If not, and they are using a fixed low current with time limit, then maybe the charging current and time could be updated via firmware.
As far as the battery indicator still being accurate with an increase in capacity, well it could go either way. With alkaline batteries, the voltage decreases as the battery discharges and it's pretty much linear. However, with a NiMH battery the voltage remains pretty constant, only dropping off once the charge is extremely low. Therefore, there is not a direct correlation between voltage level and charge level. Some level indicators can be as crude as just keeping track of the on time and calculating the level based on the average consumption rate and the battery capacity. Therefore, if this method is used and the battery capacity value can't be updated, then the indicator will be inaccurate. However, if the charging algorithm also calculates the battery capacity, then more than likely the indicator will be accurate.
If Ring, is using NiMH batteries, then there should not be any concern of the batteries developing a memory. Therefore, there is no need to fully discharge them prior to charging. In fact, fully discharging, especially multi-cell packs, can do more harm than good. That is why most devices will automatically turn-off once the battery voltage drops below 1.1 to 1 volt. Also, NiMH batteries self-discharge, so the batteries will discharge over time, even if the device is off. Therefore, if a throttle has been sitting for a while, topping off the batteries prior to a run, would help extend the run time. Placing the throttle on the charger between runs would also help extend the time. The downside is, NiMH batteries have a limited number of times they can be cycled, I believe in the 250-500 range. I've "heard" that those figures are based on deep cycling, letting the battery get down to say 10%, before charging. Therefore, some claim that only letting the battery get down to 50% before charging, can increase the lifespan (number of cycles).
I don't have much hands-on experience with NiMH batteries, so this is all based on what I've heard from customers and peers. To make matters worse, my memory is not what it used to be. Therefore, I would view my information as more speculative, than factual. I have to imagine there are a lot of published studies and white papers on the topic. When I have more time, I'll do a little research to see what's out there.
Hopefully, this is somewhat helpful,
Rian
