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I’m not sure about what the manual say but I can offer some general advice regarding state of charge. Assuming flooded lead acid type of batteries (AKA golf cart or T105 etc.) the below advice is accurate. It will not be accurate for Gel and AGM types.
31.5 volts = a totally dead battery pack under load. If you were to stop discharging the pack at that point and leave it alone for several hours then it would come up somewhere around 36 volts. This is referred to as the “resting” voltage. A resting voltage of 36 would be a totally discharged pack. I would suggest that you never let your pack voltage get under 33 volts under load. For brief moments when the load is heavy it’s normal for it to get under 33. But I would not mow on level ground when the voltage is under 33. I would be heading back to recharge at that time.
Keep in mind the one bad battery can throw voltage readings off significantly.
I don’t call my pack fully charged until my (solar array) charger has held it at 45 volts for a few hours. A few hours after this I would expect to find my pack at a resting voltage of 38.1 volts or a little higher. If I was to start mowing at this point then I would expect to see the pack voltage immediately drop down to 36 -37 depending on how loaded the tractor was. My onboard charger has never worked so I can’t comment on how it acts.
The most accurate way to know the state of charge of your pack to measure the specific gravity using a readily available hydrometer which you should find for less than $10. There are several styles to choose from and for the most part they all are accurate enough to be trusted. They will come a built in scale the will indicate the batteries capacity. You can take this reading at any time as is unaffected by charging or load and reasonably unaffected by temperature. Of course, use the hydrometer with care as you can easily get several drops of battery electrolyte on you or your tractor. Keep some water and some baking soda handy
The manual is probably giving a voltage under load so assuming you understand what’s going on with your pack the numbers they’ve given are accurate. By the way, I find that my E15’s fuel gage to be very accurate.
I really didn’t mean to go on this long, sorry.
Travis Creswell Joplin, MO E15
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I am wondering what the full charge of the pack should be. The manual would indicate that it should be 36.54V and 31.5 when discharged. www.fergusonapiaries.on.ca |