David Butcher: Corbin Sparrow Electric Car Battery Care

Introduction:

This chart lists, in order of severity, problems which may shorten the life of the 13 batteries in the Corbin Sparrow I electric car. These batteries are currently all Optima batteries, but some vehicles came from the factory with "Blue Top" and some came with "Yellow Top" deep cycle 12 volt batteries. (See notes at end for differences)

The columns list:

Description of problem
How to determine if you have the problem
Possible result if the problem occurs
Possible solutions/repairs/prevention
References

This is draft 1 - not final by any means!

What went wrong? How would I know? What will it cost? How do I prevent or cure it? References

1. Deep Discharge Major but not total power loss while driving, voltage dips below 130-140 volts when accelerating. 10% life reduction for every occurrence (estimate) What ever you do, unless it is worth approximately 1/10th the cost of the pack, do NOT drive the vehicle to the point of power loss, regardless of the voltage, percent or amp hours displayed on the E-meter. Pull over and get a charge or a tow!
There is much more information on this issue in your Owner's Manual
Query Sparrow Group for "Deep Discharge"

2. Dried Out Cell - loss of electrolyte (water) Battery may be heard whistling (venting) during charge. This does not prove that a cell has dried out, but venting absolutely results in eventual dry out. See section on "venting" for more information.
Voltage of battery with damaged cell(s) will be lower than similar batteries at similar load. Problem occurs even with a full charge, but typically requires some load to measure. Battery will weigh less than a battery with all "wet" cells.
Dead cells may have higher resistance, impeding full power flow. Dead cells distort voltage readings, which are used by the charger to "decide" when to shift from one mode of charging to another. The charger may fail to reduce charge, "thinking" that it is not yet at proper voltage, which risks overcharging the entire pack. Consider a battery with a proven dry cell to be "dead." Overcharging, resulting in venting, is the most probably cause for loss of water. There are other possible causes, such as overheating and venting of "steam" caused by extreme temperatures inside the battery case.
Overcharging is possible with the 110v charger, can be worse with the 220v charger, and can be extreme if even "faster" charging methods are used (i.e. dual chargers).
Rule of thumb: Charge current MUST taper to 2 amps or lower within a few minutes of reaching 189.5-191.5 volts. If using dual chargers, one MUST be disconnected when voltage reaches this level.
There is no reliable cure for this currently once a cell is dry, but there are many experimental methods which could possibly recover some cells. Best advice: replace the battery.
Query Sparrow Group for "Dried Out Cell"

What went wrong? How would I know? What will it cost? How do I prevent or cure it? References

3. Unequalized Pack Low pack voltage without power loss. Low standing voltage (below 168-172 volts). Differences of more than several tenths of a volt measured between individual batteries in the pack. No short-term problems, HOWEVER, the weakly charged batteries will "run out of power" before others on long trips, which may damage them, and the strongly charged batteries will reach full charge before others, which may damage them! A pack which has more than 5% capacity variation may require more than one Zivan equalization cycle to bring all cells up to capacity.
It is difficult to measure the percent of imbalance, but the more there is the longer it takes it is to restore balance.
Equalize the pack. This can be done with the Zivan charger, or by individually charging the weaker batteries in the pack. Charging individual batteries is tedious and can be dangerous, so if you decide to do this proceed with care.
There are several products available which can be used to equalize a pack or maintain equality between batteries. Search for "PowerCheq", "Zivan Smoother", "Rudman Regulator" in your favorite search engine. (Other suggestions welcome).
Query Sparrow Group for "Equalization"

4. Sulfation Lead Sulfate, an insulator, occurs naturally during the discharge of a lead-aciod battery. Sometimes it transforms into insoluable crystals, insulating plates and reducing the level of active electrolyte. This interferes with charging and discharging, and severe cases can physically damage the structure of the battery, causing permanent damage. Sulfation manifests as lower capacity. When discharging, the battery will loose voltage faster than equivalent non-sulfated batteries, and when charging, it will gain voltage faster. Sulfation gradually becomes worse. Mild cases cause unequal voltages and capacities in a pack which do not completely clear up when the pack is equalized. Severe cases may cause swelling of the battery case (bumpy top on the batteries) because the sulfate crystals take up more space than the normal active materials in the battery. Sulfated batteries may be more prone to venting as well. Mild cases of sulfation may be cured using specially designed circuits which provide pulses of energy to the battery, or which attempt to cause the electrolyte to resonate. There is more than one theory behind their operation, but the evidence generally suggests that they do force the lead sulfate crystals back into solution, counteracting the slow natural build-up.
Severe cases of sulfation generally require replacement of the battery, because the growth of the sulfate crystals can distort the internal structure of the battery. If you can see signs of swelling on the case of the battery, it MAY be caused by sulfation.
The battery should be examined by an expert. Sulfation is not the only possible cause of battery case distortion. The battery may be recoverable depending on the cause and severity of the problem.
Query Sparrow Group for "Sulfation"

What went wrong? How would I know? What will it cost? How do I prevent or cure it? References

5. Batteries Too Hot, through overcharging or rapidly charging a hot pack on a hot day. Zivan charger shuts off and beeps, if equipped with a Thermal Probe (Get one!) Batteries feel "hot" to the touch (sides, not top). Batteries are "whistling" (venting gasses through their valves). If the Zivan "catches" the overheat, there may be no consequence. If the other issues take place, damage has been done. If mild, may cost 1% of pack lifetime. If severe, may cost much more. Yes, a single brutal overheat could destroy the entire pack. Obtain the Thermal Probe (contact Corbin Motors) for the Zivan and install it. Charge batteries when cold, when possible. Leave Sparrow windows and hood partially open when charging if the weather is hot (over 75 degrees F) (this is the author's idea - well, it SOUNDS reasonable...). Use a TIMER to positively shut the charger off when the desired charge has been reached. Charge the pack in two steps with a cool-down period between them. Query Sparrow Group for "Hot Battery"

6. Venting - whistling - fitzing - burbling - hissing - whining - sounds coming from either of the two black disks on top of the Optima Caused by excess pressure inside the battery. The only way to know if a battery is venting is to listen, unless you have a gas chromatograph to analyze the air near the battery. The sounds are very quiet, so you may have to have your ear within 2-4 inches of the battery to hear them. You can safely use a few feet of vinyl tubing as a "stethoscope" by placing one end in your ear, and moving the other end from black disk to black disk. (This is much safer than sticking your head into the works!) Venting releases hydrogen, oxygen, and water vapor. These are necessary ingredients. Together with Sulfuric Acid, they make up your electrolyte. The acid will not vent out, but the gradual loss of water will change the capacity of the battery. The battery will eventually have little or no water in the venting cell(s) and it will no longer have usable capacity.
Cost of mild venting - less than 1% per event. Cost of serious venting, could be several percent of battery lifetime per incident. (Estimates)
Venting of Optimas can be caused by three things:

Continuing to charge a fully charged battery at a rate of over 2 amps
Heating the battery to the point where electrolyte boils
Factory defect - leaky valve (highly unlikely)
The most common form of venting (#1 above) takes place when hydrogen and oxygen are being generated by electrolysis within the battery FASTER than the internal "recombination" chemistry can turn it back into water. Electrolysis takes place most vigorously after a battery is fully charged, and the charge energy is no longer being used to manufacture lead plates and electrolyte (that's what charging is).
Reduce this problem by slowing the charge down near full charge (for instance, stopping the charge, waiting an hour, and restarting it when the voltage on the pack goes above 195v, for example), or skipping equalization (stopping the charge when the Zivan LED turns yellow). Skipping equalization may create problems, see problem #3.
Venting due to high temperatures (boiling) is unlikely unless the charger is pushing full power into the batteries for an extended length of time (hours). You would probably be able to feel that the side of the battery was very hot. A boiled Optima is probably damaged beyond repair. The Zivan battery temperature probe is supposed to prevent this (among other things) but it can only monitor the batteries it is close to.
Rule of thumb: When in doubt about battery temperature - stop the charge!
Venting due to a faulty valve requires battery replacement, hopefully under warranty. It is not clear how to demonstrate that this is a problem.
Query Sparrow Group for "Venting"
The Basic Chemistry of Gas Recombination in Lead-Acid Batteries - in layman's terms, why do my batteries vent?

What went wrong? How would I know? What will it cost? How do I prevent or cure it? References

7. Sudden Range Reduction, early power loss, "running out of gas" unexpectedly Range is almost impossible to predict. However, if you notice that a regular drive, such as a commute, ends with lower and lower voltages during the last mile, your range is shrinking.
You may also notice that voltage during acceleration fluctuates more and sooner (in miles) after a full charge.
And of course, you may loose power ("run out of gas"). This can be caused by the controller over temperature limit! If it is over 80 degrees F., or if the fan airflow is blocked, you can loose power. If waiting 15 minutes with the ignition on (so the controller compartment fan is running) solves the problem, it is not a battery problem.
The E-meter will not tell you how far you CAN go, only how far you HAVE GONE with respect to charge. It is up to you to detect when you are reaching the limit of your range.
You may be in for a new battery pack, or some serious work to determine the precise cause of the reduced range. This is not an easy problem to diagnose or solve.
If your range reduces gradually over the course of hundreds or thousands of miles, see #8 below. If it dropped suddenly, read on!
If you decide to live with reduced range, you may possibly continue to drive the Sparrow indefinitely. The range will probably continue to shrink, however, so your trip expectations will have to shrink with it. Don't push it! or you will encounter problem #1, the most devastating problem you can have.
If you cannot live with reduced range, there are two general courses of action:

Replace the battery pack (every owner will have to do this eventually)
Analyze the pack to determine whether it is uniformly worn out (needs replacement) or suffering from capacity problems in specific batteries (possible partial pack replacement).
If you take good care of your pack - in other words, if none of the problems listed here have ever occurred with your pack - it is highly likely that you have enjoyed everything your pack has to offer, and it is time to replace it. You should have received many thousands of miles of service.
If any of the above problems occurred, or if you have less than 1000 miles on the pack (this number is just an estimate) and your capacity has dropped more than 5%, you might be able to analyze the pack, determine the cause, and solve the problem. You might not need to replace any batteries, or you might need to replace only certain batteries.
Analyzing a pack is a black art. It is a mixture of science, experience, common sense and luck. It will be covered in a separate document, which may already exist somewhere. If not, I will write it.
Query Sparrow Group for "Short Range"

8. Pack Worn Out Range gradually drops, Zivan charger charges and equalizes successfully, voltage declines steadily while driving at a constant speed (no sudden drops), individual battery capacity tests show reduced capacity. 13 times the cost of an Optima battery, plus installation. Contact your dealer for advice. This one has no prevention, and the cure is simple pack replacement. This is where we all hope to end up - problem free, with many thousands of miles on the pack. Query Sparrow Group for "Replace Pack"

What went wrong? How would I know? What will it cost? How do I prevent or cure it? References

Other battery references, not specific to the Sparrow:

Getting the most out of your Optima Yellow Top Batteries (applies to Blue Tops as well)
Great Semi-Technical Battery Charging Explanation
Technical Information about Lead Acid Batteries
Battery FAQ
Battery Links

Notes:

Blue Top vs. Yellow Top See: Optima Website. Optima Yellow Top batteries are the most recent product released by Optima, and may not have been as well understood as the Blue Top when your Sparrow was being assembled.
Standing voltage has no universal definition. For the purposes of this document, your batteries are at standing voltage:
1. Immediately after a full charge, and:
2. After two voltage readings taken 15 minutes apart are identical.

Disclaimer: It's just a personal web page! I do not work for Corbin Motors, Optima, or any of the manufacturers mentioned here. Apply the information contained in this chart at your own risk! PLEASE get second opinions before taking any action based on the contents of this chart.

If you think you have a different problem, or need clarification on anything presented here, or feel that anything is incorrect, please mail me: davidbuATwww.los-gatos.ca.us (use @ instead of AT, of course...).

Note: "Estimate" is typically another word for "Guess" ;-)

Thank You.

What went wrong?	How would I know?	What will it cost?	How do I prevent or cure it?	References
1. Deep Discharge	Major but not total power loss while driving, voltage dips below 130-140 volts when accelerating.	10% life reduction for every occurrence (estimate)	What ever you do, unless it is worth approximately 1/10th the cost of the pack, do NOT drive the vehicle to the point of power loss, regardless of the voltage, percent or amp hours displayed on the E-meter. Pull over and get a charge or a tow! There is much more information on this issue in your Owner's Manual	Query Sparrow Group for "Deep Discharge"
2. Dried Out Cell - loss of electrolyte (water)	Battery may be heard whistling (venting) during charge. This does not prove that a cell has dried out, but venting absolutely results in eventual dry out. See section on "venting" for more information. Voltage of battery with damaged cell(s) will be lower than similar batteries at similar load. Problem occurs even with a full charge, but typically requires some load to measure. Battery will weigh less than a battery with all "wet" cells.	Dead cells may have higher resistance, impeding full power flow. Dead cells distort voltage readings, which are used by the charger to "decide" when to shift from one mode of charging to another. The charger may fail to reduce charge, "thinking" that it is not yet at proper voltage, which risks overcharging the entire pack. Consider a battery with a proven dry cell to be "dead."	Overcharging, resulting in venting, is the most probably cause for loss of water. There are other possible causes, such as overheating and venting of "steam" caused by extreme temperatures inside the battery case. Overcharging is possible with the 110v charger, can be worse with the 220v charger, and can be extreme if even "faster" charging methods are used (i.e. dual chargers). Rule of thumb: Charge current MUST taper to 2 amps or lower within a few minutes of reaching 189.5-191.5 volts. If using dual chargers, one MUST be disconnected when voltage reaches this level. There is no reliable cure for this currently once a cell is dry, but there are many experimental methods which could possibly recover some cells. Best advice: replace the battery.	Query Sparrow Group for "Dried Out Cell"
What went wrong?	How would I know?	What will it cost?	How do I prevent or cure it?	References
3. Unequalized Pack	Low pack voltage without power loss. Low standing voltage (below 168-172 volts). Differences of more than several tenths of a volt measured between individual batteries in the pack.	No short-term problems, HOWEVER, the weakly charged batteries will "run out of power" before others on long trips, which may damage them, and the strongly charged batteries will reach full charge before others, which may damage them! A pack which has more than 5% capacity variation may require more than one Zivan equalization cycle to bring all cells up to capacity. It is difficult to measure the percent of imbalance, but the more there is the longer it takes it is to restore balance.	Equalize the pack. This can be done with the Zivan charger, or by individually charging the weaker batteries in the pack. Charging individual batteries is tedious and can be dangerous, so if you decide to do this proceed with care. There are several products available which can be used to equalize a pack or maintain equality between batteries. Search for "PowerCheq", "Zivan Smoother", "Rudman Regulator" in your favorite search engine. (Other suggestions welcome).	Query Sparrow Group for "Equalization"
4. Sulfation	Lead Sulfate, an insulator, occurs naturally during the discharge of a lead-aciod battery. Sometimes it transforms into insoluable crystals, insulating plates and reducing the level of active electrolyte. This interferes with charging and discharging, and severe cases can physically damage the structure of the battery, causing permanent damage.	Sulfation manifests as lower capacity. When discharging, the battery will loose voltage faster than equivalent non-sulfated batteries, and when charging, it will gain voltage faster. Sulfation gradually becomes worse. Mild cases cause unequal voltages and capacities in a pack which do not completely clear up when the pack is equalized. Severe cases may cause swelling of the battery case (bumpy top on the batteries) because the sulfate crystals take up more space than the normal active materials in the battery. Sulfated batteries may be more prone to venting as well.	Mild cases of sulfation may be cured using specially designed circuits which provide pulses of energy to the battery, or which attempt to cause the electrolyte to resonate. There is more than one theory behind their operation, but the evidence generally suggests that they do force the lead sulfate crystals back into solution, counteracting the slow natural build-up. Severe cases of sulfation generally require replacement of the battery, because the growth of the sulfate crystals can distort the internal structure of the battery. If you can see signs of swelling on the case of the battery, it MAY be caused by sulfation. The battery should be examined by an expert. Sulfation is not the only possible cause of battery case distortion. The battery may be recoverable depending on the cause and severity of the problem.	Query Sparrow Group for "Sulfation"
What went wrong?	How would I know?	What will it cost?	How do I prevent or cure it?	References
5. Batteries Too Hot, through overcharging or rapidly charging a hot pack on a hot day.	Zivan charger shuts off and beeps, if equipped with a Thermal Probe (Get one!) Batteries feel "hot" to the touch (sides, not top). Batteries are "whistling" (venting gasses through their valves).	If the Zivan "catches" the overheat, there may be no consequence. If the other issues take place, damage has been done. If mild, may cost 1% of pack lifetime. If severe, may cost much more. Yes, a single brutal overheat could destroy the entire pack.	Obtain the Thermal Probe (contact Corbin Motors) for the Zivan and install it. Charge batteries when cold, when possible. Leave Sparrow windows and hood partially open when charging if the weather is hot (over 75 degrees F) (this is the author's idea - well, it SOUNDS reasonable...). Use a TIMER to positively shut the charger off when the desired charge has been reached. Charge the pack in two steps with a cool-down period between them.	Query Sparrow Group for "Hot Battery"
6. Venting - whistling - fitzing - burbling - hissing - whining - sounds coming from either of the two black disks on top of the Optima Caused by excess pressure inside the battery.	The only way to know if a battery is venting is to listen, unless you have a gas chromatograph to analyze the air near the battery. The sounds are very quiet, so you may have to have your ear within 2-4 inches of the battery to hear them. You can safely use a few feet of vinyl tubing as a "stethoscope" by placing one end in your ear, and moving the other end from black disk to black disk. (This is much safer than sticking your head into the works!)	Venting releases hydrogen, oxygen, and water vapor. These are necessary ingredients. Together with Sulfuric Acid, they make up your electrolyte. The acid will not vent out, but the gradual loss of water will change the capacity of the battery. The battery will eventually have little or no water in the venting cell(s) and it will no longer have usable capacity. Cost of mild venting - less than 1% per event. Cost of serious venting, could be several percent of battery lifetime per incident. (Estimates) Venting of Optimas can be caused by three things: Continuing to charge a fully charged battery at a rate of over 2 amps Heating the battery to the point where electrolyte boils Factory defect - leaky valve (highly unlikely)	The most common form of venting (#1 above) takes place when hydrogen and oxygen are being generated by electrolysis within the battery FASTER than the internal "recombination" chemistry can turn it back into water. Electrolysis takes place most vigorously after a battery is fully charged, and the charge energy is no longer being used to manufacture lead plates and electrolyte (that's what charging is). Reduce this problem by slowing the charge down near full charge (for instance, stopping the charge, waiting an hour, and restarting it when the voltage on the pack goes above 195v, for example), or skipping equalization (stopping the charge when the Zivan LED turns yellow). Skipping equalization may create problems, see problem #3. Venting due to high temperatures (boiling) is unlikely unless the charger is pushing full power into the batteries for an extended length of time (hours). You would probably be able to feel that the side of the battery was very hot. A boiled Optima is probably damaged beyond repair. The Zivan battery temperature probe is supposed to prevent this (among other things) but it can only monitor the batteries it is close to. Rule of thumb: When in doubt about battery temperature - stop the charge! Venting due to a faulty valve requires battery replacement, hopefully under warranty. It is not clear how to demonstrate that this is a problem.	Query Sparrow Group for "Venting" The Basic Chemistry of Gas Recombination in Lead-Acid Batteries - in layman's terms, why do my batteries vent?
What went wrong?	How would I know?	What will it cost?	How do I prevent or cure it?	References
7. Sudden Range Reduction, early power loss, "running out of gas" unexpectedly	Range is almost impossible to predict. However, if you notice that a regular drive, such as a commute, ends with lower and lower voltages during the last mile, your range is shrinking. You may also notice that voltage during acceleration fluctuates more and sooner (in miles) after a full charge. And of course, you may loose power ("run out of gas"). This can be caused by the controller over temperature limit! If it is over 80 degrees F., or if the fan airflow is blocked, you can loose power. If waiting 15 minutes with the ignition on (so the controller compartment fan is running) solves the problem, it is not a battery problem. The E-meter will not tell you how far you CAN go, only how far you HAVE GONE with respect to charge. It is up to you to detect when you are reaching the limit of your range. You may be in for a new battery pack, or some serious work to determine the precise cause of the reduced range. This is not an easy problem to diagnose or solve.	If your range reduces gradually over the course of hundreds or thousands of miles, see #8 below. If it dropped suddenly, read on! If you decide to live with reduced range, you may possibly continue to drive the Sparrow indefinitely. The range will probably continue to shrink, however, so your trip expectations will have to shrink with it. Don't push it! or you will encounter problem #1, the most devastating problem you can have. If you cannot live with reduced range, there are two general courses of action: Replace the battery pack (every owner will have to do this eventually) Analyze the pack to determine whether it is uniformly worn out (needs replacement) or suffering from capacity problems in specific batteries (possible partial pack replacement).	If you take good care of your pack - in other words, if none of the problems listed here have ever occurred with your pack - it is highly likely that you have enjoyed everything your pack has to offer, and it is time to replace it. You should have received many thousands of miles of service. If any of the above problems occurred, or if you have less than 1000 miles on the pack (this number is just an estimate) and your capacity has dropped more than 5%, you might be able to analyze the pack, determine the cause, and solve the problem. You might not need to replace any batteries, or you might need to replace only certain batteries. Analyzing a pack is a black art. It is a mixture of science, experience, common sense and luck. It will be covered in a separate document, which may already exist somewhere. If not, I will write it.	Query Sparrow Group for "Short Range"
8. Pack Worn Out	Range gradually drops, Zivan charger charges and equalizes successfully, voltage declines steadily while driving at a constant speed (no sudden drops), individual battery capacity tests show reduced capacity.	13 times the cost of an Optima battery, plus installation. Contact your dealer for advice.	This one has no prevention, and the cure is simple pack replacement. This is where we all hope to end up - problem free, with many thousands of miles on the pack.	Query Sparrow Group for "Replace Pack"
What went wrong?	How would I know?	What will it cost?	How do I prevent or cure it?	References