What Volt specs. from a 48V setup

[scottyb]

That sounds okay to me...... get the hydrometer that compensates for temperature!

[dereckbc]

Originally Posted by scottyb

That sounds okay to me...... get the hydrometer that compensates for temperature!

Yes they make them, but they are kind of expensive. But it is less expensive than a good thermomter and hydrometer seperately, not to mention easier to use.

Here is what you are looking for

[oxfordlawn]

OK heres some numbers from each battery \, meter hooked at terminals of individuals for each test. Under a high load...each battery dropped to voltages ranging from 6.58 to 6.71. that seems pretty darned close..I would expect to see a major difference if one had a bad cell I would think. the standing stil voltages for each battery is 8.57 to 8.63 which also looks good to me....so am I to assume all my batteries are good and no weak link in the bunch.
I am going to check voltages at motor itself and cable voltage drops to see if crappy contact or connector someplace...once my fingers warm up a little.
As for the hydrometer..I could only find one that had 5 floating balls and said if 3 or 4 or 5 balls floating type of deal....no real numbers. but they all checked as good also after testing and straining each battery for the above tests

[dereckbc]

Originally Posted by oxfordlawn

OK heres some numbers from each battery \, meter hooked at terminals of individuals for each test. Under a high load...each battery dropped to voltages ranging from 6.58 to 6.71.

Are you sure about this? Are the batteries fully charged? Yes the cells should be approx equal and indicates each battery is equal in state of charge, but these voltages indicate a very low state of charge. These are 8 volt batteries right? At full state of charge I would expect around 7 to 7.5 volts per battery under a normal load. By normal a flat/level smooth road about half of full speed.

If you are going up an incline slowly full throttle then it will be low volatage. The voltages need to be taken under a normal load condition around a 25 amp drain or mid speed on level smooth surface.

[dereckbc]

Originally Posted by oxfordlawn

I am going to check voltages at motor itself and cable voltage drops to see if crappy contact or connector someplace...once my fingers warm up a little.

That is not going to tell you much, it would take an oscilliscope to give you meaningful information. Your controller is a pulse wave modulated signal, and a voltmeter is not going to mean a whole lot other than an AVERAGE of the pulses plus voltage drop. However you can chaeck at the input of the controller.

[oxfordlawn]

I have a .40 volt drop on the circuit from the positive battery cable going into my VGlide all the way back to the stud on the motor. Considering there are 3 connectors and the contact on the vglide switch..that doesnt seem so bad..right??? am I correct in thinking my battery pack and cables are good?

[dereckbc]

Originally Posted by oxfordlawn

I have a .40 volt drop on the circuit from the positive battery cable going into my VGlide all the way back to the stud on the motor. Considering there are 3 connectors and the contact on the vglide switch..that doesnt seem so bad..right??? am I correct in thinking my battery pack and cables are good?

sounds good to me, with the loop back (neg cable circuit) of assumed .8 is 1.6 volts loss, very good.

[sbycamper]

Here are some voltage & hydrometer reading spec I found on a battery mfg web sitr (just don't remember which one)


Digital Voltmeter Approximate Hydrometer Average Electrolyte Freeze Point
Open Circuit Voltage State-of-Charge Cell Specific Gravity
6V-8V *at 80°F (26.7°C)
6.33 - 8.55 100% 1.265 -77°F (-67°C)
6.23 - 8.30 75% 1.225 -35°F (-37°C)
6.12 - 8.16 50% 1.19 -10°F (-23°C)
6.03 - 8.04 25% 1.155 15°F (-9°C)
5.95 - 8.00 or less DISCHARGED 1.120 or less 20°F (-7°C

[oxfordlawn]

Thanks for forwarding the info