need a member who understands charging systems

[jenavet]

i am totally lost as usual....i have an optima deep cycle battery in a race car with no alternator...between rounds i usually charge the battery up at 10-12 amps and the battery holds up very well...last saturday the car got into the finals and they gave us very little time to charge the battery up between rounds..i had a meter that gives the batteries percentage of charge and it was reading 65-75% when they were calling me back into the lanes....i went today to purchase a battery charger that would charge at a rate of 35-50 amps,and on the box of every charger they stated that that amperage was not recommended for deep cycle batteries....so i guess my question is,how can i charge this battery at a faster rate if i need to between rounds? should it be ok late in the races to charge it at 35-50 amps for the 10-15 minutes of time i have?? the other weird question i have is at the end of the race,i put the car on the trailer with the battery worn down to like 50%...the next morning i threw the charger on it at 12 amps for like 10 minutes and it was at 100% charge??? i dont understand that one cuz usually it takes a minimum of 45-60 minutes at the track to recharge at 12 amps?? what the hell,if it gets a good nights sleep does it charge better or something??

 

[bossvette]

Sometimes a good battery is like a good man it will build back up overnight, :L but a simple soultion would be to buy another battery and charge one while the other is in use. I would call Optima and see what they recommend as a charge rate though.
Good luck at the races, what are you racing and what are your times?

 

[Ken]

Jen, I tend to agree with Craig and suggest you invest in a second battery. That way you'll always be fully-charged and ready to go when they call you. Hate to lose a round due to a dead battery, eh?

A deep-cycle battery needs a slow charge to really do it any good.

 

[jpanek]

Jenavet,

I wonder if you really had 65-75% like your meter said. There is something called "surface charge" which makes your UNLOADED voltage high and as soon as you start pulling current out it will drop down to the real voltage. That is why when you trickle charge a battery at say 1 amp, the battery voltage reads 14.5 right after you disconnect the charger. After a short while it drops to 12.6, the correct number for a fully charged batt.

Anyway, the reason it charges better the next day is that batteries have internal resistance which is a function of temperature. At the track, your temp and resistance are high, and at home the next day they are both low. Unfortunately it's a positive feedback thing, because whenever you charge a battery you heat it up, which drives up its internal resistance, which heats it up more etc. Can you keep the battery cooler? I can't remember but I think somewhere I've seen insulation around batteries to protect them from high underhood temps. Can you run a cooling air duct to it? That might be easy if its right behind the left front wheel as in my C4.

 

[jenavet]

the battery is in the trunk area.....what i notice is when i come back from a run,the battery usually is at 60%...the meter usually shows around 12volts.....i put the charger on and after awhile it reads 85% charge but my dash guage shows 15.5-16volts....i drop it to 8 amp charge and that drops the voltage on the guage down to 14volts.......then it creeps up to 15-15.5 volts at 90-95% charge...so i drop it to 2amp charge and this brings it down to about 12.5-12.8 amps on the guage.........maybe i should be going off the amps vs the percentage of charge???

 

[stangmata50l]

All your dash gauge is measureing is the voltage across the battery. What you want to rely on is the amperage and the voltage.....mainly amperage if you are racing with no altenator.

Bottom line is that you need to get a second battery and run both batteries on trickle chargers to make sure you get the maximum life out of them, especially being deep-cycle batteries. With the charging issues, I would definately call Optima and get their solution and explanation.

P.S I see you're from Niagra Falls, where are you racing.

Ian

 

[jenavet]

thanks stang
on friday nights we run at lancaster dragway....on saturdays we race at new york international/empire or leicster....so many different names for the place...and on sundays we race at toronto motorsports park up in cayuga ontario canada

 

[stangmata50l]

thanks stang
on friday nights we run at lancaster dragway....on saturdays we race at new york international/empire or leicster....so many different names for the place...and on sundays we race at toronto motorsports park up in cayuga ontario canada

I love going up to Leicster. I was actually thinking about going up this Friday to check out the MOM's races!