Golf Cart batteries 8V... What is top voltage?

[theremart]

I am familar with 6V golf cart batteries but these 8V T 875 Trojans are new to me. Doing a radient charge with a Jetijs charger inputting 5 amps on 10 transistors how high should I go with these batteries 9V 10V 11 V?


Thanks!

[Sephiroth]

wouldn't you normally just charge them up until they reach top voltage and then start dropping?

As long as you are using the C20 it should be safe.

[theremart]

RE: top voltage..

wouldn't you normally just charge them up until they reach top voltage and then start dropping?

As long as you are using the C20 it should be safe.

That is reasonable.

So how do I calculate c20 ... for input



2 8v batteries

Inputting now 1 amp at 32 V so 32 W
and also 2 amps at 18 V and 32 W

62 W of power going in... for 2 8V batteries

[Sephiroth]

That is reasonable.

So how do I calculate c20 ... for input



2 8v batteries

Inputting now 1 amp at 32 V so 32 W
and also 2 amps at 18 V and 32 W

62 W of power going in... for 2 8V batteries

Bloody hell! I just looked up those batteries!

T-875 Trojan Battery

170ah!

C20 for those would be 8.5amps (if it was 8 volt input) so anything up to 5.5 amps with 12v input per battery should be safe.

I'm very jealous! Please tell me they're really sulphated!

[theremart]

other thoughts.

Bloody hell! I just looked up those batteries!

T-875 Trojan Battery

170ah!

C20 for those would be 8.5amps (if it was 8 volt input) so anything up to 5.5 amps with 12v input per battery should be safe.

I'm very jealous! Please tell me they're really sulphated!

he he...
Actually he had cheaper ones for $14.00 each which were bad for what ever reason. But these were tested as GOOD. he load test these as being good. I got them all 6 for $220.00 Normally as you see they run $140 each new.

I decided to forgo the months of charge / discharge and spend a few buck to save the time and actually get some good batteries and then radient charge them to the bone.

I have been asking around and what Solar panel guys do is put them in 3's for 24V so they can run the controllers off of them at this rate.

The conventional chargers normally hit these things with 20 - 50 amps for fast charging... I am targeting higher voltage to drive off sulfate that may be there.

The other question is how low do I take them.....

[Sephiroth]

he he...
Actually he had cheaper ones for $14.00 each which were bad for what ever reason. But these were tested as GOOD. he load test these as being good. I got them all 6 for $220.00 Normally as you see they run $140 each new.

I decided to forgo the months of charge / discharge and spend a few buck to save the time and actually get some good batteries and then radient charge them to the bone.

I have been asking around and what Solar panel guys do is put them in 3's for 24V so they can run the controllers off of them at this rate.

The conventional chargers normally hit these things with 20 - 50 amps for fast charging... I am targeting higher voltage to drive off sulfate that may be there.

The other question is how low do I take them.....

You're a lucky guy! There used to be a mobility center near me which had a closet full of "dead" batteries from mobility scooters and I horded all the best ones but the highest capacity there was 36ah and had been sitting on a shelf for four years and god knows how long before then in an electric scooter.

How low to take them? I have no idea I tried looking for a data sheet but there's nothing with a discharge chart.

Looks like an experiment may be in order you have a multimeter with a pc interface and you're familiar with the normal discharge curves for 12v batteries... Do a load test and keep an eye on your discharge chart. When you see the voltage start dropping faster then that will probably be the limit... but you probably thought of that already

[theremart]

At last found my answers

Trojan Battery Company


I always like to know what the specs are from the manufacture before I compare the radiant charge to standard charge.

I have ordered some 50W resistors for the Jetjis charger will trying doing multiple sets of batteries.

I also found this guide very helpful to understanding why you should not add tap water to batteries.

http://www.trojanbattery.com/Tech-Support/documents/UsersGuide_0708_English_003.pdf

Thanks Seph for your insights!

[dambit]

Hi Mart (and Seph),

You mentioned 5 amps with ten transistors. Is that what the charger draws from the wall or the conventional input to the batteries?

I only ask because I have been thinking about the tolerances of my charger, and I have realised that I can drive it much harder than I first thought. The MJL21194 can take 16A continuous through the collector. I read in the user manual for Bedini's chargers that to rejuvenate a battery quickly you need to use the more powerfull settings on the charger.

In the last couple of days I have cranked the juice so to speak and the advice does seem sound. The only issue I can see is heat. The circuitry is fine, but my coils get very hot (should have used a larger guage). I will be installing cooling fans in the coming days. Due to the resistance in my coils, using 15 transistors (had 20 but blew 5 again ) the max I can draw from the wall is 8.5A at 15V. (I want to be running on 24V but my 24V power supply can't put out more than 2A)

Let me know your thoughts on this.

Cheers,

Steve

[theremart]

Thoughts...

Hi Mart (and Seph),

You mentioned 5 amps with ten transistors. Is that what the charger draws from the wall or the conventional input to the batteries?

I only ask because I have been thinking about the tolerances of my charger, and I have realised that I can drive it much harder than I first thought. The MJL21194 can take 16A continuous through the collector. I read in the user manual for Bedini's chargers that to rejuvenate a battery quickly you need to use the more powerfull settings on the charger.

In the last couple of days I have cranked the juice so to speak and the advice does seem sound. The only issue I can see is heat. The circuitry is fine, but my coils get very hot (should have used a larger guage). I will be installing cooling fans in the coming days. Due to the resistance in my coils, using 15 transistors (had 20 but blew 5 again ) the max I can draw from the wall is 8.5A at 15V. (I want to be running on 24V but my 24V power supply can't put out more than 2A)

Let me know your thoughts on this.

Cheers,

Steve

Well...

Do well note that golf cart batteries are a whole different breed of battery than a deep cycle battery, much thicker plates.

Also do note that I am not running at 12V at my supply I am running at 18V 2 amp at one supply ( a 6 v golf cart combined with one of my alum batteries which is being charged back up with solar charge ) And on the other set of 5 transistors I am running at 34 V ( 4 8V batteries also hooked up to solar charger ). I am sorta using my batteries as HUGE capacitors with the solar system to give me 24 hour charging.

I am using 2n3055 transistors as they are cheap. I was moving a tarp around the other day and snap off came my charging battery connection and poof there went my transistors ( 38 V is NOT forgiving even with neons ) so my 5 amp breaker kicked in and I was re soldering in 5 more transistors ( some of which may be ok but glad to have that safeguard )

I am slowly working up in amperage as I have to use very heavy duty resistors with this type of amperage. Before I used to run 20 V at 2 amp on both sides of my two sets of 5 transistors, but these 8V batteries are a whole new world for me.

I do believe I ran 300 feet of wire on each of the 2nd group of 5 transistors heat is an issue you have to look out for. I will be pushing these batteries more now that I know the limitations of the batteries and what the proper resting voltage is.

16 A seems high, the question I have is at what voltage. ( they sure have died on me but I often do 24V and 32V so... that is a death sentence on transistors if you make a mistake. Neons have not saved my transistors at 24V and up you simply can't make mistakes at that voltage.

I hope to move up to 3 -4 amp for each set of 5 transistors. I wonder what the heat tolerance is for them hmmm