Cheap, small battery suggestion for 951 race car
06-01-2012, 11:45 AM
#17
Drifting
Xsdwe
I just went over the shorai web site and specs. The battery cannot take a charge using more than 24 amps. Our alternators are way more. I'm pretty sure this is the problem. I might rig the battery up with a clamped charge load of 20 amps with some magic circuitry. I think I will run a 16 volt alternator to solve my fuel delivery needs. That will also run my ignition and water pump anf fans with that voltage. I will install a step down for all the accesories. That's the gameplan for now anyway. Its a work in progress.
I just went over the shorai web site and specs. The battery cannot take a charge using more than 24 amps. Our alternators are way more. I'm pretty sure this is the problem. I might rig the battery up with a clamped charge load of 20 amps with some magic circuitry. I think I will run a 16 volt alternator to solve my fuel delivery needs. That will also run my ignition and water pump anf fans with that voltage. I will install a step down for all the accesories. That's the gameplan for now anyway. Its a work in progress.
06-01-2012, 12:15 PM
#18
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Xsdwe
I just went over the shorai web site and specs. The battery cannot take a charge using more than 24 amps. Our alternators are way more. I'm pretty sure this is the problem. I might rig the battery up with a clamped charge load of 20 amps with some magic circuitry. I think I will run a 16 volt alternator to solve my fuel delivery needs. That will also run my ignition and water pump anf fans with that voltage. I will install a step down for all the accesories. That's the gameplan for now anyway. Its a work in progress.
I just went over the shorai web site and specs. The battery cannot take a charge using more than 24 amps. Our alternators are way more. I'm pretty sure this is the problem. I might rig the battery up with a clamped charge load of 20 amps with some magic circuitry. I think I will run a 16 volt alternator to solve my fuel delivery needs. That will also run my ignition and water pump anf fans with that voltage. I will install a step down for all the accesories. That's the gameplan for now anyway. Its a work in progress.
http://www.digikey.com/product-detai...0K60A-ND/78837
A simple resistor on the battery should control overcharging. Has to be large wattage to charge a low voltage battery. Should NOT get hot under normal charge.
http://www.digikey.com/product-detai...-.50-ND/269986
If you want to reduce the wattage of the resistor, you could have a lower wattage one directly connected and parallel a zener ,5V or so, and another resistor. The zener and the second resistor are connected in series. That way when the voltage on the battery was below 5 volts, the power would be shared across two resistors. Can do this three of four times with different zener values if you wanted to.
06-01-2012, 01:56 PM
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06-01-2012, 03:23 PM
#20
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I certainly Will. I'm making it a little more complicated with my 16volt alternator set up. (Charges at 18volts) But it is truly the best solution for my needs. I no longer need to purchase a second fuel pump. - Less weight - and my ignition system will be stronger. - As long as you wire the ECU the same way so It knows the voltage and adjusts accordingly. There are a lot of details to address in this set up. But if done right, it's by far the best solution for what I need.
FANTASTIC! That is funny Brian. You were the "wizard" I was going to PM about my "magic wiring" Looks like I don't have to now. Thank you very much. Excellent description and links. Done and DONE.
Two of these in series to step down the 16 v to 13-14 volts for the fuse box battery feed.
http://www.digikey.com/product-detai...0K60A-ND/78837
A simple resistor on the battery should control overcharging. Has to be large wattage to charge a low voltage battery. Should NOT get hot under normal charge.
http://www.digikey.com/product-detai...-.50-ND/269986
If you want to reduce the wattage of the resistor, you could have a lower wattage one directly connected and parallel a zener ,5V or so, and another resistor. The zener and the second resistor are connected in series. That way when the voltage on the battery was below 5 volts, the power would be shared across two resistors. Can do this three of four times with different zener values if you wanted to.
http://www.digikey.com/product-detai...0K60A-ND/78837
A simple resistor on the battery should control overcharging. Has to be large wattage to charge a low voltage battery. Should NOT get hot under normal charge.
http://www.digikey.com/product-detai...-.50-ND/269986
If you want to reduce the wattage of the resistor, you could have a lower wattage one directly connected and parallel a zener ,5V or so, and another resistor. The zener and the second resistor are connected in series. That way when the voltage on the battery was below 5 volts, the power would be shared across two resistors. Can do this three of four times with different zener values if you wanted to.
06-01-2012, 08:10 PM
#21
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Just remember to heat sink those diodes, they are going to get hot without them. The diodes will generate about a watt per amp of load.
Have you though about using an adjustable voltage regulator in the stock alt and cranking it up to 15V-16V and put the resistor in just the battery charge path? I can't think of a single circuit in the car that would be effected by a little higher voltage with the exception of the battery.
Have you though about using an adjustable voltage regulator in the stock alt and cranking it up to 15V-16V and put the resistor in just the battery charge path? I can't think of a single circuit in the car that would be effected by a little higher voltage with the exception of the battery.
Last edited by Bri Bro; 06-01-2012 at 09:20 PM.
06-01-2012, 08:50 PM
#22
Nordschleife Master
There's nothing wrong with the Shorai. They are great.
If you have a problem with it, it's because your output voltage from the alternator is too low. These are Lipo batteries and will die quickly if the voltage drops too low. I think with the Shorai it's 13.5V. That said, you can tweak the alternator out put so that this doesn't occur.
TonyG
If you have a problem with it, it's because your output voltage from the alternator is too low. These are Lipo batteries and will die quickly if the voltage drops too low. I think with the Shorai it's 13.5V. That said, you can tweak the alternator out put so that this doesn't occur.
TonyG
06-02-2012, 02:23 PM
#25
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I have a Deka jet ski battery in my 944 racer and it has been going strong 3 years now. When I leave the master cutoff all winter it still holds plenty of charge 5 months later when I get the car out of the trailer for spring maintenance.
06-02-2012, 04:22 PM
#26
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That's pretty nice. Do you have a link? I had no idea there were so many lightweight alternative battery options out there. !
06-02-2012, 04:54 PM
#27
Nordschleife Master
I have been running the PC680 Odyssey battery for around 5 years now and its still going strong. Started out in my n/a, put it into my 951 and it will hopefully be enough to turn over the LS1 i am putting into my 951 also. Not bad for a battery that weighs like 15lbs and only cost $100.
The battery is tough, survived daily driver duties for 3 years in the north east winter.. that included cranking the car over with 15w50 oil. It cranked slow, but always started! I also reguarlly parked the car for 2-3 months at a time. Just disconnect the battery if its going to be sitting..again, never had problems starting the car.
Not too difficult to make a mount for it either, here is 'version 2' of my mount.. the previous version i made out of medium density fiberboard and it was pretty rotted from 5 years of rain, snow..etc. This is probably way over kill but it was a fun project.
The battery is tough, survived daily driver duties for 3 years in the north east winter.. that included cranking the car over with 15w50 oil. It cranked slow, but always started! I also reguarlly parked the car for 2-3 months at a time. Just disconnect the battery if its going to be sitting..again, never had problems starting the car.
Not too difficult to make a mount for it either, here is 'version 2' of my mount.. the previous version i made out of medium density fiberboard and it was pretty rotted from 5 years of rain, snow..etc. This is probably way over kill but it was a fun project.
06-02-2012, 04:57 PM
#28
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Yep, that odyssey worked just fine and cranked slow. I just don't see it turning a high compression V8. I would love to be proved wrong though.
Last edited by 95ONE; 06-02-2012 at 09:44 PM.
06-02-2012, 05:17 PM
#29
Nordschleife Master
The PC680 cranked fine during the warmer months with 15w50 oil. Though i am skeptical about it being able to turn over an LS motor also. I read some threads on LS1Tech that said it will be fine though.
Worse case scenario ill get the next larger battery, i think the PC925. Dimensionally it is about the same size as the PC680 laying on its side, just a little bit taller..will still fit in the mount i made though thankfully.. i had a "oh ****" moment when i thought about how much trouble i went through to make that aluminum mount and the possibility of the 680 not being strong enough
.
Worse case scenario ill get the next larger battery, i think the PC925. Dimensionally it is about the same size as the PC680 laying on its side, just a little bit taller..will still fit in the mount i made though thankfully.. i had a "oh ****" moment when i thought about how much trouble i went through to make that aluminum mount and the possibility of the 680 not being strong enough
.
05-12-2013, 12:01 AM
#30
Rennlist Junkie Forever
So what's up with this thread?
I have a new Shorai battery ready to install in the new race car.
From my research, the issue is not load but rather the voltage out put of the alternator. Specifically that it needs to be at least 14.5V above idle (once the voltage ramps up).
I'm very familiar with the Lipo stuff (I know it's not lipo but the charging characteristics are the same).
And I use have a nice balancing charger from out RC race trucks I can use to balance out the cells when necessary.
BTW> I have converted 3 Goped 750 ER scooters to 32Ah 6s Lipo. And wow.... I can literally run 20 miles at 20mph on a single charge.
TonyG
I have a new Shorai battery ready to install in the new race car.
From my research, the issue is not load but rather the voltage out put of the alternator. Specifically that it needs to be at least 14.5V above idle (once the voltage ramps up).
I'm very familiar with the Lipo stuff (I know it's not lipo but the charging characteristics are the same).
And I use have a nice balancing charger from out RC race trucks I can use to balance out the cells when necessary.
BTW> I have converted 3 Goped 750 ER scooters to 32Ah 6s Lipo. And wow.... I can literally run 20 miles at 20mph on a single charge.
TonyG