Starter Voltage?

[scottyb]

What is the lowest voltage your battery can get down to, that still allows you to start your Elise?

I want to make a Led Circuit that will light up when the battery gets into the “No Start Zone”

[Ian]

Originally Posted by scottyb

I want to make a Led Circuit that will light up when the battery gets into the “No Start Zone”

One more thing to help drain the battery.

[scottyb]

Originally Posted by SAElise

One more thing to help drain the battery.

Actually the circuit I'm thinking of would have a self contained rechargeable battery on it so that it would not cause a drain. Otherwise it would be self defeating.

[ChrisB]

The battery might show a fairly high voltage reading with no load and drop significantly with a heavy load like the starter. I assume you want some indication of the condition before pressing the start button. That might take some testing with a donor battery discharging it in steps until it reaches the point where it is inadequate to spin the engine and see what non-load voltage it has.

[GetBoost]

On my SUV, I have deep cycled the battery many time. Usually I can still start the engine - though it hesitates a bit - if I stop discharging at 10 volts. As part of my sound system, I have a fuse block with a digital voltage display that gives a alarm beep when the voltage drops below 10 volts.

On the Elise, I haven't kept track of what voltage it can drop before the engine doesn't start. I would imagine it depends greatly on the CA of the battery, which the stock and Odessey doesn't have much. I did notice that when I discharged the SUV battery to much to start, it will start if I wait 30 min or so. But on the Elise, if it's dead, it's dead.

One question though - why would you want to know how low you can go with the Elise? Do you plan to deep cycle it? I can play computer games for ~90min while the wife shops, before the battery dies. I managed to do that 3 times before my stock SUV battery fried and I had to get a deep cycle one. I can't image trying something like that on the Elise. Are you planning on using it as an indicator while the car is in storage? Would the LED blinks "Drive me please!"

[scottyb]

Originally Posted by GetBoost

On my SUV, I have deep cycled the battery many time. Usually I can still start the engine - though it hesitates a bit - if I stop discharging at 10 volts. As part of my sound system, I have a fuse block with a digital voltage display that gives a alarm beep when the voltage drops below 10 volts.

On the Elise, I haven't kept track of what voltage it can drop before the engine doesn't start. I would imagine it depends greatly on the CA of the battery, which the stock and Odessey doesn't have much. I did notice that when I discharged the SUV battery to much to start, it will start if I wait 30 min or so. But on the Elise, if it's dead, it's dead.

One question though - why would you want to know how low you can go with the Elise? Do you plan to deep cycle it? I can play computer games for ~90min while the wife shops, before the battery dies. I managed to do that 3 times before my stock SUV battery fried and I had to get a deep cycle one. I can't image trying something like that on the Elise. Are you planning on using it as an indicator while the car is in storage? Would the LED blinks "Drive me please!"

The circuit would tell me when the car is getting into a warning zone so that I would hook up by battery tender. Also, it would connect a rechargeable battery if the car battery got completely drained thus maintaining Radio & ECU settings. At least that is what my hopes for the circuit are. I could make it compact enough that it could be removable and just plug into the acc socket or just hard wire it. I haven’t decided yet. I’m just doing some preliminary research.

Does anyone have the specs on our starter?

[ChrisB]

Just out of curiosity, why not leave the battery tender connected?

[Stan]

You can add a decent solar charger, the kind that won't overcharge and that adds energy even in a windowed garage. Another circuit idea is to track the MAHs more directly. Also many car chargers will self-sense...sounds like you don't want to hook it up until needed? You can also add a larger battery. And cut any items that draw power when the car is parked...like the alarm, some power amps, rewire things. On the voltage thing, just look at a chart for your battery type. And make an educated guess, perhaps a few tenths of a volt below normal.

[scottyb]

Originally Posted by ChrisB

Just out of curiosity, why not leave the battery tender connected?

1) Because it’s winter
2) I’m running our of Mods
3) Jay Hass will soon have my Elise for 3 weeks
4) I don’t want to constantly open my trunk and plug in the battery tender.