Car Battery Dead - Can I Charge Using Solar Power

[cortttt]

Car battery is dead (11.8 v). Neither of two lithium jumpstarters worked. Could I just hook up the car battery to solar (360 watts) to charge it?

 

[Trebor English]

If your solar panel is not high voltage you could connect it directly to the starter battery.  You have to watch the voltage and BE the charge controller.

You can connect the battery lead of your solar charge controller to the starter battery to charge it.  

Do you have a house battery that is already charged?  Do you have an isolator to charge while you are driving?  If both are yes you can bypass the isolator connecting the house battery to the starter battery to jump start.  If you have no isolator but have a wire you could use the wire like a jumper cable.

 

[cortttt]

If your solar panel is not high voltage you could connect it directly to the starter battery.  You have to watch the voltage and BE the charge controller.

You can connect the battery lead of your solar charge controller to the starter battery to charge it.  

Do you have a house battery that is already charged?  Do you have an isolator to charge while you are driving?  If both are yes you can bypass the isolator connecting the house battery to the starter battery to jump start.  If you have no isolator but have a wire you could use the wire like a jumper cable.

I don't have an isolator. I have a charged house battery. 

It's a 12 volt solar array - is the best thing to hook the car battery to the charge controller then?

 

[John61CT]

Yes always run a panel through a controller for charging. Floating (not charging) a full batt in storage with a trickle 5-10W panel is the only exception.

I assume you're nowhere near shore power?

Recharging any big flattened battery from solar is going to take a fair bit of time. Only one full day may be enough to crank, but maybe not Full.

Maybe never, if the batt itself is old and has failed (see below)

Why is it flat? Has the cause been corrected?

It would be much quicker to recharge the jumpstart powerpack(s).

Why did **they** (both! ) fail? Has that condition been corrected?

So many failure points at the same time does not seem coincidental, are the causes connected?

If you have a full House bank, why not just jumpstart off that?

______
For the others reading this, the ability to self-jumpstart off House at the push of a button is a great feature to design into your system from the start.

But if you carry long enough jumper cables, that works too.

Also, a jumpstarter powerpack kept in reserve for a crisis must be kept charged, topped up say monthly, and not used for othet things, like recharging screen gadgets.

And failing Starter batts, just like House banks should be regularly tested and replaced long before they might unexpectedly fail, so you never get surprised.

Industry standard defines a batt as scrap when AH capacity has fallen by 20%. Pushing that to 30% is rational, but IMO any further is not.

Note that some failure modes with very deteriorated batts are violently destructive, possible explosive, acid everywhere, connected equipment wrecked etc.

 

[MrAlvinDude]

It's a 12 volt solar array - is the best thing to hook the car battery to the charge controller then?

Connecting the solar charge controller to the starter battery would indeed be a safe way to get the starter battery charged. 


If you have a chance to measure the voltage on your starter battery (before you connect anything else to it), then that would also be a good place to start, as this might tell you something about how difficult it might be to get your starter battery charged again. 


On a different note. If the starter battery has been very deeply discharged, like down towards or even under 8 volt, then it has been my experience that in order to start anything from a lithium booster pack, it is necessary to first disconnect the starter battery (remove the plus only), and only use the booster pack to start the vehicle. 

Once the engine is running, then one must push the battery connector to touch plus on the starter battery, BEFORE removing the starter boost pack. As it is not wise to try to have the engine running without any kind of battery still connected to the battery connectors.  

And remember to use a tool, to push the battery connector to touch the plus of the starter battery, as it is very likely to cause sparks, when they first touch.



It is also possible to connect the house battery to the starter battery, and get some charge into the starter battery that way.  It will however typically take some minutes (even up to 10 minutes) to get enough charge to flow, to be able to start the engine from the starter battery. 
How long time it takes, all depends on the thickness and length of wire you use, as the thickness and length of wire, determines how much power can be transferred to the starter battery per minute. 

Again, it will be helpful to have a voltmeter (or multimeter) to be able to measure the voltage of the starter battery, to see when it is likely to again have enough power stored in it, to be able to start the vehicle. Typically it will need to be over 11.2 (or even higher), before there is enough energy stored in the starter battery, for it to be able to start the vehicle.

 

[highdesertranger]

yes you can do it I have done it a few times. even with my 50 watt panel it works. I leave it on all day. hope you are not in a hurry. highdesertranger

 

[frater secessus]

If your solar panel is not high voltage you could connect it directly to the starter battery.  You have to watch the voltage and BE the charge controller.

Does panel voltage really matter in this context, assuming it is high enough to charge the battery? The direct battery connection would force the panel to run at battery voltage, right?

I agree in both cases the user would be the controller, and that the risk of overcharging through inattention could be much worse with higher voltage panels.

I also agree that running it through a charge controller would be better/safer/easier. And maybe even much faster, depending on the controller.

 

[highdesertranger]

yes, I run it through an old ASC charge controller. highdesertranger

 

[Weight]

""On a different note. If the starter battery has been very deeply discharged, like down towards or even under 8 volt, then it has been my experience that in order to start anything from a lithium booster pack, it is necessary to first disconnect the starter battery (remove the plus only), and only use the booster pack to start the vehicle. ""

This is TRUE, as the dead battery has a heavy drain and reduces the voltage available for the starter. EXCEPT, Always disconnect the negative connection first. Always connect the negative connection last. Also with a discharged or jumped battery, be careful of sparks at the dead battery. The cells could explode. better to disconnect the negative cable away from the battery.

 

[Trebor English]

Does panel voltage really matter in this context, assuming it is high enough to charge the battery?  The direct battery connection would force  the panel to run at battery voltage, right?

If "the panel" is actually 3 panels in series then there is an MPPT controller right there that will increase the battery charge current by 3 times.  Yes, direct connect would still work, eventually.

 

[MrAlvinDude]

Also with a discharged or jumped battery, be careful of sparks at the dead battery. The cells could explode. better to disconnect the negative cable away from the battery.

True.

As I have only ever worked with sealed batteries, I have not been thinking about this aspect of danger. 

Have you heard of experiences where sealed batteries have exploded? 
My thinking is, that it is mainly a danger with flooded batteries, because of the hydrogen gasses associated with the flooded batteries.

 

[DLTooley]

I recently had my alternator go out in the Utah outback. I used 150 watts of solar to recharge the starter to get out several times. It took two days.

You will get to the point of being able to re-start the vehicle before you run the risk of overcharging your starter battery. I observed charging voltages that started out low but would climb. I presume that has something to do with various stages of bulk/absorb/float charging. The max normal charging rate is 14.4, once I got a tad over that for a short time I was able to start.

I have been able to use my house battery to jump, but I pulled it from its regular location to do so. Not sure how it would work otherwise.

 

[cortttt]

Yes always run a panel through a controller for charging. Floating (not charging) a full batt in storage with a trickle 5-10W panel is the only exception.

I assume you're nowhere near shore power?

Recharging any big flattened battery from solar is going to take a fair bit of time. Only one full day may be enough to crank,  but maybe not Full.

Maybe never, if the batt itself is old and has failed (see below)

Why is it flat? Has the cause been corrected?

It would be much quicker to recharge the jumpstart powerpack(s).

Why did **they** (both! ) fail? Has that condition been corrected?

So many failure points at the same time does not seem coincidental, are the causes connected?

If you have a full House bank, why not just jumpstart off that?

______
For the others reading this,  the ability to self-jumpstart off House at the push of a button is a great feature to design into your system from the start.

But if you carry long enough jumper cables,  that works too.

Also,  a jumpstarter powerpack kept in reserve for a crisis must be kept charged,  topped up say monthly,  and not used for othet things,  like recharging screen gadgets.

And failing Starter batts,  just like House banks should be regularly tested and replaced long before they might unexpectedly fail,  so you never get surprised.

Industry standard defines a batt as scrap when AH capacity has fallen by 20%. Pushing that to 30% is rational,  but IMO any further is not.

Note that some failure modes with very deteriorated batts are violently destructive,  possible explosive,  acid everywhere, connected equipment wrecked etc.

 Thanks.....The jumpstarter looked like it was full but in fact it was not and I did continue charging it and it did eventually start the van. 

As I remember, though, this one stated, I think, that it should be discharged and recharged regularly. 

The other Lithium jumpstarter - which was quite old - one just seems to be dead; it too seemed to be at full charge but it's not charging any more. I'll probably get another one for backup. 

At least I know how to use the solar array now if necessary; actually I'll use the house battery. Very good to know! 


Thanks!

 

[John61CT]

The type of Lithium used in those powerpacks has a limited lifespan.

For something critical, I'd buy a new one every 18-24 months and use the old one for phones etc.

Maybe 200 cycles if not discharged all the way.