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Old 11-21-2009, 09:33 AM
Brabus Brabus is offline
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Default Highest AH 12V battery

I hope this is okay to ask here.

I found this forum by searching about A123 batteries, then upon further reading through the forum I read about LFP batteries. To my amazement they go up to an astonishing number of amp/hours (granted the higher the more costly).

I have a ICE Volkswagen van (camper) that I would like to replace the old/near death Optima Blue Top battery (deep cycle/starter) with a much higher capacity 12volt battery. Preferably lithium.

If I buy 4 of these LFP batteries, then wouldn't that make one 12 volt battery to use as a starter and for deep cycle needs? I see they go very high in AH. I'm looking for the highest amps possible even if it means relocating the battery outside of the engine compartment into the passenger area, so that the space the battery takes up isn't too much of a factor. I'm willing to spend a significant amount of money within reason if I can get a lot of amps/hours. I've seen how much the 160, 200 and 260AH versions sell for each.

I'm just wondering if there's something better or more bang for the buck, because it's a lot of money if there is something better for my application.

Thank you for your time.

P.S. If there is anybody here that has converted a Smart car, then let me know. I own a couple Smarts.
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Old 11-21-2009, 09:47 AM
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Default Re: Highest AH 12V battery

Quote:
Originally Posted by Brabus View Post
I hope this is okay to ask here.

I found this forum by searching about A123 batteries, then upon further reading through the forum I read about LFP batteries. To my amazement they go up to an astonishing number of amp/hours (granted the higher the more costly).

I have a ICE Volkswagen van (camper) that I would like to replace the old/near death Optima Blue Top battery (deep cycle/starter) with a much higher capacity 12volt battery. Preferably lithium.

If I buy 4 of these LFP batteries, then wouldn't that make one 12 volt battery to use as a starter and for deep cycle needs? I see they go very high in AH. I'm looking for the highest amps possible even if it means relocating the battery outside of the engine compartment into the passenger area, so that the space the battery takes up isn't too much of a factor. I'm willing to spend a significant amount of money within reason if I can get a lot of amps/hours. I've seen how much the 160, 200 and 260AH versions sell for each.

I'm just wondering if there's something better or more bang for the buck, because it's a lot of money if there is something better for my application.

Thank you for your time.

P.S. If there is anybody here that has converted a Smart car, then let me know. I own a couple Smarts.
Maybe I'm missing something in my thought process, but if you are after simple amp hours: two six volt Trojans would be a good bet at 220 Ah each (well, in series that would still be 220 Ah total). Lithium sure is awesome, but there SO many posts about charging these things that it's a nightmare I wouldn't want to get myself into even if I HAD the money....
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Old 11-21-2009, 11:02 AM
Brabus Brabus is offline
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Default Re: Highest AH 12V battery

Quote:
Originally Posted by vpoppv View Post
Maybe I'm missing something in my thought process, but if you are after simple amp hours: two six volt Trojans would be a good bet at 220 Ah each (well, in series that would still be 220 Ah total). Lithium sure is awesome, but there SO many posts about charging these things that it's a nightmare I wouldn't want to get myself into even if I HAD the money....
Thank you for the response.

The battery would be connected to my internal combustion engine. I assume it would charge like any other battery via the ICE engine. Or are you saying there are charging problems with these batteries, i.e. the batteries themselves have technical issues.

Like I saw this post about the improvement in the life cycle of a LFP 160AH battery.

* Cycle life 80% DOD from 1000 to 3000, and 70% DOD from 2000 to 5000!

And another one after that talking about 8,000 life cycles. I've read that lead-acid batteries not only do they not have a long life cycle but the available AH degrades rapidly overtime.

My 5 perceived Lithium battery advantages:

a high life cycle
charges relatively quickly
smaller & lighter
higher AH over the life of the battery
No lead

I noticed Thundersky had 12 volt versions which according to this forum they are solid one piece. Here's a link to them, but I didn't see these available to buy in the U.S., so I'm looking at the other options that seem more readily available. http://www.thunder-sky.com/products_...&fid2=&page=12


I was surprised that this guy started his car using just 4 A123 batteries. http://www.youtube.com/watch?v=qcvmvrmTMMk

Last edited by Brabus; 11-21-2009 at 11:13 AM.
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Old 11-21-2009, 11:49 AM
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Default Re: Highest AH 12V battery

Brabus,
I don't know enough about Lithium to give any advice on THAT part of it. I just know that some lead/acid batteries can pack a bunch of Ah, are readily available, and are basically plug n play. From all I have been reading (and not understanding), I think slapping in a Lithium battery as your starting battery will need some sort of monitoring system and I don't know if your vehicle's alternator can charge it without some sort of modification. I bet if you title a post about using lithium as a starting battery, someone who knows something about it will be able to answer that. I know there are companies that sell a 12v battery for drag race cars that are Lithium, but they have a charger you need to buy with it (I don't think that drag race cars use an alternator, but, again, I could be wrong. I'm sure someone will come along and tell me ).

http://4xspower.com/products/

Quote:
Originally Posted by Brabus View Post
Thank you for the response.

The battery would be connected to my internal combustion engine. I assume it would charge like any other battery via the ICE engine. Or are you saying there are charging problems with these batteries, i.e. the batteries themselves have technical issues.

Like I saw this post about the improvement in the life cycle of a LFP 160AH battery.

* Cycle life 80% DOD from 1000 to 3000, and 70% DOD from 2000 to 5000!

And another one after that talking about 8,000 life cycles. I've read that lead-acid batteries not only do they not have a long life cycle but the available AH degrades rapidly overtime.

My 5 perceived Lithium battery advantages:

a high life cycle
charges relatively quickly
smaller & lighter
higher AH over the life of the battery
No lead

I noticed Thundersky had 12 volt versions which according to this forum they are solid one piece. Here's a link to them, but I didn't see these available to buy in the U.S., so I'm looking at the other options that seem more readily available. http://www.thunder-sky.com/products_...&fid2=&page=12


I was surprised that this guy started his car using just 4 A123 batteries. http://www.youtube.com/watch?v=qcvmvrmTMMk
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Old 11-21-2009, 12:05 PM
Brabus Brabus is offline
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Default Re: Highest AH 12V battery

Quote:
Originally Posted by vpoppv View Post
I think slapping in a Lithium battery as your starting battery will need some sort of monitoring system and I don't know if your vehicle's alternator can charge it without some sort of modification.
The vehicle has a 150 amp alternator, but I don't know whether that's capable of keeping such a high capacity 12v battery charged. I've looked at lead-acid/AGM batteries that go all the way up to 230 for AGM and 260 for lead-acid. I do know the AGMs keep the amp hours significantly better over cycle usage than lead-acid.

http://www.difflock.com/diffmag/issu...ry/gel-agm.gif

I suspect lithium does far better.
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Old 11-21-2009, 12:19 PM
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Default Re: Highest AH 12V battery

If space isn't an issue and you need to have deep discharge for something and also a starting battery then I would be tempted to get a good 12v automotive starting battery in lead acid and then installing a split charge system to charge a deep discharge second 12v lead acid battery to supply the deep discharge needs.

This sort of system is often used by off road drivers so that they have a good starting battery and a good winch battery as the needs are so different.
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Old 11-21-2009, 12:25 PM
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Default Re: Highest AH 12V battery

After seeing his video months ago when I saw it the first time, I was surprised how much power those A123 cells could dish out too.

The funny thing about this is last week I took apart my booster pack that I've kept in my trunk because it lost all capacity suddenly, I put it on a charge and it would show up completely full at 14.5 volts but would pull no amps, I would then turn on the built-in compressor and it would barely turn the air compressor and the voltage would sit below 10 volts, back on the charge it would shoot right up. The battery was fine a few months before when I used its compressor to help someone who had a low tire when it was convenient to use and it charged up fine then, so it had a sudden death that I'm not aware of. Either way, with winter coming I pulled its 17.2Ah SLA out and got a $55 replacement that was 18Ah Werker that was a direct size fit. I figured the battery would be $40 so I cringed a little as I handed over the money thinking about how I could get a starting battery for that much, but knowing that the light, compressor, and jump starting pack has helped many so far other than me, I still wanted this pack.

As I drove home, I thought about the $17 8Ah Headway cells that can pump out 20C with some people drag racing and pulling even more than they are rated for short drag runs and I figured for the 2 seconds it would take to crank an engine this might not be a bad idea. After I got home I measured things up and the inside of the booster pack could take 8 of those cells, so I could run 2 strings of 4 parallel for a 12.8 volt nominal 16Ah pack rated at 320 amps, which I know it could do more for a few seconds which is likely enough to start a SUV in anything but the absolute worst conditions. ...since my current car only need a battery with 310CCA according to its specs, I could get away with a single string of 4 cells and I'm sure it would be enough to start the car because I don't really think it would pull 310 amps to start it and the impulse abilities likely can stretch enough to get the engine started. I wouldn't have to worry about charging it up every 3 months either and since I can monitor it closely when in use I know that it won't be running dead so no real need for a BMS or anything like that, I could manually charge it after use on a per-cell basis if I need to.


...back on topic, I nearly wrote a novel about a personal story based on the video link you posted...

You could use a Lithium battery but if you ever left your lights on and that battery was drained to the point where it can't start your vehicle, just like how it happens to all of us from time to time, your battery is going to be shot unless you have some sort of disconnect for when the voltage drops below its threshold cutoff voltage. You would want to have some form of battery disconnect in case the battery dropped below a certain voltage, but you would have to have a disconnect that won't operate when you are cranking the engine over since that is when you need the power and the momentary sag shouldn't be an issue for a second or two.

The lithium battery is going to be much more expensive than multiple lead packs would be if you needed to replace a few.

...but it all depends, you didn't mention what you were using this for, you want high Ah but what are you using it for. If you are just using it as a cranking battery, the high storage capacity will serve you no additional use. If you are using this to provide lighting in your camper and you plan to cycle this battery up and down a whole bunch, this starts to make more sense. I think I'd rather try and find two 220Ah 6 volt batteries IMO, even if they only give say 150Ah in a 1 hour discharge environment than getting 4 160Ah cells if the 4 160Ah lithium cells will end up being $775 and a large single lead battery will be less than a quarter the cost I would figure(although not quite the same capacity but still respectable). Larger lead would be proportionately more expensive. It all depends how deep and how often you cycle them before you really know if it is worth it on a monetary basis. Lead acid batteries get recycled, the lead will end up being repurposed so I don't see it being too big of a deal for using it as a matter of environmental concern since it will be recycled.

With some insight on how you plan to use your pack, we could better advise you to if this is a good idea or not, but IMO it is pricey for use as a starting battery if you want 160Ah out of it.

Would a 160Ah 4 cell Thundersky pack start a vehicle? Yes
Is it the most cost effective? It all depends on how you use it, it might very well be. Just don't let all of the cells in the pack drain below 2.5 volts, to be safe keep them around 2.8 volts per cell as voltage will drop like a rock when they are discharged.

As far as options, you've got various options with the Thunder Sky LiFePO4 cells, with lead there are 6 volt 220Ah batteries that you could put 2 in series to make a 12 volt battery which could very well last a long time if you get a high quality brand. I don't know what the cost of a high quality brand 220Ah battery is though.
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Old 11-21-2009, 09:34 PM
Brabus Brabus is offline
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Default Re: Highest AH 12V battery

I was hoping to avoid explaining the application as it would lead to a long post that likely would be so long that most people wouldn't want to take the time to read and at worst confuse the situation, however I'll post it anyway.

Thank you so far for your responses, they've been very helpful especially the voltage disconnect monitor for lithium batteries.

Woodsmith, What you suggested is exactly how the vehicle is configured from Winnebago, i.e. a starting battery in the engine compartment with a deep cycle in the rear of the vehicle. The deep cycle in the rear is charged via a 20 amp auxillary charger powered through the engine. Thus both starter and deep cycle are charged while driving. However, this setup provided marginal energy on extended trips.

I have given the stock 20 amp auxillary charger away as I plan to install a higher amp charger with a large rear battery bank to maintain an 500 watt air conditioner. I plan on installing a 2800 watt 110v or 2500 watt 220v cummins-onan generator in the engine compartment. It will require some fabrication to make the fit for the minimum compartment size 12.52" x 18.20" x 20.46" (I haven't found one smaller, and this one has an remote muffler).

I prefer the location of the engine compartment area as there is room & it would muffle the sound from the interior of the vehicle. The 220 volt version is quieter and consumes less fuel than the 110volt version. I'm leaning more towards the 220 volt system. http://www.cumminsonan.com/rv/produc...e?gensetId=122

Therefore the battery for the engine would be in the cabin area of the camper. This is where it gets confusing for me. What size deep cycle battery should I use for the engine and should I get one that is high amp hour to serve some of the electrical needs of the camper. Or should I get a normal size battery which would fit under the dash and leave the big energy demands to the large battery bank that I will have in the rear of the vehicle. In other words, the front engine battery and rear deep cycle setup like most RVs.

And before you say, well just do what other RVs do....well, all RVs use air conditioners that run on generators, they do not run on battery banks as they consume a couple thousand watts to run to cool even camper vans. This one will have a small household air conditioner that consumes a max of 500 watts. A very different application and at night I want to run it off the rear battery banks as I can have it on low settings thus consuming much less wattage. My application/goal is unique.

While the goal is to take as much advantage of the engine energy for the starting battery to recharge a deep cycle 12 volt as possible. I'm also aware that the alternator doesn't charge super large Amp Hour batteries yet I'm not aware what the cut-off should be. It did fine keeping the blue top optima battery with 60AH, yet would it do fine working with an AH two, three or four times that size. Essentially I don't know what the recharge of AH per hour of engine running would be to determine what is worthwhile for maximum deep cycle battery for the front. And even worse, I don't want to burn alternators up.

So back to my original question, what's the maximum AH can a engine battery be to gain the energy consumed while driving into stored deep cycle energy? The alternator is 150 amps, however when I spoke to an Interstate Battery guy he said it wouldn't charge deep cycles very fast but he didn't know how much was too much in terms of amp hour. Like I'm sure I could go higher than 60 amps, but how much higher is the question that I lack the information. I suspect the answer to my question is how quickly does an engine charge a battery.

I plan to have a large battery bank in the rear that is separate from the engine battery. I hope that helps and doesn't confuse. I've been thinking about doing this for years and well I know less than I should to make it happen.

Last edited by Brabus; 11-21-2009 at 09:56 PM.
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Old 11-21-2009, 10:33 PM
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Default Re: Highest AH 12V battery

Largest 12 AH capacity I know of is 375 AH; Surrette 12 MD 375 PM
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Old 11-21-2009, 10:44 PM
Brabus Brabus is offline
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Default Re: Highest AH 12V battery

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Originally Posted by Sunking View Post
Largest 12 AH capacity I know of is 375 AH; Surrette 12 MD 375 PM
Thank you. Very interesting. Though I still need to figure out how much charge the ICE engine provides to a battery. Even if the sky is the limit in AH, I can't make a decision on what size I should stop at if I don't know how to calculate how much the engine charges.

--------------------------------------------------------------------------------------------

Anyway, here's some examination of the link you provided in looking at their battery offerings. Apparently they offer a submarine battery at 10,000AH, ha! As for their lead-acid battery offerings they have two series called:

Series 4000 (which I assume would be similar to most lead-acid batteries) which give:
2688 cycles @ 10% DOD
2048 @ 30%
1536 @ 50%
1300 @ ??%

Series 5000 which give:
6600 cycles @ 10% DOD
5040 @ 30%
3840 @ 50%
3300 @ ??%

The only 5,000 series 12 volt is just under a thousand dollars at 357AH @ 272lbs.

That's about 3x the weight/dimensions of a 300AH Lithium, yet I'm sure less than a third of the price.

The cycle life of a thundersky is

5000 @ 70% DOD
3000 @ 80% DOD

They have much higher AH in lower voltage all the way up to 2430AH, yet weight, cost and ability to maintain a charge would be prohibitive.

Surrette also has some good options for AGM, however I haven't found information on life cycles.

http://www.surrette.com/content/mari...specifications

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Anybody know the charging rate is for an engine battery? I believe it's rather low and that my consideration of these high AH batteries is in vain because of it. But I'm not 100% sure.

Last edited by Brabus; 11-22-2009 at 12:12 AM.
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