Are 8V batteries useful?

[WanderingCanuck]

In my searching, I've discovered a source of 8V FLA golf cart batteries. These can easily be connected in series to get 24V and 48V, but not 12V.  Is it best to pass these by or could there be a way to be a way to use them effectively?

 

[Moxadox]

There are 24V and 36V solar panels, so you might wish to explore this option.

https://www.renogy.com/renogy-300-watt-24-volt-monocrystalline-solar-panel/

The Dire Wolfess

 

[Reducto]

Some people swear by their 24v systems and there are advantages but also drawbacks. Some of your lights and devices might not run on 24v so you'd need replacements or a converter. You won't be able to charge directly off your alternator, you'd need a dc-dc charger or some other means of charging.

You'll have to work out if the deal you're getting is worth making that switch.

The times I've heard of people running 48v is when they have a very big load like air conditioning.

 

[Canine]

If you're running 220 volts in your van, then, yes, the 8 volts would work. Otherwise, no. Some people disagree with me, but I cannot make the numbers work. It requires more equipment to buy, maintain, and replace. But to each their own.

 

[tx2sturgis]

If they are new and you are getting them cheap or free, then maybe it would be worth a try. You can buy 24v-120v DC-AC inverters, 24v-to12v DC-DC converters, and panels and controllers that will charge a 24v bank. Although it will be problematic to charge them from a generator or your vehicle alternator. 

But if they are used and/or cost about the same as other batteries, and your entire charging system is setup for 8v batteries, what will you do if one of them fails early and you cant find a replacement out on the road anywhere?

In that case you may have to rebuild or reconfigure your system to match a 12v (or 2x12v) battery bank.
.

 

[Weight]

They are used. Yes they are cheap. You have to commit to 24 volt system. Than isn't cheap. Then when you need new batteries. You are committed to the 24 volt system. Instead of 2 GC2, you need 4. Or multipals of 4. Or two or four more 12 volt batteries. Or good luck finding 8 volt when you need them. Then any 12 volt device you want to add needs converters and gets more expensive and on and on and on.

 

[John61CT]

There is no need for the voltage of panels to have anything to do with the voltage of the battery bank.

An 80V panel is just as good for 12V setups as 24 or higher.

The panel needs to suit the controller's specs, and the controller matches the bank.

 

[John61CT]

8V is not useful for 12V systems.

6V is best value, 2V is handy for very high AH banks so humans can still lift the cells without using a forklift or hoist.

3V and 4V also exist but less common.

12V batteries need to be selected carefully since the "deep cycle" label is very commonly used fraudulently in the NA market, and not just in automotive and big box outlets.

 

[Spaceman Spiff]

My 2¢:

You need to do the cost comparisons for your situation to see if buying 24V appliances and 24V to 12V converters makes sense.  Remembering that once you make the choice of 24V it is expensive to revert back to a 12V system.

Don't know how much demand there it for 8V batteries but Sam's Club carries 8V Duracell GC8 batteries for $107, for comparison GC2 6V are $94.

 

[WanderingCanuck]

Thanks all. It's looking like the 8V would need to be very, very cheap to make it worthwhile. My source isn't _that_ great.

Where do you find 2V cells? What are the typical applications?

 

[John61CT]

Same places you get any quality deep cycle.

Call your desired mfg and ask for local distributors.

Rolls Surette is a fine example.

Paying shipping for lead is silly if it can be avoided.

6V GCs are an exception, even good ones can be found at consumer outlets, why so much cheaper / AH.

 

[Weight]

If you design and build your system around Duracell EGC2, or even GC2, 6 volt batteries, you have a good set to learn the ins and outs. Then you can easily replace them with Duracell or upgrade to the more expensive spread. With 4 GC2 batteries you can have a very workable system. Even just 2 if your electrical needs are low.

 

[John61CT]

Yes FLA Duracell (actually Deka/East Penn) are around $200 per 200+AH pair from BatteriesPlus or Sam's Club.

Best value deep cycling on the planet.

Unless you find Trojans close to that locally, can happen sometimes.

 

[WanderingCanuck]

I'm still not completely convinced that any combination of my available charge sources will be adequate to return FLA batteries to full SOC. But now would be a good time to test that out while I still have easy access to shore/grid power. If it works I may be able to avoid the additional expense of LiFePo4, which would facilitate fast high current recharge and no damage keeping low SOCs (better, actually).

 

[John61CT]

Best combo is dino juice early in the morning

maybe just an an hour or two driving

get SoC up to 75-90% depending on the weather, how many panels etc

then let 5-6 hours of solar finish the long tail.

Only need to really get to 100% - as per endAmps - a few days a week for longevity.

And if everything else is good, might get 5+ years even if you don't.

 

[WanderingCanuck]

How about 30-60 minutes of driving in the dark followed by maybe 5 hours of weak winter sun near the 45th parallel variably obscured by the snow that inevitably settles on the panels during the day when I'm unable to keep clearing it off? It doesn't sound very doable to me, and the reason why I think lithium could work better. FLA could very well be feasible for the summer, but summer is less than 4 months here.

I _could_ probably use shore power at work, but this is not guaranteed and is unknown if I were to change employment. I may take advantage of this just to make things easier while available, but for my own piece of mind and comfort I need to know that I'm effectively self-sufficient.

 

[John61CT]

Honda suitcase gennie.

Either Trojan / Deka FLA GC bank, budget $250 a year for replacement (likely less)

Or thousands on LFP that **might** last over a decade, but pretty complex DIY project. Engineered system easy but double the price.

Supplement w/ solar in summer, maybe not worth it.

 

[WanderingCanuck]

That makes some sense. I hadn't thought about just not worrying about the batteries' lifespan.

But on the other hand, I might be able to use a generator as you suggest once a week, maybe a few times, to top off the charge.

Lithium look like they have so much going for them, but are truly expensive and not near as forgiving.

Off the top of your head, how much time do you think a generator would need to be run for? I understand this depends on the loads, but figure fairly intelligent selection of devices and use of power for one person.

 

[Spaceman Spiff]

LiFePO4 batteries do not do well in cold temperatures.  They are not to be charged when the battery temperature is much below freezing.  That ruled them out for me as I spend a lot of time winter camping in Northern Minnesota.

I find if I can get my FLA batteries up to 80% (generator or driving) in the early AM I get enough sun, even on overcast days or a little snow on the panels, to finish the absorption phase.

 

[WanderingCanuck]

LiFePO4 batteries do not do well in cold temperatures.  They are not to be charged when the battery temperature is much below freezing.  That ruled them out for me as I spend a lot of time winter camping in Northern Minnesota.

I find if I can get my FLA batteries up to 80% (generator or driving) in the early AM I get enough sun, even on overcast days or a little snow on the panels, to finish the absorption phase.

Good info.  As to the cold, if I were to go lithium they'd be inside the heated living space so that wouldn't be a problem.  I think keeping FLA warm may be more difficult due to the venting requirements.