Standard VS. Deep Cycle/Marine Batteries

Thread Starter

BrooksTech

Joined Jun 11, 2019
9
I want to use a Solar, or Deep Cycle, Sealed Battery to occasionally to start a small motor vehicle on a daily basis for a few weeks.

What if any, are the problems with doing this?

Separately, what if I chose the contrary scenario? Why do I NOT want to use a Standard Sealed Lead Acid Battery with Solar Charging?

Rather than possibly repeat a common question, feel free to direct me to any Links that might discuss this in detail for a layperson.

Thank you!
 

wayneh

Joined Sep 9, 2010
16,399
I want to use a Solar, or Deep Cycle, Sealed Battery to occasionally to start a small motor vehicle on a daily basis for a few weeks.
If the duty is just starting a motor few times a day, I'd say you don't want a Deep Cycle battery. Those are great for providing DC power at low to modest current over a long period of time, say for a trolling motor on a boat. A "regular" battery is designed for a very high current for a short time, ie. starting engines, followed by topping up with the charger.

On the other hand, if you're afraid the solar charger may not keep up the charge in the battery, I'm not sure which is the better choice. The deep cycle battery may be less damaged by undercharge and last longer, but I'm not sure which would start an engine more reliably.
 

bwilliams60

Joined Nov 18, 2012
1,332
A standard lead acid battery is not made for deep discharging and recharging. Doing so will great
y reduce the life of the battery. If you want to run cycles like this, a deep-cycle battery is strongly recommended. I would also have a look at AGM and GEL cell technology as they are also deep cycle batteries but with them you need to pay attention to charging voltage. If it is too high, catastrophic failure can occur with both of these technologies. A good marine battery will do the trick for what you propose.
 

Thread Starter

BrooksTech

Joined Jun 11, 2019
9
A standard lead acid battery is not made for deep discharging and recharging. Doing so will great
y reduce the life of the battery. If you want to run cycles like this, a deep-cycle battery is strongly recommended. I would also have a look at AGM and GEL cell technology as they are also deep cycle batteries but with them you need to pay attention to charging voltage. If it is too high, catastrophic failure can occur with both of these technologies. A good marine battery will do the trick for what you propose.

Well that explains why I practically destroyed my brand-new standard battery. I would start an engine a few times, put a long drain on it over several weeks (lights, radio, etc), then charge it overnight. I did this about 10 times and now it wont last me more than two weeks without having to recharge it. It tested BAD at several Auto Parts Stores. (this however was not the reason for my original post)
 

oz93666

Joined Sep 7, 2010
737
All lead acid batteries are yesterdays technology ... there's no economic justification for the consumer to use them ... ridiculously short life , compared to the 1000's of cycles you can get from lithium .... at a fifth of the weight!!

The only reason they're still manufactured is because the industry is established , and consumers do not understanding the true facts .
 
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nsaspook

Joined Aug 27, 2009
7,478
All lead acid batteries are yesterdays technology ... there's no economic justification for the consumer to use them ... ridiculously short life , compared to the 1000's of cycles you can get from lithium .... at a quarter of the weight!!

The only reason they're still manufactured is because the industry is established , and consumers not understanding the true facts .
I completely understanding the true facts for stationary energy storage. Lithium is great but it's not for everything. I run a solar power bank, lead acid batteries are cheaper than the equivalent lithium by a large factor (Total Lifecycle Cost is also better than Lithium) so I can over-size my bank to extend the cycles to 1000's while still having the extra capacity if needed. No need to worry about weight or size issue for most stationary energy bank applications. Plus, in an emergency I can recharge flooded cells from just about any source without a specially designed charging system.
https://www.altenergymag.com/article/2018/04/lead-acid-batteries-for-solar-storage/28297/
 

oz93666

Joined Sep 7, 2010
737
I completely understanding the true facts for stationary energy storage. Lithium is great but it's not for everything. I run a solar power bank, lead acid batteries are cheaper than the equivalent lithium by a large factor (Total Lifecycle Cost is also better than Lithium) so I can over-size my bank to extend the cycles to 1000's while still having the extra capacity if needed. No need to worry about weight or size issue for most stationary energy bank applications. Plus, in an emergency I can recharge flooded cells from just about any source without a specially designed charging system.
https://www.altenergymag.com/article/2018/04/lead-acid-batteries-for-solar-storage/28297/
Your link goes to a page on flooded lead acid ...really just a glossy advert for the company Rolls .... no information , no charts , no data ...

Here's a chart from an independent site , the graph maybe quiet old , lithium continue to go down in price and the comparison now is even more favorable for lithium , my calculations of a few years ago were they were cheaper , particularly if charged to 3.93V to get 4,000 cycles .... and bought from the right outlet ...

The miss understanding arises from comparing AHr capacity .... A deep discharge flooded lead acid may be listed as 100AHrs , but you can never get 100Ahrs out , unless you are prepared to get a ridiculously short life (175 cycles) ... even at 50% discharge you only get 450 cycles !!! ..and the battery is then only 50AHrs .capacity.
They only got the deceptive name "deep cycle " because standard lead acid only has a life of 13 cycles when full capacity rating is used!!!
https://batteryuniversity.com/learn/article/lead_based_batteries..

In addition to the hassle of having to regularly top up lead acid with water .... and lug heavy batteries around every few years to change and get new ones ....

Particularly for solar where use is constant cycling , lithium works out cheaper ....

But don't expect your local retailer to know or tell you this ... his profit margin is greater on lead , and buying lead ,you'll be back for a replacement soon .... Lithium being 20% of the weight of lead for the same storage .. can be shipped easily making prices more competitive.
 
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nsaspook

Joined Aug 27, 2009
7,478
Sure, it's a advert for batteries they sell and they continue to sell because of demand. Yes, Lead acid is still absolutely king of off-grid because of existing infrastructure. That's usually a good reason to say with something that works.

I'm dubious of very high cycle counts with Lithium in 100% deep-discharge stationary storage systems. The battery cell makers for systems like Powerwall don't claim 1000's of full cycles at full efficiency. The realistic cycles are more moderate 50% cycles for long life. Most actual test show a cell degradation to about 75% after about 2000 cycles with realistic solar driven discharge/charge profiles. The BMS systems claim longer life by being able to manage cell loss in a over-sized Lithium bank to provide a smaller x capacity from the actual larger bank capacity. In a emergency, if you need that last drop of power, completely discharging (A BMS override) a lithium ion bank, even once, can render your entire pack permanently dead. Yes, it's old less efficient technology but off-grid people easily get 1,200 @ 50% from traction FLA sets over-sized correctly for good low rate discharges that you can run flat as a pancake in a emergency with no fear of permanent death.
 
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wayneh

Joined Sep 9, 2010
16,399
In most markets, claims of superior TCO against a higher upfront cost usually go unheard. If you have to get a long life out of something to come out ahead, most buyers are (correctly) suspicious. The future cash flows are heavily discounted due to the risks. The solar power industry struggles with this. People worry that the panels won't last long enough to pay for themselves. Electric cars likewise.

How does this eventually change? Data. When it becomes obvious that the long run savings are real and attainable, buyers with capital will choose the lower operating cost. This is often the institutional buyers. Many, perhaps most buyers at the retail level will still opt for the cheaper upfront product. They have other more urgent things to do with their money. But as the savvy folks with capital prove out the technology, more and more people will see the light and make the change.

Li-ion technology probably can beat LA if everything goes well. That doesn't mean it will win for everyone all the time.
 
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