I am currently using a 12v 5Ah SLA battery in a project. I need a longer battery life than what I'm getting now so I was going to just get another battery (same kind) and put it in parallel to the existing one. However two SLA batteries are rather heavy. Am I to understand that something like this (arbitrary product page: http://www.amazon.com/Alice-Portable-9800mah-Rechargeable-Battery/dp/B00R3VDL46/) could be used to replace the battery I have now and also provide almost double the capacity? I've never used Li-ion before, hence the noob question. Thanks in advance.

 

How did you recharge the SLA?
How do you plan to recharge the LiIon?

 

Those types of products (unknown quality Li-ion battery and charger) scare me.

 

How did you recharge the SLA?
How do you plan to recharge the LiIon?

For the SLA, I use a wall wart and just hook the battery up to that. For the LiIon, I would have to look into a charger.

Those types of products (unknown quality Li-ion battery and charger) scare me.

Agreed, and the fact that it ships from China... I picked that one because it had the highest capacity and lowest price. Granted I wouldn't buy that one for the same reasons you stated, but at least I could get an idea of what the low end stuff costs.

 

Hi,

Chargers for Li-ion have to be built more carefully than for LA batteries.
The max current could be very different, as well as the tolerance of the cell voltage.
Things things should be investigated thoroughly before doing anything like building a charger.

 

Things things should be investigated thoroughly before doing anything like building a charger.

Oh I definitely wouldn't build a charger. I'd just get one made for the battery that I select.

So am I to understand that a li-ion battery would provide the same capabilities as my SLA battery? (all I need is a 12v source with a capacity of at least 5Ah (capacity, not constant current))

 

Hi,

Well Li-ion batteries although a little more temperamental than LA batteries, are of a higher quality. This means they fair better over time if treated properly. They have a higher volumetric energy density too so they fit in smaller spaces. This also means they are more expensive.

 

most lithium ion cells come at 3.7V nominally (4.1 when charged). Keep in mind that lithium IRON (LIFEPO4) cells generally come at 3.3V nominal. If you intend to reach 12V you will likely be connecting 3 or 4 in series at which point you'll require a balancing function. Balance chargers can be found, look into the imax r6 or similar. The energy density of lithium is much higher than lead acid. I would imagine that soon lead acid batteries won't exist because they're garbage.

But, what kind of current will you require at this voltage? if it's low, then look into 18650 recycled laptop battery cells. you can build it yourself and learn a lot while doing so.

Cheers

 

I would imagine that soon lead acid batteries won't exist because they're garbage.
Cheers

I won't happen, Large-format lead-acid applications that don't need high energy density, small size, and low weight like large fork lifts will always exist. The battery is part of the weight ballast in a fork so total energy density is not a big factor and the ability to brute recharge after running it totally flat without fancy electronics is a plus.

 

most lithium ion cells come at 3.7V nominally (4.1 when charged). Keep in mind that lithium IRON (LIFEPO4) cells generally come at 3.3V nominal. If you intend to reach 12V you will likely be connecting 3 or 4 in series at which point you'll require a balancing function.

But, what kind of current will you require at this voltage? if it's low, then look into 18650 recycled laptop battery cells. you can build it yourself and learn a lot while doing so.

I understand that the cells are much lower than 12v output, but it looks like there are 12v Li-ion battery packs available, which is what I need. That wouldn't require a balancing dealio, right? To be honest, I'm not sure how much current I draw right now. I have a lot of components running off the battery. How can I figure that out?

 

Get yourself a cheap multimeter and put it in series to measure the current.

Those 12v packs likely have little BMS circuits built into them to balance the cells..or they might even have 12v cells directly which is a bit rare but wouldn't surprise me. Buy one and check it out!