Which is the best battery type to use?

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Admin (Admin)
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Post Number: 4
Registered: 10-2004
Posted on Thursday, October 28, 2004 - 9:26 pm:    Edit Post    Move Post (Moderator/Admin Only)

This depends on the application.
Sealed lead acid (SLA)
Cheapest and easiest to charge but are rather heavy for their given energy density (Ah capacity). SLA batteries come in different constructions each offering advantages in certain applications such as standby use or for cyclic use.

NiMh and NiCad as well as being lighter than equivalent SLA types, offer improved performance when discharged over short periods. NiMH and NiCad batteries require special chargers and generally require more care than SLA's
Css_broadcast (Css_broadcast)
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Post Number: 2
Registered: 4-2006
Posted on Friday, April 21, 2006 - 8:50 pm:    Edit Post    Move Post (Moderator/Admin Only)

SLA BATTS are okay for (heavy) cheap power, so long as you don't mind voltage dropping as the battery is used. This results in motors and lamps running slower and slower..and..slowwwww....errr (sorry!) until there isn't enough current left to run anything. The added problem is that if SLA's are deeply discharged too often, they tend to fail. This results in the battery getting hot when charging, leading to sulphates building up on the lead plates, thus leading to splitting cases and white powdery leaks (overventing).

NICADS are okay and are quite cheap. The good point is that you get continued power right up until the last minute. The bad side is the cadmium in the cell. Highly toxic. Bad for 'todays childs future'. Soon to be outlawed too, from what I hear (NiCads, not children). NiCad's were good for their time..... but so was coal, radio valves, and Catweazle (if you are too young, ignore that Catweazle bit). Also, like NiMHs, the voltage/current supplied by NiCad's is quite consistant.

NiMHs? Good power to weight ratio (lots of power for little weight), not so toxic, high currents available (upto 14Ah on the latest NiMH cells), cheap to buy with longer life expectancy and run times. Oh, wrapped in a nice green wrapper too! :o)

Lithium Polymer (LIPO) is the next step up, but they are so dangerous (fireball if overcharged....fireball if left discharged too long too!) Oh, AND expensive to buy.

Best options for now then, is to use NiMHs. I build motion control camera systems and use NiMHs for 99% power. I do use car battery sized SLA's for some things though. If you want to use SLA's, then try to get 'Gates'(TM) cells. The BATTLE TANK of all SLA's. Leave them for five years charged and they never seem to self-discharge.

Unless you have a copious supply of them, then SLA's are good as a float supply, whereas NiCads and NiMHs are good for cylic use. But NiMHS are better value. I think I've overdone this reply somewhat.
Admin (Admin)
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Post Number: 173
Registered: 10-2004
Posted on Friday, April 21, 2006 - 9:09 pm:    Edit Post    Move Post (Moderator/Admin Only)

There are SLA batteries that have a very low internal resistance typically branded under the Hawker trade name. These can be used to deliver very high currents with minimum voltage droop but at a price.

There are good and bad NiCads, we have supplied thousands of a particular Sanyo type for use in high drain applications such as robots. In fact the particular type is the only one we found that can survive the duty. Cheaper inferior ones simply burn out.

NiMhs are rather limited at current delivery but are fine for the majority of applications.

LiPos certainly require care when charging discharging but superb performance at a price.

It's hard to generalise on battery technology as each have their pro's and con's. NiMH for general use and certainly preferred, SLAs cheap, easy to charge but heavy, Nicds very limited use except for certain high performance types, LiPos certainly have their place but best left alone unless you know what you are doing.