jstarne1, robotmaker and my self were talking about regular lead acid and gel cell batteries for supplying power to a power supply unit. Later I said I liked lithium type batteries too. robotmaker said (more or less)that gels voltage falls off to much. I started thinking this morning that if you want a battery that doesn't let the voltage drop much then NICAD and NIMH batteries may be the way to go. All batteries as soon as you start to discharge them , the voltage will start to fall until you have completely discharged them. In this case the PSU would shut off because of low voltage. Lithium batteries are bad for this too. NICAD and NIMH are about the best that I know of for holding voltage till discharged. Thats why it's hard to build a good charger for them . Chargers use voltage to judge state of charge. I guess this is an advantage of NIMH and NICAD batteries.
Asked
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If the robot is a small one, I use a NIMH battery. If it is a big one, I use one or two jet-ski sealed battery.
Hope that this helps,
Mel
Over here in Europe NiCad's and NiMH's are no longer allowed. So what's left over ? LiPo's, LiIon's and of course SLA's (Sealed Lead Acid). It is true that SLA's loose their charge rather quickly, but on the other hand the operating temperature range is much better then LiPo's/LiIon's. They don't need very expensive charges, are cheap and can handle some abuse. If you chooge DC (Deep Cycle) ones, they will hold their charge a little longer. Unfortunately they are quite heavy, but that can work as an advantage too, for instance as a counter weight or low center of gravity point. LiPo's and LiIon's are useless when it gets to 0 C (32 F) and are much more sensitive to charge currents etc... I use SLA's all the time and quite often my batteries last easily 4 to 5 years. Attachted is a pic of a robotplatform I'm working on, where the SLA is placed underneath to save space and to create a low center of gravity.
Hope this is usefull for you,
Greetz,
PhG
Stick with lead acid , proven useful and most common by robot builders. Your only.other option is lithium.ion and they cost 5 times what lead acid does.
Hobbyking.com = cost effective lipos and lipo chargers
Hey Guys,
I am trying to figure out my battery scenario.
Josh the ones you found were great price (batteries ) but I'd really like to find some where I don't have to have them shipped. I am just not sure how to pick one.
Any suggestions?
I went by this Electronics Plus store that is in San Rafael and they had the SLA- 12V 10AH
I am thinking of hitting up Batteries Plus and see what they have.
Samantha