What's a good device to check the charge an SLA holds?
 

I'm going to start testing the gradual degradation of these SLAs that I just got. However, I need the device that I can hook up to check what the voltage it holds. Don't know where to start or what it's called.

I went to Radio Shack and they were fairly clueless. They said they don't have anything that measures rechargeables like lawmower batteries and the like. I found an altimeter and they said it is for home electric current. Thanks.

um... you need a voltmeter to check the voltage. you can just get a multimeter (pronounced either MUL-ti-MET-er or mul-TIM-et-er). they read volts, amps, and ohms. You can get a cheap one for around $10. It'll have either a display screen or needle, a function selection knob, and red and black probes.

I'm rather disappointed by your Radio Shack. That store is apparently run by idiots. (btw, an altimeter is used to measure altitude).

Radio Shack used to be great, but now sadly they do little more than sell cel phones and cheep remote control toys.

bugmeot, yes you need a multimeter. Radio Shack may have one, but a better bet would be an home supply store.

I've always just said it multi-meter. But agreed, radioshack is pretty much worthless nowadays for anything hobbyist related, and sadly nothing has filled that empty space. Maybe people just don't "tinker" much anymore? Or perhaps the internet has make $3 packs of resistors hard to sell?

The above advice is good, I'll add that the ultimate for power assist bicycles is probably the device formerly known as DrainBrain:
http://ebikes.ca/drainbrain.shtml

Otherwise the watt's up is a decent power usage meter that's a lot cheaper then the device formerly known as DrainBrain, except it has no features specific to vehicular use:
http://www.all-battery.com/index.asp...OD&ProdID=1514


After a while you get to know your battery's capacity and since these meters show how many Ah you've used, it gives you a good idea how much is left. They also show instantaneous power used, so you can see when you're dumping power with little return. Example: On my first ebike, going uphill full throttle used a given amount of power, but letting go the throttle just a crack would cut the power use by about a third with very little speed difference.

Looks like the "DrainBrain" is brain dead! Maybe something in the future.

Went to lowes and picked up a multimeter. Problem is, I don't know how to use it. From reading several websites, I can hook it up to the + and -, and it will tell me the voltage i.e. my 12V battery eventually settles on 12.0002 or something like that.

Great! All I had to do was read the label if I need info like that.

I want to figure out what % of charge battery holds vs. 100% new battery usage. Any tips or website you can recommend?

My multimeter looks something like this:
https://www.wiredco.com/catalog/imag...R%20YELLOW.jpg

Only it doesnt have the A-.., temp. It does have a red V with a tilde.

The DrainBrain is definitely not dead. Right now I'm testing what is hopefully the last code revision, and there are plenty of brand new units awaiting programming and a new home. A few 'undocumented features' were discovered during my testing of the new unit, and unfortunately updating the firmware for a customer isn't as easy as clicking Windows Update, so it better be perfect before shipping.