battery for Yaesu 450D
Just wondering what people would recommend for a battery for my new Yaesu FT-450D. Like to go out in the field with it, it is already 8 pounds. Looking for something light to use at lower power levels.
I will try to help you out. Although you say low power work, it would not be wise to buy a battery that cannot supply enough current at sufficient voltage to operate at full power when and if needed.
Lead acid batteries fall into three basic categories of Cranking, Hybrid, and Deep Cycle. I am not even going to discuss Cranking batteries because they should never be used with the exception of emergencies.
Hybrids come under different marketing names like Marine Deep Cycle, RV Deep Cycle, Golf Cart, Boat Deep Cycle. Trolling Deep Cycle. Do no tbe fooled they are not deep cycle batteries, they are hybrid meaning they have thicker plates than cranking batteries to deliver fairly high currents, but not as thick and heavy as a true Deep Cycle. However they do a fairly good job for portable ham radio applications.
True deep cycle batteries are what most prefer because they have more cycle life than than Cranking and Hybrids and any worth their Salt will be Flooded Lead Acid, so they are not always a great choice for portable applications.
OK lets get right down to it. To operate your radio at full power I assume your rig is 100 watts and at full power demands about 20 to 25 amps of current @ 12 volts. All batteries have internal resistance, and the resistance is directly proportional to its Amp Hour capacity and construction. The resistance becomes a problem as current increases resulting in voltage drop at the battery terminal post. Having a 12 volt battery fully charged is no good if you key the radio and the voltage drops to 11 volts or less. It means its Amp Hour capacity is too small for the load attempting to power.
So here is the dope. For Flooded Lead Acid batteries the maximum current they can supply with significant voltage drop is C/8, and for AGM about C/4 where C = the 20 hour discharge rate of the battery Amp Hour rating. Most all hybrid and deep cycle batteries are rated using their 20 hour discharge rate.
So let's say you want to use a FLA battery and you rig draws 20 amps at full power. The minimum FLA battery you would is 8 x 20 amps = 160 AH @ 12 volts. AGM's are lighter and more portable than FLA on a AH to AH basis. The AGM minimum for the same radio is 4 x 20 amps = 80 AH. Just be aware 80 AH is half the capacity of 160 AH.
I did not discuss Gel batteries because they are poor choices requiring lower voltages, have short life cycles, and very sensitive to over charge damage which cannot be repaired.
There is several anecdotal facts we just have to kick out of our thick heads!
First, there is no such thing as deep cycle, no matter what's printed on the outside of the battery. All lead-acids, flooded or gel, are considered discharged when their voltage reaches 10.5 volts at a given imposed load. That load, for an SLI (Starting, Lights, Ignition) is typically C20 (C10 or even C5 are sometimes used). That is to say, a load of 20 amps is imposed on the battery with a full SOC (state of charge). When the voltage reaches 10.5, the battery is considered discharged. The length of time it takes to get there, is called the RC (Reserve Capacity). If you go past this SOC, you shorten the charge-cycle life, and sometimes drastically! If that SOC is essentially zero, any lead acid is dead from that point on! As another example, taking an average SLI down to 10 volts, will reduce its charge-cycle life to 30%! At nine volts, about 10%. It should be evident then, unless we're willing to sacrifice charge-cycle life, we need to be very careful of the SOC.
We cannot rely on battery voltage to give us an SOC. We can't readily measure the specific gravity of the electrolyte (we can't get at it as most SLIs are not sealed). We can, however, purchase devices which will give us an approximation, which might be useful as long as we pay attention to them.
We need to dispel the thought that a battery's usefulness (SOC) is based on some specific period of time. That's an Internet faux pas!
When we attempt calculate the length of time a specific battery will last when connected to a transceiver, we need to know a lot more than the maximum draw of the transceiver in question. For example, we need to know the duty cycle (transmits vs. receive). We also need to know the average current while we are transmitting, and that figure depends on a lot of other unknown factors like speech patterns.
We need to figure in the RC. Some lead acids are designed to have long RC times, but we trade off starting amperage to get it. So if we use a battery with a long RC time to fulfill the need as an SLI battery, we have to size it accordingly.
We need to dispel the notion that a Marine-Service battery is the one of choice. It isn't necessarily. Marine-Service batteries are designed to sit for very long periods of time. Up to two years, without any recharging, yet have enough cranking power left to start the engine.
Then we need to start thinking about output power. Depending on the transceiver in question (most are rated at 13.8 vdc), reducing the battery voltage to 12.2 (resting for most lead-acid batteries), the transceiver in question will only output about 70% of its rated output. Yet, the peak current draw is almost as much as it is at the rated supply voltage (13.8). This brings up yet another scenario. Reducing power to a modern, solid-state transceiver to 50%, does not mean the input current draw will be 50%. In fact, it is typically 75%, so that argument doesn't fly either! If that wasn't enough, most transceivers will shut down on their own, when the supply voltage reaches ≈11.5 volts.
Oh! Yes! Then comes the battery booster. Yep, you can use one to maintain power output, but the tradeoff is SOC vs. RC. In case you haven't thought about it, it will always be less than the RC would otherwise indicate!
The truth is, relying on a lead-acid battery (or any battery type for that matter) to provide us emergency power, without any means of keeping the SOC within reason, is a pig in a poke!
Reserve Capacity is defined as the number of minutes a fully charged battery at 80 ° F will discharge 25 amps until the battery drops to 10.5 volts. It is not a C/x discharge rate, it is a fixed 25 amps.
Originally Posted by K0BG
Sorry, but you're incorrect. The specific discharge amperage varies. For most SLI batteries, it is C20 which is 20 amps. It could be C5 for a cycle battery, and even C50 is used for fork lift batteries.
Here is the link: http://www.batterycouncil.org
With all due respect I am not wrong. The link you gave is for members only but if you look around you can find some information on that website, but I could not find their definition for RC, but did find some info that confirms what I have said there is a huge difference between Starting/Cranking batteries and DEEP CYCLE batteries. They are made completely different. Your own BCI site confirms this fact.
Originally Posted by K0BG
As for the RC definition it can be easily found on just about any Manufactures website which comes from BCI and defined as:
RESERVE CAPACITY RATING- The time in minutes that the battery will deliver 25 amps at 80° F until it falls below 1.75 volts per cell (10.5 volts for a 12 volt battery).
I have worked with battery manufactures all of my 34 year career span in the Telecommunication sector so I know a little bit about lead acid batteries.
Not for an SLI battery it is not.
Part of the issue is the service the battery is intended to supply power to. Batteries used to supply back up power to a cell site for example, have a complete different set of parameters which must be met. This includes a different set of parameters for measuring capacity. However, average Joe Ham doesn't (typically) use batteries meant for cell sites. Instead, he buys what he can, and that is almost universally batteries meant for SLI or marine use. And, believe it or not, from all places, WalMart!
Yes, there are a few types besides lead acid ones. Some amateurs do indeed use NiCads, or NiMH, even LFPs, and perhaps used ones from a cell site—but not that often!
I'm even amused at all of the recommendations proffered for recharging lead acid batteries. Seemingly, the rage is three stage chargers. What one has to ask oneself, do these chargers extend life? If we're talking about an SLI or marine service battery, the answer is, probably not.
Again, we have to define the service, the battery type including the electrolyte, and just how far we're wiling to let the SOC fall to. Currently, only one battery type will allow a full 100% discharge (no voltage period!), and that's a Lithium Iron Phosphate. Even then, about 20 charge-cycles is the ultimate limit. Do this to most lead acid types, and you get there just once!
So before we argue further, let us define the aforementioned.
Allan here is the definition from BCI:
reserve capacity (RC). A standard rating for lead acid batteries; established by BCI (Battery Council International). The Reserve Capacity is the time in minutes that a given battery can be discharged at a constant rate of 25 amperes, at a temperature of 80 F before the battery terminal voltage falls to 1.75 volts per cell (10.5 volts for a 12 volt system, 21 volts for a 24 volt system). Batteries are generally specified in terms of CCA and Reserve Capacity. See also cold cranking amperes.
RC, MCA and CCA are specifications used for Cranking and Hybrid batteries and do not apply to Deep Cycle batteries. Deep Cycle batteries do not have a specification for RC, MCA, and CCA. They publish AH vs hour rate discharge on Peukert Law. For Example a popular Deep cycle battery has the following AH capacity:
100 hour = 250 AH
72 Hour = 245 AH
48 hour = 240 AH
20 hour = 225 AH
10 hour = 207 AH
2 Hour 146 AH
If one wanted to estimate RC capacity could do so roughly with the 10 hour rate of (207 AH / 25 amp) x 60 minutes = 497 minutes.
Last edited by KF5LJW; 08-12-2012 at 11:42 PM.
I understand, but this indicated the C rating as C25. For example, all Optima batteries are rated C20, not C25.
Alan C rating has nothing to do with Resereve Capacity rating. C = Amp Hour rating at some hourly discharge rate usually specified at 20 hours. RC is is constant 25 amp load without respect to Amp Hour rating. In theory a 100 AH battery should have a RC = 240 minutes, and a 200 AH battery should have 480 minutes.
Originally Posted by K0BG
In practice taking Peukert Law into account the 100 AH battery RC spec would likely be around 180 minutes, and the 200 AH battery around 420 minutes because both would be discharge at a greater rate than C/20. The 100 AH battery would be discharged at C/4 hour rate and the 200 AH at half of C/8 hour rate.
Peukert Law sates: expresses the capacity of a lead–acid battery in terms of the rate at which it is discharged. As the rate increases, the battery's available capacity decreases.