WelcomeTuesday, February 7th, 2023
Radio repeater batteries
I'm trying to trouble shoot a TDL 450h repeater radio and I suspect the root of the issue is the battery being used and the charging. Is there any benefit to using a deep cycle battery over a standard battery? Most of the issues I've run into with my equipment have been battery related. Pushing 25 watts, the radio is putting a pretty good draw on the battery and in my experience if it isn't topped off at the end of each day and drops below a certain point, it begin to shut down intermittently or not work at all even though it may be at 50%. My PC like to run the battery down to make the battery last but is having trouble with reliability with the radio and my solution is to just top it off every night. I'm not a battery guru and would welcome any input from the community brain trust. TIA and have a great day.
Deep cycle batteries can drained to pretty much 100% of their capacity
Lead acid batteries don't like being discharged to below 50% or so. Doing so can damage them and they loose the ability to hold charge. I've killed a couple of batteries in my 4wd by over using the winch while not having the engine running
Sounds to me like you have killed that battery
We use a 2 amp charger/maintainer for our deep cycle batteries ( https://www.batteriesplus.com/productdetails/battery/sla-sealed-lead-acid/slaa12=18nb) and charge them nightly. We have gone as many as 2-3 days in a row without charging when working remotely, but we typically never push more than 8 watts when using a repeater.
Sealed Lead Acid and AGM batteries hold up better than ordinary ca/motorcycle batteries.
Deep cycle SLA/AGM batteries are my preference for external radios. Loved the Optima yellow tops. Heavy SOBs but got the job done.
I'm lazy so I like to try and use them with a repeater+mag mount on the roof of the truck, and never have to take them out.
Ditto on Optima, blue or Yellow tops.
I've even run them in a series for 24 and 36volts for magnetometer work and even patched in a PV cell to charge the repeater batteries sitting on top of a mountain basically giving us perpetual repeaters.
Any of the deep cycle batteries will work, and smaller AGM form factors in a parallel configuration can make it less bulky depends on the application.
Big thing is the temperature. You're up in the cold as hell region so battery performance plummets with drastic temperature drops, so does age. cooler with a hand warmer packet is an awesome booster.
All in all, if you're running new batteries and getting crap results start with cable shake tests and then the radios or even that in reverse to insure you're not buyi g batteries at 250plus per unit for a broken or decrepit device.
I once took the time to determine the slew rate of the pulse from the transceiver and figure out what the optimal (yes intended) power loss was to non functional but I'm not that ambitious anymore.
it's a calculated value that if you're a dork like me, is interesting as hell to see the physics doing it's thing.
I'm warming up my hands from the 20deg Alta I've been doing all day....dmit I'm out of crap to type, back to work
Lifepo4, half the weight of SLAs
Here is how we have our repeater setup. 20 amp hour battery in the case with the repeater. A silicone pot holder is placed over the top of the battery to prevent anything from shorting out the battery terminals.
To the right of the repeater is our base battery setup. A 20 amp hour battery in a $6 Harbor Freight plastic tool box. We normally get a year or two from the cheap tool boxes and are averaging two years per battery.
I use a Shorai lithium motorcycle battery. Small and very light weight. Can be used for radio or robotic total station.
Lifepo4 is the way to go if you don't have to put it on a commercial airliner. A little spendy but way lighter and better power curve than conventional deep celled batteries.
As for good old lead acid batteries, you need to use a deep cell battery. Car batteries are the dragsters of batteries. They are made for supplying a lot of juice for a short burst. Once the starter does its thing, the alternator supplies the power and the battery just charges while waiting for the next start. Deep cell batteries are made to provide substantially less power over a long period of time. Think trolling motors, RV lights and solar power storage.
I always had better luck in the long term with deep cycle marine batteries. Now that was years ago. They can handle the drain and re charge better than the typical lead car battery. Optima i have used on the farm for portable electric fence like rover and them state. I now have small solar panels set up and a box in spots so I let the sun re charge as needed. I have used motorcycle batteries when we had to hump a ways and knew it was only a short day. But using often they are not built for that. You must be in a no cell area and more rural area with that 25 watt. I didn’t even know they were allowed anymore. I guess i heard wrong. I just ordered a new base and rover kit and had that on as a option and it was removed. I was told not allowed. Or maybe they were pinching pennies. Lol.
Lithium battery performance drops off very rapidly with cold - might not be the best choice for Alaska (at least not in Winter)
The question of deep cycle or not, is kind of a toss up. The real crux of my problem (I speculate), is the drop in voltage. Below a 10v output, the radio will have problems. The deep cycle after a year or so of use seems to me, drops below that 10v threshold faster and cold just exasperates things. The deep cycle is meant to be drained all the way down, which is where the voltage drop gets to be an issue. The same 12v lead cell 35 Ahr battery seems to keep the voltage higher longer under the same conditions, assuming it’s topped off regularly. This at the draw of 25 W, drop that to 8 W and the deep cycle does better. I’m going to look for the Optima Yellow Tops. Sounds like they make a good battery, but a couple of winters and they are all going to need to be replaced.
Lithium batteries do have some cold weather issues.
Never charge a lithium below freezing, it will damage the chemistry. Some of the high end lithiums have temperature sensors to prevent charging in poor environments.
When using a lithium battery in cold weather, allow a small load to run for a while to internally warm up the battery prior to using at higher powers. For example, when trying to starting a motorcycle, turn on the headlights for about 5 minutes prior to trying to starting.