Gel Battery recharging

[beren]

Greetings comrades, just seeking advice from anyone who uses a Gel Battery for their astro needs. Its mainly with the correct way of recharging, i've just got a Exide G120 {120a/hr} and from what I've managed to gather is that these kind of batteries are prone to damage if using the wrong type of recharger .... any advice appreciated thanks

[Photon]

Hi Beren, I use a CTEK Multi7000 which is a multistage charger designed for many batterytypes, a tad expensive but I have a few different batteries ranging from sealed 115A/Hr in a Solar set up to 4WD, Boat, Car, rideon mower etc. It's auto operation and has well paid for itself I reckon. It can be used as a 12v power supply too and I use it to run peltier coolers in this mode. If you look around the recreational Caravan, Camper trailer, Motor home areas they have excellent chargers available for sealed/GEL cells these days. Like anything you get what you pay for. Batteries must be maintained correctly or they don't last very long. Good luck!
Regards Ian Gillespie

[PaulM (Paul)]

Hi Beren,
For years I've been using an inexpensive 2 amp trickle charger - nice & slow! Sure, it takes all day & night to charge my 38 amp/hr battery, but I hear it's good to charge these batteries slowly.

Like Photon says below, maintenance is key, and that means "exercising" the battery by using it (ie discharging it) and recharging it at least once on a monthly basis.

Cheers,

[jase (Jason)]

Depends on how automated you want the charge process. As you are probably aware with GEL, AGM and most other battery types, keeping them charged as much as possible will increase their longevity. Even if you don't use the battery, its capacity will decrease slowly over time. (Note it can take some time, but depends on environmental conditions). Cold climates can accelerate the capacity decrease process.

I used a Latronics 1230 full automatic charger for about a year. I obtain it from a sparky friend. It worked a treat. After a night out with the scope, I simply hook it up and walk away. The charger did the rest. No fuss, no need to keep an eye on it. When I wanted to head out again, maybe a day or a month later, I just unhooked the battery and its ready for use. It would suit your large capacity 120a/hr battery very well - You'd want something with reasonable charge amps. I might add that thats an impressive capacity. I had a 75a/hr which lasted what seemed eons.

Chargers that maintain the battery capacity make the task easier. You can pick up the Latronics 1230 12v 30amp intelligent charger from a few places.
http://www.solazone.com.au/battery.htm#Chargers have it for $800. I'd shop around. There are plenty of trickle chargers with intelligence (set and forget) around. Would also suggest checking out the local trading post.

[beren]

Thanks Ian,Paul and Jase. Like yourself Paul I have a 2amp Projecter trickle charger that I use on a 17a/hr powertank and 35a/hr lead sealed battery, does the trick for these but from what I can gather a Gel battery requires these three phases of charging.....

Step 1 - Bulk Charge - The battery is charged at full rated output current of the charger until the battery reaches its final charging voltage, known as the absorption voltage. This step replaces 70-80 % of the battery's capacity at the fastest possible rate.
Step 2 - Absorption Charge - When the battery reaches the absorption voltage, the charging current is steadily decreased while the battery voltage is maintained at the absorption voltage. This step replenishes the remaining 20-30% of capacity.
Step 3 - Float Charge - When the charge is fully replenished,charger voltage is reduced below the battery absorption voltage and is held constant. This prevents battery damage that would occur if the voltage was maintained at the absorption voltage yet still allows the charger to supply current to make up for self-discharge losses in the battery. The charger also supplies current to loads connected to the battery, reducing battery drain.

Thanks Jase/Ian for the suggestions on brands, looks like you can pay handsome prices for the type of charger that covers the needs of this type of battery $100-$200 min :I'll probarly check out these two... Projecter model and from Jaycar

It would suit your large capacity 120a/hr battery very well - You'd want something with reasonable charge amps. I might add that thats an impressive capacity

Had enough of being caught short and a vunerable corrector plate to boot with the portable power output I have now, hopefully this will be the solution

[Merlin66 (Ken)]

A 120Ah battery is one hellova battery!!!!!!!
We manufacture binlifters and only use 50 or 85Ah Gel batteries for continuous use!!
The recommendations are to charge at 10% of the capacity ( ie 5 or 8.5Amp ) with a three stage electronic charger, our charger units I think costs about $280.
For smaller batteries (20Ah) I use a small electronic charger which is rated for 1.5A and only cost $75. Works a treat for all my home telescope batteries.

I screwed up a couple of big Dry cell/ Gel cell batteries using a 2A "KMart" special before investing in the 3 stage unit.

[smersh (Michael)]

I use the Jaycar Battery Fighter. It is a multi stage unit and works very well.

It's about $80