Charging question

[hd59man]

Start out by apologizing for asking this on a Solar Forum, although it has to do with a off grid cabin I've been using on weekends and such. Not my full time residence. I'm using a small hydro operating out of a creek that runs 24/7/365 for my RE. Been working fine for several yrs. now. Started with 5 yr old plus 200 AH AGM batteries I got for free, all matched from a back up telecom system. They are now well over 10 yrs old. It's a 48 volt system, using 8 six volt batteries. System built by me. No I'm not a electrical genius nor claim to be a know it all, but do have some electrical knowledge. I am using Diversion Controlling with a 45 amp Tri Star controller. The batteries stayed in a float stage most of the time with the excess being dumped into a diversion load. Considering possibly adding some solar and a MPPT controller depending on what/if any advice I get. I plan on starting to spend a lot more time out there.

I've enjoyed reading Sunking's responses and have learned quite a bit about batteries and charging. Got a feeling I already know the answer but I haven't found another question quite like mine, at least not yet.

Here is my situation. The batteries have finally gone south. I've read quite a bit about forklift batteries, yes I know they are expensive. I'm looking at a refurbished one which is guaranteed to be 85%. Due to the weight I'm looking at buying two 24 volt units rated for 800 AH and wiring them in series. I believe I've read for proper charging the formula is AH/voltage = charging amps. I currently can't get anywhere near that with my hydro system, not even close. So I guess my question is; Considering I'm actually charging my batteries 24/7 and the batteries never really take a heavy discharge does that have any impact on the charging formula at all? Sulfation is one of my worries along with really not getting my monies worth on the forklift battery, or any rather expensive battery bank for that matter. By no means am I wealthy but I don't mind putting out the money for batteries, Would just like to maximize my purchase and forklift batteries intrigue me with their possible longevity.

Thanks in advance to whomever responds.

[Sunking]

Your challenge is going to be an initial charge and EQ charges. How are you going to do that?

Bottom Line is any pure off grid system must have a Generator with a properly sized battery charger.

Back to your question. Are the Forklift Batteries Sealed of Flooded? They come in both flavors.

Forklift Batteries make excellent batteries for Solar. In fact there is no better battery for the job. Only reason you do not see them used in Solar is the cost. Having said that if the batteries are AGM, low charge rate is not much of a real problem because there is no liquid electrolyte to Stratify. That means the heavier acid settles in the bottom of the Battery Jar. It takes at least a C/12 charge current to get the batteries the batteries stirred up.

On the other hand FLA is a different beast, especially Fork Lift FLA batteries. There very design makes them susceptible to Stratifying. They much taller than they are wide like a tube. No big deal in a Forklift with a Commercial Charge that charges them at C/4. Just by using the Forklift everyday keeps the acid stirred up, and with a C/4 Industrial grade charger keeps them warm and bubbly.

So if used in Solar, and the batteries are Flooded, then you have to deal with stratification. No problem normally because most systems generate at least a C/12 current.

Being Forklift aka Traction Batteries are different than most Deep Cycle batteries. They run higher Specific Gravity, this slightly higher voltages. Used in the way you want to use them, you want to FLOAT the Batteries vs 2 or 3 stage charging every day. All that means is a simple Charger with just one Voltage known as Float Voltage for the battery.

If you have FLA forklift batteries, use a genny when you get there and run a EQ charge at least once a month to stir things up. Then make sure the batteries are fully charged up before you leave using the generator to make sure they are topped off.. Use your battery hydrometer to measure the specific gravity. Just remember when they have set for a period of time, the acid is going to sink leaving water on top to fool you.

So you can do it, if you can work around FLA demands. With AGM just make sure they are topped off when you leave.

[hd59man]

Thanks for the quick response and info. What I'm looking at is a FLA forklift battery. I'm running a Magnum 4400 watt 48v pure sine wave inverter/charger. I do have a generator that I can plug into it. I haven't really had a need for it though with what I had, but I understand what you're saying.

What I'd be paying for the reburbished FLA forklift battery would be about the same as brand new 430 AH L16 Trojans. I found Crowns a little cheaper. Think I'd be better off with the either of those?

I've been looking hard at supplementing this system with some solar. My place is in the mountains of NC on the north side of a ridge. Afternoon sun is about all I get with the location of the cabin. 6 hrs of sun max on a good day. Suggestion on amount of wattage?

Much appreciated.

[Sunking]

What I'd be paying for the reburbished FLA forklift battery would be about the same as brand new 430 AH L16 Trojans. I found Crowns a little cheaper. Think I'd be better off with the either of those?

Batteries are like condoms, I do not know about you, but I only use new ones. Well 40 years ago when I was single anyway. Don't need then today.

Serously shy away from refurbished batteries. When you talk about L16 batteries you need to be a little more specific as L16 only refers the physical shape of the battery. L16 is a specific size case for Floor Machines. Anyway Trojan makes two flavors of L16, their Signature Line and Premium Line which is suffix RE. Example L-16RE-B. The L16RE-x batteries are very high quality, but not equal to Forklift batteries. OTOH Trojan Industrial Line is second to NO other manufacture.

Crown makes good batteries. Again depends on which product line you are talking about.

[Sunking]

I've been looking hard at supplementing this system with some solar. My place is in the mountains of NC on the north side of a ridge. Afternoon sun is about all I get with the location of the cabin. 6 hrs of sun max on a good day. Suggestion on amount of wattage?

This is where it gets ugly. First I would need to know is what Voltage and AH battery you have. However this is the wrong way to go about it. Really need to start from the beginning by determining how many watt hour sin a day you need. That dictates everything.

However you can get a good estimate with a simple Rule of Thumb. You want to supply a C/10 Charge Current, where C = the battery AH capaacity. Example C/10 of a 370 AH battery is 37 amps. Once you determine C/10 then Watts = C/10 x Battery Voltage.

So if you had a 24 volt 370- AH battery would require 37 amps x 24 volts = 888 watts. FWIW do not be a Bone Head and buy used condoms or try to find a 888 watts panel system. 800 to 10000 watts is fine.