Energy Matters Forums

[Tracker]

.........soon be experimenting on modifying a 24V alternator to see if I can get high enough voltage from it to charge at 54V.

If you have a suitable alternator, IMO it is best to directly charge your battery with that, rather than using a 240V generator + charger, which is much more expensive than a motor + alternator, and is what I used for many years when I had a 24V battery....

I am hoping to do similar.. make maximum use of. the technology within charge controllers.

We.are already doing battery charging, using large 24v transformers and bridge rectifiers into charge controllers.. the hope is to replace the transformer with the Alternator..

Just got to find a good alternator..

[gpigeon]

[quote="Tracker Just got to find a good alternator..[/quote]

Would this one do tracker???? (see att)
I was wondering what size garden hose or wind turbine I would need to drive it?
Only kidding fellas!!!
I got it at an auction about 15 yrs ago for $2...just too much of a bargain to miss it...absolutely no idea what I am going to use it for though.
afaik it is a 3ph slip ring motor about 55kW originally distributed by Noyes Bros.

Sorry....file is 1.5MB so will not att. even after cropping. Suggestions? About att the file that is. Not what to do with the motor...maybe boat anchor for it!

[davidg]

For files that are too large reduce the resolution till the file is small enough. Even "paint" will do the job nicely.

[Gordon-Loomberah]

Photos for Bill:

[tom rickard]

My advice is to get 200Ah 48V LiFePo4 battery bank, then see how you go. You can either use the charger in your inverter (if it has one), or get a forklift battery charger. I have a 60A charger, and regularly run the generator for an hour or 2 in the winter months (every few days). I had the generator anyway, it doesn't bother me to start and stop it, and it was a lot cheaper than getting enough PV to not need a generator at all. I spent less than $200 on diesel for the generator last year.

If you wish to upgrade, you can easily double the size of your battery later.

You can run your own figures on using minimal battery and PV, and using a generator regularly, or getting enough PV and battery to not need a generator at all. Of course some people either don't want, or are in an impractical location for a generator.

[gpigeon]

My advice is to get 200Ah 48V LiFePo4 battery bank

Thanks Tom. So, that is 9.6kWh? Correct?

I downloaded my export figures for the worst month on record (Feb 2013) and there were only 3 consecutive days on which PV production was below 7kWh/day (from a 5kW system). Days before and after that were >20kWh.
I'm thinking that if I manage my usage carefully, especially during cloudy conditions, and keep my usage down to <7kWh/day, with a 6.4kWh battery system, then running a generator will hardly ever be required. In any case, running a generator every now and again will be cheaper than installing an extra 3.2kW of battery storage. Cost of xtra storage is around $1000 /kWh.(see LG Chem batteries)

[APR]

My advice is to get 200Ah 48V LiFePo4 battery bank

Thanks Tom. So, that is 9.6kWh? Correct?

Tom will most likely be talking Lithium Iron Phosphate (LFP or LiFePO4) cells. Their rated voltage is 3.2 volt per cell, so the actual pack voltage (16 cells) will be 51.2 volt. This calculates to 10.24kWh.

Around 6-7 months ago I paid under $12000 for 20.48kWh of LiFePO4 cells complete with cell balancers.

[tom rickard]

Yes, LiFePo4 cells, yes the price varies a lot, time will tell on the variance in quality. Even for $6k i'd be looking to run a generator instead of getting extra cells if it is practical for you to do so. Keep in mind that with minimal PV, you also only need a single charge controller, and it is simpler to implement overcharge protection.

If you rely on your power, and you only have one inverter, it's only a matter of time before you will be using your generator while you wait for another inverter to plug in.

[Gordon-Loomberah]

LiFePO4) cells. Their rated voltage is 3.2 volt per cell, so the actual pack voltage (16 cells) will be 51.2 volt. This calculates to 10.24kWh.

My long term average voltage is generally just under 53V (~3.3V/cell), so I call my 400AH battery 21kWh.

However, it isn't that ATM, because 1 of the CALB 400AH cells is now only good for ~300AH, after nearly 3.5 years of use. Lithium cells are just like Lead-acid, there's an occasional dud.

Regarding generator use, if your PV array and battery capacity is larger than absolutely necessary, and you are prepared to cut back on energy use in overcast periods, then it is possible to get by without a generator, although you may need to hire one if your inverter fails as pointed out above by Tom. The need to hire a generator can also occur if your single charge controller fails and you aren't around to manually control charging by adding and removing PV inputs (it can be done, I operated with no charge controller for years in the 90s).
Having 2 or more charge controllers is good for redundancy and could get you through if one has to be repaired.
Having a spare inverter is also useful IMO, in case of lightning strike or other problem affecting your main inverter, unless you don't mind the fuel cost and having to listen to a generator for a couple of weeks.

[gpigeon]

Ok...almost 12 months has passed since my original post and in that time my ideas have changed. I will now leave the existing PV system on the farm shed earning only 10c/kWh and install a completely new OFF grid system.
I have been thinking of:
- 7.5kW panels(approx)
- 1x Sunny Island 6 (or 8)
- 1x Sunny Boy 5000TL21
- 2x LG Chem RESU 9.8's.
I have however met with a lot of opposition to such a system from my 2 local installers(N Rivers. NSW). They are both suggesting older style batteries.
Have any forum members got such a system installed?
Other comments?
Thanks. Bill W.