Optima top or side?

Re: Optima top or side?

funinthesun wrote: »

The "cheap charger" and a lamp timer sound like a good idea. I searched around and the only cheap ones don't say anything about charging batteries in parallel. Any suggestions on this would be appreciated.

For maintenance charging--1 Amp per 100 Amp*Hour charger is probably fine.

You will have to monitor the resting voltage of the batteries as they get older--At some point you will probably need to increase the timer from 1 hour to 2-4 hours as the batteries age.

The only one (reasonably priced) I found so far is Schumacher SC-8020A. http://www.batterychargers.com/Documents/00-99-000826.pdf
(It also doesn't say anything about charging batteries in parallel, but this one says the charger will be set for small battery size (2A) and 12V AGM on power up.

Nice charger--but I would wonder if you set it to run on a timer--Would it lose its settings when the power was turned off (or draw power from the battery bank when the AC power was off)?

I was just using "dumb" chargers with the timer.

Also, I would suggest getting a "real" battery charger that can charge you 150 AH of battery bank (~7-15amps would be fine). When the power returns, you can quickly recharge the batteries and be ready for the next outage.

You can get an Iota 15 amp charger for $130 (good quality and can be operated by a Honda eu1000i genset).

Or a Battery Minder for 2-8 amp charger designed for float charging for $125.

* Reasonable southern exposure to sun--No shadows/wires/etc. from ~9am to 3pm?
- Winter we get 3hrs + -?

You get 3 hours equivalent of full noon-time sun... But you need the panel to be free of shadows most of the day to gather the sun.

* Will you connector the panels with polarized plugs (panels connected backwards to a battery bank can be destroyed almost instantly.
- Currently using polarized but I plan to upgrade to use MC4 connectors when I change panels.

I don't believe the MC4 connectors are rugged enough for more than a few operations... I would pick something else (like the Anderson PowerPole Connectors).

* Solar Charge Controller picked out?
- I have the Morningstar ProStar 30 display w/battery sensor.

A PWM controller may be an issue here... More below.

* How long will the cables be from the solar panels to the battery bank?
- Approx 25-30'.

How many and what rating will be your solar panels?

Sending "12 volts" (really ~17.5 volts) for 30 feet can to the charge controller can be a big problem with voltage drop.

One way around the problem is to put two or three solar panels in series, then send the power 30' to a MPPT type charge controller. That will cut the current by 1/2 or 2/3rd's, and let you use much smaller gauge wire.

* What power are you sending to the basement (12 volts, 120 VAC) and how much (run and surge amperage)?
- The panels are from HF ( I know, cheap) with a total of 60 watts at 12 volts. I plan to get more efficient ones.

I would suggest not to even bother... They are 2x the area (less efficient thin film panels) and are not really known for even meeting their specifications.

* What gauge cable will you use to send the power down and how long will it be? Fused (if 12 vdc)?
- Each panel is fused in a junction box at the panels (pair), then a small breaker panel (indoors) and then 25-30' (10ga) to the basement.

That is OK voltage drop wise for this small array... But, I would be suggesting (assuming 150 AH at 12 volt battery bank):

• 150 AH * 14.5 volts * 1/0.77 derating * 0.05 rate of charge = 141 watts minimum solar array

For the same physical size solar panels as the HF units--you could get a single 135 watt (or so) solar panel.

And, for emergency power, I would be suggesting 282 watts or more of solar panel (based on my guess of 150 AH battery bank).

60 watts is really too small for that size battery bank (recommend 0.05 to 0.13 of rated battery bank capacity for solar array/battery charging).

* Have you sized your battery bank and solar array to the loads you need to support?
- For emergency I will use a couple of lights(led), radio, and charge my cell so I should be OK with the batteries.

It is actually difficult to keep a "Large" battery bank charged with too little amount of solar panels.

Many times, it is better to use a smaller battery bank with a small solar array instead. The batteries will charge faster and last longer (more cycle life).

* Backup genset + fuel if no-sun for a week or so (stormy weather backup)?
- I don't think that would go over very well with my neighbors.

Yea, appartment life is a pain. The small Honda eu1000i is like a carryon suitcase and you can siphon fuel from your car. Noise wise, on a city street, you cannot even hear them running. Obviously, it is not safe to run a genset on the balcony (fumes, fire hazard)--but if you had to bring the batteries to the parking lot to recharge (or run an extension cord to the basement)--It is not a bad way to go.

-Bill

Re: Optima top or side?

The Iota has a jumper... Jumper in is "high voltage" charging. Great for when the power has been out and you want to quickly recharge the battery bank. Also a good setting for use with a genset--Basically, generators are more efficient with ~50% or greater load--so having the charger dump current quickly and keeping the generator loaded can be a real fuel saver.

Once the battery is charged, the jumper is pulled out and the batteries are kept at float.

If you are going to leave the charger plugged in 24x7--leaving it at float is fine.

Batteries are supposed to last longer if occasionally discharged once in a while (cycled) rather than setting at float 100% of the time.

The IQ4 charger does do equalization every couple weeks (as I recall)--and that is really not a good idea for AGM batteries.

When (if) you cycle the battery, just put the jumper back in until the batteries are fully recharged.

AGM's can go for several months or more (depending on age/temperature) without any charging at all (they typically have very low self discharge)... So you don't really need to have them sit on float--But a short charge every day (lamp timer) or charge once every few months will work too.

I am sort of a set it up for "automatic" charging rather than having to manual recharge every X weeks kind of guy.

You should be able to leave the Iota chargers connected to the battery with or without AC power applied--But I would double check with Iota directly (or the Iota dealer).

Fusing should be 15 amps * 1.25 NEC derating = 18.75 amps or 20 amp breaker/fuse. Fuse/breaker should be near the battery bank... Fuses are to protect the cabling from short circuits (don't want wire to catch fire/melt). Just gone fuse in the + lead should be fine.

Usually you use heavier gauge wire than 12 awg @ 20 amps to avoid voltage drop. Also depends on how long the cable run is from the battery to the charger.

-Bill