Battery bank not holding charge--Please help!!

Re: Battery bank not holding charge--Please help!!

Depending on the loads/inverter--you may also get small sparks as you disconnect/reconnect the wiring...

What is a small spark--If you asking if it is a big or small spark, it is probably a small spark.

-Bill

Re: Battery bank not holding charge--Please help!!

Depending on exactly what 5kW generator you have--The one I found has an 8.3 amp 12 volt battery charger output.

That is totally unreasonable for your size battery bank. You should be around 5-13% or even 20% or more for your batteries.

If this is a 430 AH 12 volt battery bank, you should be aiming for at least 10% or 43 amp charger minimum. Or 5x the size (it appears) that is currently hooked up. 8 amps is a 2% rate of charge--just barely larger than a trickle/maintenance charger.

For a 5 kW genset, a good sized charger (fuel efficient) would be:

• 5,000 watts * 50% rated load * 80% efficient charger * 1/14.5 volts = 138 amps (typical maximum 12 volt charger that could be supported)

So, at this point the 5kW genset, unless you have other AC loads (air conditioning, several microwaves, etc.)--Sounds way over-sized, and if there is no AC battery charger connected (using the 8 amp aux battery charger from the genset)--that is ridicules.

You are running a 100 watt battery charger on a 5,000 watt genset or 1/50th of the rated load capacity. That has got to be killing you fuel cost wise.

You have some choices here--a 12 volt charger between 40 and 80 amps would be fine.

Genset wise, you can run a 40 amp charger on a eu2000i (1,600 watt) genset if you are OK with rope pull start.

Or a Honda eu3000i (2,800 watt) and a 70 amp or so 12 volt charger.

There are several 45 amp 12 volt chargers here (should work OK on a eu2000i--but somebody here or at the store should confirm).

And Iota has larger 12 volt chargers too (55, 75, 90 amp). The 90 amp is right on the ragged edge for the eu3000i (ask NAWS if 90 amp charger is OK or not for the eu3000i). Even the 75 amp is fine.

Anyway--Regarding the genset--You really need to figure out what is exactly happening. If they are taking 12 volt from the 5,000 watt generator, you need to get the model number or 12 volt output rating (current/amps).

At this point, if my guess and understanding of your setup is correct:

I'm not sure if the battery charger is AC--I'll check tonight.. It is configured to where we have to manually plug up the generator (it is not electric) up for the battery charger to work. Charger has teeny wires (which you probably saw in the picture) hooked from battery bank to charger.

The generator will be useless for charging your battery bank (way too small to properly charge your bank).

-Bill

Re: Battery bank not holding charge--Please help!!

They appear to have way too much excess wiring wrapped in the box--Extra cabling adds voltage drop to the system (losses). Is that is a circuit breaker at the top of the box (or single large fuse)?

A Clamp On DC current meter will really help you (measure current in the two battery strings and figure out if they are sharing well or not)--especially not having a battery monitor to check your current. This Sears/Craftsman 400 amp DC clamp meter is probably about the best bang for the buck ($60 plus tax/shipping). It is the same as this meter (original manufacturer).

Getting 13.5 volts -- Was that with the sun up or just around sunset?

Normally, fully charged batteries are around 12.7 volts fully charged (resting for several hours), ~13.7 volts floating (fully charged, charger on and "floating" batteries), or somewhere between 12.x and ~14.2 volts (charger is charging but battery is less than 100% full). Your batteries will not reach 14.2 volts until they are at least 80-90% full and there is full sun on the solar panels (and the charger is still charging at bulk/absorb, and not holding the batteries at float).

At least, you are seeing some charging going on--so you know the panels/charge controller are, at least, somewhat working correctly.

You do appear to have some wiring connection issues... The s1) 11.93
s2) 12.32 voltage difference is too great between the two strings and will need to be looked at eventually. One pair of batteries is carrying much more of your loads vs the others (almost 0.40 volts difference between the to string voltages). Placing a current clamp meter on each string will show you immediately how much difference in current there is.

Here is the SmartGauge web page that describes how batteries should be wired in parallel for proper sharing of current.

At this point, it is possible that the system is mostly working correctly, and you just do not have enough sun (and/or have more load) to support your needs with purely solar panel/sun charging (not unusual for winter). We will not know if your panels and solar charger are working correctly until you can measure the current flow (DC current clamp meter or Battery monitor).

So, for winter, you probably should also focus on how your generator is charging your battery bank right now. More than likely (it sounds like--still guessing) they are using the 8 amps from the generator's DC output--And you need a 40-80 amp AC powered battery charger installed instead.

In the end, this becomes a series of trade-offs (money, power usage, generator usage) to preserve your battery bank (prevent over/under charging, over discharging or setting at less than 75% state of charge for days/weeks at a time). Any/all of these conditions can take months to years of of the life of your battery bank.

Now that you are measuring voltage and have a bit more knowledge, take a read of the Battery FAQ (again if not the first time) and look at how to keep them properly charged. It should make more sense to you now that you have been monitoring your bank voltages.

Deep Cycle Battery FAQ
www.batteryfaq.org

Regarding your wiring--Somebody with some experience can probably clean it up a bit and double check your battery wiring pretty easily (it is easier to cut out extra cable than to make too short cables longer).

-Bill