[RE-wrenches] Charging a HUP

Sun Feb 9 00:38:30 PST 2014

Sounds like there is a need for a bigger generator, my gut tells me there is almost enough (but not quite), with 12kw to almost max the chargers and nothing left to feed the other loads. 

I have found that “on paper” and reality do not always mix well.

Getting max theoretical charging capacity from solar and the generator at the same time is sometimes a tough nut to crack, although batteries seem to “like” the varying charge better than a steady max charge. That battery can probably absorb 420 amps as the charging max using the usual 3 stage charging we have with inverters, you’re not getting anywhere near enough to max them with that generator. Powering down all the chargers 30% or so (or 1 inverter totally) would help stop the breaker trips but slow the charging off the generator. Then you just need to pray for lots of sun.

Is the solar alone enough to power the loads in the normal day to day usage in a best case situation, or is this a case of the generator has to run to keep up?

Up here we have seen 1 sunny day in 3 weeks, we know about generator usage…..

I can’t speak on the HUP’s. I have never used them, but might they be somewhat hard to charge?

Just some thoughts, but it’s 3 am and I hope it makes sense in the morning when I reread it….

Later,

Bob

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of bruce at willpowerelect.com
Sent: Sunday, February 09, 2014 1:29 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Charging a HUP

Hi Larry,

I have an FNDC in the system. Manufacturer wanted 2 hour EQ before adding water to the new battery. We got that and had SG between 1.260 and 1.275 on all 24 cells. Cells were very thirsty (shipped with electrolyte almost to the plates) and took 8.5 gallons between all cells. We aren't having much trouble getting voltage back up but SG is below 1.23 (within .01 on cells tested). Strategy at this point is to give a daily bulk and absorb and EQ every 3 or 4 days for extended times and monitor SG. Discontinue hard charging when SG plateaus. I generally shoot for c/10 charge current, and nervous about barely c/20 and a 12kw genset only giving me about 5.

Bruce 

-------- Original Message --------
Subject: Re: [RE-wrenches] Charging a HUP
From: "Larry Crutcher, Starlight Solar Power Systems"
<larry at starlightsolar.com>
Date: Sat, February 08, 2014 11:50 am
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>

Hi Bruce,

Please explain "feeding it properly". Charging any lead acid battery slowly actually preserves battery life. As long as you are achieving the recommended charge voltage (temperature compensated) for long enough time, and reaching 100% SoC regularly, you are caring for the battery.

At 82kWh battery capacity and 6.5kW PV, the customer may have a hard time getting to 100%. You did not mention, but I HOPE you have a battery capacity meter in the system. It's mandatory if they want to care for the battery. Since the customer has a small generator, they need to realize the limitations and reduce their loads during generator time so you can use the full output.

Larry

On Feb 7, 2014, at 11:46 PM, bruce at willpowerelect.com wrote:

Hi All,

3 VFX 3648

2 FM 80

6.5 kw solar

12 kw generator

PSX 240 on generator output and VFX stacking

Mate 3

HUP 1690 ah

System design considering 45 amp charge current from each VFX totaling 135 amps. (135 x ~55v = 7.42kw)  Potential charge current from 2 arrays and FM 80's, 90 - 100 amps. On a good day, reasonable to expect 200+ amps?

Have not been able to exceed 90 amps for more than 30 minutes, with the generator putting out about 9 kw before it's 70 amp 2pole breaker trips. L1 42 amps, L2 37 amps. 5 amps neutral. Load banked to 12.3 kw (51 amps @ 240v) resistive without breaker trip.

I have had to dial back the maximum charge current in the Mate 3 to 12 amps each on two of the inverters (L1 and L2) and 8 on inverter 3 to keep the generator from tripping out when customer turns on the microwave or coffee pot. In effect, 42 amps charge @ 240 v = 7.6 kw. At the battery, I'm only seeing 80 amps of charge current. Running loads are typically less than 1 kw but there has been a of construction going on with chop saws and compressors creating annoying spikes that are easily handled by the inverters when the generator is off.

I don't want to kill this new battery by not feeding it properly! I would have put in a larger generator, but the owner bought the 12 kw before deciding on the new battery. I thought the 12 would be merely adequate, but not so....

Any suggestions?

Thanks!

Bruce Fiero-RMI

<sigimg0.jpeg>

"I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that." T. Edison, 1931

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