[RE-wrenches] Trojan L-16s

Tue Jul 23 06:57:16 PDT 2013

Jay

Sorry I should have explained that too... Absorb starts off at around 50% of the available amps and tapers down to around 20% So I divided 20 by 50 = .40 there's a 5% loss factor hence .42

Tom Duffy
Senior Solar Design Engineer

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-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Jay Peltz
Sent: Monday, July 22, 2013 1:27 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Trojan L-16s

Hi Tom

Where did you get the .42 from?

Jay
Peltz power 

Sent from my iPhone

On Jul 22, 2013, at 11:04 AM, Tom Duffy <Tom at thesolar.biz> wrote:

> Drake
> 
> Keep the absorb rate recommended for the CC. The trimetric strays over 
> time and will become accurate again when you overcharge (equalize)
> 
> The math:
> Amp hours of battery @ 20 hour rate divided by max charge available in 
> amps, from whatever you using to charge (solar or inverter/charger) 
> Times .42 = absorb time in hours
> 
> i.e. your system 980 watts,  980 divided by 28.8 (average volts) = 34 
> amps max charge
> 370 AH divided by 34 = 10.88 X .42 = 4.57 round up to 4.6 hours absorb 
> time for the CC Your inverter VFX3524 max charge 85 amps... 370 
> divided by 85 = 4.35 X .42 = 1.82 absorb time for the inverter/charger 
> when running generator
> 
> Tom Duffy
> Senior Solar Design Engineer
> 
> Toll Free 888-895-8179
> tom at thesolar.biz
> Customer Service and Accounting 888-895-6810 Grid tie sales 
> 888-895-7847 Off Grid sales 888-895-4058 Other Product Sales 
> 888-895-9612 Central America Sales (Panama) 507-6-126-1253 Shipping 
> and Receiving 888-895-6497 Tech Support 888-895-8179
> SKYPE:  thesolarbiz
> 
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org 
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Drake
> Sent: Monday, July 22, 2013 10:04 AM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] Trojan L-16s
> 
> Hi Larry,
> 
> I will bump up the absorb voltage to 29.6 V. How long do you think the bank should stay in absorb at that rate?  The bank now seems healthy, with the bad battery replaced.  It does accept charge, without going high prematurely.  The max charge rate from the array is around C/10. The system can also be fast charged from a Honda 6500 inverter generator through the Outback 3524 VFX.
> 
> We have a Trimetric meter on the system. The discrepancy between the percent charge and the voltage is what demonstrated that we had a problem.
> 
> Thanks,
> 
> Drake
> 
> 
> 
> At 09:30 PM 7/19/2013, you wrote:
>> Hi Drake,
>> 
>> It always concerns me when I hear that a battery bank reaches absorb 
>> setting very quickly. It typically means one of two things: very few 
>> AH were removed from the bank; the battery bank has sulfated cells 
>> due to chronic undercharging. Far too often I find the latter to be true.
>> 
>> Healthy batteries will accept current and hold the charge voltage 
>> down with a fairly linear, slow climb to absorption voltage. Sulfated 
>> batteries do not accept current well which allows voltage to climb 
>> rapidly as the battery presents little load on the charging system. 
>> I'm not sure how this plays into your original post about a bad cell 
>> but it seemed worth mentioning.
>> 
>> My opinion is to aggressively charge, by using higher voltage, large 
>> flooded batteries. This is especially true when the PV system is 
>> moderate or undersized. 29.6 volts is what Trojan recommends. You can 
>> go as high as 32 volts on the L-16's but make sure the temperature 
>> compensation is installed properly and working. You will use more water.
>> 
>> One last comment, I highly recommend that ALL off grid systems have a 
>> battery capacity monitor installed. It's kind of like flying an 
>> airplane without a fuel gauge...it might not end in disaster.
>> 
>> Larry Crutcher
>> Starlight Solar Power Systems
>> 
>> 
>> 
>> On Jul 18, 2013, at 1:11 PM, Drake
>> <drake.chamberlin at redwoodalliance.org> wrote:
>> 
>> Tom,
>> 
>> The batteries usually reach absorb voltage shortly after the sun hits 
>> the array. The reason the bank wasn't working correctly is that one 
>> cell was dead in one of the batteries.
>> 
>> I could increase the absorb time to 4.6 hours and the voltage to 
>> 29.6, especially since the bank has a new battery. That is longer and 
>> higher than I'd previously heard recommended.
>> What would be the effect on water
>> consumption?  How did you calculate the absorb time?
>> 
>> Thanks,
>> 
>> 
>> Drake
>> 
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