More Surrette problems

terrynew · July 2011

Yikes, I just had to replace 16 Surrette S600 batteries that were only 9 months old. Most of their specific gravities were over 1300, and all the equalizing we could do wouldn't change things. I shipped a few back to Surrette and they discovered a bad weld on one, which they think caused the charge controller to overcharge all 16 as it kept trying to bring that one up from 4 V to 6 V. Thank goodness Surrette honored their warranty and replaced all 16 for just the shipping cost. Phew!

But the new batteries, from install time (a month ago) to now, are all between 1240 and 1255 instead of being around 1265. I did the usual stuff (checked the temperature but it was 80 F, used a second hydrometer but it read the same values) and then bought a $60 refractometer. It gave the same readings, after calibrating with distilled water.

I talked to Surrette's support man, and he thinks my panels aren't sending enough Ah to the batteries. I've got twelve REC 215 W panels, giving me 2650 W. It's a 48 VDC system (two strings of eight 6V batteries, 'S600's), so he reasons the panels are sending me 2560 / 48 = 44 A, or 22 A per string. However the batteries are rated at 450 Ah at the 20 hr rate, so a 50% discharge would use 225 Ah and therefore I'd need to put back 225 Ah. So he concludes that 225 / 22 = 10 so I should be in Absorb charging for 10 hours, but my FM80 is defaulting to 3 hrs, hence the low gravities.

He recommended I see if a 6 hr Absorb time would make a difference. So I made the change and in the last 18 days we've had lots of sun, giving me 6 Absorb hours (putting me into Float) for 14 of those 18 days. Yet the gravities are still 1240 to 1255. And my summer load is a light one, hardly ever going much below 49 VDC (85% SOC).

Anyone have any suggestions, or thoughts on his reasoning? I'd hate to find that something in my inverter/charger or charge controller is going to seriously shorten my battery life because of consistently low gravities.

Thanks,
...Terry
P.S. Absorb =57.6 V, Float = 52.5 V, EQ = 63.2 V.
P.P.S. My Magnum 4448 inverter has a 60 ADC rating, or 30 ADC per string, so he thinks I should change my inverter's Absorb time as well, from 3 hrs to 7 hrs. But ouch, the generator propane cost!! It makes me wonder why a 48 VDC system is recommended when the panels add up to over 2 kW...

Cariboocoot · July 2011

Re: More Surrette problems

I've moved this to its own thread because its a different problem.

Just running the numbers using the basic calculations:

215 * 12 = 2580 Watt array. At typical 77% efficiency: 1986 Watts / 57.6 Volts = 34 Amps peak potential current. What sort of number do you see on the FM80?

Sixteen 450 Amp hour 6 Volt batteries is 900 Amp hours @ 48 Volts. That would want 90 Amps of charge current, so you've got no place near enough panel to charge that much battery.

I suggest you disconnect one string of the S600's and see how that works. That and change the programming on the FM80 to 4 or more hours for maximum Absorb time.

Also you might want to fire up the generator and use the Magnum's charger to get those batteries pushed up.

This system is way out of balance.
BTW, it isn't array size that dictates system Voltage. You start with the loads; the amount of maximum Watts and total Watt hours is the clue to inverter and battery bank size/Voltage. The array and controller is determined by how much battery you have to recharge.

stephendv · July 2011

Re: More Surrette problems

Your system is very similar to mine, except I have 2.8kW of panels and about a 900Ah 48V battery (forklift type not Surrette). Note that I'm a relatively new off-grid solar user.

In my opinion the minimum charging current is not that big of a deal, as long as you can replace the Ah you've taken out of the battery + 20%, you should be recharging just fine, although it will take you longer to recharge and your batteries will spend more time at less than 100% state of charge after a deep discharge, which is not ideal.

The calculation they gave you which resulted in a recommended 10 hour absorb time is off in my books. In general, you will only charge at full current from 50% state of charge to 90% state of charge during the bulk phase. After you hit absorb you should not be seeing more than 5A for every 100Ah and this should only take 2-4 hours.

If you've drawn down the batteries by 450Ah, you need to replace it with 540Ah (+20%), and if you see 40A from the charge controller, you'll only be able to use that for the first 90% of the state of charge, so that's: 486Ah / 40A =~ 12 hours in the BULK stage, before you've hit absorb. Then you'll need somewhere between 2-4 hours in absorb to finish the charge, a bit difficult to work out since the charge will be tapering off gradually. In any case a 4 hour absorb is plenty, so you're looking at a 16 hour recharge time after discharging to 50%. If you discharge to 50% on a regular basis then I'd agree with 'coot that the system is out of balance, because you won't be able to recharge even in 16 hours because of the loads you'd have on during recharging. But if the 50% discharge happens very rarely, then hopefully you'd be able to recharge in a reasonable amount of time and won't leave your batteries at less than 100% SoC too long.

If you have solar, there's no point in using your inverter/charger for the full absorb charge since during absorb you'll only be able to charge at less than 40A anyway (charging will be limited during absorb to 5A for every 100Ah maximum).
For best results, use the gen in the morning for bulk and let solar do all the absorb.

Regarding your SG readings, if after doing a full EQ (with minimal loads during EQ and started with the gen early in the morning), then I can't see why you're not seeing the right SG values.
A 6 hour absorb should be more than enough to charge those batts (assuming that they do actually stay in absorb for 6 continuous hours), especially if you've got very light loads and aren't discharging much.
Looks like you've done everything right, I would contact Surrette.

petertearai · July 2011

Re: More Surrette problems

Assuming you have a temp sensor on your fm80, Check the rts compensation is set to wide (in the advanced menu).

feedhorn · July 2011

Re: More Surrette problems

Sounds like they may have sent you some 'new' batteries from some old stock. They may have been sitting around for a while and got somewhat sulphated.

My experience with 'new' batteries is that they need lengthy EQ to bring the batts up to full charge SG and this can take weeks to a month of EQ before the batts are truly new and in perfect condition.

EQ, EQ, EQ for as long as you can and don't do any discharge cycles on them until they all come up to proper SG.

This new battery conditioning is very important.

Good Luck

FH

jeffkruse · July 2011

Re: More Surrette problems

I would max out your absorb time and raise the voltage to 58.8V.

BB. · July 2011

Re: More Surrette problems

I would go out and measure the voltage at every battery under load and under charge and look for any differences (a weak battery for example). I would also check the voltage drop of each interconnect too (again under charge or under load).

And, since you have parallel banks, I would suggest a DC current clamp meter so you can ensure that each string is participating during charging/discharging.

Lastly, measure the resting voltage (no charging/discharging for 2-3 or more hours) of each battery--again looking for differences.

-Bill

terrynew · July 2011

Re: More Surrette problems

Thanks for all the feedback, folks. Here are some responses from me:

You're right to suggest checking individual battery voltages, Bill, as that was the key that I had a damaged one in my first set of batteries. But I'm hesitant to buy a dc clamp meter -- they're darned pricey up here in Canada.

Jeff and CC, I did up the FM80 absorb time to 6 hrs but that hasn't shown a difference yet. I'm hesitant to up the absorb voltage from 57.6 to 58.8 when Surrette tells me to keep it at 57.6.

FH, the battery date codes come out to May 2011, so I don't think old stock is the problem. I'm puzzled by your recommendation of lots of EQs; I agree that getting a good start on new batteries is important but Surrette's staff don't think this is the way to go, instead recommending just one after another month of 6-hr absorb charging. Anyone else have thoughts on this?

Peter, the remote temperature sensor is optional on the FM80 and my installers chose not to add it in, unfortunately. Right now the battery room is at 85 F rather than the ideal 77 F, so the FM80 doc (pg 84) says I should compensate by reducing the Absorb and Float voltages by 0.6 V. That doesn't seem like much to worry about -- anyone agree, or should I drop from 57.6 to 57.0?

Cariboocoot, you said "215 * 12 = 2580 Watt array. At typical 77% efficiency: 1986 Watts / 57.6 Volts = 34 Amps peak potential current. What sort of number do you see on the FM80?" >> I'm reading 7.5 A In and 10.8 A Out, but I don't understand how these relate to your 34 Amps peak number; it's a light-cloudy day now.

Stephen and Cariboocoot, I'm not sure how to resolve your differences. It's reassuring to hear that Stephen has a similar balance to mine, but I don't know if I just want to believe the answer that requires the least additional investment. My inverter's battery monitor kit is telling me that my average load since spring has been 2.6 kWh/day, a third of what my original load estimates had been, so I'm likely seldom getting to 50% discharge except in winter. What voltage would a 50% discharge be on my 48 V system?

Cariboocoot, I'm hesitant to disconnect one of my 2 strings as you suggest. Isn't that halving the time I can last through cloudy days without starting up the gen? That may be okay for summer but not for winters up here.

Cariboocoot, thanks also for the bit about what dictates system voltage. I fear that my overestimating my load budget at the start of all this led to my installer picking a 48 V system when a 24 V one would have been better. More importantly, my Surrette support staff agrees with you that I appear to have undersized the charging system for the battery bank. I'm now wondering if I should fix my system by switching to 24 V (yikes, a new inverter; what else?) or buying another 6 panels (from 2.5 kW to 3.8 kW), or just leave it as is?

Thoughts, anyone? Thanks again,
...Terry, One Overwhelmed Non-Techie

stephendv · July 2011

Re: More Surrette problems

I think you should focus on solving the one specific problem first, and if you get that right, then you can look at solving potential issues in the system. The only problem you seem to be having is that after an apparent full charge your batteries they are not giving you correct SG readings.

But the new batteries, from install time (a month ago) to now, are all between 1240 and 1255 instead of being around 1265.

So the priority is to do something, anything, to see the 1265 that you're supposed to see, even if it's just for 5 minutes. Best way to do this is a long EQ charge using your generator in the morning of a sunny day and let your panels complete the EQ.

EDIT: Or leave the entire EQ up to the generator to ensure that there aren't any potential voltage issues with the panels.

If after a full EQ for many hours (and no load, so as not to confuse things), you still don't see that SG, then there is something wrong with your batteries. In my opinion, of course

You can sort out any debates about panels size vs. battery size at a later date once you've established that your batteries are good.

stephendv · July 2011

Re: More Surrette problems

One other potential issue is too low voltage from the panels. How are your panels wired? They seem to have a Vmpp rating of 28V. Could you check what the voltage coming in to the Outback FM charger from the panels is?

jeffkruse · July 2011

Re: More Surrette problems

Measure the battery voltage at the battery posts when its charging. You may find a voltage drop of 1/2 to 1 volt from what the CC says! If so then up your voltage.

Vic · July 2011

Re: More Surrette problems

TN,

Do not worry about having a 48 volt system. You are better off at 48 volts than 24, and you make better use of the FM80's available charge current.

You DO need a battery RTS. Get one soon. In the old days, they were ANWAYS included with the MPPT CCs. Check to make sure it is not still in the box. In ON you will need it.

It is important to monitor the currents into and out of the CC, at mid day in full sun. The 7.5/10.8 values are very small for your array size. These values must be from the early morning, or late afternoon. As Coot noted, you should be seeing currents into the battery of 35ish amps nominal for several hours per day with no shading, in full sun.

With your consmption, you should easily be able to recharge the bank daily with good sun, once you overcome deficit. Two hours of full sun with your current array should have you in Float, easily. Are you certain that each string in the array is producing current? Check the combiner box breakers (or fuses).

And, Yes, what IS your string configuration. From the ratio of in/out currents of the CC, it appears that you have enough input voltage ... but the string data would be helpful.

Good Luck, Vic

BB. · July 2011

Re: More Surrette problems

First, (again, I am not battery expert) I would only equalize a new battery for 30-60 minutes past the last upward rise of S.G.

The only reason, I can see, to equalize a battery for hours is when you have a badly sulfated battery and are trying to "flake off" the sulfates by vigorous bubbling. Something that a new battery should never require--or should have done to it.

Second, I would suggest getting a DC clamp meter--the one I linked to is cheap from a US Sears store ($60, goes on sale to $53 from time to time). So far, seems to be the cheapest/usable meter I have seen so far. The same meter, without the Sears private label, is this Eltech MA-220 which probably retails for ~$100+ or so.

I understand that prices will be higher elsewhere. But--compared to what you have invested in your solar system/battery bank--you probably need a DC current clamp meter to debug... Not only the battery bank, but your solar array too (which sounds like it is under performing--but that may also be a configuration issue too--series/parallel question as asked by others here before me).

To debug a battery bank with parallel strings without a current clamp meter... Find an identical length of cable in each string (say ~2' long). Set a DMM to 200 mVolt (0.200 volt) full scale (if you meter goes there) and measure the voltage drop across each cable. Ideally, they should all be the same, if you see a >2x difference between cables, it may indicate that one string is carrying more/less current than its normal share (using the cable like a resistor and measuring the voltage drop across it).

Do you have some sort of Battery Monitor on your system?

-Bill

Cariboocoot · July 2011

Re: More Surrette problems

A little clarification about my persistent use of the 10% charge rate rule-of-thumb:
It is a sort of indicator of how well balanced the system is. If you have the potential for a peak charge current of 10% of the total battery bank Amp hour rating then you are likely able to: A). meet proper charging Voltage levels;

. complete both the Bulk and Absorb stages on any good, sunny day; C). replace the Amp hours used as long as DOD is not excessive.

Too many people look at only replacing the Amp hours, figuring any rate over any amount of time is okay so long as that is done. These people end up with batteries that have died before their time. Batteries want to be recharged quickly and fully every day. It's okay if a day is missed here and there, but most of the time both the Bulk and Absorb cycle needs to be completed in full or else you will be short-changed on Amp hours and the battery will sulphate more rapidly and end up dead years before its time.

If the charge rate is high enough, Bulk will be completed in time to go through a full Absorb cycle before the sun goes too low to finish it. Seeing "Float" every day, even if briefly, is a good thing and key to a long battery life.

In any case, get the batteries fully charged and the SG ump and matching between cells because every day that goes by without this is a little more time off the life of the battery.

waynefromnscanada · July 2011

Re: More Surrette problems

BB. wrote: »

First, (again, I am not battery expert) I would only equalize a new battery for 30-60 minutes past the last upward rise of S.G.

The only reason, I can see, to equalize a battery for hours is when you have a badly sulfated battery and are trying to "flake off" the sulfates by vigorous bubbling. Something that a new battery should never require--or should have done to it.
-Bill

After several decades working around and with batteries, and almost 10 years, of far better than expected experience with my six L-16 flooded batteries, I have to totally agree with Bill.
And a note on the two Surrette flooded L-16's for my cousin, which I mentioned in an earlier post, I've been looking after then until he's ready for them (has his PV's ready to go). Had them on float a few times over the last 2 months, otherwise not in use. Hooked them up all alone to the MX-60 for an hour today, Went to Float within 10 minutes. Manually selected EQ, and again within 5 minutes voltage was right up to 15.2, current had dropped way off and all cells were bubbling nicely, so discontinued charging and checked SG, which was good in all cells. So I guess I can relax, things at least as of now, look excellent! Thank you Surette:D

Vic · July 2011

Re: More Surrette problems

Yes, BB Bill,

Forgot the comment about EQ EQ EQ weeks -- a month of EQ. I'd say NO!, especially on a fairly large bank of expensive batteries.

EQ for two or three hours on a new bank, while watching SG on the Pilot Cell, and temperature of the electrolyte is prob fine. Helps mix it. And these barretirs are considered tall, and have plates packed into them. Perhaps if there is wide SG variation, then another EQ after some additional charge/discharge cycles.

EQing harms the batteries if over done. It is a balance against the harm or NOT EQing. It is all a balance.

Did we mention getting an RTS for the CC SOON? Oh, yea we did. Please do it.

And, to me the target Asorb voltage seems a bit low, especially if one seems to have low SG, but guess that this came from Surrette, so they know far more than I.

Have Fun, Vic

terrynew · July 2011

Re: More Surrette problems

Thanks, everyone, for all those great ideas and questions. Here are some replies:

My 12 REC-US 215 W solar panels are configured in four sets of three. Each has a 36.2 Voc, so I think the installer chose sets of three since a set of four would be too close to the FM80's 150 V max input. I don't know anything more about string configuration -- what should I look for and where?

I love Stephen's idea of just focusing on the low SGs now, so that's where I'm going. I had a different solar installer company (is there a fancy name you guys use?) over this afternoon, and he says the same. He recommends that on the next full-sun day, I do four hours of solar absorbing to get into Float then four hours of solar EQ. If the SGs aren't up to 1260-1265 by then, he says I should do an inverter/charger EQ after dusk with the generator.

I talked to Surrette's tech guy and he okay'ed that plan. We have full sun tomorrow so wish me luck, and I'll get back to you soon.

While in full sun tomorrow, I'll also check the voltages coming into the FM80 from the panels, and compare it to the voltage across the battery posts. And I'll note the currents in and out of the FM80 at noon at full sun.

Cariboocoot, I'm afraid your last posting (14:06 PDT) went over my head. I'll try it again tomorrow after some rest!

And for the record, I am definitely not having fun. I honestly thought solar power would be a turnkey system other than monthly watering and EQ work. I have been overwhelmed at the complexities of the system and the variations in recommended actions and the requirement for technical knowledge and instruments. I'm off to rub two sticks together.

Thanks again, team.
...Terry

mike95490 · July 2011

Re: More Surrette problems

Bulk them in the AM with the generator, and let the solar do the rest of the day.

feedhorn · July 2011

Re: More Surrette problems

Some other thoughts:

I try and match batteries in strings, weak ones, or low SG all together in the same string. On occasion I do an EQ on both strings then separate them and let one string rest disconnected and check the SG in the morning. If not good I wait until the connected string is charged then connect both strings back together and EQ again. Then disconnect and rest the weak string again. I do this day after day until the rested string is all at equal SG. I then repeat the procedure on the unrested string and get it conditioned the same way before running both strings back together.

FH

terrynew · July 2011

Re: More Surrette problems

Here's some strange news: at noon now in full sun, three hours into absorb charging, the CC shows PV input = 91.8 V and 3.3 A output = 57.6 V and 5.2 A. Cariboocoot and Vic said I should be reading around 35 A coming into the CC, so why am I so low? For that matter, why is it 3.3 A at noon under full sun today when it was 7.5 A under light clouds the day before yesterday?

Let's add an explosion to the discussion: So I decided to measure the current and voltage across the battery posts. The voltage was 47.1 V [note: typo, should be 57.1 volts. -Bill B]. But when I tried to measure the current, with a meter that has a 10 A max (fused), I contacted the black/common first and then the red -- upon touching the red positive post, a HUGE spark popped and a raised burn mark appeared on the post. YIKES! (Thank goodness for the hydrogen vent fan, eh?)

So why the boom-flash when the CC said its output current was 5.2 A and my multimeter was set for 10 A? Everything appears to be working still, but have I possibly damaged anything?

If Mr. Sun holds out (clouds are threatening), I'll start my solar EQ soon.
...Terry

jeffkruse · July 2011

Re: More Surrette problems

Let’s just talk about the Voltage measurement, I'll let someone else explain what happened for your current measurement

So, 47.1V at only 5amps? I think you should set the voltage higher. I suspect at 10amps your voltage across the batteries will be only 46.6V. That’s too low for my liking.

BB. · July 2011

Re: More Surrette problems

First, did you open the cable connection first and put put your current meter in series with the break (sort of correct). Or did you place the probes from plus to minus on the battery bank (flash/bang or worse)?

Get a dc current clamp meter. Using a DVM in a large battery system is very dangerous for direct current measurements.

Second, measure battery voltage and measure the voltage at the charge controller output. They should be almost exactly the same.

It sounds like you have a major charging problem. Focus on the charge controller setup and writing for now.

-Bill

stephendv · July 2011

Re: More Surrette problems

terrynew wrote: »

Here's some strange news: at noon now in full sun, three hours into absorb charging, the CC shows PV input = 91.8 V and 3.3 A output = 57.6 V and 5.2 A. Cariboocoot and Vic said I should be reading around 35 A coming into the CC, so why am I so low? For that matter, why is it 3.3 A at noon under full sun today when it was 7.5 A under light clouds the day before yesterday?

That's normal as your batteries have already reached absorb voltage, so the current going into them will be limited.

terrynew wrote: »

Let's add an explosion to the discussion: So I decided to measure the current and voltage across the battery posts.

You're playing with fire here! You basically created a dead short across the battery posts and are luckily that nothing worse happened. There's no point in measuring short circuit current across the battery posts, unless you want to weld your multimeter and then watch an explosion!

If you were attempting to measure the current BETWEEN the cc and the battery, then the best way to do this is with a CLAMP on DC meter that clips around the insulated wires and doesn't form part of the circuit at all. That's the safe way. You really shouldn't be trying to measure that amount of DC current with an inline multimeter.

stephendv · July 2011

Re: More Surrette problems

BB. wrote: »

Second, measure battery voltage and measure the voltage at the charge controller output. They should be almost exactly the same.

Seconded. It doesn't make sense that the output of the CC says 57.6V, yet the battery voltage is 47.1V. Did you measure both of these at the same time? How long of a cable do you have between the charge controller and the batteries?

jeffkruse · July 2011

Re: More Surrette problems

stephendv wrote: »

Seconded. It doesn't make sense that the output of the CC says 57.6V, yet the battery voltage is 47.1V. Did you measure both of these at the same time? How long of a cable do you have between the charge controller and the batteries?

I think this is normal since there are no sense leads going to the battery from the CC. .5V/5A= .1ohm Not good but not out of the question for cables, connections, and what ever happens inside the CC before the voltage is taken.

Cariboocoot · July 2011

Re: More Surrette problems

jeffkruse wrote: »

I think this is normal since there are no sense leads going to the battery from the CC. .5V/5A= .1ohm Not good but not out of the question for cables, connections, and what ever happens inside the CC before the voltage is taken.

If it's a 10 Volt difference between the output of the charge controller and the batteries that's far too much. A tenth of a Volt would be nothing. Even one Volt. But ten? Something's wrong there.

jeffkruse · July 2011

Re: More Surrette problems

Cariboocoot wrote: »

If it's a 10 Volt difference between the output of the charge controller and the batteries that's far too much. A tenth of a Volt would be nothing. Even one Volt. But ten? Something's wrong there.

Ha

I sure hope we are talking about 57 volts and not 47 volts!!!!

I hope its just a few typos!!!

mike95490 · July 2011

Re: More Surrette problems

Cariboocoot wrote: »

If it's a 10 Volt difference between the output of the charge controller and the batteries that's far too much. A tenth of a Volt would be nothing. Even one Volt. But ten? Something's wrong there.

Even one volt difference is bad, increase the size of your connections from the charge controller to the battery, you are loosing power there, fooling the controller thinking the battery is full, when it is not. This is why good charge controllers have Voltage Sense lines, to prevent this issue.

Measuring amps, usually the battery has enough amps to embed the meter into your forehead, and molten bits of metal everywhere else. You got lucky, buy a couple lottery tickets. NOW!

waynefromnscanada · July 2011

Re: More Surrette problems

terrynew wrote: »

So I decided to measure the current across the battery posts. A HUGE spark popped and a raised burn mark appeared on the post. YIKES!

To be perfectly honest and candid, you're VERY lucky you didn't trigger a battery explosion right in your face! Not kidding! And you should be likewise very thankful your meter had an internal fuse, otherwise the meter leads which you were holding in your hands could have been white hot in an instant, and it would have been quite some time before you could use your burned hands again! These things may be "only" 12 volts, but they're anything but toys, and must be treated with the greatest respect. To do otherwise can have devastating results.

And that huge voltage difference between your batteries and charger, indicate either WAY too small a wire, way too long a wire, corroded or otherwise very bad connections or connection, or a combination of all the above.

terrynew · July 2011

Re: More Surrette problems

I'm sorry, everyone. Jeff was right, I typed 47.1 V at the battery posts but it was actually 57.1 V, a difference of 0.6 V from what the CC said it was sending to the batteries. Mia culpa.

Wow, I hadn't realized how dangerous putting the ammeter across the posts was. Scary stuff. Lesson learned (and hopefully for others out there reading this, should there be others as unknowledgable as me in electricity).

The cable runs 1 foot from the CC to the e-panel and then three feet to the battery box. Does the 0.6 V drop mean I need thicker cables or that I should bump up the bulk, absorb, float and eq settings on my CC by 0.6?

Clamp-on DC ammeters are $140 at Home Depot here in Ontario, not available at Sears Canada. I'll look to see if I can borrow one instead.

Darned clouds are ruining my solar EQ. I'll likely have to switch to inverter/charger + generator.
...Terry

mike95490 · July 2011

Re: More Surrette problems

terrynew wrote: »

...

The cable runs 1 foot from the CC to the e-panel and then three feet to the battery box. Does the 0.6 V drop mean I need thicker cables or that I should bump up the bulk, absorb, float and eq settings on my CC by 0.6?......

Thicker Cable. DO NOT adjust the setpoints. As the batteries charge up, the voltage drop becomes less, and you would end up overcharging batteries.

Does your controller have terminals for Voltage Sense ??

More Surrette problems

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