Posted: 12/24/2013 3:24:13 PM EDT
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I have two 100 ah deep cycle batteries wired in parallel, both purchased new about 3 weeks ago. I've been using my Honda EB3500 generator and an Iota IQ4 45-amp charger to charge them.
I f'd up and ran them down too much yesterday. Tried to recharge today and the incoming voltage was only in the 13.7V range. It was climbing up very slowly but wasn't sure it was ever going to top 14V. I hauled the batteries and charger up to the barn, plugged it into grid power, and the voltage was immediately above 14V. I plan on leaving them there for at least 24 hours. The plan is to charge these with solar in the summer, but right now I need to use the generator. Hauling them to the barn every time I want to charge them will be a serious PITA. Not sure what's going on, don't think the batteries will properly charge at such a low voltage. The main thing I can think of is the extension cord I'm using, 50' 12/3. Once I get the batteries and charger back here I'm going to try plugging the charger directly into the generator. Any other ideas? |
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I have two 100 ah deep cycle batteries wired in parallel, both purchased new about 3 weeks ago. I've been using my Honda EB3500 generator and an Iota IQ4 45-amp charger to charge them. I f'd up and ran them down too much yesterday. Tried to recharge today and the incoming voltage was only in the 13.7V range. It was climbing up very slowly but wasn't sure it was ever going to top 14V. I hauled the batteries and charger up to the barn, plugged it into grid power, and the voltage was immediately above 14V. I plan on leaving them there for at least 24 hours. The plan is to charge these with solar in the summer, but right now I need to use the generator. Hauling them to the barn every time I want to charge them will be a serious PITA. Not sure what's going on, don't think the batteries will properly charge at such a low voltage. The main thing I can think of is the extension cord I'm using, 50' 12/3. Once I get the batteries and charger back here I'm going to try plugging the charger directly into the generator. Any other ideas? The charger is likely current limited it's 45 amp rating is and it will take some time to bring the batteries to ever higher voltage. If it is rated to 45 amps, the 110 vac power draw of about 600 watts MIGHT be limited by a too small and long extension cord, but doubtful for say a 50 foot 12 gauge cord, as Slice suggests. The 45 initial amps is likely to taper down as the battery absorbs more charge. Do you have a DC clamp on ammeter or a shunt and millivoltmeter [essential IMO to understand what's going on and only abt $15 on ebay] If you could post the specs of your charger, it's likely I can give you a lot more info what to expect. Particularly its termination voltage. Also, this is one of the disadvantages of deep discharge batteries, there's no 'easy' way to determine their state of charge, as there is with flooded batteries ---by using a hydrometer or refractometer. As Skibane and I have often pointed out, the first ~50% of charge is absorbed by lead chemistry batteries easily, the remaining charge takes time, the closer to the end point, the slower is the charge acceptance. Another thing [and not being familiar with the Iota charger] the deep discharge batteries will require something like 15.5 -maybe more -for a full charge. Would have to look at the specs of the battery to know exactly what the charge protocol and termination voltage is. This is a fairly complex issue when starting out... |
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Tried to recharge today and the incoming voltage was only in the 13.7V range. It was climbing up very slowly but wasn't sure it was ever going to top 14V. If the batteries are heavily discharged, it can take a while before the charger is capable of raising their voltage very much. Essentially, the batteries are loading the charger's output voltage down - and that load won't get smaller until the batteries have accepted some recharge. Also, recharging batteries with a generator is often problematic. Many chargers draw most of their AC current on the peaks of the AC waveform, and the generator may be incapable of supplying this current without clipping the voltage peaks. Result: Lower peak AC voltage = Lower maximum DC charging current. |
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If the batteries are heavily discharged, it can take a while before the charger is capable of raising their voltage very much. Essentially, the batteries are loading the charger's output voltage down - and that load won't get smaller until the batteries have accepted some recharge. Quoted:
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Tried to recharge today and the incoming voltage was only in the 13.7V range. It was climbing up very slowly but wasn't sure it was ever going to top 14V. If the batteries are heavily discharged, it can take a while before the charger is capable of raising their voltage very much. Essentially, the batteries are loading the charger's output voltage down - and that load won't get smaller until the batteries have accepted some recharge. Hopefully that's all it is, but I was struck by how much faster the voltage climbed when plugged into grid power. I'm going to watch the charging process like a hawk now, did some initial tests when I first set it up, seemed good to go, but now I'm not sure. Also, recharging batteries with a generator is often problematic. Many chargers draw most of their AC current on the peaks of the AC waveform, and the generator may be incapable of supplying this current without clipping the voltage peaks.
Result: Lower peak AC voltage = Lower maximum DC charging current. Something like is what I was afraid of, not that I understand all the theory. I did my best to get a good generator and a good battery charger. But will they be up to the task long term? Guess I'll find out. I'm currently getting 100% of my electricity from these batteries and generator. Strangely enough, the voltage is noticeably higher when I hook the charger up to my old 150 ah AGM battery (my 200 ah battery bank is flooded lead acid). In terms of avoiding draining my batteries so deep in the future, any suggestions for a cheap low voltage cut off solution? I don't think my cheap little 150W inverter has one, or if it does, it's set way too low. I usually use a Watts Up meter to monitor how many amp hours I've drawn (I recharge at or before 100 ah), but I was unplugging it a lot the last couple days while rewiring a bunch of stuff, apparently lost track of how much I was drawing. Doh! |
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Hopefully that's all it is, but I was struck by how much faster the voltage climbed when plugged into grid power. Quoted:
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Tried to recharge today and the incoming voltage was only in the 13.7V range. It was climbing up very slowly but wasn't sure it was ever going to top 14V. If the batteries are heavily discharged, it can take a while before the charger is capable of raising their voltage very much. Essentially, the batteries are loading the charger's output voltage down - and that load won't get smaller until the batteries have accepted some recharge. Hopefully that's all it is, but I was struck by how much faster the voltage climbed when plugged into grid power. Yep, the grid is capable of supplying almost unlimited amounts of peak AC current - So you'll see faster recharge times with it. I did my best to get a good generator and a good battery charger. But will they be up to the task long term? You're not overtaxing your generator or battery charger - They should hold up just fine over the long haul. In terms of avoiding draining my batteries so deep in the future, any suggestions for a cheap low voltage cut off solution? Powerwerx sells a nice one. Another option is to install a low battery voltage alarm (example HERE), and manually disconnect the load when the alarm sounds. |
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OP I assume the charger is dual bank charger? If not dual bank how are you connecting to charge the two in parallel? As Skibane has already chimed in, not much I can add as he is great at this stuff. And the EBseries is not a pure sine wave like the EU series. It's just two batteries, I connect the charger cables to the same posts I run to the cig lighter adapter (into which I plug inverter and 12V chargers). Here's a pic, charger isn't attached. 
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You're not overtaxing your generator or battery charger - They should hold up just fine over the long haul. It's the batteries I'm thinking about. I'm worried the batteries won't really get fully charged unless I run the gennie a lot longer than I had planned. I'm trying to minimize generator use. I'm thinking I'm going to take it easy on the batteries until I figure out the best way to manage them. I've been trying to recharge after drawing 75-90 ah (measured with a Watts Up meter), I'm thinking I may recharge at 60 or so now. I'd like these batteries to last as long as possible. |
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It's just two batteries, I connect the charger cables to the same posts I run to the cig lighter adapter (into which I plug inverter and 12V chargers). Here's a pic, charger isn't attached. http://farm6.staticflickr.com/5526/11541242394_598bd27f2d.jpg Quoted:
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OP I assume the charger is dual bank charger? If not dual bank how are you connecting to charge the two in parallel? As Skibane has already chimed in, not much I can add as he is great at this stuff. And the EBseries is not a pure sine wave like the EU series. It's just two batteries, I connect the charger cables to the same posts I run to the cig lighter adapter (into which I plug inverter and 12V chargers). Here's a pic, charger isn't attached. http://farm6.staticflickr.com/5526/11541242394_598bd27f2d.jpg I maybe wrong I think its better to say connect the charger negative to the back/rear battery in the tote and the positive lead from charger to the front battery positive. Equal charge and all that. I was explained that when I had 12 large AGM batteries trying make a run silent run deep home made UPS for TV/computers/small wattage of lights. |
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I maybe wrong I think its better to say connect the charger negative to the back/rear battery in the tote and the positive lead from charger to the front battery positive. Equal charge and all that. I was explained that when I had 12 large AGM batteries trying make a run silent run deep home made UPS for TV/computers/small wattage of lights. Quoted:
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OP I assume the charger is dual bank charger? If not dual bank how are you connecting to charge the two in parallel? As Skibane has already chimed in, not much I can add as he is great at this stuff. And the EBseries is not a pure sine wave like the EU series. It's just two batteries, I connect the charger cables to the same posts I run to the cig lighter adapter (into which I plug inverter and 12V chargers). Here's a pic, charger isn't attached. http://farm6.staticflickr.com/5526/11541242394_598bd27f2d.jpg I maybe wrong I think its better to say connect the charger negative to the back/rear battery in the tote and the positive lead from charger to the front battery positive. Equal charge and all that. I was explained that when I had 12 large AGM batteries trying make a run silent run deep home made UPS for TV/computers/small wattage of lights. From the pic it looks like he's tapping the +/- from opposing cells. OP, what size wire do you have from your charger to the batteries? It appears to not be shown in the pic. I have the identical charger (w/ a pair of L16s and the IQ4 module) for my radios. I've got #6 stranded copper, about 6 ft long from the charger to the batteries... Posted Via AR15.Com Mobile |
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From the pic it looks like he's tapping the +/- from opposing cells. OP, what size wire do you have from your charger to the batteries? It appears to not be shown in the pic. I have the identical charger (w/ a pair of L16s and the IQ4 module) for my radios. I've got #6 stranded copper, about 6 ft long from the charger to the batteries... Posted Via AR15.Com Mobile Quoted:
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OP I assume the charger is dual bank charger? If not dual bank how are you connecting to charge the two in parallel? As Skibane has already chimed in, not much I can add as he is great at this stuff. And the EBseries is not a pure sine wave like the EU series. It's just two batteries, I connect the charger cables to the same posts I run to the cig lighter adapter (into which I plug inverter and 12V chargers). Here's a pic, charger isn't attached. http://farm6.staticflickr.com/5526/11541242394_598bd27f2d.jpg I maybe wrong I think its better to say connect the charger negative to the back/rear battery in the tote and the positive lead from charger to the front battery positive. Equal charge and all that. I was explained that when I had 12 large AGM batteries trying make a run silent run deep home made UPS for TV/computers/small wattage of lights. From the pic it looks like he's tapping the +/- from opposing cells. OP, what size wire do you have from your charger to the batteries? It appears to not be shown in the pic. I have the identical charger (w/ a pair of L16s and the IQ4 module) for my radios. I've got #6 stranded copper, about 6 ft long from the charger to the batteries... Posted Via AR15.Com Mobile I'm using 4 ga wires right now (3' long I think), which are actually too big (don't fit into charger and kind of a pain to handle). I'm measuring a voltage loss of a bit under 1%, which I assume is from poor fit into charger. Acceptable, though, I think. I tried 3' of 8 ga wire, but voltage loss was a bit over 1%, probably since I used 10 ga ring terminals (can't find 8 ga locally). Also tried cutting jumper cables in half (6 ga I think, but they weren't marked), voltage loss was really high, I think due to poor connection from alligator clips. Still have yet to find the best solution. |