theoldwizard1
SE MI
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Grit dog wrote:Telecom jars is his nifty lingo for telecommunications backup batteries.
These are basically, individual lead-acid cells. Very early telephone systems ran on DC. The voltage to ring the bell somewhere between 50-100V and it was switched (mechanically) on and off.
The old versions of these batteries were HUGE! Think of a double stack full size washer and dryer. This was one cell, 2.2V ! The term "jar" refers to case/housing that contains liquid acid and the lead plates.
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pianotuna
Regina, SK, Canada
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Camper_Jeff_&_Kelli wrote: The best thing about Lithium is they always put out 13.2 volts thanks to the BMS.
It is the nature of the LI, not the BMS.
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.
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StirCrazy
Kamloops, BC, Canada
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Camper_Jeff_&_Kelli wrote: The best thing about Lithium is they always put out 13.2 volts thanks to the BMS. Lead batteries, all types, slowly drop voltage as they discharge causing brown out conditions like dim lights, slow pump motors, and weak other loads. Not so with Lithium. 13.2 volts stable all the way down to 80 or 90% discharge and then the BMS protection shuts it off till recharged. Lithium is like having your cake and eating it too.
now thats not true, at 90% discharged the voltage of a LiFePO4 battery is only 12.0V if you would have said they put out over 12V untill 90% discharged then yes that is true and still a huge advantage over a wet battery which hits 12V at about 50% discharged. an even better advantage of the LiFePO4 is the voltage level under load, you can discharge much deeper befor you get alarms from your inverter from low voltage. a flooded battery can drop to 11.5V at 100% charged if it has a C/3 load on it, so basicly a 100 amp battery with a 33amp load will dip pretty fast, which is why for big rigs people run 4 6V batteries or more. Lifepo4 doesnt have this issue to that degree as you can do a C1 discharge and stay above 12V to 90% discharge which would be a 100 amp draw on a 100amp battery. so in a way your right just your numbers are off a little.
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StirCrazy
Kamloops, BC, Canada
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pianotuna wrote:Grit dog wrote:Telecom jars is his nifty lingo for telecommunications backup batteries.
It is not my acronym. It is name used by the cell companies. They are a sub variant of AGM. I like them as I no longer have to lay down in the snow to do a specific gravity test.
I have noticed a whole bunch of telecom jars are going LifePo4 now. the ones you got are AGM?
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Camper_Jeff_&_Kelli
Seattle
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StirCrazy wrote:Camper_Jeff_&_Kelli wrote: The best thing about Lithium is they always put out 13.2 volts thanks to the BMS. Lead batteries, all types, slowly drop voltage as they discharge causing brown out conditions like dim lights, slow pump motors, and weak other loads. Not so with Lithium. 13.2 volts stable all the way down to 80 or 90% discharge and then the BMS protection shuts it off till recharged. Lithium is like having your cake and eating it too.
now thats not true, at 90% discharged the voltage of a LiFePO4 battery is only 12.0V if you would have said they put out over 12V untill 90% discharged then yes that is true and still a huge advantage over a wet battery which hits 12V at about 50% discharged. an even better advantage of the LiFePO4 is the voltage level under load, you can discharge much deeper befor you get alarms from your inverter from low voltage. a flooded battery can drop to 11.5V at 100% charged if it has a C/3 load on it, so basicly a 100 amp battery with a 33amp load will dip pretty fast, which is why for big rigs people run 4 6V batteries or more. Lifepo4 doesnt have this issue to that degree as you can do a C1 discharge and stay above 12V to 90% discharge which would be a 100 amp draw on a 100amp battery. so in a way your right just your numbers are off a little.
I will agree that you have a more precise answer. The bigger the load, the more likely the voltage will drop and that effect will increase the more it is discharged. Nonetheless, the voltage is more stable than lead.
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Grit dog
Black Diamond, WA
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^Now you guys are pickin chit with the chickens!
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deltabravo
Spokane, WA
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Hemi Joel wrote:If I wanted to run a fridge while on the highway and not on propane, I would mount an inverter under the hood close to the battery, then run a 110 volt cord back to the fridge circuit.
Or you could plug the whole camper into it and the built-in charger in the camper would keep the camper batteries up.
Having the inverter in the camper is far more logical, then you hook it up to the house battery bank, not the engine start battery.
DC to DC Charger takes car of the charging needs while driving, rather than dealing with inefficiencies of inverter doing DC to AC (with underhood mounted inverter) and then the DC charger in camper converting the AC back to DC.
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Camper_Jeff_&_Kelli
Seattle
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I ran the truck an hour and a half the other day. My Victron 30 amp dc to dc got pretty darn hot. Hotter than I wanted to touch. During that time, the 2, 200AH lifepo batteries were charged from 79% to 93% each. Minimal solar now, about 0 to 175 watts for a couple hours of winter time, low sun days. My 45 amp Boondocker has stopped working. Exterior fuses are good but there may be an interior fuse. I'll have to pull out the unit to inspect since it's in a difficult location. I plan to replace it with a Victron 3000 watt inverter charger when I get to Quartzite. This is why you need proper equipment to charge Lithium batteries, they can accept so much current they can destroy your alternator burning it out. My guess is the old boondocks couldn't handle the batteries either.
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pianotuna
Regina, SK, Canada
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Camper Jeff & Kelli,
Is there a cooling fan in the Victron dc to DC unit?
The charging total from the numbers posted suggest about 56 amp-hours went into the 400 amp-hour battery bank.
Were you driving or was this just idling the engine?
Does anyone know the efficiency numbers for the Victron dc to DC charger? (appears to be 87%)
The unit puts out 25 amps at normal input voltage, according to the pdf. That seems a bit strange to me. Perhaps I'm reading the wrong pdf? The "sales" pages says 30 amps continuous to 40 amps, at nominal out put voltage.
From that 87% it appears the alternator had to produce about 65 amp-hours.
The Victron apparently boost charges for 2 hours on the Li settings.
I know my unit does 19.6 amps. It is the 20 amp renogy unit.
I'm glad to hear yours is doing what you need!
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Camper_Jeff_&_Kelli
Seattle
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pianotuna wrote:Camper Jeff & Kelli,
Is there a cooling fan in the Victron dc to DC unit?
The charging total from the numbers posted suggest about 56 amp-hours went into the 400 amp-hour battery bank.
Were you driving or was this just idling the engine?
Does anyone know the efficiency numbers for the Victron dc to DC charger? (appears to be 87%)
The unit puts out 25 amps at normal input voltage, according to the pdf. That seems a bit strange to me. Perhaps I'm reading the wrong pdf? The "sales" pages says 30 amps continuous to 40 amps, at nominal out put voltage.
From that 87% it appears the alternator had to produce about 65 amp-hours.
The Victron apparently boost charges for 2 hours on the Li settings.
I know my unit does 19.6 amps. It is the 20 amp renogy unit.
I'm glad to hear yours is doing what you need!
I'm out in the TC again today idling the engine. Today I shut off all DC loads except 1 LED dinette table light. Inverter and all else is off excepting for dc electronic controls in fridge and water heater. Idling away, my input voltage is 13.6 and the output charge voltage is 13.7. The unit is hot again. It took half an hour to get to the too hot to touch point. Just guessing, 150 to 160 degrees. The unit has a large heat sink on it. Not smelling electronics. If I were to drive the truck and bring up the speed of the alternator and the output voltage, it may raise the charge voltage lowering the current and possibly the temperature. I have not felt the alternator to see what it's temp is/feels like. I'll run out and do a feel temp test on the alternator, and bring the engine up to 2K RPM for a couple minutes to see if that changes voltage readings to the DC DC input and outputs, hang on...
OK, the alternator is warm on the front just after the big radiator cooling fan, and hot a couple inches back to the rear of the alternator. The truck voltage goes from 13.6 at idle to 13.8 when revved to 2K RPM and current goes up just a little varying from 13.2 to 13.8 according to the BMS. The Victron dc dc charger only reports input and output voltage. I need to look at each battery's BMS for its report which differs and includes current. So, Engine RPM makes a small difference on my setup, I don't know if it's enough to change the time to charge or heat profile. I will have to take a drive to do that. My alternator is 160 amps so it should be able to handle the truck load and the dc to dc. It took an hour at idle to bring both batteries up to 90 and 91 percent charge. My latest weather forecast shows clouds and snow the next 6 days so I'll have to do some driving in the TC to keep the system charged. About an hour a day but tomorrow, I think I'll do some extra running around and bring the batteries back up to about 100%, then watch it slowly go down from there, with all the DC stuff that isn't necessary shut off to make things last longer.
About 5 weeks till I get the new Victron 3000 and get shore power again. Even though I installed 675 watts of solar on the roof, it just isn't enough for winter up here in the Seattle area.
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