10-06-2019, 10:58 PM
The battery I would choose, depends on how much solar can be stuffed on the roof, and whether the alternator is going to contribute to charging, and perhaps contribute to powering induction cooker. Will she be plugging into the grid to recharge the battery occasionally, and if so, how occasionally?
Its basically impossible to have too much solar, but far too easy to have too little. Too much usually means a happy long lived battery and a non chalance about electrical usage, not enough means constant stress about maximizing exposure to sun and minimizing electrical usage.
The engle on a 75 degree day( inside the van) will use about 1Ah each hour, hopefully and likely less. If it is asked to do its job in a 95 degree locked up closed up van, double that figure. 105f double that again.
I don't know how much a charging Ipad consumes, for how long. 2.1 amps@5v (10.2 watts) for 1 hour? 2 hours, 3? no idea. Is it going to be fully dead when asjed to be charged, some fraction of that, any idea of that fraction.
Same for the cell phone, i know mine maxes out at about 5 watts, but I know some others can take 10 or 15 watts.
The battery is going to have to maintain enough voltage to power the induction cooker for the time required, through the inverter.
Lets use 400 watts as the load and battery maintaining 11.5v, in a morning situation when the battery is discharged as low as it generally goes. That is a 34.8 amp load, but we need to add 15% for inverter inefficiency, and perhaps 20% would be more realistic, so another 7 amps.
So 42 amps to induction cook through inverter at 400 watts. That is a considerable load. The starter motor is about 180 amps, for 2 or 3 seconds and a relatively large 12.8v healthy battery struggles to maintain 12v+ during engine cranking.
A single battery is not going to be all that happy to supply the induction cooker at less than full charge, especially not at lower states of charge. and not after many days of cycling and not reaching true full charge.
A tppl AGM battery like Northstar or Odyssey has very high CCA figures due to very low resistance. these are great batteries for powering high loads, but they are not good 'solar only' batteries. When deeply discharged they need high amp recharging, regularly, from a low state of charge, to give good service. Odyssey says no less than 40 amps for their 100Ah group 31 battery when deeply discharged.
If one wants just one single battery to reliably power the induction cooker, then the TPPL AGM$$ are the best lead acid battery choice, but you cant just feed them whatever charging current is available from solar, and expect them to maintain that performance. More solar is obviously better but 40 amps is not going to fit on a transit van roof and its not like the instant the sun rises the panels full output is available.
Now if one is going to be able to plug in every 7 to 10 days or so, and gets a 40+ amp charger/converter and applies that charger at a low state of charge and holds it until the battery is full, they can keep the TPPl AGM fairly happy.
Batteries plus sells relabelled Northstar batteries as X2 power. They are not cheap. I've gotten tremendous service from my Northstar group 27, but I can and do feed it the high amp recharge regularly.
If one cannot feed their battery properly, they just replace it more often and likely at an inconvenient time. If they treat it very poorly they then get to deal with trying to get the store to warranty it.
So John, how much solar can she fit on the roof?
a Lifepo4 battery is very good at maintaining voltages at lower states of charge but they are a whole different animal that i have no experience with, and would not recommend a newb to set up, or have set up, unless they got loads of money and find a legitimate pro to set it up properly, not cut corners, and be able to instruct the owner on the proper use and care of the system.
Its basically impossible to have too much solar, but far too easy to have too little. Too much usually means a happy long lived battery and a non chalance about electrical usage, not enough means constant stress about maximizing exposure to sun and minimizing electrical usage.
The engle on a 75 degree day( inside the van) will use about 1Ah each hour, hopefully and likely less. If it is asked to do its job in a 95 degree locked up closed up van, double that figure. 105f double that again.
I don't know how much a charging Ipad consumes, for how long. 2.1 amps@5v (10.2 watts) for 1 hour? 2 hours, 3? no idea. Is it going to be fully dead when asjed to be charged, some fraction of that, any idea of that fraction.
Same for the cell phone, i know mine maxes out at about 5 watts, but I know some others can take 10 or 15 watts.
The battery is going to have to maintain enough voltage to power the induction cooker for the time required, through the inverter.
Lets use 400 watts as the load and battery maintaining 11.5v, in a morning situation when the battery is discharged as low as it generally goes. That is a 34.8 amp load, but we need to add 15% for inverter inefficiency, and perhaps 20% would be more realistic, so another 7 amps.
So 42 amps to induction cook through inverter at 400 watts. That is a considerable load. The starter motor is about 180 amps, for 2 or 3 seconds and a relatively large 12.8v healthy battery struggles to maintain 12v+ during engine cranking.
A single battery is not going to be all that happy to supply the induction cooker at less than full charge, especially not at lower states of charge. and not after many days of cycling and not reaching true full charge.
A tppl AGM battery like Northstar or Odyssey has very high CCA figures due to very low resistance. these are great batteries for powering high loads, but they are not good 'solar only' batteries. When deeply discharged they need high amp recharging, regularly, from a low state of charge, to give good service. Odyssey says no less than 40 amps for their 100Ah group 31 battery when deeply discharged.
If one wants just one single battery to reliably power the induction cooker, then the TPPL AGM$$ are the best lead acid battery choice, but you cant just feed them whatever charging current is available from solar, and expect them to maintain that performance. More solar is obviously better but 40 amps is not going to fit on a transit van roof and its not like the instant the sun rises the panels full output is available.
Now if one is going to be able to plug in every 7 to 10 days or so, and gets a 40+ amp charger/converter and applies that charger at a low state of charge and holds it until the battery is full, they can keep the TPPl AGM fairly happy.
Batteries plus sells relabelled Northstar batteries as X2 power. They are not cheap. I've gotten tremendous service from my Northstar group 27, but I can and do feed it the high amp recharge regularly.
If one cannot feed their battery properly, they just replace it more often and likely at an inconvenient time. If they treat it very poorly they then get to deal with trying to get the store to warranty it.
So John, how much solar can she fit on the roof?
a Lifepo4 battery is very good at maintaining voltages at lower states of charge but they are a whole different animal that i have no experience with, and would not recommend a newb to set up, or have set up, unless they got loads of money and find a legitimate pro to set it up properly, not cut corners, and be able to instruct the owner on the proper use and care of the system.
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