chevy step van

I was approached by a client, about an install in his Chevy Step Van. I looks like an Ice Cream truck. Right now they just have the basic head unit and 4 speakers. They want to convert the van into a mobile store. So they will need to be parked for 5 or 6 hours at a time. While parked they want to run the radio, and addition lighting (4 - Four foot fluorescent tube lights). I know they will need an inverter to plug the lights into and an additional battery to power everything while the vans engine is off. They'll also require an addition power source. I'm thinking deep cycle battery, and a relay isolator to separate the load while the van is parked, and reconnect when the engine is turned on. Is this the correct setup? Am I missing anything? Will the vans alternator we the correct method of recharging the 2nd battery?DTS Performance

St Petersburg, FL

Start with the power they need - how much? Ice-cream vans usually run generators due to the power required (fridges etc), but fluoros and radio should be fine. But I would consider using 12V inverters for the lighting - why bother with the inverter? And apparently there are 12V radio systems. (LOL - I assume it is 12V...) But from the power consumption you can figure out the battery size required (for 6 hours). As for the isolator, does it have a charge lamp (for/from the alternator)? Then given the spare alternator output, calculate if that is enough to recharge. Otherwise suck & see... Keep in mind that batteries are not generally the best solution nor suited as a regular high-power supply source.

For now, I just want to make sure that in theory everything I want to put in will work. I haven't seen the lights they want to put in, but I was informed that they were Lithonia Shop Lights 4foot dual T8. They bought them from Home Depot. The truck has no generator, just a single 12v battery. As for the isolator I was thinking about a PAC Unit SPR-200. I've worked on boats with a similar setup. Except no inverter just a dual battery setup, with 1 battery powering the live well,trolling motor and boat electronics.DTS Performance

St Petersburg, FL

Cool - you theory is sound, except that not being a boat, you probably don't need a PAC or similar - hence my charge-lamp question. Just a plan old relay controlled by the charge lamp circuit. I presume the LithLamps are 4 x 2 x 40W tubes hence 320W. Hence a 600W inverter and probably an effective 400W load, hence ~40 Amps. So just an initial calc: For 6 hours = 6 x 40A = 240AH. So maybe 2 series Trojan T-125 6V 240Ah flooded batteries if externally vented (RRP about $230 => $460) or FullRiver 12V 240Ah AGM for about $560. Mind you - check battery specs - you may have to double the above etc to limit discharge to (say) 50% for better battery life. Then the above need to be charged at 10A for 24 hours or can be fast charged at 40A for 6 hours.    So how long will the run the engine? If 2 hours per session, then fast charging means 120A for 32 hours with 3x the number of batteries for fast charging, else 12x the number of batteries for normal charging. Not that the above should be a minimum design, but they need a sanity check.... May I suggest LEDs instead of tubes?

With thanks to Mike M2 whose reply has unfortunately since been deleted... It's as I wrote above...

oldspark wrote: Keep in mind that batteries are not generally the best solution nor suited as a regular high-power supply source.

I keep trying to warn people. (BEFORE they complain about costs.) But money does the trick - like the guy that wanted to run his remote resort quietly at night and the diesel-gen was too noisy. (Hey man, just house it quietly!) Then he was told the batteries would cost about $500,000 but MIGHT only last 2 weeks, maybe a year, and certainly no more than 3 years. LOL - he had no chance even buying the first set!! Even $2 per liter for diesel fuel is way cheaper than that! And often a SIMPLE consideration (as Mike M2 mentioned) is the recharging. Normally maximum recharging time will be much longer than the discharge time. EG, recharging a 100AH battery (rated as 5 Amps for 20 hours) at 20 Amps for 5 hours requires 10A for over 10 hours. This could be reduced to a bit over 4 hours at 25A using quick-charging, but that is usually not good for the battery. Besides, an 8A charger may cost a bit, but a 25A charge is quite expensive. And HOW will you recharge? If you are remote, will you run your vehicle for 4 hours, or 10 hours just to recharge?     Therein the logic of it - NO! You run your vehicle INSTEAD of using the batteries (unless you normally drive 4-10 hours between drains). IE - engines/generators are a supplier of power - NOT batteries. (Batteries merely store. They are good for low power demands.) Note that the above calcs are in principle only. real figures will be worse due do inefficiencies, and that 100AH at C20 (20-hour rate) will not be 100AH at a 5 (C5) hour rate. Not for lead acids anyhow; for LiPo, yes.) As to UPS versus RUPS.... (Rotary UPS - a must for any building that requires big UPS!)