amperage for starting

84dime · November 30, 2009, 10:38:00 PM

Ok guy need to buy starting batteries. What amperage do i need to get that engine started? 600?

luvrbus · December 01, 2009, 04:10:42 AM

84, you need 950 to 1250 cc and a good reserve for a Detroit the more the better saves your starter for instance 3 group 31 batteries for a 12 volt system 4 group 31's for a 24 volt or my favorite 2 8D for either system.
Deep cyle batteries are not good for starting but some do use them

good luck

Dreamscape · December 01, 2009, 04:30:44 AM

Clifford is again right on. I have two group 31's now, after yesterday I'm going down to buy another one to add to the mix. In cooler weather two is not enough cranking power to spin it fast enough for the proper speed for firring. 8V71N

Paul

rv_safetyman · December 01, 2009, 07:45:34 AM

Agree fully with Clifford as usual!

One strong rule of thumb that seems to be universal: replace all batteries at the same time. Folks do get away with putting a new battery in with old batteries, but the "experts" suggest the new battery will not be happy.

Jim

84dime · December 01, 2009, 07:53:26 AM

Now what if i rarly start my bus at all. I mabe start it once a month. Also the deep cycles dont like the jolt of the starter so the more deep cycles i have the easier it is on each? Say if i had 8 T105s and only started once a month could i get away with that?

TomC · December 01, 2009, 08:15:00 AM

I have two 950cca Interstate 31's for starting. If I'm in cold, or want more cranking time, I can just throw the jumper solenoid from the dash and tap into the two 8D Lifeline AGM batteries. Have started the bus on the 8D's when the starting batteries have gone dead. Why carry the extra battery when you only need occasionally? Good Luck, TomC

Len Silva · December 01, 2009, 08:19:51 AM

Quote from: 84dime on December 01, 2009, 07:53:26 AM
Now what if i rarly start my bus at all. I mabe start it once a month. Also the deep cycles dont like the jolt of the starter so the more deep cycles i have the easier it is on each? Say if i had 8 T105s and only started once a month could i get away with that?

I don't know the numbers but I would guess that stomping the pedal on a loaded golf cart would be fairly close to the starting current of your engine. I don't think you are going to hurt them with that occasional use.

84dime · December 01, 2009, 08:22:07 AM

And thats what im trying to figure out. If i only use them once in awhile and it takes 6 months off the life of the battery then thats fine. So how much life do you think the batteries will be reduced by given only starting it once a month mabe twice if shes lucky.

Len Silva · December 01, 2009, 08:48:49 AM

I don't know, but I'd bet it's less than the cost of a set of start batteries that may well be shot by the time you are on the road.

BTW, it is generally recommended NOT to start the engine once a month if you are not going to drive it and get it thoroughly warmed up (50 miles or more). Better to just let it sit for a year or so.

84dime · December 01, 2009, 09:21:46 AM

So if i were going to put in start batteries all i would need to do is put the starter on that circuit? Anything else need to go on that circuit?

bevans6 · December 01, 2009, 11:02:47 AM

As a rule the start battery circuits include everything related to the bus side of the equation. The starter, all of the on-the-road control circuits, wipers (if they are electrical), head lights, tail-running-brake-turn signal lights, dash radio, heater fans, defroster fans, bus AC if you still retain it. Everything related to the bus as a transportation vehicle. The house batteries run everything related to the RV side of the equation. You can merge the two, but there are good reasons for keeping them separate (mostly redundancy).

From what I have read and from talking to my battery supplier, you don't really harm 'golf cart' batteries by using them as start batteries so much as they just aren't very good at it and don't do it very well. Since they aren't physically optimized for releasing such a large current rush, they don't release much and act like a much smaller start battery, than their overall capacity would imply. Also, they like to be charged slower than a start battery, so when the alternator kicks in with a big rush of current immediately after a start, you might be charging them too fast.

In your case I might get a set of 8D's used or maybe refurbished, keep them on a shelf with a Battery Tender trickle charger, and only install them when you need them. When you get up and running, then invest in a new set of batteries.

Brian

Brian