| Author |
Message |
Matt (Hgtech)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 1:12 am: | |
Just curious - what do you guys with 8v71's use for starting batteries? My bus originally came with two 8D's. Is it really necessary to have two - or will one work fine? How about going with something other than 8D's?
Matt
1979 Silver Eagle Model 05 |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 5:34 am: | |
A long Long discussion of what you loose with tiny replavcement setups is in the ARCHIVES.
FAST FRED |
Nick Morris (Nick3751)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 8:33 am: | |
Just for convinance sake I'll tell you here Mat. My experince with a 671, which I realize isn't the same animal at all, is that one 8D will start her fine when the world is perfect (above about 55 and I don't need to get anywhere right now) but if it cools off a little or I'm in a hurry or it's raining or...... then having the extra juice insures that she'll turn over. |
Bill Gerrie
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 9:33 am: | |
Matt
One of the newer type of 8D's with 1500 CCA will start an 8V71 as long as you don't go where the temp drops much below freezeing. One way of getting around only using one 8D in colder weather is to have a boost switch where you can join your house batteries to the 8D just in case it isn't enough. This will give the starter the little extra power it needs to get you going. The boost switch must have ample capacity. Hope this helps. Bill |
Matt (Hgtech)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 10:29 am: | |
Thanks for the input. I've got two new 8D's right now. "Most" of the time the bus starts better off one battery than two. I had the batteries tested by the company I bought them from and they both performed excellently. I've got brand new battery cables, new switches, and new feeds / grounds on the starter. There's obviously something going on I've missed. |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 11:00 am: | |
snip I had the batteries tested by the company I bought them from and they both performed excellently. snip
Do you mean that the bus starts better with either battery or one particular battery?
As frequently comes up in answers, check the ground circuit. My experience dictates taking the battery ground directly to the starter ground terminal and then to chassis instead of having the chassis in the middle of the ground circuit. |
Phil Smith
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 11:05 am: | |
I use two group 31's and the 8v-71 starts fine if the temps above 45 or so. If it's colder, I plug in the block heater.
I've thought about going back to 4-group 31's, but will have to rearrange the battery box a little. At this point, it's not an issue for me.
Phil in Az ( 80-RTS- 8v-71N, N60's,4:10's,blah,blah,blah). |
David Dulmage (Daved)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 11:26 am: | |
I haven't found the 8D's to be all that expensive. They work well for me. For those who mention starting on one 8D, I gather these must be for GM's with a 12V system, as 24V systems such as in an MCI need the two batteries to be in series. I recently started my bus to move it when the temperature was just around freezing without any cranking difficulty. However for the sake of the engine and the starter I probably should have plugged in the block heater for a couple of hours first. The bus has been sitting for the winter and I had to make a number of attempts before it would fire up, although it turned over well.
DaveD
(MC-8) |
Matt (Hgtech)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 3:12 pm: | |
Stan,
I'll check and see if there is a difference between the batteries (can't remember which one I usually use). I may relocate the grounds as you suggest as I just sounds like a smart thing to do (even if it doesn't fix the problem).
Matt
1979 Silver Eagle Model 05 |
Nick Morris (Nick3751)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 3:25 pm: | |
Matt check all the grounding points from the block to the chasis. The only place your starter will be grounded is to the block so if your block isn't grounded you've got trouble often time intermiten trouble. If in doubt got to the parts store and get the widest braded ground strap you can get and use it. |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 8:24 pm: | |
Nick; A DD starter does not ground to the block. It has an insulated ground bolt on the end of the starter body. |
Nick Morris (Nick3751)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 9:04 pm: | |
Mine does. |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 02, 2006 - 10:09 pm: | |
Mine also, Nick. The manual indicates it as well.
(he made me go look) |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 03, 2006 - 8:36 am: | |
Technically, the block should have a ground cable to the cradle and the cradle should have a ground cable to the chassis and the chassis should have a ground cable to the battery.
BUT if there is no ground cable to the ground terminal on the end of the starter it will not work! It does not have an internal ground like a car starter.
Like any low voltage circuit, the fewer number of connecting points the better for high current loads. Since the starter is your highest current draw on the bus (not house) keep the number of connections to a minimum. |
Jarlaxle
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 03, 2006 - 7:02 pm: | |
2 healthy 900+CCA Group 31's should light off a healthy Detroit easily. If the engine has bad compression, you may need more capacity (or a shot of ether, or both), but 2 good 31's will start an 8V71 in sub-freezing weather. Many semi tractors had that exact setup: an 8V71 engine, with two group 31 batteries. |
JR
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 03, 2006 - 8:38 pm: | |
The 8Ds and 50DN alternators are usually found on buses with huge AC systems...most buses? The big batts ballast the AC when engine's idling.
Trucks with identical engines don't use huge alternators or batteries. If you lose the bus AC, you can move the battery bank (2 gp 31s) to the AC compressor mount and save a lot of potential wiring resistance. Ideally, the original battery wiring should be retained for paralelling the starter with house batt (assuming same volt). Then the original batt box could house the house batteries...it's already wired, vented, etc. And if 24/12 system is used, an equalizer will solve the imbalance issue, allow 24V inverter and one alternator.
Just be sure you can disconnect the engine cranking batteries from the system. They will defeat the master switch, and if you have bay lights or anything is left on...dead cranking batteries. Another idea is to be sure that any additional isolating switches or solenoids are matched to the potential cranking amp load.
JR |
Stephen Fessenden (Sffess)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 04, 2006 - 12:42 am: | |
You can start an 8V71 on even smaller batteries. I have been using two Optima 875 CCA batteries from Sams Club in series for my bus since August. Starts in freezing weather too. I would rather have the big storage capacity for the house batteries. |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 04, 2006 - 6:16 am: | |
"The 8Ds and 50DN alternators are usually found on buses with huge AC systems...most buses? The big batts ballast the AC when engine's idling.
Every Air Cond system I have seen in a coach is engine drive. There is NO ballast required .
Thye usual setup will have some large blowers (GM is 80A each at 12V) that do use electric , but this is easily provided at fast idle , with or without any batteries (except for alt excitation).
FAST FRED |